tidb-server v2.0.4

New Features

• Support the ALTER TABLE t DROP COLUMN a CASCADE syntax
• Support configuring the value of tidb_snapshot to TSO

Improvements

• Refine the display of statement types in monitoring items
• Optimize the accuracy of query cost estimation
• Configure the backoff max delay parameter of gRPC
• Support configuring the memory threshold of a single statement in the configuration file
• Refactor the error of Optimizer

Bug Fixes

• Fix the side effects of the Cast Decimal data
• Fix the wrong result issue of the Merge Join operator in specific scenarios
• Fix the issue of converting the Null object to String
• Fix the issue of casting the JSON type of data to the JSON type
• Fix the issue that the result order is not consistent with MySQL in the condition of Union + OrderBy
• Fix the compliance rules issue when the Union statement checks the Limit/OrderBy clause
• Fix the compatibility issue of the Union All result
• Fix a bug in predicate pushdown
• Fix the compatibility issue of the Union statement with the For Update clause
• Fix the issue that the concat_ws function mistakenly truncates the result

tidb-server v2.1.0-alpha

add pull request template (#6718)

tidb-server v2.0.3

New Features

• Support modifying the log level online
• Support the COM_CHANGE_USER command
• Support using the TIME type parameters under the binary protocol

Improvements

• Optimize the cost estimation of query conditions with the BETWEEN expression
• Do not display the FOREIGN KEY information in the result of SHOW CREATE TABLE
• Optimize the cost estimation for queries with the LIMIT clause

Bug Fixes

• Fix the issue about the YEAR type as the unique index
• Fix the issue about ON DUPLICATE KEY UPDATE in conditions without the unique index
• Fix the compatibility issue of the CEIL function
• Fix the accuracy issue of the DIV calculation in the DECIMAL type
• Fix the false alarm of ADMIN CHECK TABLE
• Fix the panic issue of MAX/MIN under specific expression parameters
• Fix the issue that the result of JOIN is null in special conditions
• Fix the IN expression issue when building and querying Range
• Fix a Range calculation issue when using Prepare to query and Plan Cache is enabled
• Fix the issue that the Schema information is frequently loaded in abnormal conditions

tidb-server v2.0.2

• Fix the issue of pushing down the Decimal division expression
• Support using the USE INDEX syntax in the Delete statement
• Forbid using the shard_row_id_bits feature in columns with Auto-Increment
• Add the timeout mechanism for writing Binlog

tidb-server v2.0.1

• Update the progress of Add Index to the DDL job information in real time
• Add the tidb_auto_analyze_ratio session variable to control the threshold value of automatic statistics update
• Fix an issue that not all residual states are cleaned up when the transaction commit fails
• Fix a bug about adding indexes in some conditions
• Fix the correctness related issue when DDL modifies surface operations in some concurrent scenarios
• Fix a bug that the result of LIMIT is incorrect in some conditions
• Fix a capitalization issue of the ADMIN CHECK INDEX statement to make its index name case insensitive
• Fix a compatibility issue about the UNION statement
• Fix a compatibility issue when inserting data of TIME type
• Fix a goroutine leak issue caused by copIteratorTaskSender in some conditions
• Add an option for TiDB to control the behaviour of Binlog failure
• Refactor the Coprocessor slow log，distinguish the scenario of tasks with long processing time and long waiting time
• Log nothing when meeting MySQL protocol handshake error. Avoid too many logs caused by load balancer keep alive mechanism
• Refine “Out of range value for column” error message
• Fix a bug when there is a subquery in an Update statement
• Change the behaviour of handling SIGTERM, do not wait for all queries to terminate anymore

tidb-server v2.0.0

• SQL Optimizer
  • Use more compact data structure to reduce the memory usage of statistics information
  • Speed up the loading statistics information when starting a tidb-server process
  • Support updating statistics information dynamically [experimental]
  • Optimize the cost model to provide more accurate query cost evaluation
  • Use Count-Min Sketch to estimate the cost of point queries more accurately
  • Support analyzing more complex conditions to make full use of indexes
  • Support manually specifying the Join order using the STRAIGHT_JOIN syntax
  • Use the Stream Aggregation operator when the GROUP BY clause is empty to improve the performance
  • Support using indexes for the MAX/MIN function
  • Optimize the processing algorithms for correlated subqueries to support decorrelating more types of correlated subqueries and transform them to Left Outer Join
  • Extend IndexLookupJoin to be used in matching the index prefix
• SQL Execution Engine
  • Refactor all operators using the Chunk architecture, improve the execution performance of analytical queries, and reduce memory usage.There is a significant improvement in the TPC-H benchmark result.
  • Support the Streaming Aggregation operators pushdown
  • Optimize the Insert Into Ignore statement to improve the performance by over 10 times
  • Optimize the Insert On Duplicate Key Update statement to improve the performance by over 10 times
  • Optimize Load Data to improve the performance by over 10 times
  • Push down more data types and functions to TiKV
  • Support computing the memory usage of physical operators, and specifying the processing behavior in the configuration file and system variables when the memory usage exceeds the threshold
  • Support limiting the memory usage by a single SQL statement to reduce the risk of OOM
  • Support using implicit RowID in CRUD operations
  • Improve the performance of point queries
• Server
  • Support the Proxy Protocol
  • Add more monitoring metrics and refine the log
  • Support validating the configuration files
  • Support obtaining the information of TiDB parameters through HTTP API
  • Resolve Lock in the Batch mode to speed up garbage collection
  • Support multi-threaded garbage collection
  • Support TLS
• Compatibility
  • Support more MySQL syntaxes
  • Support modifying the lower_case_table_names system variable in the configuration file to support the OGG data synchronization tool
  • Improve compatibility with the Navicat management tool
  • Support displaying the table creating time in Information_Schema
  • Fix the issue that the return types of some functions/expressions differ from MySQL
  • Improve compatibility with JDBC
  • Support more SQL Modes
• DDL
  • Optimize the Add Index operation to greatly improve the execution speed in some scenarios
  • Attach a lower priority to the Add Index operation to reduce the impact on online business
  • Output more detailed status information of the DDL jobs in Admin Show DDL Jobs
  • Support querying the original statements of currently running DDL jobs using Admin Show DDL Job Queries JobID
  • Support recovering the index data using Admin Recover Index for disaster recovery
  • Support modifying Table Options using the Alter statement

tidb-server v1.0.9

• Fix a panic error in the Drop Column or Add Column statement
• Fix the issue that Alter Table Modify Column reports an error in extreme conditions
• Fix the issue that the NULL value is inserted while adding NOT NULL columns

tidb-server v2.0.0-rc.6

• Fix an issue about rolling update to release candidate version higher than 2.0.0-rc4

tidb-server v2.0.0-rc.5

• Fix the issue about applying the Top-N pushdown rule
• Fix the estimation of the number of rows for the columns that contain NULL values
• Fix the zero value of the Binary type
• Fix the BatchGet issue within a transaction
• Clean up the written data while rolling back the Add Index operation, to reduce consumed space
• Optimize the insert on duplicate key update statement to improve the performance by 10 times
• Fix the issue about the type of the results returned by the UNIX_TIMESTAMP function
• Fix the issue that the NULL value is inserted while adding NOT NULL columns
• Support showing memory usage of the executing statements in the Show Process List statement
• Fix the issue that Alter Table Modify Column reports an error in extreme conditions
• Support setting the table comment using the Alter statement

tidb-server v2.0.0-rc.4

• Support SHOW GRANTS FOR CURRENT_USER();
• Fix the issue that the Expression in UnionScan is not cloned
• Support the SET TRANSACTION syntax
• Fix the potential goroutine leak issue in copIterator
• Fix the issue that admin check table misjudges the unique index including null
• Support displaying floating point numbers using scientific notation
• Fix the type inference issue during binary literal computing
• Fix the issue in parsing the CREATE VIEW statement
• Fix the panic issue when one statement contains both ORDER BY and LIMIT 0
• Improve the execution performance of DecodeBytes
• Optimize LIMIT 0 to TableDual, to avoid building useless execution plans