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TiDB 2.1.16 Release Notes

Release date: August 15, 2019

TiDB version: 2.1.16

TiDB Ansible version: 2.1.16


  • SQL Optimizer
    • Fix the issue that row count is estimated inaccurately for the equal condition on the time column #11526
    • Fix the issue that TIDB_INLJ Hint does not take effect or take effect on the specified table #11361
    • Change the implementation of NOT EXISTS in a query from OUTER JOIN to ANTI JOIN to find a more optimized execution plan #11291
    • Support subqueries within SHOW statements, allowing syntaxes such as SHOW COLUMNS FROM tbl WHERE FIELDS IN (SELECT 'a') #11461
    • Fix the issue that the SELECT … CASE WHEN … ELSE NULL ... query gets an incorrect result caused by the constant folding optimization #11441
  • SQL Execution Engine
    • Fix the issue that the DATE_ADD function gets a wrong result when INTERVAL is negative #11616
    • Fix the issue that the DATE_ADD function might get an incorrect result because it performs type conversion wrongly when it accepts an argument of the FLOAT, DOUBLE, or DECIMAL type #11628
    • Fix the issue that the error message is inaccurate when CAST(JSON AS SIGNED) overflows #11562
    • Fix the issue that other child nodes are not closed when one child node fails to be closed and returns an error during the process of closing Executor #11598
    • Support SPLIT TABLE statements that return the number of Regions that are successfully split and a finished percentage rather than an error when the scheduling is not finished for Region scatter before the timeout #11487
    • Make REGEXP BINARY function case sensitive to be compatible with MySQL #11505
    • Fix the issue that NULL is not returned correctly because the value of YEAR in the DATE_ADD/DATE_SUB result overflows when it is smaller than 0 or larger than 65535 #11477
    • Add in the slow query table a Succ field that indicates whether the execution succeeds #11412
    • Fix the MySQL incompatibility issue caused by fetching the current timestamp multiple times when a SQL statement involves calculations of the current time (such as CURRENT_TIMESTAMP or NOW) #11392
    • Fix the issue that the AUTO_INCREMENT columns do not handle the FLOAT or DOUBLE type #11389
    • Fix the issue that NULL is not returned correctly when the CONVERT_TZ function accepts an invalid argument #11357
    • Fix the issue that an error is reported by the PARTITION BY LIST statement. (Currently only the syntax is supported; when TiDB executes the statement, a regular table is created and a prompting message is provided) #11236
    • Fix the issue that Mod(%), Multiple(*), and Minus(-) operations return an inconsistent 0 result with that in MySQL when there are many decimal digits (such as select 0.000 % 0.11234500000000000000) #11353
  • Server
    • Fix the issue that the plugin gets a NULL domain when OnInit is called back #11426
    • Fix the issue that the table information in a schema can still be obtained through the HTTP interface after the schema has been deleted #11586
  • DDL
    • Disallow dropping indexes on auto-increment columns to avoid incorrect results of the auto-increment columns caused by this operation #11402
    • Fix the issue that the character set of the column is not correct when creating and modifying the table with different character sets and collations #11423
    • Fix the issue that the column schema might get wrong when alter table ... set default... and another DDL statement that modifies this column are executed in parallel #11374
    • Fix the issue that data fails to be backfilled when Generated Column A depends on Generated Column B and A is used to create an index #11538
    • Speed up ADMIN CHECK TABLE operations #11538


  • Support returning an error message when the client accesses a TiKV Region that is being closed #4820
  • Support reverse raw_scan and raw_batch_scan interfaces #5148


  • TiDB Binlog
    • Add the ignore-txn-commit-ts configuration item in Drainer to skip executing some statements in a transaction #697
    • Add the configuration item check on startup, which stops Pump and Drainer from running and returns an error message when meeting invalid configuration items #708
    • Add the node-id configuration in Drainer to specify Drainer’s node ID #706
  • TiDB Lightning
    • Fix the issue that tikv_gc_life_time fails to be changed back to its original value when 2 checksums are running at the same time #224

TiDB Ansible

  • Add the log4j configuration file in Spark #842
  • Update the tispark jar package to v2.1.2 #863
  • Fix the issue that the Prometheus configuration file is generated in the wrong format when TiDB Binlog uses Kafka or ZooKeeper #845
  • Fix the bug that PD fails to switch the Leader when executing the rolling_update.yml operation #888
  • Optimize the logic of rolling updating PD nodes - upgrade Followers first and then the Leader - to improve stability #895
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