TiDB 5.2.2 Release Notes

Release Date: October 29, 2021

TiDB version: 5.2.2

Improvements

• TiDB

  • Show the affected SQL statements in the debug log when the coprocessor encounters a lock, which is helpful in diagnosing problems#27718
  • Support showing the size of the backup and restore data when backing up and restoring data in the SQL logical layer#27247

• TiKV

  • Simplify the algorithm of L0 flow control#10879
  • Improve the error log report in the raft client module#10983
  • Improve logging threads to avoid them becoming a performance bottleneck#10841
  • Add more statistics types of write queries#10507

• PD

  • Add more types of write queries to QPS dimensions in the hotspot scheduler#3869
  • Support dynamically adjusting the retry limit of the balance region scheduler to improve the performance of the scheduler#3744
  • Update TiDB Dashboard to v2021.10.08.1#4070
  • Support that the evict leader scheduler can schedule regions with unhealthy peers#4093
  • Speed up the exit process of schedulers#4146

• Tools

  • TiCDC

    • Reduce the default value of the Kafka sink configuration itemMaxMessageBytesfrom 64 MB to 1 MB to fix the issue that large messages are rejected by the Kafka Broker#3104
    • Reduce memory usage in the relpication pipeline#2553#3037#2726
    • Optimize monitoring items and alert rules to improve observability of synchronous links, memory GC, and stock data scanning processes# 2735#1606#3000# 2985#2156
    • When the sync task status is normal, no more historical error messages are displayed to avoid misleading users#2242

Bug Fixes

• TiDB

  • Fix the issue that plan-cache cannot detect changes of unsigned flags#28254
  • Fix the wrong partition pruning when the partition function is out of range#28233
  • Fix the issue that planner might cache invalid plans forjoinin some cases#28087
  • Fix wrong index hash join when hash column type is enum#27893
  • Fix a batch client bug that recycling idle connection might block sending requests in some rare cases#27688
  • Fix the TiDB Lightning panic issue when it fails to perform checksum on a target cluster#27686
  • Fix wrong results of thedate_addanddate_subfunctions in some cases#27232
  • Fix wrong results of thehourfunction in vectorized expression#28643
  • Fix the authenticating issue when connecting to MySQL 5.1 or an older client version#27855
  • 解决汽车分析可能引发的问题out of the specified time when a new index is added#28698
  • Fix a bug that setting any session variable invalidatestidb_snapshot#28683
  • Fix a bug that BR is not working for clusters with many missing-peer regions#27534
  • Fix the unexpected error liketidb_cast to Int32 is not supportedwhen the unsupportedcast下推TiFlash吗#23907
  • Fix the issue thatDECIMAL overflowis missing in the%s value is out of range in '%s'error message#27964
  • Fix a bug that the availability detection of MPP node does not work in some corner cases#3118
  • Fix theDATA RACEissue when assigningMPP task ID#27952
  • Fix theINDEX OUT OF RANGEerror for a MPP query after deleting an emptydual table.#28250
  • Fix the issue of false positive error loginvalid cop task execution summaries lengthfor MPP queries#1791
  • Fix the issue of error logcannot found column in Schema columnfor MPP queries#28149
  • Fix the issue that TiDB might panic when TiFlash is shuting down#28096
  • Remove the support for insecure 3DES (Triple Data Encryption Algorithm) based TLS cipher suites#27859
  • Fix the issue that Lightning connects to offline TiKV nodes during pre-check and causes import failures#27826
  • Fix the issue that pre-check cost too much time when importing many files to tables#27605
  • Fix the issue that rewriting expressions makesbetweeninfer wrong collation#27146
  • Fix the issue thatgroup_concatfunction did not consider the collation#27429
  • Fix the result wrong that occurs when the argument of theextractfunction is a negative duration#27236
  • Fix the issue that creating partition fails ifNO_UNSIGNED_SUBTRACTIONis set#26765
  • Avoid expressions with side effects in column pruning and aggregation pushdown#27106
  • Remove useless gRPC logs#24190
  • Limit the valid decimal length to fix precision-related issues#3091
  • Fix the issue of a wrong way to check for overflow inplusexpression#26977
  • Fix the issue ofdata too longerror when dumping statistics from the table withnew collationdata#27024
  • Fix the issue that the retried transactions' statements are not included inTIDB_TRX#28670

• TiKV

  • Fix the issue that CDC adds scan retries frequently due to the Congest error#11082
  • Fix the issue that the raft connection is broken when the channel is full#11047
  • Fix the issue that batch messages are too large in Raft client implementation#9714
  • Fix the issue that some coroutines leak inresolved_ts#10965
  • Fix a panic issue that occurs to the coprocessor when the size of response exceeds 4 GiB#9012
  • Fix the issue that snapshot Garbage Collection (GC) misses GC snapshot files when snapshot files cannot be garbage collected#10813
  • Fix a panic issue caused by timeout when processing Coprocessor requests#10852

• PD

  • Fix the issue that PD incorrectly delete the peers with data and in pending status because the number of peers exceeds the number of configured peers#4045
  • Fix the issue that PD does not fix down peers in time#4077
  • Fix the issue that the scatter range scheduler cannot schedule empty regions# 4118
  • Fix the issue that the key manager cost too much CPU#4071
  • Fix the data race issue that might occur when setting configurations of hot region scheduler#4159
  • Fix slow leader election caused by stuck region syncer#3936

• TiFlash

  • Fix the issue that TiFlash fails to start up on some platforms due to the absence of librarynsl

• Tools

  • TiCDC

    • Fix the issue that TiCDC replication task might terminate when the upstream TiDB instance unexpectedly exits#3061
    • Fix the issue that TiCDC process might panic when TiKV sends duplicate requests to the same Region#2386
    • Fix unnecessary CPU consumption when verifying downstream TiDB/MySQL availability#3073
    • Fix the issue that the volume of Kafka messages generated by TiCDC is not constrained bymax-message-size# 2962
    • Fix the issue that TiCDC sync task might pause when an error occurs during writing a Kafka message# 2978
    • Fix the issue that some partitioned tables without valid indexes might be ignored whenforce-replicateis enabled#2834
    • Fix the issue that scanning stock data might fail due to TiKV performing GC when scanning stock data takes too long#2470
    • Fix a possible panic issue when encoding some types of columns into Open Protocol format#2758
    • Fix a possible panic issue when encoding some types of columns into Avro format#2648

  • TiDB Binlog

    • Fix the issue that when most tables are filtered out, checkpoint cannot be updated under some special load#1075