TiDB 4.0.7 Release Notes

Release date: September 29, 2020

TiDB version: 4.0.7

New Features

• PD

  • Add the GetAllMembers function in the PD client to get PD member information #2980

• TiDB Dashboard

  • Support generating the metrics relationship graph #760

Improvements

• TiDB

  • Add more runtime information for the join operator #20093
  • Add the hit ratio information of coprocessor cache in EXPLAIN ANALYZE #19972
  • Support pushing down the ROUND function to TiFlash #19967
  • Add the default value of CMSketch for ANALYZE #19927
  • Refine error message desensitization #20004
  • Accept connections from clients using connectors from MySQL 8.0 #19959

• TiKV

  • Support the JSON log format #8382

• PD

  • Count schedule operators when they are finished rather than added #2983
  • Set the make-up-replica operator to high priority #2977

• TiFlash

  • Improve the error handling of the Region meta change that occurs during reads

• Tools

  • TiCDC

    • Support translating more execution-efficient SQL statements in MySQL sink when the old value feature is enabled #955

  • Backup & Restore (BR)

    • Add connection retry when the connection is broken during backup #508

  • TiDB Lightning

    • Support dynamically updating the log level via the HTTP interface #393

Bug Fixes

• TiDB

  • Fix a vectorization bug from and/or/COALESCE caused by shortcut #20092
  • Fix the issue that plan digests are the same when the cop task stores are of different types #20076
  • Fix the wrong behavior of the != any() function #20062
  • Fix the query error that occurs when the slow-log file does not exist #20051
  • Fix the issue that Region requests continue to retry when the context is canceled #20031
  • Fix the issue that querying the time type of the cluster_slow_query table in streaming request might result in an error #19943
  • Fix the issue that DML statements using case when might cause schema change #20095
  • Fix the issue that the prev_stmt information in slow log is not desensitized #20048
  • Fix the issue that tidb-server does not release the table lock when it exits abnormally #20020
  • Fix the incorrect error message that occurs when inserting data of the ENUM and SET type #19950
  • Fix the wrong behavior of the IsTrue function in some situations #19903
  • Fix the issue that the CLUSTER_INFO system table might not work normally after PD is scaled in or out #20026
  • Avoid unnecessary warnings or errors when folding constants in control expressions #19910
  • Update the method of updating statistics to avoid Out of Memory (OOM) #20013

• TiKV

  • Fix the issue of unavailable Status API when TLS handshake fails #8649
  • Fix the potential undefined behaviors #7782
  • Fix the possible panic caused by generating snapshots when executing UnsafeDestroyRange #8681

• PD

  • Fix the bug that PD might panic if some Regions have no Leader when balance-region is enabled #2994
  • Fix the statistical deviation of Region size and Region keys after Region merge #2985
  • Fix the incorrect hotspot statistics #2991
  • Fix the issue that there is no nil check in redirectSchedulerDelete #2974

• TiFlash

  • Fix the wrong result of right outer join

• Tools

  • Backup & Restore (BR)

    • Fix a bug that causes the TiDB configuration to change after the restore process #509

  • Dumpling

    • Fix the issue that Dumpling fails to parse metadata when some variables are NULL #150