TiDB 3.0.15 Release Notes

Release date: June 5, 2020

TiDB version: 3.0.15

New Features

• TiDB

  • Forbid the query in partitioned tables to use the plan cache feature #16759
  • Support the admin recover index and admin check index statements on partitioned tables #17315 #17390
  • Support partition pruning of the in condition for Range partitioned tables #17318
  • Optimize the output of SHOW CREATE TABLE, and add quotation marks to the partition name #16315
  • Support the ORDER BY clause in the GROUP_CONCAT function #16988
  • Optimize the memory allocation mechanism of CMSketch statistics to reduce the impact of garbage collection (GC) on performance #17543

• PD

  • Add a policy in which PD performs scheduling in terms of the number of Leaders #2479

Bug Fixes

• TiDB

  • Use deep copy to copy the enum and set type data in the Hash aggregate function; fix an issue of correctness #16890
  • Fix the issue that PointGet returns incorrect results because of the wrong processing logic of integer overflow #16753
  • Fix the issue of incorrect results caused by incorrect processing logic when the CHAR() function is used in the query predicate #16557
  • Fix the issue of inconsistent results in the storage layer and calculation layer of the IsTrue and IsFalse functions #16627
  • Fix the incorrect NotNull flags in some expressions, such as case when #16993
  • Fix the issue that the optimizer cannot find a physical plan for TableDual in some scenarios #17014
  • Fix the issue that the syntax for partition selection does not take effect correctly in the Hash partitioned table #17051
  • Fix the inconsistent results between TiDB and MySQL when XOR operates on a floating-point number #16976
  • Fix the error that occurs when executing DDL statement in the prepared manner #17415
  • Fix the incorrect processing logic of computing the batch size in the ID allocator #17548
  • Fix the issue that the MAX_EXEC_TIME SQL hint does not take effect when the time exceeds the expensive threshold #17534

• TiKV

  • Fix the issue that memory defragmentation is not effective after running for a long time #7790
  • Fix the panic issue caused by incorrectly removing snapshot files after TiKV is restarted accidentally #7925
  • Fix the gRPC disconnection caused by too large message packages #7822