Add MergeTree Write-Ahead-Log(WAL) dump tool

utils/CMakeLists.txt

@@ -28,6 +28,7 @@ if (NOT DEFINED ENABLE_UTILS OR ENABLE_UTILS)
     add_subdirectory (test-data-generator)
     add_subdirectory (convert-month-partitioned-parts)
     add_subdirectory (checksum-for-compressed-block)
+    add_subdirectory (wal-dump)
 endif ()
 
 if (ENABLE_CODE_QUALITY)

utils/wal-dump/CMakeLists.txt

@@ -0,0 +1,2 @@
+add_executable (wal-dump main.cpp)
+target_link_libraries(wal-dump PRIVATE dbms boost::program_options)

utils/wal-dump/main.cpp

@@ -0,0 +1,78 @@
+#include <iostream>
+
+#include <boost/program_options.hpp>
+
+#include <Compression/CompressedReadBuffer.h>
+#include <Compression/CompressedReadBufferFromFile.h>
+#include <Compression/CompressedWriteBuffer.h>
+#include <DataStreams/NativeBlockInputStream.h>
+#include <IO/Operators.h>
+#include <IO/ReadBufferFromFile.h>
+#include <IO/ReadHelpers.h>
+#include <IO/WriteBufferFromFileDescriptor.h>
+#include <Storages/MergeTree/MergeTreeWriteAheadLog.h>
+
+/*
+ * Dump the Write Ahead Log file, outputs:
+ * Part 0, Version: 0, Action : ADD_PART, Name: 4_1_1_0, Block:
+   a Int32 Int32(size = 2), b Int32 Int32(size = 2), c Int32 Int32(size = 2)
+ */
+
+static void dump(const std::string & bin_path)
+{
+    DB::ReadBufferFromFile in(bin_path);
+    DB::NativeBlockInputStream block_in(in, 0);
+    DB::Block block;
+
+    DB::WriteBufferFromFileDescriptor out(STDOUT_FILENO);
+
+    for (size_t part_num = 0; !in.eof(); ++part_num)
+    {
+        UInt8 version;
+        String part_name;
+        DB::MergeTreeWriteAheadLog::ActionType action_type;
+
+        DB::readIntBinary(version, in);
+        DB::readIntBinary(action_type, in);
+        DB::readStringBinary(part_name, in);
+        block = block_in.read();
+
+        out << "Part " << part_num << ", Version: " << version
+            << ", Action : " << (action_type == DB::MergeTreeWriteAheadLog::ActionType::ADD_PART ? "ADD_PART" : "DROP_PART")
+            << ", Name: " << part_name << ", Block:\n";
+        out << block.dumpStructure() << "\n";
+        out << "\n" << DB::flush;
+    }
+}
+
+
+int main(int argc, char ** argv)
+{
+    boost::program_options::options_description desc("Allowed options");
+    desc.add_options()("help,h", "produce help message");
+
+    boost::program_options::variables_map options;
+    boost::program_options::store(boost::program_options::parse_command_line(argc, argv, desc), options);
+
+    if (options.count("help") || argc != 2)
+    {
+        std::cout << "Usage: " << argv[0] << " wal.bin" << std::endl;
+        std::cout << desc << std::endl;
+        return 1;
+    }
+
+    try
+    {
+        dump(argv[1]);
+    }
+    catch (const DB::Exception & e)
+    {
+        std::cerr << e.what() << ", " << e.message() << std::endl
+                  << std::endl
+                  << "Stack trace:" << std::endl
+                  << e.getStackTraceString() << std::endl;
+        throw;
+    }
+
+    return 0;
+}