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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 item MaxMessageBytes from 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 for join in 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 the date_add and date_sub functions in some cases #27232
    • Fix wrong results of the hour function in vectorized expression #28643
    • Fix the authenticating issue when connecting to MySQL 5.1 or an older client version #27855
    • Fix the issue that auto analyze might be triggered out of the specified time when a new index is added #28698
    • Fix a bug that setting any session variable invalidates tidb_snapshot #28683
    • Fix a bug that BR is not working for clusters with many missing-peer regions #27534
    • Fix the unexpected error like tidb_cast to Int32 is not supported when the unsupported cast is pushed down to TiFlash #23907
    • Fix the issue that DECIMAL overflow is 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 the DATA RACE issue when assigning MPP task ID #27952
    • Fix the INDEX OUT OF RANGE error for a MPP query after deleting an empty dual table. #28250
    • Fix the issue of false positive error log invalid cop task execution summaries length for MPP queries #1791
    • Fix the issue of error log cannot found column in Schema column for 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 makes between infer wrong collation #27146
    • Fix the issue that group_concat function did not consider the collation #27429
    • Fix the result wrong that occurs when the argument of the extract function is a negative duration #27236
    • Fix the issue that creating partition fails if NO_UNSIGNED_SUBTRACTION is 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 in plus expression #26977
    • Fix the issue of data too long error when dumping statistics from the table with new collation data #27024
    • Fix the issue that the retried transactions' statements are not included in TIDB_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 in resolved_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 library nsl

  • 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 by max-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 when force-replicate is 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 can not be updated under some special load #1075
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