Update README.md

Change-Id: I2c7ceb113bae25e02f6fb7e9df02c6193eccd920

README.md

@@ -1,8 +1,8 @@
 # HugeGraph
 
 [![License](https://img.shields.io/badge/license-Apache%202-0E78BA.svg)](https://www.apache.org/licenses/LICENSE-2.0.html)
-[![Build Status](https://travis-ci.org/hugegraph/hugegraph.svg?branch=master)](https://travis-ci.org/hugegraph/hugegraph)
-[![codecov](https://codecov.io/gh/hugegraph/hugegraph/branch/master/graph/badge.svg)](https://codecov.io/gh/hugegraph/hugegraph)
+[![Build Status](https://travis-ci.org/hugegraph/hugegraph.svg?branch=release-0.11)](https://travis-ci.org/hugegraph/hugegraph)
+[![codecov](https://codecov.io/gh/hugegraph/hugegraph/branch/release-0.11/graph/badge.svg)](https://codecov.io/gh/hugegraph/hugegraph)
 
 HugeGraph is a fast-speed and highly-scalable [graph database](https://en.wikipedia.org/wiki/Graph_database). Billions of vertices and edges can be easily stored into and queried from HugeGraph due to its excellent OLTP ability. As compliance to [Apache TinkerPop 3](https://tinkerpop.apache.org/) framework, various complicated graph queries can be accomplished through [Gremlin](https://tinkerpop.apache.org/gremlin.html)(a powerful graph traversal language).
 

hugegraph-api/src/main/java/com/baidu/hugegraph/api/auth/AccessAPI.java

@@ -149,6 +149,8 @@ public class AccessAPI extends API {
                        @PathParam("id") String id) {
         LOG.debug("Graph [{}] delete access: {}", graph, id);
 
+        @SuppressWarnings("unused") // just check if the graph exists
+        HugeGraph g = graph(manager, graph);
         try {
             manager.userManager().deleteAccess(UserAPI.parseId(id));
         } catch (NotFoundException e) {

hugegraph-api/src/main/java/com/baidu/hugegraph/api/auth/BelongAPI.java

@@ -148,6 +148,8 @@ public class BelongAPI extends API {
                        @PathParam("id") String id) {
         LOG.debug("Graph [{}] delete belong: {}", graph, id);
 
+        @SuppressWarnings("unused") // just check if the graph exists
+        HugeGraph g = graph(manager, graph);
         try {
             manager.userManager().deleteBelong(UserAPI.parseId(id));
         } catch (NotFoundException e) {

hugegraph-api/src/main/java/com/baidu/hugegraph/api/auth/GroupAPI.java

@@ -134,6 +134,8 @@ public class GroupAPI extends API {
                        @PathParam("id") String id) {
         LOG.debug("Graph [{}] delete group: {}", graph, id);
 
+        @SuppressWarnings("unused") // just check if the graph exists
+        HugeGraph g = graph(manager, graph);
         try {
             manager.userManager().deleteGroup(IdGenerator.of(id));
         } catch (NotFoundException e) {

hugegraph-api/src/main/java/com/baidu/hugegraph/api/auth/TargetAPI.java

@@ -134,6 +134,9 @@ public class TargetAPI extends API {
                        @PathParam("graph") String graph,
                        @PathParam("id") String id) {
         LOG.debug("Graph [{}] delete target: {}", graph, id);
+
+        @SuppressWarnings("unused") // just check if the graph exists
+        HugeGraph g = graph(manager, graph);
         try {
             manager.userManager().deleteTarget(UserAPI.parseId(id));
         } catch (NotFoundException e) {

hugegraph-api/src/main/java/com/baidu/hugegraph/api/auth/UserAPI.java

@@ -136,6 +136,8 @@ public class UserAPI extends API {
                        @PathParam("id") String id) {
         LOG.debug("Graph [{}] get user role: {}", graph, id);
 
+        @SuppressWarnings("unused") // just check if the graph exists
+        HugeGraph g = graph(manager, graph);
         HugeUser user = manager.userManager().getUser(IdGenerator.of(id));
         return manager.userManager().rolePermission(user).toJson();
     }
@@ -149,6 +151,8 @@ public class UserAPI extends API {
                        @PathParam("id") String id) {
         LOG.debug("Graph [{}] delete user: {}", graph, id);
 
+        @SuppressWarnings("unused") // just check if the graph exists
+        HugeGraph g = graph(manager, graph);
         try {
             manager.userManager().deleteUser(IdGenerator.of(id));
         } catch (NotFoundException e) {

hugegraph-api/src/main/java/com/baidu/hugegraph/api/graph/BatchAPI.java

@@ -148,7 +148,7 @@ public class BatchAPI extends API {
             } else if (oldElement.property(key).isPresent() &&
                        newElement.properties.get(key) == null) {
                 // If new property is null & old is present, use old property
-                newElement.properties.put(key, oldElement.property(key).value());
+                newElement.properties.put(key, oldElement.value(key));
             }
         }
     }

hugegraph-api/src/main/java/com/baidu/hugegraph/api/graph/EdgeAPI.java

@@ -233,15 +233,15 @@ public class EdgeAPI extends BatchAPI {
 
         if (jsonEdge.id != null) {
             E.checkArgument(id.equals(jsonEdge.id),
-                            "The ids are different between url('%s') and " +
-                            "request body('%s')", id, jsonEdge.id);
+                            "The ids are different between url and " +
+                            "request body ('%s' != '%s')", id, jsonEdge.id);
         }
 
         // Parse action param
         boolean append = checkAndParseAction(action);
 
         HugeGraph g = graph(manager, graph);
-        HugeEdge edge = (HugeEdge) g.edges(id).next();
+        HugeEdge edge = (HugeEdge) g.edge(id);
         EdgeLabel edgeLabel = edge.schemaLabel();
 
         for (String key : jsonEdge.properties.keySet()) {
@@ -458,8 +458,11 @@ public class EdgeAPI extends BatchAPI {
                                    HugeVertex.getIdValue(newEdge.target));
         if (newEdge.id != null) {
             E.checkArgument(edgeId.equals(newEdge.id),
-                            "The sort key values either be null " +
-                            "or equal to origin when specified edge id");
+                            "The ids are different between server and " +
+                            "request body ('%s' != '%s'). And note the sort " +
+                            "key values should either be null or equal to " +
+                            "the origin value when specified edge id",
+                            edgeId, newEdge.id);
         }
         return edgeId;
     }

hugegraph-api/src/main/java/com/baidu/hugegraph/api/graph/VertexAPI.java

@@ -201,7 +201,7 @@ public class VertexAPI extends BatchAPI {
         boolean append = checkAndParseAction(action);
 
         HugeGraph g = graph(manager, graph);
-        HugeVertex vertex = (HugeVertex) g.vertices(id).next();
+        HugeVertex vertex = (HugeVertex) g.vertex(id);
         VertexLabel vertexLabel = vertex.schemaLabel();
 
         for (String key : jsonVertex.properties.keySet()) {

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/AllShortestPathsAPI.java

@@ -22,7 +22,7 @@ package com.baidu.hugegraph.api.traversers;
 import java.util.List;
 
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_CAPACITY;
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 
 import javax.inject.Singleton;
 import javax.ws.rs.DefaultValue;
@@ -66,7 +66,7 @@ public class AllShortestPathsAPI extends API {
                       @QueryParam("label") String edgeLabel,
                       @QueryParam("max_depth") int depth,
                       @QueryParam("max_degree")
-                      @DefaultValue(DEFAULT_DEGREE) long degree,
+                      @DefaultValue(DEFAULT_MAX_DEGREE) long maxDegree,
                       @QueryParam("skip_degree")
                       @DefaultValue("0") long skipDegree,
                       @QueryParam("capacity")
@@ -75,7 +75,7 @@ public class AllShortestPathsAPI extends API {
                   "direction {}, edge label {}, max depth '{}', " +
                   "max degree '{}', skipped degree '{}' and capacity '{}'",
                   graph, source, target, direction, edgeLabel, depth,
-                  degree, skipDegree, capacity);
+                  maxDegree, skipDegree, capacity);
 
         Id sourceId = VertexAPI.checkAndParseVertexId(source);
         Id targetId = VertexAPI.checkAndParseVertexId(target);
@@ -88,7 +88,7 @@ public class AllShortestPathsAPI extends API {
                                   ImmutableList.of(edgeLabel);
         HugeTraverser.PathSet paths = traverser.allShortestPaths(
                                       sourceId, targetId, dir, edgeLabels,
-                                      depth, degree, skipDegree, capacity);
+                                      depth, maxDegree, skipDegree, capacity);
         return manager.serializer(g).writePaths("paths", paths, false);
     }
 }

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/CountAPI.java

@@ -19,7 +19,7 @@
 
 package com.baidu.hugegraph.api.traversers;
 
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_SKIP_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.NO_LIMIT;
 
@@ -48,6 +48,7 @@ import com.baidu.hugegraph.type.define.Directions;
 import com.baidu.hugegraph.util.E;
 import com.baidu.hugegraph.util.Log;
 import com.codahale.metrics.annotation.Timed;
+import com.fasterxml.jackson.annotation.JsonAlias;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.google.common.collect.ImmutableMap;
 
@@ -74,7 +75,8 @@ public class CountAPI extends API {
                                "The steps of request can't be null or empty");
         E.checkArgumentNotNull(request.dedupSize == NO_LIMIT ||
                                request.dedupSize >= 0L,
-                               "The dedupSize of request must >= 0, but got '%s'",
+                               "The dedup size of request " +
+                               "must >= 0 or == -1, but got: '%s'",
                                request.dedupSize);
 
         HugeGraph g = graph(manager, graph);
@@ -109,7 +111,7 @@ public class CountAPI extends API {
         @Override
         public String toString() {
             return String.format("CountRequest{source=%s,steps=%s," +
-                                 "contains_traversed=%s,dedupSize=%s}",
+                                 "containsTraversed=%s,dedupSize=%s}",
                                  this.source, this.steps,
                                  this.containsTraversed, this.dedupSize);
         }
@@ -123,22 +125,24 @@ public class CountAPI extends API {
         public List<String> labels;
         @JsonProperty("properties")
         public Map<String, Object> properties;
-        @JsonProperty("degree")
-        public long degree = Long.valueOf(DEFAULT_DEGREE);
+        @JsonAlias("degree")
+        @JsonProperty("max_degree")
+        public long maxDegree = Long.parseLong(DEFAULT_MAX_DEGREE);
         @JsonProperty("skip_degree")
-        public long skipDegree = Long.valueOf(DEFAULT_SKIP_DEGREE);
+        public long skipDegree = Long.parseLong(DEFAULT_SKIP_DEGREE);
 
         @Override
         public String toString() {
             return String.format("Step{direction=%s,labels=%s,properties=%s" +
-                                 "degree=%s,skipDegree=%s}",
+                                 "maxDegree=%s,skipDegree=%s}",
                                  this.direction, this.labels, this.properties,
-                                 this.degree, this.skipDegree);
+                                 this.maxDegree, this.skipDegree);
         }
 
         private EdgeStep jsonToStep(HugeGraph graph) {
             return new EdgeStep(graph, this.direction, this.labels,
-                                this.properties, this.degree, this.skipDegree);
+                                this.properties, this.maxDegree,
+                                this.skipDegree);
         }
     }
 }

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/CrosspointsAPI.java

@@ -20,7 +20,7 @@
 package com.baidu.hugegraph.api.traversers;
 
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_CAPACITY;
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_PATHS_LIMIT;
 
 import javax.inject.Singleton;
@@ -64,7 +64,7 @@ public class CrosspointsAPI extends API {
                       @QueryParam("label") String edgeLabel,
                       @QueryParam("max_depth") int depth,
                       @QueryParam("max_degree")
-                      @DefaultValue(DEFAULT_DEGREE) long degree,
+                      @DefaultValue(DEFAULT_MAX_DEGREE) long maxDegree,
                       @QueryParam("capacity")
                       @DefaultValue(DEFAULT_CAPACITY) long capacity,
                       @QueryParam("limit")
@@ -73,7 +73,7 @@ public class CrosspointsAPI extends API {
                   "with direction '{}', edge label '{}', max depth '{}', " +
                   "max degree '{}', capacity '{}' and limit '{}'",
                   graph, source, target, direction, edgeLabel,
-                  depth, degree, capacity, limit);
+                  depth, maxDegree, capacity, limit);
 
         Id sourceId = VertexAPI.checkAndParseVertexId(source);
         Id targetId = VertexAPI.checkAndParseVertexId(target);
@@ -83,7 +83,7 @@ public class CrosspointsAPI extends API {
         PathsTraverser traverser = new PathsTraverser(g);
         HugeTraverser.PathSet paths = traverser.paths(sourceId, dir, targetId,
                                                       dir, edgeLabel, depth,
-                                                      degree, capacity, limit);
+                                                      maxDegree, capacity, limit);
         return manager.serializer(g).writePaths("crosspoints", paths, true);
     }
 }

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/CustomizedCrosspointsAPI.java

@@ -20,7 +20,7 @@
 package com.baidu.hugegraph.api.traversers;
 
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_CAPACITY;
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_PATHS_LIMIT;
 
 import java.util.ArrayList;
@@ -53,6 +53,7 @@ import com.baidu.hugegraph.type.define.Directions;
 import com.baidu.hugegraph.util.E;
 import com.baidu.hugegraph.util.Log;
 import com.codahale.metrics.annotation.Timed;
+import com.fasterxml.jackson.annotation.JsonAlias;
 import com.fasterxml.jackson.annotation.JsonProperty;
 
 @Path("graphs/{graph}/traversers/customizedcrosspoints")
@@ -136,9 +137,9 @@ public class CustomizedCrosspointsAPI extends API {
         @JsonProperty("path_patterns")
         public List<PathPattern> pathPatterns;
         @JsonProperty("capacity")
-        public long capacity = Long.valueOf(DEFAULT_CAPACITY);
+        public long capacity = Long.parseLong(DEFAULT_CAPACITY);
         @JsonProperty("limit")
-        public long limit = Long.valueOf(DEFAULT_PATHS_LIMIT);
+        public long limit = Long.parseLong(DEFAULT_PATHS_LIMIT);
         @JsonProperty("with_path")
         public boolean withPath = false;
         @JsonProperty("with_vertex")
@@ -173,24 +174,25 @@ public class CustomizedCrosspointsAPI extends API {
         public List<String> labels;
         @JsonProperty("properties")
         public Map<String, Object> properties;
-        @JsonProperty("degree")
-        public long degree = Long.valueOf(DEFAULT_DEGREE);
+        @JsonAlias("degree")
+        @JsonProperty("max_degree")
+        public long maxDegree = Long.parseLong(DEFAULT_MAX_DEGREE);
         @JsonProperty("skip_degree")
         public long skipDegree = 0L;
 
         @Override
         public String toString() {
             return String.format("Step{direction=%s,labels=%s,properties=%s," +
-                                 "degree=%s,skipDegree=%s}",
+                                 "maxDegree=%s,skipDegree=%s}",
                                  this.direction, this.labels, this.properties,
-                                 this.degree, this.skipDegree);
+                                 this.maxDegree, this.skipDegree);
         }
 
         private CustomizedCrosspointsTraverser.Step jsonToStep(HugeGraph g) {
             return new CustomizedCrosspointsTraverser.Step(g, this.direction,
                                                            this.labels,
                                                            this.properties,
-                                                           this.degree,
+                                                           this.maxDegree,
                                                            this.skipDegree);
         }
     }

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/CustomizedPathsAPI.java

@@ -20,7 +20,7 @@
 package com.baidu.hugegraph.api.traversers;
 
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_CAPACITY;
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_PATHS_LIMIT;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_SAMPLE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_WEIGHT;
@@ -56,6 +56,7 @@ import com.baidu.hugegraph.type.define.Directions;
 import com.baidu.hugegraph.util.E;
 import com.baidu.hugegraph.util.Log;
 import com.codahale.metrics.annotation.Timed;
+import com.fasterxml.jackson.annotation.JsonAlias;
 import com.fasterxml.jackson.annotation.JsonProperty;
 
 @Path("graphs/{graph}/traversers/customizedpaths")
@@ -136,9 +137,9 @@ public class CustomizedPathsAPI extends API {
         @JsonProperty("sort_by")
         public SortBy sortBy;
         @JsonProperty("capacity")
-        public long capacity = Long.valueOf(DEFAULT_CAPACITY);
+        public long capacity = Long.parseLong(DEFAULT_CAPACITY);
         @JsonProperty("limit")
-        public long limit = Long.valueOf(DEFAULT_PATHS_LIMIT);
+        public long limit = Long.parseLong(DEFAULT_PATHS_LIMIT);
         @JsonProperty("with_vertex")
         public boolean withVertex = false;
 
@@ -160,31 +161,32 @@ public class CustomizedPathsAPI extends API {
         public List<String> labels;
         @JsonProperty("properties")
         public Map<String, Object> properties;
-        @JsonProperty("degree")
-        public long degree = Long.valueOf(DEFAULT_DEGREE);
+        @JsonAlias("degree")
+        @JsonProperty("max_degree")
+        public long maxDegree = Long.parseLong(DEFAULT_MAX_DEGREE);
         @JsonProperty("skip_degree")
         public long skipDegree = 0L;
         @JsonProperty("weight_by")
         public String weightBy;
         @JsonProperty("default_weight")
-        public double defaultWeight = Double.valueOf(DEFAULT_WEIGHT);
+        public double defaultWeight = Double.parseDouble(DEFAULT_WEIGHT);
         @JsonProperty("sample")
-        public long sample = Long.valueOf(DEFAULT_SAMPLE);
+        public long sample = Long.parseLong(DEFAULT_SAMPLE);
 
         @Override
         public String toString() {
             return String.format("Step{direction=%s,labels=%s,properties=%s," +
-                                 "degree=%s,skipDegree=%s," +
+                                 "maxDegree=%s,skipDegree=%s," +
                                  "weightBy=%s,defaultWeight=%s,sample=%s}",
                                  this.direction, this.labels, this.properties,
-                                 this.degree, this.skipDegree,
+                                 this.maxDegree, this.skipDegree,
                                  this.weightBy, this.defaultWeight,
                                  this.sample);
         }
 
         private WeightedEdgeStep jsonToStep(HugeGraph g) {
             return new WeightedEdgeStep(g, this.direction, this.labels,
-                                        this.properties, this.degree,
+                                        this.properties, this.maxDegree,
                                         this.skipDegree, this.weightBy,
                                         this.defaultWeight, this.sample);
         }

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/FusiformSimilarityAPI.java

@@ -20,7 +20,7 @@
 package com.baidu.hugegraph.api.traversers;
 
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_CAPACITY;
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_PATHS_LIMIT;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.NO_LIMIT;
 
@@ -76,9 +76,9 @@ public class FusiformSimilarityAPI extends API {
         E.checkArgument(request.minNeighbors > 0,
                         "The min neighbor count must be > 0, but got: %s",
                         request.minNeighbors);
-        E.checkArgument(request.degree > 0 || request.degree == NO_LIMIT,
-                        "The degree of request must be > 0, but got: %s",
-                        request.degree);
+        E.checkArgument(request.maxDegree > 0L || request.maxDegree == NO_LIMIT,
+                        "The max degree of request must be > 0 or == -1, " +
+                        "but got: %s", request.maxDegree);
         E.checkArgument(request.alpha > 0 && request.alpha <= 1.0,
                         "The alpha of request must be in range (0, 1], " +
                         "but got '%s'", request.alpha);
@@ -108,13 +108,13 @@ public class FusiformSimilarityAPI extends API {
                              request.minNeighbors, request.alpha,
                              request.minSimilars, request.top,
                              request.groupProperty, request.minGroups,
-                             request.degree, request.capacity, request.limit,
-                             request.withIntermediary);
+                             request.maxDegree, request.capacity,
+                             request.limit, request.withIntermediary);
 
         CloseableIterator.closeIterator(sources);
 
         Iterator<Vertex> iterator = QueryResults.emptyIterator();
-        if (request.withVertex) {
+        if (request.withVertex && !result.isEmpty()) {
             iterator = g.vertices(result.vertices().toArray());
         }
         return manager.serializer(g).writeSimilars(result, iterator);
@@ -141,11 +141,11 @@ public class FusiformSimilarityAPI extends API {
         @JsonProperty("min_groups")
         public int minGroups;
         @JsonProperty("max_degree")
-        public long degree = Long.valueOf(DEFAULT_DEGREE);
+        public long maxDegree = Long.parseLong(DEFAULT_MAX_DEGREE);
         @JsonProperty("capacity")
-        public long capacity = Long.valueOf(DEFAULT_CAPACITY);
+        public long capacity = Long.parseLong(DEFAULT_CAPACITY);
         @JsonProperty("limit")
-        public long limit = Long.valueOf(DEFAULT_PATHS_LIMIT);
+        public long limit = Long.parseLong(DEFAULT_PATHS_LIMIT);
         @JsonProperty("with_intermediary")
         public boolean withIntermediary = false;
         @JsonProperty("with_vertex")
@@ -157,13 +157,13 @@ public class FusiformSimilarityAPI extends API {
                                  "label=%s,direction=%s,minNeighbors=%s," +
                                  "alpha=%s,minSimilars=%s,top=%s," +
                                  "groupProperty=%s,minGroups=%s," +
-                                 "degree=%s,capacity=%s,limit=%s," +
+                                 "maxDegree=%s,capacity=%s,limit=%s," +
                                  "withIntermediary=%s,withVertex=%s}",
                                  this.sources, this.label, this.direction,
                                  this.minNeighbors, this.alpha,
                                  this.minSimilars, this.top,
                                  this.groupProperty, this.minGroups,
-                                 this.degree, this.capacity, this.limit,
+                                 this.maxDegree, this.capacity, this.limit,
                                  this.withIntermediary, this.withVertex);
         }
     }

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/JaccardSimilarityAPI.java

@@ -20,7 +20,7 @@
 package com.baidu.hugegraph.api.traversers;
 
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_CAPACITY;
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_LIMIT;
 
 import java.util.Map;
@@ -71,10 +71,10 @@ public class JaccardSimilarityAPI extends TraverserAPI {
                       @QueryParam("direction") String direction,
                       @QueryParam("label") String edgeLabel,
                       @QueryParam("max_degree")
-                      @DefaultValue(DEFAULT_DEGREE) long degree) {
+                      @DefaultValue(DEFAULT_MAX_DEGREE) long maxDegree) {
         LOG.debug("Graph [{}] get jaccard similarity between '{}' and '{}' " +
                   "with direction {}, edge label {} and max degree '{}'",
-                  graph, vertex, other, direction, edgeLabel, degree);
+                  graph, vertex, other, direction, edgeLabel, maxDegree);
 
         Id sourceId = VertexAPI.checkAndParseVertexId(vertex);
         Id targetId = VertexAPI.checkAndParseVertexId(other);
@@ -84,8 +84,8 @@ public class JaccardSimilarityAPI extends TraverserAPI {
         double similarity;
         try (JaccardSimilarTraverser traverser =
                                      new JaccardSimilarTraverser(g)) {
-             similarity = traverser.jaccardSimilarity(sourceId, targetId,
-                                                      dir, edgeLabel, degree);
+             similarity = traverser.jaccardSimilarity(sourceId, targetId, dir,
+                                                      edgeLabel, maxDegree);
         }
         return JsonUtil.toJson(ImmutableMap.of("jaccard_similarity",
                                                similarity));
@@ -132,9 +132,9 @@ public class JaccardSimilarityAPI extends TraverserAPI {
         @JsonProperty("step")
         public TraverserAPI.Step step;
         @JsonProperty("top")
-        public int top = Integer.valueOf(DEFAULT_LIMIT);
+        public int top = Integer.parseInt(DEFAULT_LIMIT);
         @JsonProperty("capacity")
-        public long capacity = Long.valueOf(DEFAULT_CAPACITY);
+        public long capacity = Long.parseLong(DEFAULT_CAPACITY);
 
         @Override
         public String toString() {

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/KneighborAPI.java

@@ -19,9 +19,8 @@
 
 package com.baidu.hugegraph.api.traversers;
 
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_ELEMENTS_LIMIT;
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_PATHS_LIMIT;
 
 import java.util.ArrayList;
 import java.util.HashSet;
@@ -76,14 +75,14 @@ public class KneighborAPI extends TraverserAPI {
                       @QueryParam("label") String edgeLabel,
                       @QueryParam("max_depth") int depth,
                       @QueryParam("max_degree")
-                      @DefaultValue(DEFAULT_DEGREE) long degree,
+                      @DefaultValue(DEFAULT_MAX_DEGREE) long maxDegree,
                       @QueryParam("limit")
                       @DefaultValue(DEFAULT_ELEMENTS_LIMIT) long limit) {
         LOG.debug("Graph [{}] get k-neighbor from '{}' with " +
                   "direction '{}', edge label '{}', max depth '{}', " +
                   "max degree '{}' and limit '{}'",
                   graph, sourceV, direction, edgeLabel, depth,
-                  degree, limit);
+                  maxDegree, limit);
 
         Id source = VertexAPI.checkAndParseVertexId(sourceV);
         Directions dir = Directions.convert(EdgeAPI.parseDirection(direction));
@@ -93,7 +92,7 @@ public class KneighborAPI extends TraverserAPI {
         Set<Id> ids;
         try (KneighborTraverser traverser = new KneighborTraverser(g)) {
             ids = traverser.kneighbor(source, dir, edgeLabel,
-                                      depth, degree, limit);
+                                      depth, maxDegree, limit);
         }
         return manager.serializer(g).writeList("vertices", ids);
     }
@@ -171,7 +170,7 @@ public class KneighborAPI extends TraverserAPI {
         @JsonProperty("max_depth")
         public int maxDepth;
         @JsonProperty("limit")
-        public long limit = Long.valueOf(DEFAULT_PATHS_LIMIT);
+        public long limit = Long.parseLong(DEFAULT_ELEMENTS_LIMIT);
         @JsonProperty("count_only")
         public boolean countOnly = false;
         @JsonProperty("with_vertex")

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/KoutAPI.java

@@ -20,9 +20,8 @@
 package com.baidu.hugegraph.api.traversers;
 
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_CAPACITY;
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_ELEMENTS_LIMIT;
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_PATHS_LIMIT;
 
 import java.util.ArrayList;
 import java.util.HashSet;
@@ -80,7 +79,7 @@ public class KoutAPI extends TraverserAPI {
                       @QueryParam("nearest")
                       @DefaultValue("true")  boolean nearest,
                       @QueryParam("max_degree")
-                      @DefaultValue(DEFAULT_DEGREE) long degree,
+                      @DefaultValue(DEFAULT_MAX_DEGREE) long maxDegree,
                       @QueryParam("capacity")
                       @DefaultValue(DEFAULT_CAPACITY) long capacity,
                       @QueryParam("limit")
@@ -89,7 +88,7 @@ public class KoutAPI extends TraverserAPI {
                   "direction '{}', edge label '{}', max depth '{}', nearest " +
                   "'{}', max degree '{}', capacity '{}' and limit '{}'",
                   graph, source, direction, edgeLabel, depth, nearest,
-                  degree, capacity, limit);
+                  maxDegree, capacity, limit);
 
         Id sourceId = VertexAPI.checkAndParseVertexId(source);
         Directions dir = Directions.convert(EdgeAPI.parseDirection(direction));
@@ -99,7 +98,7 @@ public class KoutAPI extends TraverserAPI {
         Set<Id> ids;
         try (KoutTraverser traverser = new KoutTraverser(g)) {
             ids = traverser.kout(sourceId, dir, edgeLabel, depth,
-                                 nearest, degree, capacity, limit);
+                                 nearest, maxDegree, capacity, limit);
         }
         return manager.serializer(g).writeList("vertices", ids);
     }
@@ -185,9 +184,9 @@ public class KoutAPI extends TraverserAPI {
         @JsonProperty("count_only")
         public boolean countOnly = false;
         @JsonProperty("capacity")
-        public long capacity = Long.valueOf(DEFAULT_CAPACITY);
+        public long capacity = Long.parseLong(DEFAULT_CAPACITY);
         @JsonProperty("limit")
-        public long limit = Long.valueOf(DEFAULT_PATHS_LIMIT);
+        public long limit = Long.parseLong(DEFAULT_ELEMENTS_LIMIT);
         @JsonProperty("with_vertex")
         public boolean withVertex = false;
         @JsonProperty("with_path")

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/MultiNodeShortestPathAPI.java

@@ -112,7 +112,7 @@ public class MultiNodeShortestPathAPI extends TraverserAPI {
         @JsonProperty("max_depth")
         public int maxDepth;
         @JsonProperty("capacity")
-        public long capacity = Long.valueOf(DEFAULT_CAPACITY);
+        public long capacity = Long.parseLong(DEFAULT_CAPACITY);
         @JsonProperty("with_vertex")
         public boolean withVertex = false;
 

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/NeighborRankAPI.java

@@ -20,7 +20,7 @@
 package com.baidu.hugegraph.api.traversers;
 
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_CAPACITY;
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEPTH;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_PATHS_LIMIT;
 
@@ -48,6 +48,7 @@ import com.baidu.hugegraph.type.define.Directions;
 import com.baidu.hugegraph.util.E;
 import com.baidu.hugegraph.util.Log;
 import com.codahale.metrics.annotation.Timed;
+import com.fasterxml.jackson.annotation.JsonAlias;
 import com.fasterxml.jackson.annotation.JsonProperty;
 
 @Path("graphs/{graph}/traversers/neighborrank")
@@ -123,8 +124,9 @@ public class NeighborRankAPI extends API {
         public Directions direction;
         @JsonProperty("labels")
         public List<String> labels;
-        @JsonProperty("degree")
-        public long degree = Long.parseLong(DEFAULT_DEGREE);
+        @JsonAlias("degree")
+        @JsonProperty("max_degree")
+        public long maxDegree = Long.parseLong(DEFAULT_MAX_DEGREE);
         @JsonProperty("skip_degree")
         public long skipDegree = 0L;
         @JsonProperty("top")
@@ -134,15 +136,15 @@ public class NeighborRankAPI extends API {
 
         @Override
         public String toString() {
-            return String.format("Step{direction=%s,labels=%s,degree=%s," +
+            return String.format("Step{direction=%s,labels=%s,maxDegree=%s," +
                                  "top=%s}", this.direction, this.labels,
-                                 this.degree, this.top);
+                                 this.maxDegree, this.top);
         }
 
         private NeighborRankTraverser.Step jsonToStep(HugeGraph g) {
             return new NeighborRankTraverser.Step(g, this.direction,
                                                   this.labels,
-                                                  this.degree,
+                                                  this.maxDegree,
                                                   this.skipDegree,
                                                   this.top,
                                                   DEFAULT_CAPACITY_PER_LAYER);

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/PathsAPI.java

@@ -25,7 +25,7 @@ import java.util.Iterator;
 import java.util.Set;
 
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_CAPACITY;
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_PATHS_LIMIT;
 
 import javax.inject.Singleton;
@@ -76,7 +76,7 @@ public class PathsAPI extends TraverserAPI {
                       @QueryParam("label") String edgeLabel,
                       @QueryParam("max_depth") int depth,
                       @QueryParam("max_degree")
-                      @DefaultValue(DEFAULT_DEGREE) long degree,
+                      @DefaultValue(DEFAULT_MAX_DEGREE) long maxDegree,
                       @QueryParam("capacity")
                       @DefaultValue(DEFAULT_CAPACITY) long capacity,
                       @QueryParam("limit")
@@ -85,7 +85,7 @@ public class PathsAPI extends TraverserAPI {
                   "direction {}, edge label {}, max depth '{}', " +
                   "max degree '{}', capacity '{}' and limit '{}'",
                   graph, source, target, direction, edgeLabel, depth,
-                  degree, capacity, limit);
+                  maxDegree, capacity, limit);
 
         Id sourceId = VertexAPI.checkAndParseVertexId(source);
         Id targetId = VertexAPI.checkAndParseVertexId(target);
@@ -95,7 +95,7 @@ public class PathsAPI extends TraverserAPI {
         PathsTraverser traverser = new PathsTraverser(g);
         HugeTraverser.PathSet paths = traverser.paths(sourceId, dir, targetId,
                                                       dir.opposite(), edgeLabel,
-                                                      depth, degree, capacity,
+                                                      depth, maxDegree, capacity,
                                                       limit);
         return manager.serializer(g).writePaths("paths", paths, false);
     }
@@ -164,9 +164,9 @@ public class PathsAPI extends TraverserAPI {
         @JsonProperty("nearest")
         public boolean nearest = false;
         @JsonProperty("capacity")
-        public long capacity = Long.valueOf(DEFAULT_CAPACITY);
+        public long capacity = Long.parseLong(DEFAULT_CAPACITY);
         @JsonProperty("limit")
-        public long limit = Long.valueOf(DEFAULT_PATHS_LIMIT);
+        public long limit = Long.parseLong(DEFAULT_PATHS_LIMIT);
         @JsonProperty("with_vertex")
         public boolean withVertex = false;
 

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/PersonalRankAPI.java

@@ -43,7 +43,7 @@ import com.baidu.hugegraph.util.Log;
 import com.codahale.metrics.annotation.Timed;
 import com.fasterxml.jackson.annotation.JsonProperty;
 
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_LIMIT;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEPTH;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.NO_LIMIT;
@@ -68,29 +68,29 @@ public class PersonalRankAPI extends API {
         E.checkArgument(request.alpha > 0 && request.alpha <= 1.0,
                         "The alpha of rank request must be in range (0, 1], " +
                         "but got '%s'", request.alpha);
-        E.checkArgument(request.degree > 0 || request.degree == NO_LIMIT,
-                        "The degree of rank request must be > 0, but got: %s",
-                        request.degree);
-        E.checkArgument(request.limit > 0 || request.limit == NO_LIMIT,
-                        "The limit of rank request must be > 0, but got: %s",
-                        request.limit);
-        E.checkArgument(request.maxDepth > 0 &&
-                        request.maxDepth <= Long.valueOf(DEFAULT_MAX_DEPTH),
+        E.checkArgument(request.maxDegree > 0L || request.maxDegree == NO_LIMIT,
+                        "The max degree of rank request must be > 0 " +
+                        "or == -1, but got: %s", request.maxDegree);
+        E.checkArgument(request.limit > 0L || request.limit == NO_LIMIT,
+                        "The limit of rank request must be > 0 or == -1, " +
+                        "but got: %s", request.limit);
+        E.checkArgument(request.maxDepth > 0L &&
+                        request.maxDepth <= Long.parseLong(DEFAULT_MAX_DEPTH),
                         "The max depth of rank request must be " +
                         "in range (0, %s], but got '%s'",
                         DEFAULT_MAX_DEPTH, request.maxDepth);
 
         LOG.debug("Graph [{}] get personal rank from '{}' with " +
-                  "edge label '{}', alpha '{}', degree '{}', " +
+                  "edge label '{}', alpha '{}', maxDegree '{}', " +
                   "max depth '{}' and sorted '{}'",
                   graph, request.source, request.label, request.alpha,
-                  request.degree, request.maxDepth, request.sorted);
+                  request.maxDegree, request.maxDepth, request.sorted);
 
         Id sourceId = HugeVertex.getIdValue(request.source);
         HugeGraph g = graph(manager, graph);
 
         PersonalRankTraverser traverser;
-        traverser = new PersonalRankTraverser(g, request.alpha, request.degree,
+        traverser = new PersonalRankTraverser(g, request.alpha, request.maxDegree,
                                               request.maxDepth);
         Map<Id, Double> ranks = traverser.personalRank(sourceId, request.label,
                                                        request.withLabel);
@@ -106,10 +106,10 @@ public class PersonalRankAPI extends API {
         private String label;
         @JsonProperty("alpha")
         private double alpha;
-        @JsonProperty("degree")
-        private long degree = Long.valueOf(DEFAULT_DEGREE);
+        @JsonProperty("max_degree")
+        private long maxDegree = Long.parseLong(DEFAULT_MAX_DEGREE);
         @JsonProperty("limit")
-        private long limit = Long.valueOf(DEFAULT_LIMIT);
+        private long limit = Long.parseLong(DEFAULT_LIMIT);
         @JsonProperty("max_depth")
         private int maxDepth;
         @JsonProperty("with_label")
@@ -121,10 +121,10 @@ public class PersonalRankAPI extends API {
         @Override
         public String toString() {
             return String.format("RankRequest{source=%s,label=%s,alpha=%s," +
-                                 "degree=%s,limit=%s,maxDepth=%s," +
+                                 "maxDegree=%s,limit=%s,maxDepth=%s," +
                                  "withLabel=%s,sorted=%s}",
                                  this.source, this.label, this.alpha,
-                                 this.degree, this.limit, this.maxDepth,
+                                 this.maxDegree, this.limit, this.maxDepth,
                                  this.withLabel, this.sorted);
         }
     }

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/RaysAPI.java

@@ -20,7 +20,7 @@
 package com.baidu.hugegraph.api.traversers;
 
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_CAPACITY;
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_PATHS_LIMIT;
 
 import javax.inject.Singleton;
@@ -63,7 +63,7 @@ public class RaysAPI extends API {
                       @QueryParam("label") String edgeLabel,
                       @QueryParam("max_depth") int depth,
                       @QueryParam("max_degree")
-                      @DefaultValue(DEFAULT_DEGREE) long degree,
+                      @DefaultValue(DEFAULT_MAX_DEGREE) long maxDegree,
                       @QueryParam("capacity")
                       @DefaultValue(DEFAULT_CAPACITY) long capacity,
                       @QueryParam("limit")
@@ -71,7 +71,7 @@ public class RaysAPI extends API {
         LOG.debug("Graph [{}] get rays paths from '{}' with " +
                   "direction '{}', edge label '{}', max depth '{}', " +
                   "max degree '{}', capacity '{}' and limit '{}'",
-                  graph, sourceV, direction, edgeLabel, depth, degree,
+                  graph, sourceV, direction, edgeLabel, depth, maxDegree,
                   capacity, limit);
 
         Id source = VertexAPI.checkAndParseVertexId(sourceV);
@@ -81,7 +81,7 @@ public class RaysAPI extends API {
 
         SubGraphTraverser traverser = new SubGraphTraverser(g);
         HugeTraverser.PathSet paths = traverser.rays(source, dir, edgeLabel,
-                                                     depth, degree,
+                                                     depth, maxDegree,
                                                      capacity, limit);
         return manager.serializer(g).writePaths("rays", paths, false);
     }

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/RingsAPI.java

@@ -20,7 +20,7 @@
 package com.baidu.hugegraph.api.traversers;
 
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_CAPACITY;
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_PATHS_LIMIT;
 
 import javax.inject.Singleton;
@@ -65,7 +65,7 @@ public class RingsAPI extends API {
                       @QueryParam("source_in_ring")
                       @DefaultValue("true") boolean sourceInRing,
                       @QueryParam("max_degree")
-                      @DefaultValue(DEFAULT_DEGREE) long degree,
+                      @DefaultValue(DEFAULT_MAX_DEGREE) long maxDegree,
                       @QueryParam("capacity")
                       @DefaultValue(DEFAULT_CAPACITY) long capacity,
                       @QueryParam("limit")
@@ -75,7 +75,7 @@ public class RingsAPI extends API {
                   "source in ring '{}', max degree '{}', capacity '{}' " +
                   "and limit '{}'",
                   graph, sourceV, direction, edgeLabel, depth, sourceInRing,
-                  degree, capacity, limit);
+                  maxDegree, capacity, limit);
 
         Id source = VertexAPI.checkAndParseVertexId(sourceV);
         Directions dir = Directions.convert(EdgeAPI.parseDirection(direction));
@@ -85,7 +85,7 @@ public class RingsAPI extends API {
         SubGraphTraverser traverser = new SubGraphTraverser(g);
         HugeTraverser.PathSet paths = traverser.rings(source, dir, edgeLabel,
                                                       depth, sourceInRing,
-                                                      degree, capacity, limit);
+                                                      maxDegree, capacity, limit);
         return manager.serializer(g).writePaths("rings", paths, false);
     }
 }

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/SameNeighborsAPI.java

@@ -19,7 +19,7 @@
 
 package com.baidu.hugegraph.api.traversers;
 
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_PATHS_LIMIT;
 
 import java.util.Set;
@@ -63,12 +63,12 @@ public class SameNeighborsAPI extends API {
                       @QueryParam("direction") String direction,
                       @QueryParam("label") String edgeLabel,
                       @QueryParam("max_degree")
-                      @DefaultValue(DEFAULT_DEGREE) long degree,
+                      @DefaultValue(DEFAULT_MAX_DEGREE) long maxDegree,
                       @QueryParam("limit")
                       @DefaultValue(DEFAULT_PATHS_LIMIT) long limit) {
         LOG.debug("Graph [{}] get same neighbors between '{}' and '{}' with " +
                   "direction {}, edge label {}, max degree '{}' and limit '{}'",
-                  graph, vertex, other, direction, edgeLabel, degree, limit);
+                  graph, vertex, other, direction, edgeLabel, maxDegree, limit);
 
         Id sourceId = VertexAPI.checkAndParseVertexId(vertex);
         Id targetId = VertexAPI.checkAndParseVertexId(other);
@@ -77,7 +77,7 @@ public class SameNeighborsAPI extends API {
         HugeGraph g = graph(manager, graph);
         SameNeighborTraverser traverser = new SameNeighborTraverser(g);
         Set<Id> neighbors = traverser.sameNeighbors(sourceId, targetId, dir,
-                                                    edgeLabel, degree, limit);
+                                                    edgeLabel, maxDegree, limit);
         return manager.serializer(g).writeList("same_neighbors", neighbors);
     }
 }

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/ShortestPathAPI.java

@@ -22,7 +22,7 @@ package com.baidu.hugegraph.api.traversers;
 import java.util.List;
 
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_CAPACITY;
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 
 import javax.inject.Singleton;
 import javax.ws.rs.DefaultValue;
@@ -66,16 +66,16 @@ public class ShortestPathAPI extends API {
                       @QueryParam("label") String edgeLabel,
                       @QueryParam("max_depth") int depth,
                       @QueryParam("max_degree")
-                      @DefaultValue(DEFAULT_DEGREE) long degree,
+                      @DefaultValue(DEFAULT_MAX_DEGREE) long maxDegree,
                       @QueryParam("skip_degree")
                       @DefaultValue("0") long skipDegree,
                       @QueryParam("capacity")
                       @DefaultValue(DEFAULT_CAPACITY) long capacity) {
         LOG.debug("Graph [{}] get shortest path from '{}', to '{}' with " +
                   "direction {}, edge label {}, max depth '{}', " +
-                  "max degree '{}', skipped degree '{}' and capacity '{}'",
+                  "max degree '{}', skipped maxDegree '{}' and capacity '{}'",
                   graph, source, target, direction, edgeLabel, depth,
-                  degree, skipDegree, capacity);
+                  maxDegree, skipDegree, capacity);
 
         Id sourceId = VertexAPI.checkAndParseVertexId(source);
         Id targetId = VertexAPI.checkAndParseVertexId(target);
@@ -89,7 +89,7 @@ public class ShortestPathAPI extends API {
                                   ImmutableList.of(edgeLabel);
         HugeTraverser.Path path = traverser.shortestPath(sourceId, targetId,
                                                          dir, edgeLabels, depth,
-                                                         degree, skipDegree,
+                                                         maxDegree, skipDegree,
                                                          capacity);
         return manager.serializer(g).writeList("path", path.vertices());
     }

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/SingleSourceShortestPathAPI.java

@@ -20,7 +20,7 @@
 package com.baidu.hugegraph.api.traversers;
 
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_CAPACITY;
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_PATHS_LIMIT;
 
 import java.util.Iterator;
@@ -67,7 +67,7 @@ public class SingleSourceShortestPathAPI extends API {
                       @QueryParam("label") String edgeLabel,
                       @QueryParam("weight") String weight,
                       @QueryParam("max_degree")
-                      @DefaultValue(DEFAULT_DEGREE) long degree,
+                      @DefaultValue(DEFAULT_MAX_DEGREE) long maxDegree,
                       @QueryParam("skip_degree")
                       @DefaultValue("0") long skipDegree,
                       @QueryParam("capacity")
@@ -79,7 +79,7 @@ public class SingleSourceShortestPathAPI extends API {
                   "with direction {}, edge label {}, weight property {}, " +
                   "max degree '{}', limit '{}' and with vertex '{}'",
                   graph, source, direction, edgeLabel,
-                  weight, degree, withVertex);
+                  weight, maxDegree, withVertex);
 
         Id sourceId = VertexAPI.checkAndParseVertexId(source);
         Directions dir = Directions.convert(EdgeAPI.parseDirection(direction));
@@ -89,7 +89,7 @@ public class SingleSourceShortestPathAPI extends API {
                 new SingleSourceShortestPathTraverser(g);
         WeightedPaths paths = traverser.singleSourceShortestPaths(
                               sourceId, dir, edgeLabel, weight,
-                              degree, skipDegree, capacity, limit);
+                              maxDegree, skipDegree, capacity, limit);
         Iterator<Vertex> iterator = QueryResults.emptyIterator();
         assert paths != null;
         if (!paths.isEmpty() && withVertex) {

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/TemplatePathsAPI.java

@@ -117,7 +117,7 @@ public class TemplatePathsAPI extends TraverserAPI {
     private static RepeatEdgeStep repeatEdgeStep(HugeGraph graph,
                                                  TemplatePathStep step) {
         return new RepeatEdgeStep(graph, step.direction, step.labels,
-                                  step.properties, step.degree,
+                                  step.properties, step.maxDegree,
                                   step.skipDegree, step.maxTimes);
     }
 
@@ -132,9 +132,9 @@ public class TemplatePathsAPI extends TraverserAPI {
         @JsonProperty("with_ring")
         public boolean withRing = false;
         @JsonProperty("capacity")
-        public long capacity = Long.valueOf(DEFAULT_CAPACITY);
+        public long capacity = Long.parseLong(DEFAULT_CAPACITY);
         @JsonProperty("limit")
-        public long limit = Long.valueOf(DEFAULT_PATHS_LIMIT);
+        public long limit = Long.parseLong(DEFAULT_PATHS_LIMIT);
         @JsonProperty("with_vertex")
         public boolean withVertex = false;
 
@@ -157,10 +157,11 @@ public class TemplatePathsAPI extends TraverserAPI {
         @Override
         public String toString() {
             return String.format("TemplatePathStep{direction=%s,labels=%s," +
-                                 "properties=%s,degree=%s,skipDegree=%s," +
+                                 "properties=%s,maxDegree=%s,skipDegree=%s," +
                                  "maxTimes=%s}",
                                  this.direction, this.labels, this.properties,
-                                 this.degree, this.skipDegree, this.maxTimes);
+                                 this.maxDegree, this.skipDegree,
+                                 this.maxTimes);
         }
     }
 }

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/TraverserAPI.java

@@ -26,15 +26,16 @@ import com.baidu.hugegraph.HugeGraph;
 import com.baidu.hugegraph.api.API;
 import com.baidu.hugegraph.traversal.algorithm.steps.EdgeStep;
 import com.baidu.hugegraph.type.define.Directions;
+import com.fasterxml.jackson.annotation.JsonAlias;
 import com.fasterxml.jackson.annotation.JsonProperty;
 
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 
 public class TraverserAPI extends API {
 
     protected static EdgeStep step(HugeGraph graph, Step step) {
         return new EdgeStep(graph, step.direction, step.labels, step.properties,
-                            step.degree, step.skipDegree);
+                            step.maxDegree, step.skipDegree);
     }
 
     protected static class Step {
@@ -45,17 +46,18 @@ public class TraverserAPI extends API {
         public List<String> labels;
         @JsonProperty("properties")
         public Map<String, Object> properties;
-        @JsonProperty("degree")
-        public long degree = Long.valueOf(DEFAULT_DEGREE);
+        @JsonAlias("degree")
+        @JsonProperty("max_degree")
+        public long maxDegree = Long.parseLong(DEFAULT_MAX_DEGREE);
         @JsonProperty("skip_degree")
         public long skipDegree = 0L;
 
         @Override
         public String toString() {
             return String.format("Step{direction=%s,labels=%s,properties=%s," +
-                                 "degree=%s,skipDegree=%s}",
+                                 "maxDegree=%s,skipDegree=%s}",
                                  this.direction, this.labels, this.properties,
-                                 this.degree, this.skipDegree);
+                                 this.maxDegree, this.skipDegree);
         }
     }
 }

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/WeightedShortestPathAPI.java

@@ -20,7 +20,7 @@
 package com.baidu.hugegraph.api.traversers;
 
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_CAPACITY;
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 
 import java.util.Iterator;
 
@@ -68,7 +68,7 @@ public class WeightedShortestPathAPI extends API {
                       @QueryParam("label") String edgeLabel,
                       @QueryParam("weight") String weight,
                       @QueryParam("max_degree")
-                      @DefaultValue(DEFAULT_DEGREE) long degree,
+                      @DefaultValue(DEFAULT_MAX_DEGREE) long maxDegree,
                       @QueryParam("skip_degree")
                       @DefaultValue("0") long skipDegree,
                       @QueryParam("capacity")
@@ -78,8 +78,8 @@ public class WeightedShortestPathAPI extends API {
                   "'{}' with direction {}, edge label {}, weight property {}, " +
                   "max degree '{}', skip degree '{}', capacity '{}', " +
                   "and with vertex '{}'",
-                  graph, source, target, direction, edgeLabel, weight, degree,
-                  skipDegree, capacity, withVertex);
+                  graph, source, target, direction, edgeLabel, weight,
+                  maxDegree, skipDegree, capacity, withVertex);
 
         Id sourceId = VertexAPI.checkAndParseVertexId(source);
         Id targetId = VertexAPI.checkAndParseVertexId(target);
@@ -92,7 +92,7 @@ public class WeightedShortestPathAPI extends API {
 
         NodeWithWeight path = traverser.weightedShortestPath(
                               sourceId, targetId, dir, edgeLabel, weight,
-                              degree, skipDegree, capacity);
+                              maxDegree, skipDegree, capacity);
         Iterator<Vertex> iterator = QueryResults.emptyIterator();
         if (path != null && withVertex) {
             assert !path.node().path().isEmpty();

hugegraph-cassandra/src/main/java/com/baidu/hugegraph/backend/store/cassandra/CassandraEntryIterator.java

@@ -20,6 +20,7 @@
 package com.baidu.hugegraph.backend.store.cassandra;
 
 import java.util.Iterator;
+import java.util.List;
 import java.util.function.BiFunction;
 
 import com.baidu.hugegraph.backend.page.PageState;
@@ -27,6 +28,7 @@ import com.baidu.hugegraph.backend.query.Query;
 import com.baidu.hugegraph.backend.store.BackendEntry;
 import com.baidu.hugegraph.backend.store.BackendEntryIterator;
 import com.baidu.hugegraph.util.E;
+import com.datastax.driver.core.ExecutionInfo;
 import com.datastax.driver.core.PagingState;
 import com.datastax.driver.core.ResultSet;
 import com.datastax.driver.core.Row;
@@ -37,7 +39,8 @@ public class CassandraEntryIterator extends BackendEntryIterator {
     private final Iterator<Row> rows;
     private final BiFunction<BackendEntry, Row, BackendEntry> merger;
 
-    private long remaining;
+    private int fetchdPageSize;
+    private long expected;
     private BackendEntry next;
 
     public CassandraEntryIterator(ResultSet results, Query query,
@@ -45,16 +48,41 @@ public class CassandraEntryIterator extends BackendEntryIterator {
         super(query);
         this.results = results;
         this.rows = results.iterator();
-        this.remaining = results.getAvailableWithoutFetching();
         this.merger = merger;
+
+        this.fetchdPageSize = results.getAvailableWithoutFetching();
         this.next = null;
 
-        this.skipOffset();
-
         if (query.paging()) {
-            E.checkState(this.remaining == query.limit() ||
-                         results.isFullyFetched(),
-                         "Unexpected fetched page size: %s", this.remaining);
+            assert query.offset() == 0L;
+            assert query.limit() >= 0L || query.noLimit() : query.limit();
+            // Skip page offset
+            this.expected = PageState.fromString(query.page()).offset();
+            this.skipPageOffset(query.page());
+            // Check the number of available rows
+            E.checkState(this.fetchdPageSize <= query.limit(),
+                         "Unexpected fetched page size: %s",
+                         this.fetchdPageSize);
+            if (results.isFullyFetched()) {
+                /*
+                 * All results fetched
+                 * NOTE: it may be enough or not enough for the entire page
+                 */
+                this.expected = this.fetchdPageSize;
+            } else {
+                /*
+                 * Not fully fetched, that's fetchdPageSize == query.limit(),
+                 *
+                 * NOTE: but there may be fetchdPageSize < query.limit(), means
+                 * not fetched the entire page (ScyllaDB may go here #1340),
+                 * try to fetch next page later until got the expected count.
+                 * Can simulate by: `select.setFetchSize(total - 1)`
+                 */
+                this.expected = query.total();
+            }
+        } else {
+            this.expected = query.total();
+            this.skipOffset();
         }
     }
 
@@ -71,11 +99,18 @@ public class CassandraEntryIterator extends BackendEntryIterator {
             this.next = null;
         }
 
-        while (this.remaining > 0 && this.rows.hasNext()) {
-            if (this.query.paging()) {
-                this.remaining--;
-            }
+        while (this.expected > 0L && this.rows.hasNext()) {
+            // Limit expected count, due to rows.hasNext() will fetch next page
+            this.expected--;
             Row row = this.rows.next();
+            if (this.query.paging()) {
+                // Update fetchdPageSize if auto fetch the next page
+                if (this.expected > 0L && this.availableLocal() == 0) {
+                    if (this.rows.hasNext()) {
+                        this.fetchdPageSize = this.availableLocal();
+                    }
+                }
+            }
             BackendEntry merged = this.merger.apply(this.current, row);
             if (this.current == null) {
                 // The first time to read
@@ -112,11 +147,50 @@ public class CassandraEntryIterator extends BackendEntryIterator {
 
     @Override
     protected PageState pageState() {
-        PagingState page = this.results.getExecutionInfo().getPagingState();
-        if (page == null || this.results.isExhausted()) {
-            return new PageState(PageState.EMPTY_BYTES, 0, (int) this.count());
+        byte[] position;
+        int offset = 0;
+        int count = (int) this.count();
+        assert this.fetched() == count;
+        int extra = this.availableLocal();
+        List<ExecutionInfo> infos = this.results.getAllExecutionInfo();
+        if (extra > 0 && infos.size() >= 2) {
+            /*
+             * Go back to the previous page if there are still available
+             * results fetched to local memory but not consumed, and set page
+             * offset with consumed amount of results.
+             *
+             * Safely, we should get the remaining size of the current page by:
+             *  `Whitebox.getInternalState(results, "currentPage").size()`
+             * instead of
+             *  `results.getAvailableWithoutFetching()`
+             */
+            ExecutionInfo previous = infos.get(infos.size() - 2);
+            PagingState page = previous.getPagingState();
+            position = page.toBytes();
+            offset = this.fetchdPageSize - extra;
+        } else {
+            PagingState page = this.results.getExecutionInfo().getPagingState();
+            if (page == null || this.expected > 0L) {
+                // Call isExhausted() will lead to try to fetch the next page
+                E.checkState(this.results.isExhausted(),
+                             "Unexpected paging state with expected=%s, " +
+                             "ensure consume all the fetched results before " +
+                             "calling pageState()", this.expected);
+                position = PageState.EMPTY_BYTES;
+            } else {
+                /*
+                 * Exist page position which used to fetch the next page.
+                 * Maybe it happens to the last page (that's the position is
+                 * at the end of results and next page is empty)
+                 */
+                position = page.toBytes();
+            }
         }
-        byte[] position = page.toBytes();
-        return new PageState(position, 0, (int) this.count());
+
+        return new PageState(position, offset, count);
+    }
+
+    private int availableLocal() {
+        return this.results.getAvailableWithoutFetching();
     }
 }

hugegraph-cassandra/src/main/java/com/baidu/hugegraph/backend/store/cassandra/CassandraTable.java

@@ -204,18 +204,39 @@ public abstract class CassandraTable
     }
 
     protected void setPageState(Query query, List<Select> selects) {
-        if (query.noLimit()) {
+        if (query.noLimit() && !query.paging()) {
             return;
         }
         for (Select select : selects) {
-            long total = query.total();
+            int total = (int) query.total();
+            if (!query.noLimit()) {
+                E.checkArgument(total == query.total(),
+                                "Invalid query limit %s", query.limit());
+            } else {
+                assert total == -1 : total;
+            }
+
             String page = query.page();
             if (page == null) {
                 // Set limit
-                select.limit((int) total);
+                assert total > 0 : total;
+                select.limit(total);
             } else {
-                select.setFetchSize((int) total);
-                // It's the first time if page is empty
+                /*
+                 * NOTE: the `total` may be -1 when query.noLimit(),
+                 * setFetchSize(-1) means the default fetch size will be used.
+                 */
+                assert total > 0 || total == -1 : total;
+                select.setFetchSize(total);
+
+                /*
+                 * Can't set limit here `select.limit(total)`
+                 * due to it will cause can't get the next page-state.
+                 * Also can't set `select.limit(total + 1)` due to it will
+                 * cause error "Paging state mismatch" when setPagingState().
+                 */
+
+                // It's the first time if page is empty, skip setPagingState
                 if (!page.isEmpty()) {
                     byte[] position = PageState.fromString(page).position();
                     try {

hugegraph-core/pom.xml

@@ -152,6 +152,11 @@
             <artifactId>lz4-java</artifactId>
             <version>1.7.1</version>
         </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-compress</artifactId>
+            <version>1.20</version>
+        </dependency>
     </dependencies>
 
     <build>

hugegraph-core/src/main/java/com/baidu/hugegraph/StandardHugeGraph.java

@@ -106,16 +106,16 @@ public class StandardHugeGraph implements HugeGraph {
            StandardHugeGraph.SysTransaction.class
     };
 
-    public static final Set<ConfigOption> ALLOWED_CONFIGS = ImmutableSet.of(
-            CoreOptions.TASK_WAIT_TIMEOUT,
-            CoreOptions.TASK_SYNC_DELETION,
-            CoreOptions.TASK_TTL_DELETE_BATCH,
-            CoreOptions.TASK_INPUT_SIZE_LIMIT,
-            CoreOptions.TASK_RESULT_SIZE_LIMIT,
-            CoreOptions.OLTP_CONCURRENT_THREADS,
-            CoreOptions.OLTP_CONCURRENT_DEPTH,
-            CoreOptions.VERTEX_DEFAULT_LABEL,
-            CoreOptions.VERTEX_ENCODE_PK_NUMBER
+    public static final Set<ConfigOption<?>> ALLOWED_CONFIGS = ImmutableSet.of(
+           CoreOptions.TASK_WAIT_TIMEOUT,
+           CoreOptions.TASK_SYNC_DELETION,
+           CoreOptions.TASK_TTL_DELETE_BATCH,
+           CoreOptions.TASK_INPUT_SIZE_LIMIT,
+           CoreOptions.TASK_RESULT_SIZE_LIMIT,
+           CoreOptions.OLTP_CONCURRENT_THREADS,
+           CoreOptions.OLTP_CONCURRENT_DEPTH,
+           CoreOptions.VERTEX_DEFAULT_LABEL,
+           CoreOptions.VERTEX_ENCODE_PK_NUMBER
     );
 
     private static final Logger LOG = Log.logger(HugeGraph.class);

hugegraph-core/src/main/java/com/baidu/hugegraph/backend/page/PageState.java

@@ -29,6 +29,8 @@ public class PageState {
 
     public static final byte[] EMPTY_BYTES = new byte[0];
     public static final PageState EMPTY = new PageState(EMPTY_BYTES, 0, 0);
+    public static final char SPACE = ' ';
+    public static final char PLUS = '+';
 
     private final byte[] position;
     private final int offset;
@@ -72,6 +74,13 @@ public class PageState {
     }
 
     public static PageState fromString(String page) {
+        E.checkNotNull(page, "page");
+        /*
+         * URLDecoder will auto decode '+' to space in url due to the request
+         * of HTML4, so we choose to replace the space to '+' after getting it
+         * More details refer to #1437
+         */
+        page = page.replace(SPACE, PLUS);
         return fromBytes(toBytes(page));
     }
 

hugegraph-core/src/main/java/com/baidu/hugegraph/backend/serializer/BinaryEntryIterator.java

@@ -46,10 +46,12 @@ public class BinaryEntryIterator<Elem> extends BackendEntryIterator {
         this.merger = m;
         this.next = null;
 
-        this.skipOffset();
-
         if (query.paging()) {
+            assert query.offset() == 0L;
+            assert PageState.fromString(query.page()).offset() == 0;
             this.skipPageOffset(query.page());
+        } else {
+            this.skipOffset();
         }
     }
 
@@ -98,22 +100,9 @@ public class BinaryEntryIterator<Elem> extends BackendEntryIterator {
         return this.current != null;
     }
 
-    public final static long sizeOfBackendEntry(BackendEntry entry) {
-        /*
-         * 3 cases:
-         *  1) one vertex per entry
-         *  2) one edge per column (one entry <==> a vertex),
-         *  3) one element id per column (one entry <==> an index)
-         */
-        if (entry.type().isEdge() || entry.type().isIndex()) {
-            return entry.columnsSize();
-        }
-        return 1L;
-    }
-
     @Override
     protected final long sizeOf(BackendEntry entry) {
-        return sizeOfBackendEntry(entry);
+        return sizeOfEntry(entry);
     }
 
     @Override
@@ -140,10 +129,16 @@ public class BinaryEntryIterator<Elem> extends BackendEntryIterator {
         ((BinaryBackendEntry) this.current).removeColumn(lastOne);
     }
 
-    private void skipPageOffset(String page) {
-        PageState pagestate = PageState.fromString(page);
-        if (pagestate.offset() > 0 && this.fetch()) {
-            this.skip(this.current, pagestate.offset());
+    public final static long sizeOfEntry(BackendEntry entry) {
+        /*
+         * 3 cases:
+         *  1) one vertex per entry
+         *  2) one edge per column (one entry <==> a vertex),
+         *  3) one element id per column (one entry <==> an index)
+         */
+        if (entry.type().isEdge() || entry.type().isIndex()) {
+            return entry.columnsSize();
         }
+        return 1L;
     }
 }

hugegraph-core/src/main/java/com/baidu/hugegraph/backend/store/BackendEntryIterator.java

@@ -128,28 +128,47 @@ public abstract class BackendEntryIterator implements CIter<BackendEntry> {
         return this.count + ccount;
     }
 
+    protected final void skipPageOffset(String page) {
+        PageState pageState = PageState.fromString(page);
+        int pageOffset = pageState.offset();
+        if (pageOffset > 0) {
+            /*
+             * Don't update this.count even if skipped page offset,
+             * because the skipped records belongs to the last page.
+             */
+            this.skipOffset(pageOffset);
+        }
+    }
+
     protected void skipOffset() {
         long offset = this.query.offset() - this.query.actualOffset();
         if (offset <= 0L) {
             return;
         }
+        long skipped = this.skipOffset(offset);
+        this.count += skipped;
+        this.query.goOffset(skipped);
+    }
 
+    protected long skipOffset(long offset) {
+        assert offset >= 0L;
+        long skipped = 0L;
         // Skip offset
-        while (this.count < offset && this.fetch()) {
+        while (skipped < offset && this.fetch()) {
             assert this.current != null;
             final long size = this.sizeOf(this.current);
-            this.count += size;
-            if (this.count > offset) {
+            skipped += size;
+            if (skipped > offset) {
                 // Skip part of sub-items in an entry
-                final long skip = size - (this.count - offset);
-                this.count -= this.skip(this.current, skip);
-                assert this.count == offset;
+                final long skip = size - (skipped - offset);
+                skipped -= this.skip(this.current, skip);
+                assert skipped == offset;
             } else {
                 // Skip entry
                 this.current = null;
             }
         }
-        this.query.goOffset(this.count);
+        return skipped;
     }
 
     protected long sizeOf(BackendEntry entry) {

hugegraph-core/src/main/java/com/baidu/hugegraph/backend/store/BackendTable.java

@@ -168,9 +168,9 @@ public abstract class BackendTable<Session extends BackendSession, Entry> {
             long maxKey = this.maxKey();
             double each = maxKey / count;
 
-            long offset = 0L;
-            String last = this.position(offset);
             List<Shard> splits = new ArrayList<>((int) count);
+            String last = START;
+            long offset = 0L;
             while (offset < maxKey) {
                 offset += each;
                 if (offset > maxKey) {

hugegraph-core/src/main/java/com/baidu/hugegraph/backend/store/raft/RaftSharedContext.java

@@ -72,7 +72,7 @@ public final class RaftSharedContext {
     public static final int BUSY_SLEEP_FACTOR = 3 * 1000;
     public static final int WAIT_RPC_TIMEOUT = 30 * 60 * 1000;
     // compress block size
-    public static final int BLOCK_SIZE = 4096;
+    public static final int BLOCK_SIZE = 8192;
 
     public static final String DEFAULT_GROUP = "default";
 

hugegraph-core/src/main/java/com/baidu/hugegraph/backend/store/raft/StoreSnapshotFile.java

@@ -37,9 +37,9 @@ import com.alipay.sofa.jraft.error.RaftError;
 import com.alipay.sofa.jraft.storage.snapshot.SnapshotReader;
 import com.alipay.sofa.jraft.storage.snapshot.SnapshotWriter;
 import com.alipay.sofa.jraft.util.CRC64;
+import com.baidu.hugegraph.util.CompressUtil;
 import com.baidu.hugegraph.util.E;
 import com.baidu.hugegraph.util.Log;
-import com.baidu.hugegraph.util.ZipUtil;
 
 public class StoreSnapshotFile {
 
@@ -133,7 +133,8 @@ public class StoreSnapshotFile {
         String outputFile = Paths.get(writerPath, SNAPSHOT_ARCHIVE).toString();
         try {
             Checksum checksum = new CRC64();
-            ZipUtil.compress(writerPath, SNAPSHOT_DIR, outputFile, checksum);
+            CompressUtil.compressTar(writerPath, SNAPSHOT_DIR,
+                                     outputFile, checksum);
             metaBuilder.setChecksum(Long.toHexString(checksum.getValue()));
             if (writer.addFile(SNAPSHOT_ARCHIVE, metaBuilder.build())) {
                 done.run(Status.OK());
@@ -155,7 +156,7 @@ public class StoreSnapshotFile {
                                     throws IOException {
         String sourceFile = Paths.get(readerPath, SNAPSHOT_ARCHIVE).toString();
         Checksum checksum = new CRC64();
-        ZipUtil.decompress(sourceFile, readerPath, checksum);
+        CompressUtil.decompressTar(sourceFile, readerPath, checksum);
         if (meta.hasChecksum()) {
             E.checkArgument(meta.getChecksum().equals(
                             Long.toHexString(checksum.getValue())),

hugegraph-core/src/main/java/com/baidu/hugegraph/io/HugeGraphSONModule.java

@@ -24,10 +24,15 @@ import java.io.IOException;
 import java.util.Date;
 import java.util.Map;
 import java.util.Optional;
+import java.util.Set;
 import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 
+import org.apache.tinkerpop.gremlin.process.traversal.Path;
+import org.apache.tinkerpop.gremlin.process.traversal.step.util.Tree;
+import org.apache.tinkerpop.gremlin.structure.Element;
 import org.apache.tinkerpop.gremlin.structure.io.graphson.GraphSONIo;
+import org.apache.tinkerpop.gremlin.structure.io.graphson.GraphSONTokens;
 import org.apache.tinkerpop.gremlin.structure.io.graphson.TinkerPopJacksonModule;
 import org.apache.tinkerpop.shaded.jackson.core.JsonGenerator;
 import org.apache.tinkerpop.shaded.jackson.core.JsonParser;
@@ -70,10 +75,10 @@ public class HugeGraphSONModule extends TinkerPopJacksonModule {
 
     private static final long serialVersionUID = 6480426922914059122L;
 
-    public static boolean OPTIMIZE_SERIALIZE = true;
-
     private static final String TYPE_NAMESPACE = "hugegraph";
 
+    private static boolean OPTIMIZE_SERIALIZE = true;
+
     @SuppressWarnings("rawtypes")
     private static final Map<Class, String> TYPE_DEFINITIONS;
 
@@ -198,6 +203,9 @@ public class HugeGraphSONModule extends TinkerPopJacksonModule {
          */
         module.addSerializer(HugeVertex.class, new HugeVertexSerializer());
         module.addSerializer(HugeEdge.class, new HugeEdgeSerializer());
+
+        module.addSerializer(Path.class, new PathSerializer());
+        module.addSerializer(Tree.class, new TreeSerializer());
     }
 
     @SuppressWarnings("rawtypes")
@@ -485,6 +493,49 @@ public class HugeGraphSONModule extends TinkerPopJacksonModule {
         }
     }
 
+    private static class PathSerializer extends StdSerializer<Path> {
+
+        public PathSerializer() {
+            super(Path.class);
+        }
+
+        @Override
+        public void serialize(Path path, JsonGenerator jsonGenerator,
+                              SerializerProvider provider) throws IOException {
+            jsonGenerator.writeStartObject();
+            jsonGenerator.writeObjectField(GraphSONTokens.LABELS,
+                                           path.labels());
+            jsonGenerator.writeObjectField(GraphSONTokens.OBJECTS,
+                                           path.objects());
+            jsonGenerator.writeEndObject();
+        }
+    }
+
+    @SuppressWarnings("rawtypes") // Tree<T>
+    private static class TreeSerializer extends StdSerializer<Tree> {
+
+        public TreeSerializer() {
+            super(Tree.class);
+        }
+
+        @Override
+        public void serialize(Tree tree, JsonGenerator jsonGenerator,
+                              SerializerProvider provider) throws IOException {
+            jsonGenerator.writeStartArray();
+            @SuppressWarnings("unchecked")
+            Set<Map.Entry<Element, Tree>> set = tree.entrySet();
+            for (Map.Entry<Element, Tree> entry : set) {
+                jsonGenerator.writeStartObject();
+                jsonGenerator.writeObjectField(GraphSONTokens.KEY,
+                                               entry.getKey());
+                jsonGenerator.writeObjectField(GraphSONTokens.VALUE,
+                                               entry.getValue());
+                jsonGenerator.writeEndObject();
+            }
+            jsonGenerator.writeEndArray();
+        }
+    }
+
     private static class ShardSerializer extends StdSerializer<Shard> {
 
         public ShardSerializer() {
@@ -493,8 +544,7 @@ public class HugeGraphSONModule extends TinkerPopJacksonModule {
 
         @Override
         public void serialize(Shard shard, JsonGenerator jsonGenerator,
-                              SerializerProvider provider)
-                              throws IOException {
+                              SerializerProvider provider) throws IOException {
             jsonGenerator.writeStartObject();
             jsonGenerator.writeStringField("start", shard.start());
             jsonGenerator.writeStringField("end", shard.end());
@@ -511,8 +561,7 @@ public class HugeGraphSONModule extends TinkerPopJacksonModule {
 
         @Override
         public void serialize(File file, JsonGenerator jsonGenerator,
-                              SerializerProvider provider)
-                              throws IOException {
+                              SerializerProvider provider) throws IOException {
             jsonGenerator.writeStartObject();
             jsonGenerator.writeStringField("file", file.getName());
             jsonGenerator.writeEndObject();
@@ -527,8 +576,7 @@ public class HugeGraphSONModule extends TinkerPopJacksonModule {
 
         @Override
         public void serialize(Blob blob, JsonGenerator jsonGenerator,
-                              SerializerProvider provider)
-                              throws IOException {
+                              SerializerProvider provider) throws IOException {
             jsonGenerator.writeBinary(blob.bytes());
         }
     }

hugegraph-core/src/main/java/com/baidu/hugegraph/schema/builder/AbstractBuilder.java

@@ -26,7 +26,6 @@ import com.baidu.hugegraph.HugeGraph;
 import com.baidu.hugegraph.backend.id.Id;
 import com.baidu.hugegraph.backend.id.IdGenerator;
 import com.baidu.hugegraph.backend.tx.SchemaTransaction;
-import com.baidu.hugegraph.config.CoreOptions;
 import com.baidu.hugegraph.exception.ExistedException;
 import com.baidu.hugegraph.schema.EdgeLabel;
 import com.baidu.hugegraph.schema.IndexLabel;

hugegraph-core/src/main/java/com/baidu/hugegraph/schema/builder/EdgeLabelBuilder.java

@@ -466,11 +466,15 @@ public class EdgeLabelBuilder extends AbstractBuilder
                         "must belong to the origin/new properties: %s/%s ",
                         this.nullableKeys, originProps, appendProps);
 
-        E.checkArgument(!CollectionUtil.hasIntersection(this.sortKeys,
+        List<String> sortKeys = edgeLabel == null ?
+                                this.sortKeys :
+                                this.graph()
+                                    .mapPkId2Name(edgeLabel.sortKeys());
+        E.checkArgument(!CollectionUtil.hasIntersection(sortKeys,
                                                         this.nullableKeys),
                         "The nullableKeys: %s are not allowed to " +
                         "belong to sortKeys: %s of edge label '%s'",
-                        this.nullableKeys, this.sortKeys, this.name);
+                        this.nullableKeys, sortKeys, this.name);
 
         if (action == Action.APPEND) {
             Collection<String> newAddedProps = CollectionUtils.subtract(

hugegraph-core/src/main/java/com/baidu/hugegraph/schema/builder/VertexLabelBuilder.java

@@ -461,11 +461,15 @@ public class VertexLabelBuilder extends AbstractBuilder
                         "must belong to the origin/new properties: %s/%s",
                         this.nullableKeys, originProps, appendProps);
 
-        E.checkArgument(!CollectionUtil.hasIntersection(this.primaryKeys,
+        List<String> primaryKeys = vertexLabel == null ?
+                                   this.primaryKeys :
+                                   this.graph()
+                                       .mapPkId2Name(vertexLabel.primaryKeys());
+        E.checkArgument(!CollectionUtil.hasIntersection(primaryKeys,
                                                         this.nullableKeys),
                         "The nullableKeys: %s are not allowed to " +
                         "belong to primaryKeys: %s of vertex label '%s'",
-                        this.nullableKeys, this.primaryKeys, this.name);
+                        this.nullableKeys, primaryKeys, this.name);
 
         if (action == Action.APPEND) {
             Collection<String> newAddedProps = CollectionUtils.subtract(

hugegraph-core/src/main/java/com/baidu/hugegraph/security/HugeSecurityManager.java

@@ -108,6 +108,11 @@ public class HugeSecurityManager extends SecurityManager {
             "com.baidu.hugegraph.backend.store.raft.rpc.RpcForwarder"
     );
 
+    private static final Map<String, Set<String>> NEW_SECURITY_EXCEPTION = ImmutableMap.of(
+            "com.baidu.hugegraph.security.HugeSecurityManager",
+            ImmutableSet.of("newSecurityException")
+    );
+
     @Override
     public void checkPermission(Permission permission) {
         if (DENIED_PERMISSIONS.contains(permission.getName()) &&
@@ -306,7 +311,7 @@ public class HugeSecurityManager extends SecurityManager {
 
     @Override
     public void checkPropertiesAccess() {
-        if (callFromGremlin()) {
+        if (callFromGremlin() && !callFromNewSecurityException()) {
             throw newSecurityException(
                   "Not allowed to access system properties via Gremlin");
         }
@@ -441,6 +446,10 @@ public class HugeSecurityManager extends SecurityManager {
         return callFromWorkerWithClass(RAFT_CLASSES);
     }
 
+    private static boolean callFromNewSecurityException() {
+        return callFromMethods(NEW_SECURITY_EXCEPTION);
+    }
+
     private static boolean callFromWorkerWithClass(Set<String> classes) {
         Thread curThread = Thread.currentThread();
         if (curThread.getName().startsWith(GREMLIN_SERVER_WORKER) ||

hugegraph-core/src/main/java/com/baidu/hugegraph/task/HugeTask.java

@@ -222,9 +222,13 @@ public class HugeTask<V> extends FutureTask<V> {
         return this.result;
     }
 
-    private void result(String result) {
+    private synchronized boolean result(TaskStatus status, String result) {
         checkPropertySize(result, P.RESULT);
-        this.result = result;
+        if (this.status(status)) {
+            this.result = result;
+            return true;
+        }
+        return false;
     }
 
     public void server(Id server) {
@@ -319,18 +323,17 @@ public class HugeTask<V> extends FutureTask<V> {
             LOG.warn("An exception occurred when running task: {}",
                      this.id(), e);
             // Update status to FAILED if exception occurred(not interrupted)
-            if (this.status(TaskStatus.FAILED)) {
-                this.result(e.toString());
+            if (this.result(TaskStatus.FAILED, e.toString())) {
                 return true;
             }
         }
         return false;
     }
 
-    public void failSave(Throwable e) {
+    public void failToSave(Throwable e) {
         if (!this.fail(e)) {
             // Can't update status, just set result to error message
-            this.result(e.toString());
+            this.result = e.toString();
         }
     }
 
@@ -352,9 +355,7 @@ public class HugeTask<V> extends FutureTask<V> {
     protected void set(V v) {
         String result = JsonUtil.toJson(v);
         checkPropertySize(result, P.RESULT);
-        if (this.status(TaskStatus.SUCCESS)) {
-            this.result = result;
-        } else {
+        if (!this.result(TaskStatus.SUCCESS, result)) {
             assert this.completed();
         }
         // Will call done() and may cause to save to store
@@ -381,22 +382,21 @@ public class HugeTask<V> extends FutureTask<V> {
         if (this.dependencies == null || this.dependencies.isEmpty()) {
             return true;
         }
+        TaskScheduler scheduler = this.scheduler();
         for (Id dependency : this.dependencies) {
-            HugeTask<?> task = this.scheduler().task(dependency);
+            HugeTask<?> task = scheduler.task(dependency);
             if (!task.completed()) {
                 // Dependent task not completed, re-schedule self
-                this.scheduler().schedule(this);
+                scheduler.schedule(this);
                 return false;
             } else if (task.status() == TaskStatus.CANCELLED) {
-                this.status(TaskStatus.CANCELLED);
-                this.result(String.format(
+                this.result(TaskStatus.CANCELLED, String.format(
                             "Cancelled due to dependent task '%s' cancelled",
                             dependency));
                 this.done();
                 return false;
             } else if (task.status() == TaskStatus.FAILED) {
-                this.status(TaskStatus.FAILED);
-                this.result(String.format(
+                this.result(TaskStatus.FAILED, String.format(
                             "Failed due to dependent task '%s' failed",
                             dependency));
                 this.done();
@@ -483,7 +483,7 @@ public class HugeTask<V> extends FutureTask<V> {
         }
     }
 
-    protected Object[] asArray() {
+    protected synchronized Object[] asArray() {
         E.checkState(this.type != null, "Task type can't be null");
         E.checkState(this.name != null, "Task name can't be null");
 
@@ -563,7 +563,7 @@ public class HugeTask<V> extends FutureTask<V> {
         return this.asMap(true);
     }
 
-    public Map<String, Object> asMap(boolean withDetails) {
+    public synchronized Map<String, Object> asMap(boolean withDetails) {
         E.checkState(this.type != null, "Task type can't be null");
         E.checkState(this.name != null, "Task name can't be null");
 

hugegraph-core/src/main/java/com/baidu/hugegraph/task/StandardTaskScheduler.java

@@ -205,6 +205,15 @@ public class StandardTaskScheduler implements TaskScheduler {
     public <V> Future<?> schedule(HugeTask<V> task) {
         E.checkArgumentNotNull(task, "Task can't be null");
 
+        if (task.status() == TaskStatus.QUEUED) {
+            /*
+             * Just submit to queue if status=QUEUED (means re-schedule task)
+             * NOTE: schedule() method may be called multi times by
+             * HugeTask.checkDependenciesSuccess() method
+             */
+            return this.resubmitTask(task);
+        }
+
         if (task.callable() instanceof EphemeralJob) {
             /*
              * Due to EphemeralJob won't be serialized and deserialized through
@@ -252,6 +261,16 @@ public class StandardTaskScheduler implements TaskScheduler {
         return this.taskExecutor.submit(task);
     }
 
+    private <V> Future<?> resubmitTask(HugeTask<V> task) {
+        E.checkArgument(task.status() == TaskStatus.QUEUED,
+                        "Can't resubmit task '%s' with status %s",
+                        task.id(), TaskStatus.QUEUED);
+        E.checkArgument(this.tasks.containsKey(task.id()),
+                        "Can't resubmit task '%s' not been submitted before",
+                        task.id());
+        return this.taskExecutor.submit(task);
+    }
+
     public <V> void initTaskCallable(HugeTask<V> task) {
         task.scheduler(this);
 

hugegraph-core/src/main/java/com/baidu/hugegraph/task/TaskCallable.java

@@ -20,6 +20,7 @@
 package com.baidu.hugegraph.task;
 
 import java.util.Date;
+import java.util.Set;
 import java.util.concurrent.Callable;
 
 import org.apache.tinkerpop.gremlin.structure.Transaction;
@@ -30,13 +31,29 @@ import com.baidu.hugegraph.HugeGraph;
 import com.baidu.hugegraph.HugeGraphParams;
 import com.baidu.hugegraph.util.E;
 import com.baidu.hugegraph.util.Log;
+import com.google.common.collect.ImmutableSet;
 
 public abstract class TaskCallable<V> implements Callable<V> {
 
     private static final Logger LOG = Log.logger(HugeTask.class);
 
-    private static final String ERROR_MAX_LEN = "Failed to commit changes: " +
-                                                "The max length of bytes is";
+    private static final String ERROR_COMMIT = "Failed to commit changes: ";
+    private static final Set<String> ERROR_MESSAGES = ImmutableSet.of(
+            /*
+             * "The max length of bytes is" exception message occurs when
+             * task input size exceeds TASK_INPUT_SIZE_LIMIT or task result size
+             * exceeds TASK_RESULT_SIZE_LIMIT
+             */
+            "The max length of bytes is",
+            /*
+             * "Batch too large" exception message occurs when using
+             * cassandra store and task input size is in
+             * [batch_size_fail_threshold_in_kb, TASK_INPUT_SIZE_LIMIT) or
+             * task result size is in
+             * [batch_size_fail_threshold_in_kb, TASK_RESULT_SIZE_LIMIT)
+             */
+            "Batch too large"
+    );
 
     private HugeTask<V> task = null;
     private HugeGraph graph = null;
@@ -65,7 +82,7 @@ public abstract class TaskCallable<V> implements Callable<V> {
 
     public void setMinSaveInterval(long seconds) {
         E.checkArgument(seconds > 0,
-                        "Must set interval > 0, bug got '%s'", seconds);
+                        "Must set interval > 0, but got '%s'", seconds);
         this.saveInterval = seconds * 1000L;
     }
 
@@ -98,8 +115,9 @@ public abstract class TaskCallable<V> implements Callable<V> {
                  */
                 LOG.error("Failed to save task with error \"{}\": {}",
                           e, task.asMap(false));
-                if (e.getMessage().contains(ERROR_MAX_LEN)) {
-                    task.failSave(e);
+                String message = e.getMessage();
+                if (message.contains(ERROR_COMMIT) && needSaveWithEx(message)) {
+                    task.failToSave(e);
                     this.graph().taskScheduler().save(task);
                     return;
                 }
@@ -138,6 +156,15 @@ public abstract class TaskCallable<V> implements Callable<V> {
         }
     }
 
+    private static boolean needSaveWithEx(String message) {
+        for (String error : ERROR_MESSAGES) {
+            if (message.contains(error)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     public static <V> TaskCallable<V> empty(Exception e) {
         return new TaskCallable<V>() {
             @Override

hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/HugeTraverser.java

@@ -44,6 +44,7 @@ import com.baidu.hugegraph.backend.query.ConditionQuery;
 import com.baidu.hugegraph.backend.query.Query;
 import com.baidu.hugegraph.backend.query.QueryResults;
 import com.baidu.hugegraph.backend.tx.GraphTransaction;
+import com.baidu.hugegraph.backend.tx.GraphTransaction.LimitIterator;
 import com.baidu.hugegraph.config.CoreOptions;
 import com.baidu.hugegraph.exception.NotFoundException;
 import com.baidu.hugegraph.iterator.ExtendableIterator;
@@ -71,7 +72,7 @@ public class HugeTraverser {
     public static final String DEFAULT_ELEMENTS_LIMIT = "10000000";
     public static final String DEFAULT_PATHS_LIMIT = "10";
     public static final String DEFAULT_LIMIT = "100";
-    public static final String DEFAULT_DEGREE = "10000";
+    public static final String DEFAULT_MAX_DEGREE = "10000";
     public static final String DEFAULT_SKIP_DEGREE = "100000";
     public static final String DEFAULT_SAMPLE = "100";
     public static final String DEFAULT_MAX_DEPTH = "50";
@@ -96,9 +97,10 @@ public class HugeTraverser {
         return this.graph.option(CoreOptions.OLTP_CONCURRENT_DEPTH);
     }
 
-    protected Set<Id> adjacentVertices(Set<Id> vertices, Directions dir,
-                                       Id label, Set<Id> excluded,
-                                       long degree, long limit) {
+    protected Set<Id> adjacentVertices(Id sourceV, Set<Id> vertices,
+                                       Directions dir, Id label,
+                                       Set<Id> excluded, long degree,
+                                       long limit) {
         if (limit == 0) {
             return ImmutableSet.of();
         }
@@ -110,7 +112,10 @@ public class HugeTraverser {
             while (edges.hasNext()) {
                 HugeEdge e = (HugeEdge) edges.next();
                 Id target = e.id().otherVertexId();
-                if (excluded != null && excluded.contains(target)) {
+                boolean matchExcluded = (excluded != null &&
+                                         excluded.contains(target));
+                if (matchExcluded || neighbors.contains(target) ||
+                    sourceV.equals(target)) {
                     continue;
                 }
                 neighbors.add(target);
@@ -140,15 +145,19 @@ public class HugeTraverser {
         return neighbors;
     }
 
-    protected Set<Node> adjacentVertices(Set<Node> vertices, EdgeStep step,
-                                         Set<Node> excluded, long remaining) {
+    protected Set<Node> adjacentVertices(Id start, Set<Node> vertices,
+                                         EdgeStep step, Set<Node> excluded,
+                                         long remaining) {
         Set<Node> neighbors = newSet();
         for (Node source : vertices) {
             Iterator<Edge> edges = this.edgesOfVertex(source.id(), step);
             while (edges.hasNext()) {
                 Id target = ((HugeEdge) edges.next()).id().otherVertexId();
                 KNode kNode = new KNode(target, (KNode) source);
-                if (excluded != null && excluded.contains(kNode)) {
+                boolean matchExcluded = (excluded != null &&
+                                         excluded.contains(kNode));
+                if (matchExcluded || neighbors.contains(kNode) ||
+                    start.equals(kNode.id())) {
                     continue;
                 }
                 neighbors.add(kNode);
@@ -182,10 +191,17 @@ public class HugeTraverser {
         ExtendableIterator<Edge> results = new ExtendableIterator<>();
         for (Id label : labels.keySet()) {
             E.checkNotNull(label, "edge label");
-            // TODO: limit should be applied to all labels
             results.extend(this.edgesOfVertex(source, dir, label, limit));
         }
-        return results;
+
+        if (limit == NO_LIMIT) {
+            return results;
+        }
+
+        long[] count = new long[1];
+        return new LimitIterator<>(results, e -> {
+            return count[0]++ >= limit;
+        });
     }
 
     protected Iterator<Edge> edgesOfVertex(Id source, EdgeStep edgeStep) {
@@ -358,14 +374,14 @@ public class HugeTraverser {
                         Query.DEFAULT_CAPACITY, skipDegree);
         if (capacity != NO_LIMIT) {
             E.checkArgument(degree != NO_LIMIT && degree < capacity,
-                            "The degree must be < capacity");
+                            "The max degree must be < capacity");
             E.checkArgument(skipDegree < capacity,
                             "The skipped degree must be < capacity");
         }
         if (skipDegree > 0L) {
             E.checkArgument(degree != NO_LIMIT && skipDegree >= degree,
-                            "The skipped degree must be >= degree, " +
-                            "but got skipped degree '%s' and degree '%s'",
+                            "The skipped degree must be >= max degree, " +
+                            "but got skipped degree '%s' and max degree '%s'",
                             skipDegree, degree);
         }
     }

hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/KneighborTraverser.java

@@ -47,15 +47,14 @@ public class KneighborTraverser extends OltpTraverser {
         Id labelId = this.getEdgeLabelId(label);
 
         Set<Id> latest = newSet();
-        latest.add(sourceV);
-
         Set<Id> all = newSet();
-        all.add(sourceV);
+
+        latest.add(sourceV);
 
         while (depth-- > 0) {
             long remaining = limit == NO_LIMIT ? NO_LIMIT : limit - all.size();
-            latest = this.adjacentVertices(latest, dir, labelId, all,
-                                           degree, remaining);
+            latest = this.adjacentVertices(sourceV, latest, dir, labelId,
+                                           all, degree, remaining);
             all.addAll(latest);
             if (limit != NO_LIMIT && all.size() >= limit) {
                 break;
@@ -86,11 +85,10 @@ public class KneighborTraverser extends OltpTraverser {
         Node sourceV = new KNode(source, null);
 
         latest.add(sourceV);
-        all.add(sourceV);
 
         while (maxDepth-- > 0) {
             long remaining = limit == NO_LIMIT ? NO_LIMIT : limit - all.size();
-            latest = this.adjacentVertices(latest, step, all,
+            latest = this.adjacentVertices(source, latest, step, all,
                                            remaining, single);
             int size = all.size() + latest.size();
             if (limit != NO_LIMIT && size >= limit) {

hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/KoutTraverser.java

@@ -70,12 +70,12 @@ public class KoutTraverser extends OltpTraverser {
                 remaining = limit;
             }
             if (nearest) {
-                latest = this.adjacentVertices(latest, dir, labelId, all,
-                                               degree, remaining);
+                latest = this.adjacentVertices(sourceV, latest, dir, labelId,
+                                               all, degree, remaining);
                 all.addAll(latest);
             } else {
-                latest = this.adjacentVertices(latest, dir, labelId, null,
-                                               degree, remaining);
+                latest = this.adjacentVertices(sourceV, latest, dir, labelId,
+                                               null, degree, remaining);
             }
             if (capacity != NO_LIMIT) {
                 // Update 'remaining' value to record remaining capacity
@@ -130,11 +130,11 @@ public class KoutTraverser extends OltpTraverser {
                          NO_LIMIT : capacity - latest.size();
         while (depth-- > 0) {
             if (nearest) {
-                latest = this.adjacentVertices(latest, step, all,
+                latest = this.adjacentVertices(source, latest, step, all,
                                                remaining, single);
                 all.addAll(latest);
             } else {
-                latest = this.adjacentVertices(latest, step, null,
+                latest = this.adjacentVertices(source, latest, step, null,
                                                remaining, single);
             }
             if (capacity != NO_LIMIT) {

hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/MultiNodeShortestPathTraverser.java

@@ -36,8 +36,6 @@ import com.baidu.hugegraph.traversal.algorithm.steps.EdgeStep;
 import com.baidu.hugegraph.type.define.Directions;
 import com.baidu.hugegraph.util.E;
 
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.Path.EMPTY_PATH;
-
 public class MultiNodeShortestPathTraverser extends OltpTraverser {
 
     public MultiNodeShortestPathTraverser(HugeGraph graph) {
@@ -82,7 +80,7 @@ public class MultiNodeShortestPathTraverser extends OltpTraverser {
         this.traversePairs(pairs.iterator(), pair -> {
             Path path = traverser.shortestPath(pair.getLeft(), pair.getRight(),
                                                step, maxDepth, capacity);
-            if (!EMPTY_PATH.equals(path)) {
+            if (!Path.EMPTY_PATH.equals(path)) {
                 results.add(path);
             }
         });
@@ -99,7 +97,7 @@ public class MultiNodeShortestPathTraverser extends OltpTraverser {
         for (Pair<Id, Id> pair : pairs) {
             Path path = traverser.shortestPath(pair.getLeft(), pair.getRight(),
                                                step, maxDepth, capacity);
-            if (!EMPTY_PATH.equals(path)) {
+            if (!Path.EMPTY_PATH.equals(path)) {
                 results.add(path);
             }
         }
@@ -109,7 +107,7 @@ public class MultiNodeShortestPathTraverser extends OltpTraverser {
     private static <T> void cmn(List<T> all, int m, int n, int current,
                                 List<T> result, Consumer<List<T>> consumer) {
         assert m <= all.size();
-        assert current < all.size();
+        assert current <= all.size();
         if (result == null) {
             result = new ArrayList<>(n);
         }

hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/NeighborRankTraverser.java

@@ -244,7 +244,8 @@ public class NeighborRankTraverser extends HugeTraverser {
         public Step(HugeGraph g, Directions direction, List<String> labels,
                     long degree, long skipDegree, int top, int capacity) {
             E.checkArgument(top > 0 && top <= MAX_TOP,
-                            "The top of each layer can't exceed %s", MAX_TOP);
+                            "The top of each layer must be in (0, %s], but " +
+                            "got %s", MAX_TOP, top);
             E.checkArgument(capacity > 0,
                             "The capacity of each layer must be > 0, " +
                             "but got %s", capacity);
@@ -281,7 +282,8 @@ public class NeighborRankTraverser extends HugeTraverser {
 
         public long degree() {
             E.checkArgument(this.degree > 0,
-                            "The degree must be > 0, but got %s", this.degree);
+                            "The max degree must be > 0, but got %s",
+                            this.degree);
             return this.degree;
         }
 

hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/OltpTraverser.java

@@ -81,11 +81,11 @@ public abstract class OltpTraverser extends HugeTraverser
         }
     }
 
-    protected Set<Node> adjacentVertices(Set<Node> latest, EdgeStep step,
-                                         Set<Node> all, long remaining,
-                                         boolean single) {
+    protected Set<Node> adjacentVertices(Id source, Set<Node> latest,
+                                         EdgeStep step, Set<Node> all,
+                                         long remaining, boolean single) {
         if (single) {
-            return this.adjacentVertices(latest, step, all, remaining);
+            return this.adjacentVertices(source, latest, step, all, remaining);
         } else {
             AtomicLong remain = new AtomicLong(remaining);
             return this.adjacentVertices(latest, step, all, remain);

hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/PathsTraverser.java

@@ -60,7 +60,7 @@ public class PathsTraverser extends HugeTraverser {
 
         PathSet paths = new PathSet();
         if (sourceV.equals(targetV)) {
-            paths.add(new Path(sourceV, ImmutableList.of(sourceV)));
+            return paths;
         }
 
         Id labelId = this.getEdgeLabelId(label);

hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/SingleSourceShortestPathTraverser.java

@@ -38,6 +38,7 @@ import com.baidu.hugegraph.type.define.Directions;
 import com.baidu.hugegraph.util.CollectionUtil;
 import com.baidu.hugegraph.util.E;
 import com.baidu.hugegraph.util.InsertionOrderUtil;
+import com.baidu.hugegraph.util.NumericUtil;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 
@@ -212,7 +213,8 @@ public class SingleSourceShortestPathTraverser extends HugeTraverser {
                 !edge.property(this.weight).isPresent()) {
                 edgeWeight = 1.0;
             } else {
-                edgeWeight = edge.value(this.weight);
+                edgeWeight = NumericUtil.convertToNumber(
+                             edge.value(this.weight)).doubleValue();
             }
             return edgeWeight;
         }

hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/steps/EdgeStep.java

@@ -19,7 +19,7 @@
 
 package com.baidu.hugegraph.traversal.algorithm.steps;
 
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.NO_LIMIT;
 
 import java.util.HashMap;
@@ -66,14 +66,14 @@ public class EdgeStep {
     public EdgeStep(HugeGraph g, Directions direction, List<String> labels,
                     Map<String, Object> properties) {
         this(g, direction, labels, properties,
-             Long.valueOf(DEFAULT_DEGREE), 0L);
+             Long.parseLong(DEFAULT_MAX_DEGREE), 0L);
     }
 
     public EdgeStep(HugeGraph g, Directions direction, List<String> labels,
                     Map<String, Object> properties,
                     long degree, long skipDegree) {
         E.checkArgument(degree == NO_LIMIT || degree > 0L,
-                        "The degree must be > 0 or == -1, but got: %s",
+                        "The max degree must be > 0 or == -1, but got: %s",
                         degree);
         HugeTraverser.checkSkipDegree(skipDegree, degree,
                                       HugeTraverser.NO_LIMIT);

hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/steps/RepeatEdgeStep.java

@@ -19,7 +19,7 @@
 
 package com.baidu.hugegraph.traversal.algorithm.steps;
 
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 
 import java.util.List;
 import java.util.Map;
@@ -76,7 +76,7 @@ public class RepeatEdgeStep extends EdgeStep {
                           List<String> labels,
                           Map<String, Object> properties) {
         this(g, direction, labels, properties,
-             Long.valueOf(DEFAULT_DEGREE), 0L, 1);
+             Long.parseLong(DEFAULT_MAX_DEGREE), 0L, 1);
     }
 
     public RepeatEdgeStep(HugeGraph g, Directions direction,

hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/steps/WeightedEdgeStep.java

@@ -19,7 +19,7 @@
 
 package com.baidu.hugegraph.traversal.algorithm.steps;
 
-import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_DEGREE;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_SAMPLE;
 import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.NO_LIMIT;
 
@@ -59,24 +59,24 @@ public class WeightedEdgeStep {
     public WeightedEdgeStep(HugeGraph g, Directions direction, List<String> labels,
                             Map<String, Object> properties) {
         this(g, direction, labels, properties,
-             Long.valueOf(DEFAULT_DEGREE), 0L, null, 0.0D,
-             Long.valueOf(DEFAULT_SAMPLE));
+             Long.parseLong(DEFAULT_MAX_DEGREE), 0L, null, 0.0D,
+             Long.parseLong(DEFAULT_SAMPLE));
     }
 
     public WeightedEdgeStep(HugeGraph g, Directions direction, List<String> labels,
                             Map<String, Object> properties,
-                            long degree, long skipDegree,
+                            long maxDegree, long skipDegree,
                             String weightBy, double defaultWeight, long sample) {
         E.checkArgument(sample > 0L || sample == NO_LIMIT,
                         "The sample must be > 0 or == -1, but got: %s",
                         sample);
-        E.checkArgument(degree == NO_LIMIT || degree >= sample,
-                        "Degree must be greater than or equal to sample," +
-                        " but got degree %s and sample %s",
-                        degree, sample);
+        E.checkArgument(maxDegree == NO_LIMIT || maxDegree >= sample,
+                        "The max degree must be greater than or equal to " +
+                        "sample, but got max degree %s and sample %s",
+                        maxDegree, sample);
 
         this.edgeStep = new EdgeStep(g, direction, labels, properties,
-                                     degree, skipDegree);
+                                     maxDegree, skipDegree);
         if (weightBy != null) {
             this.weightBy = g.propertyKey(weightBy);
         } else {

hugegraph-core/src/main/java/com/baidu/hugegraph/util/CompressUtil.java

@@ -0,0 +1,241 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.baidu.hugegraph.util;
+
+import java.io.BufferedInputStream;
+import java.io.BufferedOutputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.FileVisitResult;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.SimpleFileVisitor;
+import java.nio.file.StandardCopyOption;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.util.zip.CheckedInputStream;
+import java.util.zip.CheckedOutputStream;
+import java.util.zip.Checksum;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipInputStream;
+import java.util.zip.ZipOutputStream;
+
+import org.apache.commons.compress.archivers.ArchiveEntry;
+import org.apache.commons.compress.archivers.tar.TarArchiveEntry;
+import org.apache.commons.compress.archivers.tar.TarArchiveInputStream;
+import org.apache.commons.compress.archivers.tar.TarArchiveOutputStream;
+import org.apache.commons.io.FileUtils;
+import org.apache.commons.io.IOUtils;
+import org.apache.commons.io.output.NullOutputStream;
+
+import com.baidu.hugegraph.backend.store.raft.RaftSharedContext;
+
+import net.jpountz.lz4.LZ4BlockInputStream;
+import net.jpountz.lz4.LZ4BlockOutputStream;
+import net.jpountz.lz4.LZ4Compressor;
+import net.jpountz.lz4.LZ4Factory;
+import net.jpountz.lz4.LZ4FastDecompressor;
+
+public final class CompressUtil {
+
+    /**
+     * Reference: https://mkyong.com/java/how-to-create-tar-gz-in-java/
+     */
+    public static void compressTar(String rootDir, String sourceDir,
+                                   String outputFile, Checksum checksum)
+                                   throws IOException {
+        LZ4Factory factory = LZ4Factory.fastestInstance();
+        LZ4Compressor compressor = factory.fastCompressor();
+        int blockSize = RaftSharedContext.BLOCK_SIZE;
+        try (FileOutputStream fos = new FileOutputStream(outputFile);
+             CheckedOutputStream cos = new CheckedOutputStream(fos, checksum);
+             BufferedOutputStream bos = new BufferedOutputStream(cos);
+             LZ4BlockOutputStream lz4os = new LZ4BlockOutputStream(bos,
+                                                                   blockSize,
+                                                                   compressor);
+             TarArchiveOutputStream tos = new TarArchiveOutputStream(lz4os)) {
+            Path source = Paths.get(rootDir, sourceDir);
+            CompressUtil.tarDir(source, tos);
+            tos.flush();
+            fos.getFD().sync();
+        }
+    }
+
+    private static void tarDir(Path source, TarArchiveOutputStream tos)
+                               throws IOException {
+        Files.walkFileTree(source, new SimpleFileVisitor<Path>() {
+            @Override
+            public FileVisitResult preVisitDirectory(Path dir,
+                                                     BasicFileAttributes attrs)
+                                                     throws IOException {
+                String entryName = buildTarEntryName(source, dir);
+                if (!entryName.isEmpty()) {
+                    TarArchiveEntry entry = new TarArchiveEntry(dir.toFile(),
+                                                                entryName);
+                    tos.putArchiveEntry(entry);
+                    tos.closeArchiveEntry();
+                }
+                return FileVisitResult.CONTINUE;
+            }
+
+            @Override
+            public FileVisitResult visitFile(Path file,
+                                             BasicFileAttributes attributes)
+                                             throws IOException {
+                // Only copy files, no symbolic links
+                if (attributes.isSymbolicLink()) {
+                    return FileVisitResult.CONTINUE;
+                }
+                String targetFile = buildTarEntryName(source, file);
+                TarArchiveEntry entry = new TarArchiveEntry(file.toFile(),
+                                                            targetFile);
+                tos.putArchiveEntry(entry);
+                Files.copy(file, tos);
+                tos.closeArchiveEntry();
+                return FileVisitResult.CONTINUE;
+            }
+
+            @Override
+            public FileVisitResult visitFileFailed(Path file, IOException e) {
+                return FileVisitResult.TERMINATE;
+            }
+        });
+    }
+
+    private static String buildTarEntryName(Path topLevel, Path current) {
+        return topLevel.getFileName().resolve(topLevel.relativize(current))
+                       .toString();
+    }
+
+    public static void decompressTar(String sourceFile, String outputDir,
+                                     Checksum checksum) throws IOException {
+        Path source = Paths.get(sourceFile);
+        Path target = Paths.get(outputDir);
+        if (Files.notExists(source)) {
+            throw new IOException(String.format(
+                                  "The source file %s doesn't exists", source));
+        }
+        LZ4Factory factory = LZ4Factory.fastestInstance();
+        LZ4FastDecompressor decompressor = factory.fastDecompressor();
+        try (InputStream fis = Files.newInputStream(source);
+             CheckedInputStream cis = new CheckedInputStream(fis, checksum);
+             BufferedInputStream bis = new BufferedInputStream(cis);
+             LZ4BlockInputStream lz4is = new LZ4BlockInputStream(bis,
+                                                                 decompressor);
+             TarArchiveInputStream tis = new TarArchiveInputStream(lz4is)) {
+            ArchiveEntry entry;
+            while ((entry = tis.getNextEntry()) != null) {
+                // Create a new path, zip slip validate
+                Path newPath = zipSlipProtect(entry, target);
+                if (entry.isDirectory()) {
+                    Files.createDirectories(newPath);
+                } else {
+                    // check parent folder again
+                    Path parent = newPath.getParent();
+                    if (parent != null) {
+                        if (Files.notExists(parent)) {
+                            Files.createDirectories(parent);
+                        }
+                    }
+                    // Copy TarArchiveInputStream to Path newPath
+                    Files.copy(tis, newPath,
+                               StandardCopyOption.REPLACE_EXISTING);
+                }
+            }
+        }
+    }
+
+    private static Path zipSlipProtect(ArchiveEntry entry, Path targetDir)
+                                       throws IOException {
+        Path targetDirResolved = targetDir.resolve(entry.getName());
+        /*
+         * Make sure normalized file still has targetDir as its prefix,
+         * else throws exception
+         */
+        Path normalizePath = targetDirResolved.normalize();
+        if (!normalizePath.startsWith(targetDir)) {
+            throw new IOException(String.format("Bad entry: %s",
+                                                entry.getName()));
+        }
+        return normalizePath;
+    }
+
+    public static void compressZip(String rootDir, String sourceDir,
+                                   String outputFile, Checksum checksum)
+                                   throws IOException {
+        try (FileOutputStream fos = new FileOutputStream(outputFile);
+             CheckedOutputStream cos = new CheckedOutputStream(fos, checksum);
+             BufferedOutputStream bos = new BufferedOutputStream(cos);
+             ZipOutputStream zos = new ZipOutputStream(bos)) {
+            CompressUtil.zipDir(rootDir, sourceDir, zos);
+            zos.flush();
+            fos.getFD().sync();
+        }
+    }
+
+    private static void zipDir(String rootDir, String sourceDir,
+                               ZipOutputStream zos) throws IOException {
+        String dir = Paths.get(rootDir, sourceDir).toString();
+        File[] files = new File(dir).listFiles();
+        E.checkNotNull(files, "files");
+        for (File file : files) {
+            String child = Paths.get(sourceDir, file.getName()).toString();
+            if (file.isDirectory()) {
+                zipDir(rootDir, child, zos);
+            } else {
+                zos.putNextEntry(new ZipEntry(child));
+                try (FileInputStream fis = new FileInputStream(file);
+                     BufferedInputStream bis = new BufferedInputStream(fis)) {
+                    IOUtils.copy(bis, zos);
+                }
+            }
+        }
+    }
+
+    public static void decompressZip(String sourceFile, String outputDir,
+                                     Checksum checksum) throws IOException {
+        try (FileInputStream fis = new FileInputStream(sourceFile);
+             CheckedInputStream cis = new CheckedInputStream(fis, checksum);
+             BufferedInputStream bis = new BufferedInputStream(cis);
+             ZipInputStream zis = new ZipInputStream(bis)) {
+            ZipEntry entry;
+            while ((entry = zis.getNextEntry()) != null) {
+                String fileName = entry.getName();
+                File entryFile = new File(Paths.get(outputDir, fileName)
+                                               .toString());
+                FileUtils.forceMkdir(entryFile.getParentFile());
+                try (FileOutputStream fos = new FileOutputStream(entryFile);
+                     BufferedOutputStream bos = new BufferedOutputStream(fos)) {
+                    IOUtils.copy(zis, bos);
+                    bos.flush();
+                    fos.getFD().sync();
+                }
+            }
+            /*
+             * Continue to read all remaining bytes(extra metadata of ZipEntry)
+             * directly from the checked stream, Otherwise, the checksum value
+             * maybe unexpected.
+             * See https://coderanch.com/t/279175/java/ZipInputStream
+             */
+            IOUtils.copy(cis, NullOutputStream.NULL_OUTPUT_STREAM);
+        }
+    }
+}

hugegraph-core/src/main/java/com/baidu/hugegraph/util/ZipUtil.java

@@ -1,101 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements.  See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.baidu.hugegraph.util;
-
-import java.io.BufferedInputStream;
-import java.io.BufferedOutputStream;
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.nio.file.Paths;
-import java.util.zip.CheckedInputStream;
-import java.util.zip.CheckedOutputStream;
-import java.util.zip.Checksum;
-import java.util.zip.ZipEntry;
-import java.util.zip.ZipInputStream;
-import java.util.zip.ZipOutputStream;
-
-import org.apache.commons.io.FileUtils;
-import org.apache.commons.io.IOUtils;
-import org.apache.commons.io.output.NullOutputStream;
-
-public final class ZipUtil {
-
-    public static void compress(String rootDir, String sourceDir,
-                                String outputFile, Checksum checksum)
-                                throws IOException {
-        try (FileOutputStream fos = new FileOutputStream(outputFile);
-             CheckedOutputStream cos = new CheckedOutputStream(fos, checksum);
-             BufferedOutputStream bos = new BufferedOutputStream(cos);
-             ZipOutputStream zos = new ZipOutputStream(bos)) {
-            ZipUtil.compressDirectoryToZipFile(rootDir, sourceDir, zos);
-            zos.flush();
-            fos.getFD().sync();
-        }
-    }
-
-    private static void compressDirectoryToZipFile(String rootDir,
-                                                   String sourceDir,
-                                                   ZipOutputStream zos)
-                                                   throws IOException {
-        String dir = Paths.get(rootDir, sourceDir).toString();
-        File[] files = new File(dir).listFiles();
-        E.checkNotNull(files, "files");
-        for (File file : files) {
-            String child = Paths.get(sourceDir, file.getName()).toString();
-            if (file.isDirectory()) {
-                compressDirectoryToZipFile(rootDir, child, zos);
-            } else {
-                zos.putNextEntry(new ZipEntry(child));
-                try (FileInputStream fis = new FileInputStream(file);
-                     BufferedInputStream bis = new BufferedInputStream(fis)) {
-                    IOUtils.copy(bis, zos);
-                }
-            }
-        }
-    }
-
-    public static void decompress(String sourceFile, String outputDir,
-                                  Checksum checksum) throws IOException {
-        try (FileInputStream fis = new FileInputStream(sourceFile);
-             CheckedInputStream cis = new CheckedInputStream(fis, checksum);
-             BufferedInputStream bis = new BufferedInputStream(cis);
-             ZipInputStream zis = new ZipInputStream(bis)) {
-            ZipEntry entry;
-            while ((entry = zis.getNextEntry()) != null) {
-                String fileName = entry.getName();
-                File entryFile = new File(Paths.get(outputDir, fileName)
-                                               .toString());
-                FileUtils.forceMkdir(entryFile.getParentFile());
-                try (FileOutputStream fos = new FileOutputStream(entryFile);
-                     BufferedOutputStream bos = new BufferedOutputStream(fos)) {
-                    IOUtils.copy(zis, bos);
-                    bos.flush();
-                    fos.getFD().sync();
-                }
-            }
-            // Continue to read all remaining bytes(extra metadata of ZipEntry)
-            // directly from the checked stream, Otherwise, the checksum value
-            // maybe unexpected.
-            //
-            // See https://coderanch.com/t/279175/java/ZipInputStream
-            IOUtils.copy(cis, NullOutputStream.NULL_OUTPUT_STREAM);
-        }
-    }
-}

hugegraph-dist/src/assembly/static/bin/util.sh

@@ -154,8 +154,10 @@ function free_memory() {
         free=`expr $mem_free + $mem_buffer + $mem_cached`
         free=`expr $free / 1024`
     elif [ "$os" == "Darwin" ]; then
-        free=`top -l 1 | head -n 10 | grep PhysMem | awk -F',' '{print $2}' \
-             | awk -F'M' '{print $1}' | tr -d " "`
+        local pages_free=`vm_stat | awk '/Pages free/{print $0}' | awk -F'[:.]+' '{print $2}' | tr -d " "`
+        local pages_inactive=`vm_stat | awk '/Pages inactive/{print $0}' | awk -F'[:.]+' '{print $2}' | tr -d " "`
+        local pages_available=`expr $pages_free + $pages_inactive`
+        free=`expr $pages_available \* 4096 / 1024 / 1024`
     else
         echo "Unsupported operating system $os"
         exit 1

hugegraph-dist/src/main/resources/verify-license.json

@@ -1,7 +1,7 @@
 {
   "subject": "hugegraph-license",
   "public_alias": "publiccert",
-  "store_password": "803b6cc3-d144-47e8-948f-ec8b39c8881e",
+  "store_ticket": "803b6cc3-d144-47e8-948f-ec8b39c8881e",
   "publickey_path": "/public-certs.store",
   "license_path": "conf/hugegraph-community.license"
 }

hugegraph-rocksdb/src/main/java/com/baidu/hugegraph/backend/store/rocksdb/RocksDBSessions.java

@@ -79,9 +79,11 @@ public abstract class RocksDBSessions extends BackendSessionPool {
         public abstract void merge(String table, byte[] key, byte[] value);
         public abstract void increase(String table, byte[] key, byte[] value);
 
-        public abstract void remove(String table, byte[] key);
-        public abstract void delete(String table, byte[] keyFrom, byte[] keyTo);
         public abstract void delete(String table, byte[] key);
+        public abstract void deleteSingle(String table, byte[] key);
+        public abstract void deletePrefix(String table, byte[] key);
+        public abstract void deleteRange(String table,
+                                         byte[] keyFrom, byte[] keyTo);
 
         public abstract byte[] get(String table, byte[] key);
 

hugegraph-rocksdb/src/main/java/com/baidu/hugegraph/backend/store/rocksdb/RocksDBStdSessions.java

@@ -512,7 +512,7 @@ public class RocksDBStdSessions extends RocksDBSessions {
             E.checkArgument(compressions.isEmpty() ||
                             compressions.size() == numLevels,
                             "Elements number of '%s' must be 0 or " +
-                            "be the same as '%s', bug got %s != %s",
+                            "be the same as '%s', but got %s != %s",
                             RocksDBOptions.LEVELS_COMPRESSIONS.name(),
                             RocksDBOptions.NUM_LEVELS.name(),
                             compressions.size(), numLevels);
@@ -840,7 +840,20 @@ public class RocksDBStdSessions extends RocksDBSessions {
          * Delete a record by key from a table
          */
         @Override
-        public void remove(String table, byte[] key) {
+        public void delete(String table, byte[] key) {
+            try (CFHandle cf = cf(table)) {
+                this.batch.delete(cf.get(), key);
+            } catch (RocksDBException e) {
+                throw new BackendException(e);
+            }
+        }
+
+        /**
+         * Delete the only one version of a record by key from a table
+         * NOTE: requires that the key exists and was not overwritten.
+         */
+        @Override
+        public void deleteSingle(String table, byte[] key) {
             try (CFHandle cf = cf(table)) {
                 this.batch.singleDelete(cf.get(), key);
             } catch (RocksDBException e) {
@@ -852,7 +865,7 @@ public class RocksDBStdSessions extends RocksDBSessions {
          * Delete a record by key(or prefix with key) from a table
          */
         @Override
-        public void delete(String table, byte[] key) {
+        public void deletePrefix(String table, byte[] key) {
             byte[] keyFrom = key;
             byte[] keyTo = Arrays.copyOf(key, key.length);
             keyTo = BinarySerializer.increaseOne(keyTo);
@@ -867,7 +880,7 @@ public class RocksDBStdSessions extends RocksDBSessions {
          * Delete a range of keys from a table
          */
         @Override
-        public void delete(String table, byte[] keyFrom, byte[] keyTo) {
+        public void deleteRange(String table, byte[] keyFrom, byte[] keyTo) {
             try (CFHandle cf = cf(table)) {
                 this.batch.deleteRange(cf.get(), keyFrom, keyTo);
             } catch (RocksDBException e) {

hugegraph-rocksdb/src/main/java/com/baidu/hugegraph/backend/store/rocksdb/RocksDBTable.java

@@ -103,7 +103,7 @@ public class RocksDBTable extends BackendTable<Session, BackendEntry> {
         } else {
             for (BackendColumn col : entry.columns()) {
                 assert entry.belongToMe(col) : entry;
-                session.remove(this.table(), col.name);
+                session.delete(this.table(), col.name);
             }
         }
     }
@@ -271,7 +271,7 @@ public class RocksDBTable extends BackendTable<Session, BackendEntry> {
     }
 
     protected static final long sizeOfBackendEntry(BackendEntry entry) {
-        return BinaryEntryIterator.sizeOfBackendEntry(entry);
+        return BinaryEntryIterator.sizeOfEntry(entry);
     }
 
     private static class RocksDBShardSpliter extends ShardSpliter<Session> {
@@ -327,7 +327,7 @@ public class RocksDBTable extends BackendTable<Session, BackendEntry> {
 
         @Override
         public byte[] position(String position) {
-            if (END.equals(position)) {
+            if (START.equals(position) || END.equals(position)) {
                 return null;
             }
             return StringEncoding.decodeBase64(position);

hugegraph-rocksdb/src/main/java/com/baidu/hugegraph/backend/store/rocksdb/RocksDBTables.java

@@ -75,7 +75,20 @@ public class RocksDBTables {
         }
     }
 
-    public static class VertexLabel extends RocksDBTable {
+    public static class SchemaTable extends RocksDBTable {
+
+        public SchemaTable(String database, String table) {
+            super(database, table);
+        }
+
+        @Override
+        public void delete(Session session, BackendEntry entry) {
+            assert entry.columns().isEmpty();
+            session.deletePrefix(this.table(), entry.id().asBytes());
+        }
+    }
+
+    public static class VertexLabel extends SchemaTable {
 
         public static final String TABLE = HugeType.VERTEX_LABEL.string();
 
@@ -84,7 +97,7 @@ public class RocksDBTables {
         }
     }
 
-    public static class EdgeLabel extends RocksDBTable {
+    public static class EdgeLabel extends SchemaTable {
 
         public static final String TABLE = HugeType.EDGE_LABEL.string();
 
@@ -93,7 +106,7 @@ public class RocksDBTables {
         }
     }
 
-    public static class PropertyKey extends RocksDBTable {
+    public static class PropertyKey extends SchemaTable {
 
         public static final String TABLE = HugeType.PROPERTY_KEY.string();
 
@@ -102,7 +115,7 @@ public class RocksDBTables {
         }
     }
 
-    public static class IndexLabel extends RocksDBTable {
+    public static class IndexLabel extends SchemaTable {
 
         public static final String TABLE = HugeType.INDEX_LABEL.string();
 
@@ -168,7 +181,7 @@ public class RocksDBTables {
              */
             for (BackendEntry.BackendColumn column : entry.columns()) {
                 // Don't assert entry.belongToMe(column), length-prefix is 1*
-                session.delete(this.table(), column.name);
+                session.deletePrefix(this.table(), column.name);
             }
         }
     }

hugegraph-rocksdb/src/main/java/com/baidu/hugegraph/backend/store/rocksdbsst/RocksDBSstSessions.java

@@ -325,24 +325,33 @@ public class RocksDBSstSessions extends RocksDBSessions {
          * Delete a record by key from a table
          */
         @Override
-        public void remove(String table, byte[] key) {
-            throw new NotSupportException("RocksDBSstStore remove()");
+        public void delete(String table, byte[] key) {
+            throw new NotSupportException("RocksDBSstStore delete()");
+        }
+
+        /**
+         * Delete the only one version of a record by key from a table
+         * NOTE: requires that the key exists and was not overwritten.
+         */
+        @Override
+        public void deleteSingle(String table, byte[] key) {
+            throw new NotSupportException("RocksDBSstStore deleteSingle()");
         }
 
         /**
          * Delete a record by key(or prefix with key) from a table
          */
         @Override
-        public void delete(String table, byte[] key) {
-            throw new NotSupportException("RocksDBSstStore delete()");
+        public void deletePrefix(String table, byte[] key) {
+            throw new NotSupportException("RocksDBSstStore deletePrefix()");
         }
 
         /**
          * Delete a range of keys from a table
          */
         @Override
-        public void delete(String table, byte[] keyFrom, byte[] keyTo) {
-            throw new NotSupportException("RocksDBSstStore delete()");
+        public void deleteRange(String table, byte[] keyFrom, byte[] keyTo) {
+            throw new NotSupportException("RocksDBSstStore deleteRange()");
         }
 
         /**

hugegraph-test/src/main/java/com/baidu/hugegraph/api/EdgeApiTest.java

@@ -107,7 +107,7 @@ public class EdgeApiTest extends BaseApiTest {
         // Now allowed to modify sortkey values, the property 'date' has changed
         content = assertResponseStatus(400, r);
         Assert.assertTrue(content.contains(
-                          "either be null or equal to origin when " +
+                          "either be null or equal to the origin value when " +
                           "specified edge id"));
 
         // Update edge without edgeId

hugegraph-test/src/main/java/com/baidu/hugegraph/core/EdgeCoreTest.java

@@ -5114,9 +5114,15 @@ public class EdgeCoreTest extends BaseCoreTest {
         while (page != null) {
             GraphTraversal<?, ?> iterator = graph.traversal().V(james).bothE()
                                                  .has("~page", page).limit(1);
-            Assert.assertEquals(1, IteratorUtils.count(iterator));
+            long size = IteratorUtils.count(iterator);
+            if (size == 0L) {
+                // The last page is empty
+                Assert.assertEquals(6, count);
+            } else {
+                Assert.assertEquals(1, size);
+            }
             page = TraversalUtil.page(iterator);
-            count++;
+            count += size;
         }
         Assert.assertEquals(6, count);
     }
@@ -5134,9 +5140,15 @@ public class EdgeCoreTest extends BaseCoreTest {
         while (page != null) {
             GraphTraversal<?, ?> iterator = graph.traversal().V(james).outE()
                                                  .has("~page", page).limit(1);
-            Assert.assertEquals(1, IteratorUtils.count(iterator));
+            long size = IteratorUtils.count(iterator);
+            if (size == 0L) {
+                // The last page is empty
+                Assert.assertEquals(4, count);
+            } else {
+                Assert.assertEquals(1, size);
+            }
             page = TraversalUtil.page(iterator);
-            count++;
+            count += size;
         }
         Assert.assertEquals(4, count);
     }
@@ -5154,9 +5166,15 @@ public class EdgeCoreTest extends BaseCoreTest {
         while (page != null) {
             GraphTraversal<?, ?> iterator = graph.traversal().V(james).inE()
                                                  .has("~page", page).limit(1);
-            Assert.assertEquals(1, IteratorUtils.count(iterator));
+            long size = IteratorUtils.count(iterator);
+            if (size == 0L) {
+                // The last page is empty
+                Assert.assertEquals(2, count);
+            } else {
+                Assert.assertEquals(1, size);
+            }
             page = TraversalUtil.page(iterator);
-            count++;
+            count += size;
         }
         Assert.assertEquals(2, count);
     }
@@ -6728,7 +6746,48 @@ public class EdgeCoreTest extends BaseCoreTest {
     }
 
     @Test
-    public void testQueryEdgeByPageResultsMatched() {
+    public void testQueryEdgeByPageResultsMatchedAll() {
+        Assume.assumeTrue("Not support paging",
+                          storeFeatures().supportsQueryByPage());
+
+        HugeGraph graph = graph();
+        init100LookEdges();
+
+        List<Edge> all = graph.traversal().E().toList();
+
+        GraphTraversal<Edge, Edge> iter;
+
+        String page = PageInfo.PAGE_NONE;
+        int size = 21;
+
+        Set<Edge> pageAll = new HashSet<>();
+        for (int i = 0; i < 100 / size; i++) {
+            iter = graph.traversal().E()
+                        .has("~page", page).limit(size);
+            @SuppressWarnings("unchecked")
+            List<Edge> edges = IteratorUtils.asList(iter);
+            Assert.assertEquals(size, edges.size());
+
+            pageAll.addAll(edges);
+
+            page = TraversalUtil.page(iter);
+        }
+
+        iter = graph.traversal().E()
+                    .has("~page", page).limit(size);
+        @SuppressWarnings("unchecked")
+        List<Edge> edges = IteratorUtils.asList(iter);
+        Assert.assertEquals(16, edges.size());
+        pageAll.addAll(edges);
+        page = TraversalUtil.page(iter);
+
+        Assert.assertEquals(100, pageAll.size());
+        Assert.assertTrue(all.containsAll(pageAll));
+        Assert.assertNull(page);
+    }
+
+    @Test
+    public void testQueryEdgeByPageResultsMatchedAllWithFullPage() {
         Assume.assumeTrue("Not support paging",
                           storeFeatures().supportsQueryByPage());
 
@@ -6756,6 +6815,15 @@ public class EdgeCoreTest extends BaseCoreTest {
         }
         Assert.assertEquals(100, pageAll.size());
         Assert.assertTrue(all.containsAll(pageAll));
+
+        if (page != null) {
+            iter = graph.traversal().E().has("~page", page);
+            long count = IteratorUtils.count(iter);
+            Assert.assertEquals(0L, count);
+
+            page = TraversalUtil.page(iter);
+            CloseableIterator.closeIterator(iter);
+        }
         Assert.assertNull(page);
     }
 
@@ -6962,9 +7030,10 @@ public class EdgeCoreTest extends BaseCoreTest {
         int count = 0;
         while (page != null) {
             GraphTraversal<?, ?> iterator = fetcher.apply(page);
-            Assert.assertEquals(1, IteratorUtils.count(iterator));
+            long size = IteratorUtils.count(iterator);
+            Assert.assertLte(1L, size);
             page = TraversalUtil.page(iterator);
-            count++;
+            count += size;
         }
         return count;
     }

hugegraph-test/src/main/java/com/baidu/hugegraph/core/EdgeLabelCoreTest.java

@@ -765,6 +765,31 @@ public class EdgeLabelCoreTest extends SchemaCoreTest {
 
     }
 
+    @Test
+    public void testAppendEdgeLabelWithSkAsNullableProperties() {
+        super.initPropertyKeys();
+        SchemaManager schema = graph().schema();
+        schema.vertexLabel("person")
+              .properties("name", "age", "city")
+              .primaryKeys("name")
+              .create();
+        schema.vertexLabel("book").properties("id", "name")
+              .primaryKeys("id").create();
+        schema.edgeLabel("look")
+              .properties("time")
+              .link("person", "book")
+              .multiTimes().sortKeys("time")
+              .create();
+
+        Assert.assertThrows(IllegalArgumentException.class, () -> {
+            schema.edgeLabel("look")
+                  .properties("time", "weight")
+                  .nullableKeys("time", "weight")
+                  .append();
+        });
+
+    }
+
     @Test
     public void testRemoveEdgeLabel() {
         super.initPropertyKeys();

hugegraph-test/src/main/java/com/baidu/hugegraph/core/TaskCoreTest.java

@@ -255,9 +255,9 @@ public class TaskCoreTest extends BaseCoreTest {
                 + "schema.propertyKey('lang').asText().ifNotExist().create();"
                 + "schema.propertyKey('date').asDate().ifNotExist().create();"
                 + "schema.propertyKey('price').asInt().ifNotExist().create();"
-                + "person1=schema.vertexLabel('person1').properties('name','age').ifNotExist().create();"
-                + "person2=schema.vertexLabel('person2').properties('name','age').ifNotExist().create();"
-                + "knows=schema.edgeLabel('knows').sourceLabel('person1').targetLabel('person2').properties('date').ifNotExist().create();"
+                + "schema.vertexLabel('person1').properties('name','age').ifNotExist().create();"
+                + "schema.vertexLabel('person2').properties('name','age').ifNotExist().create();"
+                + "schema.edgeLabel('knows').sourceLabel('person1').targetLabel('person2').properties('date').ifNotExist().create();"
                 + "for(int i = 0; i < 1000; i++) {"
                 + "  p1=graph.addVertex(T.label,'person1','name','p1-'+i,'age',29);"
                 + "  p2=graph.addVertex(T.label,'person2','name','p2-'+i,'age',27);"
@@ -302,6 +302,89 @@ public class TaskCoreTest extends BaseCoreTest {
         Assert.assertEquals("[1000]", task.result());
     }
 
+    @Test
+    public void testGremlinJobWithSerializedResults() throws TimeoutException {
+        HugeGraph graph = graph();
+        TaskScheduler scheduler = graph.taskScheduler();
+
+        String script = "schema=graph.schema();"
+                + "schema.propertyKey('name').asText().ifNotExist().create();"
+                + "schema.vertexLabel('char').useCustomizeNumberId().properties('name').ifNotExist().create();"
+                + "schema.edgeLabel('next').sourceLabel('char').targetLabel('char').properties('name').ifNotExist().create();"
+                + "g.addV('char').property(id,1).property('name','A').as('a')"
+                + " .addV('char').property(id,2).property('name','B').as('b')"
+                + " .addV('char').property(id,3).property('name','C').as('c')"
+                + " .addV('char').property(id,4).property('name','D').as('d')"
+                + " .addV('char').property(id,5).property('name','E').as('e')"
+                + " .addV('char').property(id,6).property('name','F').as('f')"
+                + " .addE('next').from('a').to('b').property('name','ab')"
+                + " .addE('next').from('b').to('c').property('name','bc')"
+                + " .addE('next').from('b').to('d').property('name','bd')"
+                + " .addE('next').from('c').to('d').property('name','cd')"
+                + " .addE('next').from('c').to('e').property('name','ce')"
+                + " .addE('next').from('d').to('e').property('name','de')"
+                + " .addE('next').from('e').to('f').property('name','ef')"
+                + " .addE('next').from('f').to('d').property('name','fd')"
+                + " .iterate();"
+                + "g.tx().commit(); g.E().count();";
+
+        HugeTask<Object> task = runGremlinJob(script);
+        task = scheduler.waitUntilTaskCompleted(task.id(), 10);
+        Assert.assertEquals("test-gremlin-job", task.name());
+        Assert.assertEquals("gremlin", task.type());
+        Assert.assertEquals(TaskStatus.SUCCESS, task.status());
+        Assert.assertEquals("[8]", task.result());
+
+        Id edgeLabelId = graph.schema().getEdgeLabel("next").id();
+
+        script = "g.V(1).outE().inV().path()";
+        task = runGremlinJob(script);
+        task = scheduler.waitUntilTaskCompleted(task.id(), 10);
+        Assert.assertEquals(TaskStatus.SUCCESS, task.status());
+        String expected = String.format("[{\"labels\":[[],[],[]],\"objects\":["
+                + "{\"id\":1,\"label\":\"char\",\"type\":\"vertex\",\"properties\":{\"name\":\"A\"}},"
+                + "{\"id\":\"L1>%s>>L2\",\"label\":\"next\",\"type\":\"edge\",\"outV\":1,\"outVLabel\":\"char\",\"inV\":2,\"inVLabel\":\"char\",\"properties\":{\"name\":\"ab\"}},"
+                + "{\"id\":2,\"label\":\"char\",\"type\":\"vertex\",\"properties\":{\"name\":\"B\"}}"
+                + "]}]", edgeLabelId);
+        Assert.assertEquals(expected, task.result());
+
+        script = "g.V(1).out().out().path()";
+        task = runGremlinJob(script);
+        task = scheduler.waitUntilTaskCompleted(task.id(), 10);
+        Assert.assertEquals(TaskStatus.SUCCESS, task.status());
+        expected = "[{\"labels\":[[],[],[]],\"objects\":["
+                + "{\"id\":1,\"label\":\"char\",\"type\":\"vertex\",\"properties\":{\"name\":\"A\"}},"
+                + "{\"id\":2,\"label\":\"char\",\"type\":\"vertex\",\"properties\":{\"name\":\"B\"}},"
+                + "{\"id\":3,\"label\":\"char\",\"type\":\"vertex\",\"properties\":{\"name\":\"C\"}}]},"
+                + "{\"labels\":[[],[],[]],\"objects\":["
+                + "{\"id\":1,\"label\":\"char\",\"type\":\"vertex\",\"properties\":{\"name\":\"A\"}},"
+                + "{\"id\":2,\"label\":\"char\",\"type\":\"vertex\",\"properties\":{\"name\":\"B\"}},"
+                + "{\"id\":4,\"label\":\"char\",\"type\":\"vertex\",\"properties\":{\"name\":\"D\"}}]}]";
+        Assert.assertEquals(expected, task.result());
+
+        script = "g.V(1).outE().inV().tree()";
+        task = runGremlinJob(script);
+        task = scheduler.waitUntilTaskCompleted(task.id(), 10);
+        Assert.assertEquals(TaskStatus.SUCCESS, task.status());
+        expected = String.format("[[{\"key\":{\"id\":1,\"label\":\"char\",\"type\":\"vertex\",\"properties\":{\"name\":\"A\"}},"
+                + "\"value\":["
+                + "{\"key\":{\"id\":\"L1>%s>>L2\",\"label\":\"next\",\"type\":\"edge\",\"outV\":1,\"outVLabel\":\"char\",\"inV\":2,\"inVLabel\":\"char\",\"properties\":{\"name\":\"ab\"}},"
+                + "\"value\":[{\"key\":{\"id\":2,\"label\":\"char\",\"type\":\"vertex\",\"properties\":{\"name\":\"B\"}},\"value\":[]}]}]}]]",
+                edgeLabelId);
+        Assert.assertEquals(expected, task.result());
+
+        script = "g.V(1).out().out().tree()";
+        task = runGremlinJob(script);
+        task = scheduler.waitUntilTaskCompleted(task.id(), 10);
+        Assert.assertEquals(TaskStatus.SUCCESS, task.status());
+        expected = "[[{\"key\":{\"id\":1,\"label\":\"char\",\"type\":\"vertex\",\"properties\":{\"name\":\"A\"}},"
+                + "\"value\":[{\"key\":{\"id\":2,\"label\":\"char\",\"type\":\"vertex\",\"properties\":{\"name\":\"B\"}},"
+                + "\"value\":["
+                + "{\"key\":{\"id\":3,\"label\":\"char\",\"type\":\"vertex\",\"properties\":{\"name\":\"C\"}},\"value\":[]},"
+                + "{\"key\":{\"id\":4,\"label\":\"char\",\"type\":\"vertex\",\"properties\":{\"name\":\"D\"}},\"value\":[]}]}]}]]";
+        Assert.assertEquals(expected, task.result());
+    }
+
     @Test
     public void testGremlinJobWithFailure() throws TimeoutException {
         HugeGraph graph = graph();

hugegraph-test/src/main/java/com/baidu/hugegraph/core/VertexCoreTest.java

@@ -52,6 +52,7 @@ import com.baidu.hugegraph.backend.id.IdGenerator;
 import com.baidu.hugegraph.backend.id.SnowflakeIdGenerator;
 import com.baidu.hugegraph.backend.id.SplicingIdGenerator;
 import com.baidu.hugegraph.backend.page.PageInfo;
+import com.baidu.hugegraph.backend.page.PageState;
 import com.baidu.hugegraph.backend.query.Condition;
 import com.baidu.hugegraph.backend.query.ConditionQuery;
 import com.baidu.hugegraph.backend.query.Query;
@@ -6456,7 +6457,49 @@ public class VertexCoreTest extends BaseCoreTest {
     }
 
     @Test
-    public void testQueryByPageResultsMatched() {
+    public void testQueryByPageResultsMatchedAll() {
+        Assume.assumeTrue("Not support paging",
+                          storeFeatures().supportsQueryByPage());
+
+        HugeGraph graph = graph();
+        init100Books();
+
+        List<Vertex> all = graph.traversal().V().toList();
+
+        GraphTraversal<Vertex, Vertex> iter;
+
+        String page = PageInfo.PAGE_NONE;
+        int size = 22;
+
+        Set<Vertex> pageAll = new HashSet<>();
+        for (int i = 0; i < 100 / size; i++) {
+            iter = graph.traversal().V()
+                        .has("~page", page).limit(size);
+            @SuppressWarnings("unchecked")
+            List<Vertex> vertices = IteratorUtils.asList(iter);
+            Assert.assertEquals(size, vertices.size());
+
+            pageAll.addAll(vertices);
+
+            page = TraversalUtil.page(iter);
+            CloseableIterator.closeIterator(iter);
+        }
+
+        iter = graph.traversal().V()
+                    .has("~page", page).limit(size);
+        @SuppressWarnings("unchecked")
+        List<Vertex> vertices = IteratorUtils.asList(iter);
+        Assert.assertEquals(12, vertices.size());
+        pageAll.addAll(vertices);
+        page = TraversalUtil.page(iter);
+
+        Assert.assertEquals(100, pageAll.size());
+        Assert.assertTrue(all.containsAll(pageAll));
+        Assert.assertNull(page);
+    }
+
+    @Test
+    public void testQueryByPageResultsMatchedAllWithFullPage() {
         Assume.assumeTrue("Not support paging",
                           storeFeatures().supportsQueryByPage());
 
@@ -6485,6 +6528,15 @@ public class VertexCoreTest extends BaseCoreTest {
         }
         Assert.assertEquals(100, pageAll.size());
         Assert.assertTrue(all.containsAll(pageAll));
+
+        if (page != null) {
+            iter = graph.traversal().V().has("~page", page);
+            long count = IteratorUtils.count(iter);
+            Assert.assertEquals(0L, count);
+
+            page = TraversalUtil.page(iter);
+            CloseableIterator.closeIterator(iter);
+        }
         Assert.assertNull(page);
     }
 
@@ -6511,6 +6563,35 @@ public class VertexCoreTest extends BaseCoreTest {
         });
     }
 
+    @Test
+    public void testQueryByPageWithSpecialBase64Chars() {
+        Assume.assumeTrue("Not support paging",
+                          storeFeatures().supportsQueryByPage());
+        final String pageWith3Base64Chars = "AAAAADsyABwAEAqI546LS6WW57unBgA" +
+                                            "EAAAAAPB////+8H////4alhxAZS8va6" +
+                                            "opcAKpklipAAQAAAAAAAAAAQ==";
+
+        final String pageWithSpace = "AAAAADsyABwAEAqI546LS6WW57unBgAEAAAAAP" +
+                                     "B//// 8H////4alhxAZS8va6opcAKpklipAAQA" +
+                                     "AAAAAAAAAQ==";
+
+        HugeGraph graph = graph();
+        init100Books();
+
+        // Contains valid character '+' and '/' and '='
+        GraphTraversal<Vertex, Vertex> traversal;
+        traversal = graph.traversal().V()
+                         .has("~page", pageWith3Base64Chars).limit(10);
+        Assert.assertNotNull(traversal);
+        CloseableIterator.closeIterator(traversal);
+
+        // Contains invalid base64 character ' ', will be replaced to '+'
+        traversal = graph.traversal().V()
+                         .has("~page", pageWithSpace).limit(10);
+        Assert.assertNotNull(traversal);
+        CloseableIterator.closeIterator(traversal);
+    }
+
     @Test
     public void testQueryByPageWithInvalidLimit() {
         Assume.assumeTrue("Not support paging",

hugegraph-test/src/main/java/com/baidu/hugegraph/core/VertexLabelCoreTest.java

@@ -737,6 +737,23 @@ public class VertexLabelCoreTest extends SchemaCoreTest {
         });
     }
 
+    @Test
+    public void testAppendVertexLabelWithPkAsNullableProperties() {
+        super.initPropertyKeys();
+        SchemaManager schema = graph().schema();
+
+        schema.vertexLabel("person")
+              .properties("name", "age")
+              .primaryKeys("name")
+              .create();
+        Assert.assertThrows(IllegalArgumentException.class, () -> {
+            schema.vertexLabel("person")
+                  .properties("name", "city")
+                  .nullableKeys("name", "city")
+                  .append();
+        });
+    }
+
     @Test
     public void testRemoveVertexLabel() {
         super.initPropertyKeys();

hugegraph-test/src/main/java/com/baidu/hugegraph/tinkerpop/TestGraph.java

@@ -44,6 +44,7 @@ import com.baidu.hugegraph.perf.PerfUtil.Watched;
 import com.baidu.hugegraph.schema.PropertyKey;
 import com.baidu.hugegraph.schema.SchemaManager;
 import com.baidu.hugegraph.task.TaskScheduler;
+import com.baidu.hugegraph.testutil.Whitebox;
 import com.baidu.hugegraph.type.define.IdStrategy;
 import com.baidu.hugegraph.type.define.NodeRole;
 import com.google.common.collect.ImmutableSet;
@@ -251,7 +252,8 @@ public class TestGraph implements Graph {
     @SuppressWarnings({ "unchecked", "rawtypes" })
     @Override
     public <I extends Io> I io(final Io.Builder<I> builder) {
-        HugeGraphSONModule.OPTIMIZE_SERIALIZE = false;
+        Whitebox.setInternalState(HugeGraphSONModule.class,
+                                  "OPTIMIZE_SERIALIZE", false);
         return (I) builder.graph(this).onMapper(mapper ->
             mapper.addRegistry(HugeGraphIoRegistry.instance())
         ).create();

hugegraph-test/src/main/java/com/baidu/hugegraph/unit/UnitTestSuite.java

@@ -37,6 +37,7 @@ import com.baidu.hugegraph.unit.core.DataTypeTest;
 import com.baidu.hugegraph.unit.core.DirectionsTest;
 import com.baidu.hugegraph.unit.core.ExceptionTest;
 import com.baidu.hugegraph.unit.core.LocksTableTest;
+import com.baidu.hugegraph.unit.core.PageStateTest;
 import com.baidu.hugegraph.unit.core.QueryTest;
 import com.baidu.hugegraph.unit.core.RangeTest;
 import com.baidu.hugegraph.unit.core.RolePermissionTest;
@@ -59,6 +60,7 @@ import com.baidu.hugegraph.unit.serializer.SerializerFactoryTest;
 import com.baidu.hugegraph.unit.serializer.StoreSerializerTest;
 import com.baidu.hugegraph.unit.serializer.TableBackendEntryTest;
 import com.baidu.hugegraph.unit.serializer.TextBackendEntryTest;
+import com.baidu.hugegraph.unit.util.CompressUtilTest;
 import com.baidu.hugegraph.unit.util.JsonUtilTest;
 import com.baidu.hugegraph.unit.util.StringEncodingTest;
 import com.baidu.hugegraph.unit.util.VersionTest;
@@ -98,6 +100,7 @@ import com.baidu.hugegraph.unit.util.VersionTest;
     ExceptionTest.class,
     BackendStoreSystemInfoTest.class,
     TraversalUtilTest.class,
+    PageStateTest.class,
 
     /* serializer */
     BytesBufferTest.class,
@@ -123,7 +126,8 @@ import com.baidu.hugegraph.unit.util.VersionTest;
     /* utils */
     VersionTest.class,
     JsonUtilTest.class,
-    StringEncodingTest.class
+    StringEncodingTest.class,
+    CompressUtilTest.class
 })
 public class UnitTestSuite {
 }

hugegraph-test/src/main/java/com/baidu/hugegraph/unit/core/PageStateTest.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2017 HugeGraph Authors
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with this
+ * work for additional information regarding copyright ownership. The ASF
+ * licenses this file to You under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+
+package com.baidu.hugegraph.unit.core;
+
+import java.util.Arrays;
+
+import org.junit.Test;
+
+import com.baidu.hugegraph.backend.BackendException;
+import com.baidu.hugegraph.backend.page.PageState;
+import com.baidu.hugegraph.testutil.Assert;
+
+public class PageStateTest {
+
+    private String pageWith3Base64Chars = "AAAAADsyABwAEAqI546LS6WW57unBgA" +
+                                          "EAAAAAPB////+8H////4alhxAZS8va6" +
+                                          "opcAKpklipAAQAAAAAAAAAAQ==";
+
+    private String pageWithSpace = "AAAAADsyABwAEAqI546LS6WW57unBgAEAAAAAP" +
+                                   "B//// 8H////4alhxAZS8va6opcAKpklipAAQA" +
+                                   "AAAAAAAAAQ==";
+
+    @Test
+    public void testOriginalStringPageToBytes() {
+        byte[] validPage = PageState.toBytes(pageWith3Base64Chars);
+        Assert.assertNotNull(validPage);
+
+        Assert.assertThrows(BackendException.class, () -> {
+            PageState.toBytes(pageWithSpace);
+        }, e -> {
+            Assert.assertContains("Invalid page:", e.toString());
+        });
+    }
+
+    @Test
+    public void testDecodePageWithSpecialBase64Chars() {
+        // Assert decode '+' and '/' and '=' and space successfully
+        Assert.assertNotNull(PageState.fromString(pageWith3Base64Chars));
+
+        byte[] decodePlus = PageState.fromString(pageWith3Base64Chars)
+                                     .position();
+        byte[] decodeSpace = PageState.fromString(pageWithSpace).position();
+
+        Assert.assertTrue(Arrays.equals(decodePlus, decodeSpace));
+    }
+
+    @Test
+    public void testDecodePageWithInvalidStringPage() {
+        final String invalidPageWithBase64Chars = "dGVzdCBiYXNlNjQ=";
+
+        Assert.assertThrows(BackendException.class, () -> {
+            PageState.fromString(invalidPageWithBase64Chars);
+        }, e -> {
+            Assert.assertContains("Invalid page: '0x", e.toString());
+        });
+
+        final String invalidBase64Chars = "!abc~";
+        Assert.assertThrows(BackendException.class, () -> {
+            PageState.fromString(invalidBase64Chars);
+        }, e -> {
+            Assert.assertContains("Invalid page:", e.toString());
+        });
+    }
+
+    @Test
+    public void testEmptyPageState() {
+        Assert.assertEquals(0, PageState.EMPTY.offset());
+        Assert.assertNull(PageState.EMPTY.toString());
+
+        Assert.assertEquals(PageState.EMPTY,
+                            PageState.fromBytes(PageState.EMPTY_BYTES));
+    }
+}

hugegraph-test/src/main/java/com/baidu/hugegraph/unit/rocksdb/BaseRocksDBUnitTest.java

@@ -77,7 +77,8 @@ public class BaseRocksDBUnitTest extends BaseUnitTest {
 
     protected void clearData() throws RocksDBException {
         for (String table : new ArrayList<>(this.rocks.openedTables())) {
-            this.rocks.session().delete(table, new byte[]{0}, new byte[]{-1});
+            this.rocks.session().deleteRange(table,
+                                             new byte[]{0}, new byte[]{-1});
         }
         this.commit();
     }

hugegraph-test/src/main/java/com/baidu/hugegraph/unit/rocksdb/RocksDBPerfTest.java

@@ -141,7 +141,7 @@ public class RocksDBPerfTest extends BaseRocksDBUnitTest {
             for (int i = 0; i < n; i++) {
                 int value =  comms.get(i);
                 String old = String.format("index:%3d:%d", i, value);
-                session.remove(TABLE, b(old));
+                session.delete(TABLE, b(old));
 
                 value = r.nextInt(n); // TODO: aggregate
                 value =  i + 1;

hugegraph-test/src/main/java/com/baidu/hugegraph/unit/rocksdb/RocksDBSessionsTest.java

@@ -285,7 +285,7 @@ public class RocksDBSessionsTest extends BaseRocksDBUnitTest {
         Assert.assertEquals("19", get("person:1gage"));
         Assert.assertEquals("Beijing", get("person:1gcity"));
 
-        this.rocks.session().remove(TABLE, b("person:1gage"));
+        this.rocks.session().delete(TABLE, b("person:1gage"));
         this.commit();
 
         Assert.assertEquals("James", get("person:1gname"));
@@ -303,7 +303,7 @@ public class RocksDBSessionsTest extends BaseRocksDBUnitTest {
         Assert.assertEquals("19", get("person:1gage"));
         Assert.assertEquals("Beijing", get("person:1gcity"));
 
-        this.rocks.session().remove(TABLE, b("person:1"));
+        this.rocks.session().delete(TABLE, b("person:1"));
         this.commit();
 
         Assert.assertEquals("James", get("person:1gname"));
@@ -325,7 +325,7 @@ public class RocksDBSessionsTest extends BaseRocksDBUnitTest {
         Assert.assertEquals("19", get("person:1gage"));
         Assert.assertEquals("Beijing", get("person:1gcity"));
 
-        this.rocks.session().delete(TABLE, b("person:1"));
+        this.rocks.session().deletePrefix(TABLE, b("person:1"));
         this.commit();
 
         Assert.assertEquals(null, get("person:1gname"));
@@ -353,7 +353,7 @@ public class RocksDBSessionsTest extends BaseRocksDBUnitTest {
         Assert.assertEquals("Lisa", get("person:2gname"));
         Assert.assertEquals("Hebe", get("person:3gname"));
 
-        this.rocks.session().delete(TABLE, b("person:1"), b("person:3"));
+        this.rocks.session().deleteRange(TABLE, b("person:1"), b("person:3"));
         this.commit();
 
         Assert.assertEquals(null, get("person:1gname"));
@@ -385,7 +385,7 @@ public class RocksDBSessionsTest extends BaseRocksDBUnitTest {
         byte[] value21 = b("value-2-1");
         session.put(TABLE, key21, value21);
 
-        session.delete(TABLE, key11, new byte[]{1, 3});
+        session.deleteRange(TABLE, key11, new byte[]{1, 3});
         this.commit();
 
         Assert.assertArrayEquals(null, session.get(TABLE, key11));
@@ -409,14 +409,14 @@ public class RocksDBSessionsTest extends BaseRocksDBUnitTest {
         byte[] value21 = b("value-2-1");
         session.put(TABLE, key21, value21);
 
-        session.delete(TABLE, new byte[]{1, -3}, new byte[]{1, 3});
+        session.deleteRange(TABLE, new byte[]{1, -3}, new byte[]{1, 3});
         this.commit();
 
         Assert.assertArrayEquals(value11, session.get(TABLE, key11));
         Assert.assertArrayEquals(value12, session.get(TABLE, key12));
         Assert.assertArrayEquals(value21, session.get(TABLE, key21));
 
-        session.delete(TABLE, new byte[]{1, 1}, new byte[]{1, -1});
+        session.deleteRange(TABLE, new byte[]{1, 1}, new byte[]{1, -1});
         this.commit();
 
         Assert.assertArrayEquals(null, session.get(TABLE, key11));
@@ -448,7 +448,8 @@ public class RocksDBSessionsTest extends BaseRocksDBUnitTest {
         byte[] value20 = b("value-2-0");
         session.put(TABLE, key20, value20);
 
-        session.delete(TABLE, new byte[]{1, 0}, new byte[]{1, (byte) 0xff});
+        session.deleteRange(TABLE,
+                            new byte[]{1, 0}, new byte[]{1, (byte) 0xff});
         this.commit();
 
         Assert.assertArrayEquals(null, session.get(TABLE, key11));
@@ -457,7 +458,8 @@ public class RocksDBSessionsTest extends BaseRocksDBUnitTest {
         Assert.assertArrayEquals(value14, session.get(TABLE, key14));
         Assert.assertArrayEquals(value20, session.get(TABLE, key20));
 
-        session.delete(TABLE, new byte[]{1, (byte) 0xff}, new byte[]{2, 0});
+        session.deleteRange(TABLE,
+                            new byte[]{1, (byte) 0xff}, new byte[]{2, 0});
         this.commit();
 
         Assert.assertArrayEquals(null, session.get(TABLE, key11));

hugegraph-test/src/main/java/com/baidu/hugegraph/unit/util/CompressUtilTest.java

@@ -0,0 +1,134 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.baidu.hugegraph.unit.util;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.FileVisitResult;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.SimpleFileVisitor;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.util.Arrays;
+import java.util.zip.Checksum;
+
+import org.apache.commons.io.FileUtils;
+import org.junit.Test;
+
+import com.alipay.sofa.jraft.util.CRC64;
+import com.baidu.hugegraph.util.CompressUtil;
+import com.google.common.collect.ImmutableList;
+
+import junit.framework.AssertionFailedError;
+
+public class CompressUtilTest {
+
+    @Test
+    public void testZipCompress() throws IOException {
+        String rootDir = "temp";
+        // temp/ss
+        String sourceDir = "ss";
+        String zipFile = "output.zip";
+        String output = "output";
+        try {
+            prepareFiles(rootDir, sourceDir);
+
+            Checksum checksum = new CRC64();
+            CompressUtil.compressZip(rootDir, sourceDir, zipFile, checksum);
+
+            CompressUtil.decompressZip(zipFile, output, checksum);
+            assertDirEquals(rootDir, output);
+        } finally {
+            FileUtils.deleteQuietly(new File(rootDir));
+            FileUtils.deleteQuietly(new File(zipFile));
+            FileUtils.deleteQuietly(new File(output));
+        }
+    }
+
+    @Test
+    public void testTarCompress() throws IOException {
+        String rootDir = "temp";
+        // temp/ss
+        String sourceDir = "ss";
+        String tarFile = "output.tar";
+        String output = "output";
+        try {
+            prepareFiles(rootDir, sourceDir);
+
+            Checksum checksum = new CRC64();
+            CompressUtil.compressTar(rootDir, sourceDir, tarFile, checksum);
+
+            CompressUtil.decompressTar(tarFile, output, checksum);
+            assertDirEquals(rootDir, output);
+        } finally {
+            FileUtils.deleteQuietly(new File(rootDir));
+            FileUtils.deleteQuietly(new File(tarFile));
+            FileUtils.deleteQuietly(new File(output));
+        }
+    }
+
+    private static void prepareFiles(String rootDir, String sourceDir)
+                                     throws IOException {
+        // temp/ss/g
+        String gDir = Paths.get(rootDir, sourceDir, "g").toString();
+        File file1 = new File(gDir, "file-1");
+        FileUtils.writeLines(file1, ImmutableList.of("g1-aaa", "g1-bbb"));
+        File file2 = new File(gDir, "file-2");
+        FileUtils.writeLines(file2, ImmutableList.of("g2-aaa", "g2-bbb"));
+        // temp/ss/m
+        String mDir = Paths.get(rootDir, sourceDir, "m").toString();
+        file1 = new File(mDir, "file-1");
+        FileUtils.writeLines(file1, ImmutableList.of("m1-aaa", "m1-bbb"));
+        file2 = new File(mDir, "file-2");
+        FileUtils.writeLines(file2, ImmutableList.of("m2-aaa", "m2-bbb"));
+        // temp/ss/s
+        String sDir = Paths.get(rootDir, sourceDir, "s").toString();
+        file1 = new File(sDir, "file-1");
+        FileUtils.writeLines(file1, ImmutableList.of("s1-aaa", "s1-bbb"));
+        file2 = new File(sDir, "file-2");
+        FileUtils.writeLines(file2, ImmutableList.of("s2-aaa", "s2-bbb"));
+    }
+
+    private static void assertDirEquals(String expect, String actual)
+                                        throws IOException {
+        Path expectDir = Paths.get(expect);
+        Path actualDir = Paths.get(actual);
+        Files.walkFileTree(expectDir, new SimpleFileVisitor<Path>() {
+            @Override
+            public FileVisitResult visitFile(Path file,
+                                             BasicFileAttributes attrs)
+                                             throws IOException {
+                FileVisitResult result = super.visitFile(file, attrs);
+
+                // Get the relative file name from path "one"
+                Path relativize = expectDir.relativize(file);
+                // Construct the path for the counterpart file in "other"
+                Path fileInOther = actualDir.resolve(relativize);
+
+                byte[] theseBytes = Files.readAllBytes(file);
+                byte[] otherBytes = Files.readAllBytes(fileInOther);
+                if (!Arrays.equals(theseBytes, otherBytes)) {
+                    throw new AssertionFailedError(file + " is not equal to " +
+                                                   fileInOther);
+                }
+                return result;
+            }
+        });
+    }
+}

pom.xml

@@ -96,7 +96,7 @@
         <compiler.target>1.8</compiler.target>
         <slf4j.version>1.7.5</slf4j.version>
         <log4j.version>1.2.17</log4j.version>
-        <log4j2.version>2.12.1</log4j2.version>
+        <log4j2.version>2.17.0</log4j2.version>
         <junit.version>4.12</junit.version>
         <tinkerpop.version>3.4.3</tinkerpop.version>
         <commons.io.version>2.4</commons.io.version>