* create iotdb format refactor branch
* make DbFileReader, DbRowGroupReader inheritance relation for TsFile
* Modify bufferwriteprocessor iotdb
* Modify bufferwriteprocessor iotdb
* add RowGroupReader LRUMap
* resolve error code in this two class
* resolve the error code in overflow metadata test case
* Modify bufferwriteprocessor iotdb
* refactor writing process in iotdb
* add cache frameworf for new format
* add LRU in ReaderManager, change the implementation of OverflowValueReader
* fix bug caused by IoTDB format refactor
* add metadata cache framework and tsfilereader utils
* complete the metadata cache
* modify some class in query
* add group by batch read function - 1
* ReaderManager modification
* add RowGroupReader cache
* unit test case occurs error sometimes
* add comment for RecordReaderFactory
* modify method
* optimize the singleton pattern and add annotation
* add FileMetaData min time, max time filter
* group by batch
* add output all content method in LocalFileLogReader
* fix exception log for unsupport aggregation function
* add group by multiple aggregation function test in GroupBySmallDataTest.java
* fix QueryDataSet return usage
* add log info for group by calculation
* add info logs in OverflowQPExecutor and Utils, modify partitionFetchSize in GroupByEngineNoFilter
* add info log in OverflowQueryEngine
* modify group by log
* add test case statement size error in GroupBySmallDataTest
* add selectMultiTimeTest in GroupBySmallDataTest
* fix conflict with master
* fix ThrealLocal position in group by function
* fix unit test in GroupBySmallDataTest
* comment test flag in GroupBySmallDataTest
* add ConnectMain test for group by
* add exception.printStackTrace
* complete unlockForOneRequest method in ReadLockManager
* fix null check in GroupByEngineWithFilter
* fix a query data dealing method in GroupByEngineWithFilter
* put data in queryPathResult
* test fix effiency in OverflowBufferWriteProcessor
* add default value for aggregation function
* create iotdb format refactor branch
* make DbFileReader, DbRowGroupReader inheritance relation for TsFile
* Modify bufferwriteprocessor iotdb
* Modify bufferwriteprocessor iotdb
* add RowGroupReader LRUMap
* resolve error code in this two class
* resolve the error code in overflow metadata test case
* Modify bufferwriteprocessor iotdb
* refactor writing process in iotdb
* add cache frameworf for new format
* add LRU in ReaderManager, change the implementation of OverflowValueReader
* fix bug caused by IoTDB format refactor
* add metadata cache framework and tsfilereader utils
* complete the metadata cache
* modify some class in query
* ReaderManager modification
* add RowGroupReader cache
* unit test case occurs error sometimes
* add comment for RecordReaderFactory
* optimize the singleton pattern and add annotation
* add FileMetaData min time, max time filter
* comment RecordReaderFactory queryStructure output
* fix exception log for unsupport aggregation function
* fix bug: merge and produce multiple tsfile; add debug log for cache hint rate
* fix bug in QueryMerger
* delete test
* add log level in OverflowBufferWriteProcessor
* fix a bug : flush start, end flag in LocalFileReader processing logic is wrong
* fix ouputAllValidLog comment in LocalFileReader
* fix bug: multiple device lastupdate time update in asynchrnous
* add volatile to all multiple thread variable
* Solve the map.remove during iterating error in FileNodeProcessor.merge() function
* delete 'temp' in rowgroupblock metadata in bufferwriteprocessor, add static final variable for cache class
* delete system out code
* fix WriteLogNodeTest stream close bug
* add volatile to all variable in filenodeprocessor
XuYi