TiDB 7.5.6 Release Notes

Release date: March 14, 2025

TiDB version: 7.5.6

Quick access: Quick start | Production deployment

Compatibility changes

• Support the openEuler 22.03 LTS SP3/SP4 operating system. For more information, see OS and platform requirements.

Improvements

• TiDB

  • Adjust estimation results from 0 to 1 for equality conditions that do not hit TopN when statistics are entirely composed of TopN and the modified row count in the corresponding table statistics is non-zero #47400 @terry1purcell
  • Enhance the timestamp validity check #57786 @MyonKeminta
  • Limit the execution of GC for TTL tables and related statistics collection tasks to the owner node, thereby reducing overhead #59357 @lcwangchao

• TiKV

  • Add the detection mechanism for invalid max_ts updates #17916 @ekexium
  • Add slow logs for peer and store messages #16600 @Connor1996
  • Optimize the jittery access delay when restarting TiKV due to waiting for the log to be applied, improving the stability of TiKV #15874 @LykxSassinator

• TiFlash

  • Mitigate the issue that TiFlash might panic due to updating certificates after TLS is enabled #8535 @windtalker

• Tools

  • Backup & Restore (BR)

    • Disable the table-level checksum calculation during full backups by default (--checksum=false) to improve backup performance #56373 @Tristan1900
    • Add a check to verify whether the target cluster contains a table with the same name for non-full restore #55087 @RidRisR

  • TiDB Lightning

    • Add a row width check when parsing CSV files to prevent OOM issues #58590 @D3Hunter

Bug fixes

• TiDB

  • Fix the issue that some predicates might be lost when constructing IndexMerge #58476 @hawkingrei
  • Fix the issue that the ONLY_FULL_GROUP_BY setting does not take effect on statements in views #53175 @mjonss
  • Fix the issue that creating two views with the same name does not report an error #58769 @tiancaiamao
  • Fix the issue that converting data from the BIT type to the CHAR type might cause TiKV panics #56494 @lcwangchao
  • Fix the issue that a TTL job that loses the heartbeat blocks other jobs from getting heartbeats #57915 @YangKeao
  • Fix the issue that querying partitioned tables using an IN condition containing a mismatched value type and a type conversion error leads to incorrect query results #54746 @mjonss
  • Fix the issue that the default value of the BIT column is incorrect #57301 @YangKeao
  • Fix the issue that in the Prepare protocol, an error occurs when the client uses a non-UTF8 character set #58870 @xhebox
  • Fix the issue that using variables or parameters in the CREATE VIEW statement does not report errors #53176 @mjonss
  • Fix the issue that loading statistics manually might fail when the statistics file contains null values #53966 @King-Dylan
  • Fix the issue that when querying the information_schema.cluster_slow_query table, if the time filter is not added, only the latest slow log file is queried #56100 @crazycs520
  • Fix the issue that querying temporary tables might trigger unexpected TiKV requests in some cases #58875 @tiancaiamao
  • Fix the issue that the data in the Stats Healthy Distribution panel of Grafana might be incorrect #57176 @hawkingrei
  • Fix the issue that some TTL jobs might hang when modifying tidb_ttl_delete_rate_limit #58484 @lcwangchao
  • Fix the issue that improper exception handling for statistics causes in-memory statistics to be mistakenly deleted when background tasks time out #57901 @hawkingrei
  • Fix the issue that using ORDER BY when querying cluster_slow_query table might generate unordered results #51723 @Defined2014
  • Fix the issue that when a virtual generated column's dependencies contain a column with the ON UPDATE attribute, the data of the updated row and its index data might be inconsistent #56829 @joechenrh
  • Fix the issue that TTL jobs cannot be canceled if the TiDB heartbeat is lost #57784 @YangKeao
  • When the parameter is of Enum, Bit, or Set type, the Conv() function is no longer pushed down to TiKV #51877 @yibin87
  • Fix the issue that after executing ALTER TABLE ... PLACEMENT POLICY ... in a cluster with TiFlash nodes in the disaggregated storage and compute architecture, Region peers might be accidentally added to TiFlash Compute nodes #58633 @JaySon-Huang
  • Fix the issue that job status is overwritten when the DDL owner changes #52747 @D3Hunter
  • Fix the issue that queries with is null conditions on Hash partitioned tables cause a panic #58374 @Defined2014
  • Fix the issue that an error occurs when querying partitioned tables that contain generated columns #58475 @joechenrh
  • Fix the issue that TTL jobs might be ignored or processed multiple times #59347 @YangKeao
  • Fix the issue that incorrect judgment in exchange partition causes execution failure #59534 @mjonss
  • Fix the issue that setting the tidb_audit_log variable with multi-level relative paths causes errors in the log directory #58971 @lcwangchao
  • Fix the issue that different data types on both sides of the equality condition in Join might cause incorrect results in TiFlash #59877 @yibin87

• TiKV

  • Fix the issue that the leader could not be quickly elected after Region split #17602 @LykxSassinator
  • Fix the issue that time rollback might cause abnormal RocksDB flow control, leading to performance jitter #17995 @LykxSassinator
  • Fix the issue that the latest written data might not be readable when only one-phase commit (1PC) is enabled and Async Commit is not enabled #18117 @zyguan
  • Fix the issue that TiKV converts the time zone incorrectly for Brazil and Egypt #16220 @overvenus
  • Fix the issue that a deadlock might occur when GC Worker is under heavy load #18214 @zyguan
  • Fix the issue that disk stalls might prevent leader migration, leading to performance jitter #17363 @hhwyt
  • Fix the issue that encoding might fail when processing GBK/GB18030 encoded data #17618 @CbcWestwolf
  • Fix the issue that CDC connections might cause resource leakage when encountering exceptions #18245 @wlwilliamx
  • Fix the issue that Region merge might lead to TiKV abnormal exit due to Raft index mismatch #18129 @glorv
  • Fix the issue that Resolved-TS monitoring and logs might be abnormal #17989 @ekexium
  • Fix the issue that an incompatibility with the Titan component causes upgrade failure #18263 @v01dstar @LykxSassinator

• PD

  • Fix the issue that the default value of max-size for a single log file is not correctly set #9037 @rleungx
  • Fix the issue that the value of the flow-round-by-digit configuration item might be overwritten after a restart #8980 @nolouch
  • Fix the issue that operations in data import or adding index scenarios might fail due to unstable PD network #8962 @okJiang
  • Fix the issue that PD might panic when the tidb_enable_tso_follower_proxy system variable is enabled #8950 @okJiang
  • Fix the issue that the tidb_enable_tso_follower_proxy system variable might not take effect #8947 @JmPotato
  • Fix the issue that memory leaks might occur when allocating TSOs #9004 @rleungx
  • Fix the issue that Region syncer might not exit in time during the PD Leader switch #9017 @rleungx
  • Fix the issue that a PD node might still generate TSOs even when it is not the Leader #9051 @rleungx

• TiFlash

  • Fix the issue that TiFlash might unexpectedly reject processing Raft messages when memory usage is low #9745 @CalvinNeo
  • Fix the issue that TiFlash might maintain high memory usage after importing large amounts of data #9812 @CalvinNeo
  • Fix the issue that queries on a partitioned table might return errors after executing ALTER TABLE ... RENAME COLUMN on that partitioned table #9787 @Lloyd-Pottiger
  • Fix the issue that TiFlash might fail to print error stack traces when it unexpectedly exits in certain situations #9902 @JaySon-Huang
  • Fix the issue that TiFlash startup might be blocked when profiles.default.init_thread_count_scale is set to 0 #9906 @JaySon-Huang
  • Fix the issue that a Not found column error might occur when a query involves virtual columns and triggers remote reads #9561 @guo-shaoge
  • Fix the issue that in the disaggregated storage and compute architecture, TiFlash compute nodes might be incorrectly selected as target nodes for adding Region peers #9750 @JaySon-Huang

• Tools

  • Backup & Restore (BR)

    • Fix the issue that log backup fails to exit properly when encountering a fatal error due to not being able to access PD #18087 @YuJuncen
    • Fix the issue that BR fails to restore due to getting the rpcClient is idle error when sending requests to TiKV #58845 @Tristan1900
    • Fix the issue that PITR fails to restore indexes larger than 3072 bytes #58430 @YuJuncen
    • Fix the issue that the status field is missing in the result when querying log backup tasks using br log status --json #57959 @Leavrth
    • Fix the issue that log backup might unexpectedly enter a paused state when the advancer owner switches #58031 @3pointer

  • TiCDC

    • Fix the issue that enabling TiCDC in scenarios with many small tables might cause TiKV to restart #18142 @hicqu
    • Fix the issue that after the default value of a newly added column in the upstream is changed from NOT NULL to NULL, the default values of that column in the downstream are incorrect #12037 @wk989898
    • Fix the issue that out-of-order messages resent by the Sarama client cause Kafka message order to be incorrect #11935 @3AceShowHand
    • Fix the issue that TiCDC uses incorrect table names for filtering during RENAME TABLE operations #11946 @wk989898
    • Fix the issue that goroutines leak occurs after a changefeed is deleted #11954 @hicqu
    • Fix the issue that using the --overwrite-checkpoint-ts parameter in the changefeed pause command might cause the changefeed to be stuck #12055 @hongyunyan
    • Fix the issue that TiCDC reports errors when replicating default NULL SQL statements via the Avro protocol #11994 @wk989898
    • Fix the issue that TiCDC fails to properly connect to PD after PD scale-in #12004 @lidezhu

  • TiDB Lightning

    • Fix the issue that logs are not properly desensitized #59086 @GMHDBJD