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TiDB 5.0.1 Release Notes
TiDB 5.0.1 was released on April 24, 2021. The default value of `committer-concurrency` changed to 128. Various bug fixes and improvements were made to TiDB, TiKV, PD, TiFlash, and Tools. For example, TiDB fixed issues with query results and performance regression, while TiKV fixed issues with coprocessors and startup failures. Tools like TiDB Lightning and Backup & Restore also received bug fixes.

TiDB 5.0.1 Release Notes

Release date: April 24, 2021

TiDB version: 5.0.1

Compatibility change

  • The default value of the committer-concurrency configuration item is changed from 16 to 128.

Improvements

  • TiDB

    • Support the built-in function VITESS_HASH() #23915

  • TiKV

    • Use zstd to compress the Region snapshot #10005

  • PD

    • Modify the Region score calculator to better satisfy isomerous stores #3605
    • Avoid unexpected statistics after adding the scatter region scheduler #3602

  • Tools

    • Backup & Restore (BR)

      • Remove some misleading information from the summary log #1009

Bug Fixes

  • TiDB

    • Fix the issue that the execution result of project elimination might be wrong when the projection result is empty #24093
    • Fix the issue of wrong query results when a column contains NULL values in some cases #24063
    • Forbid generating MPP plans when the scan contains virtual columns #24058
    • Fix the wrong reuse of PointGet and TableDual in Plan Cache #24043
    • Fix the error that occurs when the optimizer builds the IndexMerge plan for clustered indexes #24042
    • Fix the type inference of the BIT-type errors #24027
    • Fix the issue that some optimizer hints do not take effect when the PointGet operator exists #23685
    • Fix the issue that DDL operations might fail when rolling back due to an error #24080
    • Fix the issue that the index range of the binary literal constant is incorrectly built #24041
    • Fix the potential wrong results of the IN clause in some cases #24023
    • Fix the wrong results of some string functions #23879
    • Users now need both INSERT and DELETE privileges on a table to perform REPLACE operations #23939
    • Fix the performance regression when executing the point query #24070
    • Fix the wrong TableDual plans caused by incorrectly comparing binaries and bytes #23918

  • TiKV

    • Fix the issue that the coprocessor fails to properly handle the signed or unsigned integer types in the IN expression #10018
    • Fix the issue of many empty Regions after batch ingesting SST files #10015
    • Fix the potential panic that occurs when the input of cast_string_as_time is invalid UTF-8 bytes #9995
    • Fix a bug that TiKV cannot start up after the file dictionary file is damaged #9992

  • TiFlash

    • Fix the issue that the storage engine fails to remove the data of some ranges
    • Fix the issue of incorrect results when casting the time type to the integer type
    • Fix a bug that the receiver cannot find corresponding tasks within 10 seconds
    • Fix the issue that there might be invalid iterators in cancelMPPQuery
    • Fix a bug that the behavior of the bitwise operator is different from that of TiDB
    • Fix the alert issue caused by overlapping ranges when using the prefix key
    • Fix the issue of incorrect results when casting the string type to the integer type
    • Fix the issue that consecutive and fast writes might make TiFlash out of memory
    • Fix the issue that duplicated column names will make TiFlash raise errors
    • Fix the issue that TiFlash fails to parse MPP plans
    • Fix the potential issue that the exception of null pointer might be raised during the table GC
    • Fix the TiFlash panic issue that occurs when writing data to dropped tables
    • Fix the issue that TiFlash might panic during BR restore

  • Tools

    • TiDB Lightning

      • Fix the issue of the inaccurate table count in the progress log during the import #1005

    • Backup & Restore (BR)

      • Fix a bug that the actual backup speed exceeds the --ratelimit limit #1026
      • Fix the issue of backup interruption caused by the failure of a few TiKV nodes #1019
      • Fix the issue of the inaccurate table count in the progress log during TiDB Lightning's import #1005

    • TiCDC

      • Fix the concurrency issue in Unified Sorter and filter the unhelpful error messages #1678
      • Fix a bug that the creation of redundant directories might interrupt the replication with MinIO #1672
      • Set the default value of the explicit_defaults_for_timestamp session variable to ON to make the MySQL 5.7 downstream keep the same behavior with the upstream TiDB #1659
      • Fix the issue that the incorrect handling of io.EOF might cause replication interruption #1648
      • Correct the TiKV CDC endpoint CPU metric in the TiCDC dashboard #1645
      • Increase defaultBufferChanSize to avoid replication blocking in some cases #1632