tidb-server v2.0.0-rc.1

• Support limiting the memory usage by a single SQL statement, to reduce the risk of OOM
• Support pushing the Stream Aggregate operator down to TiKV
• Support validating the configuration file
• Support obtaining the configuration of TiDB through HTTP API
• Compatible with more MySQL syntax in Parser
• Improve the compatibility with Navicat
• Improve the optimizer and extract common expressions with multiple OR conditions, to choose a better query plan
• Improve the optimizer and convert subqueries to Join operators in more scenarios, to choose a better query plan
• Resolve Lock in the Batch mode to increase the garbage collection speed
• Fix the length of Boolean field to improve compatibility
• Optimize the Add Index operation and give lower priority to all write and read operations, to reduce the impact on online business

tidb-server v1.1.0-beta

• Add more monitoring metrics and refine the log
• Compatible with more MySQL syntax
• Support displaying the table creating time in information_schema
• Optimize queries containing the MaxOneRow operator
• Configure the size of intermediate result sets generated by Join, to further reduce the memory used by Join
• Add the tidb_config session variable to output the current TiDB configuration
• Fix the panic issue in the Union and Index Join operators
• Fix the wrong result issue of the Sort Merge Join operator in some scenarios
• Fix the issue that the Show Index statement shows indexes that are in the process of adding
• Fix the failure of the Drop Stats statement
• Optimize the query performance of the SQL engine to improve the test result of the Sysbench -
  Select/OLTP by 10%
• Improve the computing speed of subqueries in the optimizer using the new execution engine; compared with TiDB 1.0, TiDB 1.1 Beta has great improvement in tests like TPC-H and TPC-DS

tidb-server v1.0.8

• Fix issues in the Outer Join result in some scenarios
• Optimize the performance of the InsertIntoIgnore statement
• Fix the issue in the ShardRowID option
• Add limitation (Configurable, the default value is 5000) to the DML statements number within a transaction
• Fix an issue in the Table/Column aliases returned by the Prepare statement
• Fix an issue in updating statistics delta
• Fix a panic error in the Drop Column statement
• Fix an DML issue when running the Add Column After statement
• Improve the stability of the GC process by ignoring the regions with GC errors
• Run GC concurrently to accelerate the GC process
• Provide syntax support for the CREATE INDEX statement

tidb-server v1.1.0-alpha.1

• SQL parser
  • Support more syntax
• SQL query optimizer
  • Use more compact structure to reduce statistics info memory usage
  • Speed up loading statistics info when starting the tidb-server
  • Provide more accurate query cost evaluation
  • Use Count-Min Sketch to evaluate the cost of queries using unique index more accurately
  • Support more complex conditions to make full use of index
• SQL executor
  • Refactor all executor operators using Chunk architecture, improve the execution performance of analytical statements and reduce memory usage
  • Optimize performance of the INSERT IGNORE statement
  • Push down more types and functions to TiKV
  • Support more SQL_MODE
  • Optimize the Load Data performance to increase the speed by 10 times
  • Optimize the Use Database performance
  • Support statistics on the memory usage of physical operators
• Server
  • Support the PROXY protocol

tidb-server v1.0.7

• Optimize the FIELD_LIST command
• Fix data race of the information schema
• Avoid adding read-only statements to history
• Add the session variable to control the log query
• Fix the resource leak issue in statistics
• Fix the goroutine leak issue
• Add schema info API for the http status server
• Fix an issue about IndexJoin
• Update the behavior when RunWorker is false in DDL
• Improve the stability of test results in statistics
• Support PACK_KEYS syntax for the CREATE TABLE statement
• Add row_id column for the null pushdown schema to optimize performance

tidb-server v1.0.6

• Support the Alter Table Auto_Increment syntax
• Fix the bug in Cost Based computation and the Null Json issue in statistics
• Support the extension syntax to shard the implicit row ID to avoid write hot spot for a single table
• Fix a potential DDL issue
• Consider the timezone setting in the curtime, sysdate and curdate functions
• Support the SEPARATOR syntax in the GROUP_CONCAT function
• Fix the wrong return type issue of the GROUP_CONCAT function

tidb-server v1.0.5

• Add the max value for the current Auto_Increment ID in the Show Create Table statement.
• Fix a potential goroutine leak.
• Support outputting slow queries into a separate file.
• Load the TimeZone variable from TiKV when creating a new session.
• Support the schema state check so that the Show Create Tableand Analyze statements process the public table/index only.
• The set transaction read only should affect the tx_read_only variable.
• Clean up incremental statistic data when rolling back.
• Fix the issue of missing index length in the Show Create Table statement.

tidb-server v1.0.4

• Speed up the loading of the statistics when starting the tidb-server
• Improve the performance of the show variables statement
• Fix a potential issue when using the Add Index statement to handle the combined indexes
• Fix a potential issue when using the Rename Table statement to move a table to another database
• Accelerate the effectiveness for the Alter/Drop User statement

tidb-server v1.0.3

• Optimize the performance in transaction conflicts scenario
• Add the TokenLimit option in the config file
• Output the default database in slow query logs
• Remove the DDL statement from query duration metrics
• Optimize the query cost estimation
• Fix the index prefix issue when creating tables
• Support pushing down the expressions for the Float type to TiKV
• Fix the issue that it is slow to add index for tables with discrete integer primary index
• Reduce the unnecessary statistics updates
• Fix a potential issue during the transaction retry

To upgrade from 1.0.2 to 1.0.3, follow the rolling upgrade order of PD->TiKV->TiDB.

tidb-server v1.0.2

• Optimize the cost estimation of index point query.
• Support the Alter Table Add Column ( ColumnDef ColumnPosition) syntax.
• Optimize the queries whose where conditions are contradictory.
• Optimize the Add Index operation to rectify the progress and reduce repetitive operations.
• Optimize the Index Look Join operator to accelerate the query speed for small data size.
• Fix the issue with prefix index judgement.