TiDB is an open source distributed HTAP database compatible with the MySQL protocol

For new features, improvements, and bug fixes released in 6.5.0 for tidb server, see TiDB 6.5.0 release notes.

Bug fixes

• Fix the issue that the window function causes TiDB to panic instead of reporting an error #30326
• Fix the wrong result that occurs when enabling dynamic mode in partitioned tables for TiFlash #37254
• Fix wrong results of GREATEST and LEAST when passing in unsigned BIGINT arguments #30101
• Fix wrong results of deleting data of multiple tables using left join #31321
• Fix the issue that the result of concat(ifnull(time(3))) in TiDB is different from that in MySQL #29498
• Fix the issue that the SQL statements that contain cast(integer as char) union string return wrong results #29513
• Fix the issue that INL_HASH_JOIN might hang when used with LIMIT #35638
• Fix the wrong ANY_VALUE result that occurs when a Region returns empty data #30923
• Fix wrong results of index join caused by an innerWorker panic #31494
• Fix the issue that a SQL operation is canceled when its JSON type column joins its CHAR type column #29401
• Fix the issue that the background HTTP service of TiDB might not exit successfully and makes the cluster in an abnormal state #30571
• Fix the issue that concurrent column type change causes inconsistency between the schema and the data #31048
• Fix the issue that KILL TIDB cannot take effect immediately on idle connections #24031
• Fix the bug that setting any session variable will make tidb_snapshot fail to work #35515
• Fix the issue that the Region cache is not cleaned up in time when the Region is merged #37141
• Fix the panic issue caused by the connection array race in the KV client #33773
• Fix the issue that when TiDB Binlog is enabled, executing the ALTER SEQUENCE statement might cause a wrong metadata version and cause Drainer to exit #36276
• Fix the bug that TiDB may panic when querying statement summary tables #35340
• Fix the issue that TiDB gets the wrong result when using TiFlash to scan tables with empty range although TiFlash does not support reading tables with empty range yet #33083
• Fix the issue that the avg() function returns ERROR 1105 (HY000): other error for mpp stream: Could not convert to the target type - -value is out of range. when queried from TiFlash #29952
• Fix the issue that ERROR 1105 (HY000): close of nil channel is returned when using HashJoinExec #30289
• Fix the issue that TiKV and TiFlash return different results when querying logical operations #37258
• Fix the issue that the EXECUTE statement might throw an unexpected error in specific scenarios #37187
• Fix the planner wrong behaviors that occur when tidb_opt_agg_push_down and tidb_enforce_mpp are enabled #34465
• Fix a bug that TiDB might send coprocessor requests when executing the SHOW COLUMNS statement #36496
• Add warnings for lock tables and unlock tables when the enable-table-lock flag is not enabled #28967
• Fix the issue that range partitions allow multiple MAXVALUE partitions #36329

Bug fixes

• Fix the issue that restore tasks fail when using old framework for collations in databases or tables #39150 @MoCuishle28

Improvements

• Allow modifying the noop variable lc_messages #38231 @djshow832
• Support the AUTO_RANDOM column as the first column of the clustered composite index #38572 @tangenta
• Use pessimistic transactions in internal transaction retry to avoid retry failure and reduce time consumption #38136 @jackysp
• Improve the mechanism for loading the metadata. The metadata is loaded into memory only when necessary, which significantly reduces the memory usage during PITR #38404 @YuJuncen
• Optimize the file scanning logic to accelerate the scan of schema files #38598 @dsdashun

Bug fixes

• Fix the potential issue of index inconsistency that occurs after you create a new index #38165 @tangenta
• Fix a permission issue of the INFORMATION_SCHEMA.TIKV_REGION_STATUS table #38407 @CbcWestwolf
• Fix the issue that the grantor field is missing in the mysql.tables_priv table #38293 @CbcWestwolf
• Fix the issue that the join result of common table expressions might be wrong #38170 @wjhuang2016
• Fix the issue that the union result of common table expressions might be wrong #37928 @YangKeao
• Fix the issue that the information in the transaction region num monitoring panel is incorrect #38139 @jackysp
• Fix the issue that the system variable tidb_constraint_check_in_place_pessimistic might affect internal transactions. The variable scope is modified to SESSION. #38766
• Fix the issue that conditions in a query are mistakenly pushed down to projections #35623 @Reminiscent
• Fix the issue that the wrong isNullRejected check results for AND and OR cause wrong query results #38304 @Yisaer
• Fix the issue that ORDER BY in GROUP_CONCAT is not considered when the outer join is eliminated, which causes wrong query results #18216 @winoros
• Fix the issue of the wrong query result that occurs when the mistakenly pushed-down conditions are discarded by Join Reorder #38736 @winoros
• Fix the restoration failure issue caused by PD leader switch during the restoration process #36910 @MoCuishle28
• Fix the issue that the log backup task cannot be paused #38250 @joccau
• Fix the issue that when BR deletes log backup data, it mistakenly deletes data that should not be deleted #38939 @Leavrth
• Fix the issue that BR fails to delete data when deleting the log backup data stored in Azure Blob Storage or Google Cloud Storage for the first time #38229 @Leavrth
• Fix the import performance degradation when importing the Apache Parquet files to the target tables that contain the string type columns in thebinary encoding format #38351 @dsdashun

Bug fixes

• Fix the issue that the Region cache is not cleaned up in time when the Region is merged #37141
• Fix the issue that TiDB writes wrong data due to the wrong encoding of the ENUM or SET column #32302
• Fix the issue that database-level privileges are incorrectly cleaned up #38363
• Fix the issue that the grantor field is missing in the mysql.tables_priv table #38293
• Fix the issue that KILL TIDB cannot take effect immediately on idle connections #24031
• Fix the issue that the return type of date_add and date_sub is different between TiDB and MySQL #36394, #27573
• Fix the incorrect INSERT_METHOD value when Parser restores table options #38368
• Fix the issue that authentication fails when a MySQL client of v5.1 or earlier connects to the TiDB server #29725
• Fix wrong results of GREATEST and LEAST when passing in unsigned BIGINT arguments #30101
• Fix the issue that the result of concat(ifnull(time(3)) in TiDB is different from that in MySQL #29498
• Fix the issue that the avg() function returns ERROR 1105 (HY000): other error for mpp stream: Could not convert to the target type - -value is out of range. when queried from TiFlash #29952
• Fix the issue that ERROR 1105 (HY000): close of nil channel is returned when using HashJoinExec #30289
• Fix the issue that TiKV and TiFlash return different results when querying logical operations #37258
• Fix the issue that the EXPLAIN ANALYZE statement with DML executors might return result before the transaction commit finishes #37373
• Fix the issue that Region cache is not cleared properly after merging many Regions #37174
• Fix the issue that the EXECUTE statement might throw an unexpected error in specific scenarios #37187
• Fix the issue that GROUP CONCAT with ORDER BY might fail when the ORDER BY clause contains a correlated subquery #18216
• Fix wrong results returned when length and width are incorrectly set for Decimal and Real when using plan cache #29565

Improvements

• Allow setting placement rules and TiFlash replicas at the same time in one table #37171 @lcwangchao

Bug fixes

• Fix the issue that database-level privileges are incorrectly cleaned up #38363 @dveeden
• Fix the incorrect output of SHOW CREATE PLACEMENT POLICY #37526 @xhebox
• Fix the issue that when one PD node goes down, the query of information_schema.TIKV_REGION_STATUS fails due to not retrying other PD nodes #35708 @tangenta
• Fix the issue that the UNION operator might return unexpected empty result #36903 @tiancaiamao
• Fix the wrong result that occurs when enabling dynamic mode in partitioned tables for TiFlash #37254 @wshwsh12
• Fix the issue that the Region cache is not cleaned up in time when the Region is merged #37141 @sticnarf
• Fix the issue that the KV client sends unnecessary ping messages #36861 @jackysp
• Fix the issue that the EXPLAIN ANALYZE statement with DML executors might return result before the transaction commit finishes #37373 @cfzjywxk
• Fix the issue that GROUP CONCAT with ORDER BY might fail when the ORDER BY clause contains a correlated subquery #18216 @winoros
• Fix the issue that Can't find column is reported if an UPDATE statement contains common table expressions (CTE) #35758 @AilinKid
• Fix the issue that the EXECUTE might throw an unexpected error in specific scenarios #37187 @Reminiscent

Bug fixes

• Fix the incorrect output of SHOW CREATE PLACEMENT POLICY #37526
• Fix the issue that some DDL statements might be stuck for a period after the PD node of a cluster is replaced #33908
• Fix the issue that KILL TIDB cannot take effect immediately on idle connections #24031
• Fix the issue that incorrect results are returned in the DATA_TYPE and COLUMN_TYPE columns when querying the INFORMSTION_SCHEMA.COLUMNS system table #36496
• Fix the issue that when TiDB Binlog is enabled, executing the ALTER SEQUENCE statement might cause a wrong metadata version and cause Drainer to exit #36276
• Fix the issue that the UNION operator might return unexpected empty result #36903
• Fix the wrong result that occurs when enabling dynamic mode in partitioned tables for TiFlash #37254
• Fix the issue that INL_HASH_JOIN might hang when used with LIMIT #35638
• Fix the issue that TiDB might return the invalid memory address or nil pointer dereference error when executing the SHOW WARNINGS statement #31569
• Fix the invalid transaction error that occurs when performing Stale Read in the RC isolation level #30872
• Fix the issue that the EXPLAIN ANALYZE statement with DML executors might return result before the transaction commit finishes #37373
• Fix the issue of the data and columnID count not match error that occurs when inserting duplicated values with TiDB Binlog enabled #33608
• Fix the issue that in the static partition prune mode, SQL statements with an aggregate condition might return wrong result when the table is empty #35295
• Fix the issue that TiDB might panic when executing the UPDATE statement #32311
• Fix the issue of wrong query result because the UnionScan operator cannot maintain the order #33175
• Fix the issue that the UPDATE statements incorrectly eliminate the projection in some cases, which causes the Can't find column error #37568
• Fix the issue that partitioned tables cannot fully use indexes to scan data in some cases #33966
• Fix the issue that the EXECUTE might throw an unexpected error in specific scenarios #37187
• Fix the issue that TiDB might return wrong results when using a BIT type index with prepared plan cache enabled #33067

Improvements

• TiDB is now case-insensitive to the target table name when checking the table existence #34610 @tiancaiamao
• Improve MySQL compatibility by adding a parsing check when setting the value of init_connect #35324 @CbcWestwolf
• Improve the log warning generated for new connections #34964 @xiongjiwei
• Optimize the HTTP API for querying DDL history jobs, and add support for the start_job_id parameter #35838 @tiancaiamao
• Report errors when the JSON path has wrong syntax #22525 #34959 @xiongjiwei
• Improve the performance of Join operations by fixing a false sharing issue #37641 @gengliqi
• Support exporting the execution plan information of multiple SQL statements at a time using PLAN REPLAYER, which makes troubleshooting more efficient #37798 @Yisaer

Bug fixes

• Fix the issue that the privilege check is skipped for PREPARE statements #35784 @lcwangchao
• Fix the issue that the system variable tidb_enable_noop_variable can be set to WARN #36647 @lcwangchao
• Fix the issue that when an expression index is defined, the ORDINAL_POSITION column of the INFORMAITON_SCHEMA.COLUMNS table might be incorrect #31200 @bb7133
• Fix the issue that TiDB does not report an error when the timestamp is larger than MAXINT32 #31585 @bb7133
• Fix the issue that TiDB server cannot be started when the enterprise plugin is used #37319 @xhebox
• Fix the incorrect output of SHOW CREATE PLACEMENT POLICY #37526 @xhebox
• Fix the unexpected EXCHANGE PARTITION behaviors with temporary tables #37201 @lcwangchao
• Fix the issue that querying INFORMATION_SCHEMA.TIKV_REGION_STATUS returns an incorrect result @zimulala
• Fix the issue that the EXPLAIN query on views does not check privileges #34326 @hawkingrei
• Fix the issue that JSON null cannot be updated to NULL #37852 @YangKeao
• Fix the issue that row_count of DDL jobs is inaccurate #25968 @Defined2014
• Fix the issue that FLASHBACK TABLE does not work properly #37386 @tiancaiamao
• Fix the issue of failing to handle prepared statement flags in the typical MySQL protocol #36731 @dveeden
• Fix the issue of incorrect TiDB status that might appear on startup in some extreme cases #36791 @xhebox
• Fix the issue that INFORMATION_SCHEMA.VARIABLES_INFO does not comply with security enhanced mode (SEM) #37586 @CbcWestwolf
• Fix the issue that casting string to string goes wrong in queries with UNION #31678 @cbcwestwolf
• Fix the wrong result that occurs when enabling dynamic mode in partitioned tables for TiFlash #37254 @wshwsh12
• Fix the issue that the cast and comparison between binary strings and JSON in TiDB are incompatible with MySQL #31918 #25053 @YangKeao
• Fix the issue that JSON_OBJECTAGG and JSON_ARRAYAGG in TiDB are not compatible with MySQL on binary values #25053 @YangKeao
• Fix the issue that the comparison between JSON opaque values causes panic #37315 @YangKeao
• Fix the issue that the single precision float cannot be used in JSON aggregation funtions #37287 @YangKeao
• Fix the issue that the UNION operator might return unexpected empty result #36903 @tiancaiamao
• Fix the issue that the result of the castRealAsTime expression is inconsistent with MySQL #37462 @mengxin9014
• Fix the issue that pessimistic DML operations lock non-unique index keys #36235 @ekexium
• Fix the issue that auto-commit change affects transaction commit behaviours #36581 @cfzjywxk
• Fix the issue that the EXPLAIN ANALYZE statement with DML executors might return result before the transaction commit finishes #37373 @cfzjywxk
• Fix the issue that the UPDATE statements incorrectly eliminate the projection in some cases, which causes the Can't find column error #37568 @AilinKid
• Fix the issue that the Join Reorder operation will mistakenly push down its Outer Join condition #37238 @AilinKid
• Fix the issue that the IN and NOT IN subqueries in some patterns report the Can't find column error #37032 @AilinKid
• Fix the issue that Can't find column is reported if an UPDATE statement contains common table expressions (CTE) #35758 @AilinKid
• Fix incorrect PromQL #35856 @Defined2014

Compatibility changes

• Make the SHOW DATABASES LIKE … statement case-insensitive #34766 @e1ijah1
• Change the default value of tidb_enable_outer_join_reorder from 1 to 0, which disables Join Reorder's support for Outer Join by default.

Improvements

• Add a new optimizer SEMI_JOIN_REWRITE to improve the performance of EXISTS queries #35323 @winoros

Bug fixes

• Fix the issue that INL_HASH_JOIN might hang when used with LIMIT #35638 @guo-shaoge
• Fix the issue that TiDB might panic when executing the UPDATE statement #32311 @Yisaer
• Fix a bug that TiDB might send coprocessor requests when executing the SHOW COLUMNS statement #36496 @tangenta
• Fix a bug that TiDB might return the invalid memory address or nil pointer dereference error when executing the SHOW WARNINGS statement #31569 @zyguan
• Fix a bug that in the static partition prune mode, SQL statements with an aggregate condition might return wrong result when the table is empty #35295 @tiancaiamao
• Fix the issue that the Join Reorder operation will mistakenly push down its Outer Join condition #37238 @winoros
• Fix the issue that CTE-schema hash code is cloned mistakenly, which causes the Can't find column ... in schema ... error when CTE is referenced more than once #35404 @AilinKid
• Fix the issue that the wrong join reorder in some right outer join scenarios causes wrong query result #36912 @winoros
• Fix the issue of incorrectly inferred null flag of the TiFlash firstrow aggregate function in the EqualAll case #34584 @fixdb
• Fix the issue that Plan Cache does not work when a binding is created with the IGNORE_PLAN_CACHE hint #34596 @fzzf678
• Fix the issu that an EXCHANGE operator is missing between the hash-partition window and the single-partition window #35990 @LittleFall
• Fix the issue that partitioned tables cannot fully use indexes to scan data in some cases #33966 @mjonss
• Fix the issue of wrong query result when a wrong default value is set for partial aggregation after the aggregation is pushed down #35295 @tiancaiamao
• Fix the issue that querying partitioned tables might get the index-out-of-range error in some cases #35181 @mjonss
• Fix the issue that a partition is incorrectly pruned if a partition key is used in the query condition and the collate is different from the one in the query partition table #32749 @mjonss
• Fix the issue that when TiDB Binlog is enabled, executing the ALTER SEQUENCE statement might cause a wrong metadata version and cause Drainer to exit #36276 @AilinKid
• Fix the issue of incorrect TiDB status that might appear on startup in some extreme cases #36791 @xhebox
• Fix the potential UnknownPlanID issue that occurs when querying the execution plans for partitioned tables in TiDB Dashboard #35153 @time-and-fate
• Fix the issue that the column list does not work in the LOAD DATA statement #35198 @SpadeA-Tang
• Fix the issue of the data and columnID count not match error that occurs when inserting duplicated values with TiDB Binlog enabled #33608 @zyguan
• Remove the limitation of tidb_gc_life_time #35392 @TonsnakeLin
• Fix the LOAD DATA statement dead loop when an empty filed terminator is used #33298 @zyguan
• Avoid sending requests to unhealthy TiKV nodes to improve availability #34906 @sticnarf

For the complete and official release notes, see https://docs.pingcap.com/tidb/v6.2/release-6.2.0.

Improvements

• Support the SHOW COUNT(*) WARNINGS and SHOW COUNT(*) ERRORS statements #25068 @likzn
• Add validation check for some system variables #35048 @morgo
• Optimize the error messages for some type conversions #32447 @fanrenhoo
• The KILL command now supports DDL operations #24144 @morgo
• Make the output of SHOW TABLES/DATABASES LIKE … more MySQL-compatible. The column names in the output contain the LIKE value #35116 @likzn
• Improve the performance of JSON-related functions #35859 @wjhuang2016
• Improve the verification speed of password login using SHA-2 #35998 @virusdefender
• Simplify some log outputs #36011 @dveeden
• Optimize the Coprocessor communication protocol. This can greatly reduce the memory consumption of the TiDB processes when reading data, and further alleviate the OOM issue in the scenario of scanning tables and exporting data by Dumpling. The system variable tidb_enable_paging is introduced to control whether to enable this communication protocol (with the scope of SESSION or GLOBAL). This protocol is disabled by default. To enable it, set the variable value to true #35633 @tiancaiama @wshwsh12
• Optimize the accuracy of memory tracking for some operators (HashJoin, HashAgg, Update, Delete) (#35634, #35631, #35635 @wshwsh12) (#34096 @ekexium)
• The system table INFORMATION_SCHEMA.DATA_LOCK_WAIT supports recording the locking information of optimistic transactions #34609 @longfangson
• Add some monitoring metrics for transactions #34456 @longfangsong
• ...

Bug fixes

• Fix the issue that a partition is incorrectly pruned if a partition key is used in the query condition and the collate is different from the one in the query partition table #32749 @mjonss
• Fix the issue that SET ROLE cannot match the granted role if there are capital letters in the host #33061 @morgo
• Fix the issue that columns with auto_increment cannot be dropped #34891 @Defined2014
• Fix the issue that SHOW CONFIG shows some configuration items that have been removed #34867 @morgo
• Fix the issue that SHOW DATABASES LIKE … is case-sensitive #34766 @e11jah
• Fix the issue that SHOW TABLE STATUS LIKE ... is case-sensitive #7518 @likzn
• Fix the issue that max-index-length still reports an error in non-strict mode #34931 @e11jah
• Fix the issue that ALTER COLUMN ... DROP DEFAULT does not work #35018 @Defined2014
• Fix the issue that when you create a table, the default value and the type of a column are not consistent and are not automatically corrected #34881 @Lloyd-Pottiger
• Fix the issue that data in the mysql.columns_priv table is not deleted synchronously after you run DROP USER #35059 @lcwangchao
• Fix the issue of DDL jam by disallowing creating tables within the schemas of some systems #35205 @tangenta
• Fix the issue that querying partitioned tables might report "index-out-of-range" and "non used index" errors in some cases #35181 @mjonss
• Fix the issue that INTERVAL expr unit + expr might report an error #30253 @mjonss
• Fix a bug that a temporary table cannot be found after being created in a transaction #35644 @djshow832
• Fix the panic issue that occurs when setting collation to the ENUM column #31637 @wjhuang2016
• Fix the issue that when one PD node goes down, the query of information_schema.TIKV_REGION_STATUS fails due to not retrying other PD nodes #35708 @tangenta
• Fix the issue that SHOW CREATE TABLE … cannot correctly display set or ENUM columns after SET character_set_results = GBK #31338 @tangenta
• Fix the incorrect scope of the system variables tidb_log_file_max_days and tidb_config #35190 @morgo
• Fix the issue that the output of SHOW CREATE TABLE is not compatible with MySQL for the ENUM or SET column #36317 @Defined2014
• Fix the issue that when creating a table, the behavior of a LONG BYTE column is not compatible with MySQL #36239 @Defined2014
• Fix the issue that auto_increment = x does not take effect on temporary tables #36224 @djshow832
• Fix the wrong default value when modifying columns concurrently #35846 @wjhuang2016
• Avoid sending requests to unhealthy TiKV nodes to improve availability #34906 @sticnarf
• Fix the issue that the column list does not work in the LOAD DATA statement #35198 @SpadeA-Tang
• Fix the issue that in some scenarios the pessimistic lock is incorrectly added to the non-unique secondary index #36235 @ekexium
• ...

Improvements

• Avoid sending requests to unhealthy TiKV nodes to improve availability #34906

Bug Fixes

• Fix the issue of wrong TableDual plans cached in binary protocol #34690 #34678
• Fix the issue of incorrectly inferred null flag of the TiFlash firstrow aggregate function in the EqualAll case #34584
• Fix the issue that the planner generates wrong 2-phase aggregate plan for TiFlash #34682
• Fix the planner wrong behaviors that occur when tidb_opt_agg_push_down and tidb_enforce_mpp are enabled #34465
• Fix the wrong memory-usage value used when Plan Cache is evicted #34613
• Fix the issue that the column list does not work in the LOAD DATA statement #35198
• Avoid reporting WriteConflict errors in pessimistic transactions #11612
• Fix the issue that the prewrite requests are not idempotency when Region errors and network issues occur #34875
• Fix the issue that the async commit transactions being rolled back might not meet atomicity #33641
• Previously, when a network connectivity issue occurred, TiDB did not always correctly free the resources held by the disconnected session. This issue has been fixed so that open transactions can be rolled back and other associated resources can be released. #34722
• Fix the issue that the references invalid table error might be incorrectly reported when TiDB queries views with CTE #33965
• Fix the panic issue caused by the fatal error: concurrent map read and map write error #35340
• Fix the error that occurs when reading from the INFORMATION_SCHEMA.ATTRIBUTES table by skipping the unidentifiable table attributes #33665

There is no release note for this version.

Compatibility Changes

• Fix the issue that the REPLACE statement incorrectly changes other rows when the auto ID is out of range #29483

Bug Fixes

• Fix the issue that Amazon S3 cannot correctly calculate the size of compressed data #30534
• Fix the issue of potential data index inconsistency in optimistic transaction mode #30410
• Fix the issue that a SQL operation is canceled when its JSON type column joins its CHAR type column #29401
• Previously, when a network connectivity issue occurred, TiDB did not always correctly free the resources held by the disconnected session. This issue has been fixed so that open transactions can be rolled back and other associated resources can be released. #34722
• Fix the issue of the data and columnID count not match error that occurs when inserting duplicated values with TiDB Binlog enabled #33608
• Fix the issue that query result might be wrong when Plan Cache is started in the RC isolation level #34447
• Fix the session panic that occurs when executing the prepared statement after table schema change with the MySQL binary protocol #33509
• Fix the issue that the table attributes are not indexed when a new partition is added and the issue that the table range information is not updated when the partition changes #33929
• Fix the issue that the TiDB server might run out of memory when the INFORMATION_SCHEMA.CLUSTER_SLOW_QUERY table is queried. This issue can be triggered when you check slow queries on the Grafana dashboard #33893
• Fix the issue that some DDL statements might be stuck for a period after the PD node of a cluster is replaced #33908
• Fix the issue that granting the all privilege might fail in clusters that are upgraded from v4.0 #33588
• Fix wrong results of deleting data of multiple tables using left join #31321
• Fix a bug that TiDB may dispatch duplicate tasks to TiFlash #32814
• Fix the issue that the background HTTP service of TiDB might not exit successfully and makes the cluster in an abnormal state #30571
• Fix the panic issue caused by the fatal error: concurrent map read and map write error #35340

Improvements

• Improve the performance of the UnionScanRead operator #32433
• Improve the display of task types in the output of EXPLAIN (add the MPP task type) #33332
• Support using rand() as the default value of a column #10377
• Support using uuid() as the default value of a column #33870
• Support modifying the character set of columns from latin1 to utf8/utf8mb4 #34008

Bug fixes

• Fix the issue of possible panic that might occur when the in function processes the bit type data #33070
• Fix the issue of wrong query result because the UnionScan operator cannot maintain the order #33175
• Fix the issue that the Merge Join operator gets wrong results in certain cases #33042
• Fix the issue that the index join result might be wrong in the dynamic pruning mode #33231
• Fix the issue that data might not be garbage-collected when some partitions of a partitioned table is dropped #33620
• Fix the issue that some DDL statements might be stuck for a period after the PD node of a cluster is replaced #33908
• Fix the issue that the TiDB server might run out of memory when the INFORMATION_SCHEMA.CLUSTER_SLOW_QUERY table is queried. This issue can be triggered when you check slow queries on the Grafana dashboard #33893
• Fix the issue that the system variable max_allowed_packet does not take effect #31422
• Fix the issue of memory leak in the TopSQL module #34525 #34502
• Fix the issue that the Plan Cache might be wrong on the PointGet plan #3237
• Fix the issue that query result might be wrong when Plan Cache is started in the RC isolation level #34447

Improvements

• Support using the PointGet plan for queries that read the _tidb_rowid column #31543
• Add more logs and metrics for the Apply operator to show whether it is parallel #33887
• Improve the TopN pruning logic for Analyze Version 2 used for collecting statistics #34256
• Support displaying multiple Kubernetes clusters in the Grafana dashboard #32593

Bug Fixes

• Fix the issue that date_format in TiDB handles '\n' in a MySQL-incompatible way #32232
• Fix the issue that TiDB writes wrong data due to the wrong encoding of the ENUM or SET column #32302
• Fix the issue that the Merge Join operator gets wrong results in certain cases #33042
• Fix the issue that TiDB gets a wrong result when a correlated subquery returns a constant #32089
• Fix the issue that TiDB gets the wrong result when using TiFlash to scan tables with empty range although TiFlash does not support reading tables with empty range yet #33083
• Fix the issue that the MAX or MIN function on the ENUM or SET column returns a wrong result when the new collation is enabled in TiDB #31638
• Fix a bug that CTE might be blocked when a query reports errors #31302
• Fix wrong range calculation results for Nulleq function on Enum values #32428
• Fix TiDB OOM when exporting data using ChunkRPC #31981 #30880
• Fix a bug that tidb_super_read_only is not automatically enabled when tidb_restricted_read_only is enabled #31745
• Fix the issue that the greatest or least function with collation gets a wrong result #31789
• Fix load data panic if the data is broken at an escape character #31589
• Fix the invalid transaction error when executing a query using index lookup join #30468
• Fix wrong results of deleting data of multiple tables using left join #31321
• Fix a bug that TiDB may dispatch duplicate tasks to TiFlash #32814
• Fix the issue that granting the all privilege might fail in clusters that are upgraded from v4.0 #33588
• Fix the session panic that occurs when executing the prepared statement after table schema change with the MySQL binary protocol #33509
• Fix the issue that executing SQL statements that have the compress() expression with tidb_enable_vectorized_expression enabled will fail #33397
• Fix the issue of high CPU usage by the reArrangeFallback function #30353
• Fix the issue that the table attributes are not indexed when a new partition is added and the issue that the table range information is not updated when the partition changes #33929
• Fix a bug that the TopN statistical information of a table during the initialization is not correctly sorted #34216
• Fix the error that occurs when reading from the INFORMATION_SCHEMA.ATTRIBUTES table by skipping the unidentifiable table attributes #33665
• Fix a bug that even if @@tidb_enable_parallel_apply is set, the Apply operator is not paralleled when an order property exists #34237
• Fix a bug that '0000-00-00 00:00:00' can be inserted into a datetime column when sql_mode is set to NO_ZERO_DATE #34099
• Fix the issue that the TiDB server might run out of memory when the INFORMATION_SCHEMA.CLUSTER_SLOW_QUERY table is queried. This issue can be triggered when you check slow queries on the Grafana dashboard. #33893
• Fix a bug that in the NOWAIT statement, a transaction being executed does not return immediately when encountering a lock #32754
• Fix a bug that causes a failure when creating a table with the GBK charset and gbk_bin collation #31308
• Fix a bug that when enable-new-charset is on, creating a GBK charset table with collation fails with the "Unknown character set" error #31297

There is no release note for this version.

Improvements

• Clear the placement rule settings of a table automatically after restoring the table using the FLASHBACK or RECOVER statement #31668
• Add a performance overview dashboard to show core performance metrics on typical critical paths, making metrics analysis on TiDB easier #31676
• Support using the REPLACE keyword in the LOAD DATA LOCAL INFILE statement #24515
• (dup: release-5.1.4.md > Improvements> TiDB)- Support partition pruning for the built-in IN expression in Range partition tables #26739
• Improve query efficiency by eliminating potentially redundant Exchange operations in MPP aggregation queries #31762
• Improve compatibility with MySQL by allowing duplicate partition names in the TRUNCATE PARTITION and DROP PARTITION statements #31681
• Support showing the CREATE_TIME information in the results of the ADMIN SHOW DDL JOBS statement #23494
• Support a new built-in function CHARSET() #3931
• Support filtering a baseline capturing blocklist by usernames #32558
• Optimize the results of the ADMIN SHOW DDL JOBS and SHOW TABLE STATUS statements by displaying the time according to the current time_zone #26642
• Supports pushing down the DAYNAME() and MONTHNAME() functions to TiFlash #32594
• Support pushing down the REGEXP function to TiFlash #32637
• Support tracking the execution of the UnionScan operator #32631
• Support pushing down the GREATEST and LEAST functions to TiFlash #32787
• Support using the PointGet plan for queries that read the _tidb_rowid column #31543
• Support using wildcards in a baseline capturing blocklist #32714
• Support showing the original partition name in the output of the EXPLAIN statement without converting the name to lowercase #32719
• Enable partition pruning for RANGE COLUMNS partitionings on IN conditions and string type columns #32626
• Return an error message when a system variable is set to NULL #32850
• Remove Broadcast Join from the non-MPP mode #31465
• Support pushing down the DAYOFMONTH() and LAST_DAY() functions to TiFlash #33012
• Support pushing down the DAYOFWEEK() and DAYOFYEAR() functions to TiFlash #33130
• Support pushing down the IS_TRUE, IS_FALSE, and IS_TRUE_WITH_NULL functions to TiFlash #33047
• Support executing MPP plans on partitioned tables in dynamic pruning mode #32347
• Support enabling the switch to reduce read latency in transactions at the READ-COMMITTED isolation level for the read-consistency read #33159
• Support pushing down predicates for common table expressions (CTEs) #28163
• Simplify the configurations of Statement Summary and Capture Plan Baselines to be available on a global basis only #30557
• Update gopsutil to v3.21.12 to address alarms reported when building binary on macOS 12 #31607

Bug Fixes

• Fix the bug that the placement rule reports an error when SCHEDULE = majority_in_primary, and PrimaryRegion and Regions are of the same value #31271
• (dup: release-5.3.1.md > Bug fixes> TiDB)- Fix the invalid transaction error when executing a query using index lookup join #30468
• Fix the bug that show grants returns incorrect results when two or more privileges are granted #30855
• Fix the bug that INSERT INTO t1 SET timestamp_col = DEFAULT would set the timestamp to the zero timestamp for the field defaulted to CURRENT_TIMESTAMP #29926)
• ​Fix errors reported in reading the results by avoiding encoding the maximum value and minimum non-null value of the string type #31721
• Fix load data panic if the data is broken at an escape character #31589
• (dup: release-5.3.1.md > Bug fixes> TiDB)- Fix the issue that the greatest or least function with collation gets a wrong result #31789
• Fix the bug that the date_add and date_sub functions may return incorrect data types #31809
• Fix possible panic when inserting data to virtually generated columns using an insert statement #31735
• Fix the bug that no error is reported when duplicate columns are present in the created list partition #31784
• Fix wrong results returned when select for update union select uses incorrect snapshots #31530
• (dup: release-5.3.1.md > Bug fixes> Tools> Backup & Restore (BR))- Fix the potential issue that Regions might be unevenly distributed after a restore operation is finished #31034
• Fix the bug that COERCIBILITY is wrong for the json type #31541
• Fix wrong collation of the json type when this type is processed using builtin-func #31320
• Fix the bug that PD rules are not deleted when the count of TiFlash replicas is set to 0 #32190
• (dup: release-5.3.1.md > Bug fixes> TiDB)- Fix the issue that alter column set default wrongly updates the table schema #31074
• (dup: release-5.3.1.md > Bug fixes> TiDB)- Fix the issue that date_format in TiDB handles in a MySQL-incompatible way #32232
• Fix the bug that errors may occur when updating partitioned tables using join #31629
• Fix wrong range calculation for Nulleq function on Enum values #32428
• Fix possible panic in upper() and lower() functions #32488
• Fix time zone problems encountered when changing the other type columns to timestamp type columns #29585
• Fix TiDB OOM when exporting data using ChunkRPC #31981 #30880
• Fix the bug that sub SELECT LIMIT does not work as expected in dynamic partition pruning mode #32516
• Fix wrong or inconsistent format of bit default value on INFORMATION_SCHEMA.COLUMNS #32655
• Fix the bug that partition table pruning might not work for listing partition tables after server restart #32416
• Fix the bug that add column may use wrong default timestamp after executing SET timestamp #31968
• Fix the bug that connecting to a TiDB passwordless account from MySQL 5.5 or 5.6 client may fail #32334
• Fix wrong results when reading partitioned tables in dynamic mode in transactions #29851
• Fix the bug that TiDB may dispatch duplicate tasks to TiFlash #32814
• Fix wrong results returned when the timdiff function contains a millisecond #31680
• Fix wrong results when explicitly reading partitions and using the IndexJoin plan #32007
• Fix the bug that "rename column" fails when changing column type concurrently #31075
• Fix the bug that the formula for calculating net cost for TiFlash plans is not aligned with TiKV plans #30103
• Fix the bug that KILL TIDB cannot take effect immediately on idle links #24031
• Fix the bug that reading from a table with generated columns may get wrong results #33038
• Fix wrong results of deleting data of multiple tables using left join #31321
• Fix the bug that the SUBTIME function returns a wrong result in case of overflow #31868
• Fix the bug that the selection operator can not be pushed down when an aggregation contains the having condition #33166
• Fix the bug that CTE may be blocked when a query reports errors #31302
• Fix the bug that excessive length of varbinary or varchar columns when creating tables in non-strict mode may result in errors #30328
• Fix the wrong number of followers in information_schema.placement_policieswhen no follower is specified #31702
• Fix the issue that TiDB allows to specify column prefix length as 0 when an index is created #31972
• Fix the issue that TiDB allows partition names ending with spaces #31535
• Fix the wrong message of the RENAME TABLE statement #29893

Compatibility changes

• Change the default value of the system variable tidb_analyze_version from 2 to 1 #31748
• Since v5.1.4, if TiKV is configured with storage.enable-ttl = true, the requests from TiDB are rejected, because the TTL feature of TiKV only supports the RawKV mode #27303

Feature enhancements

• Support partition pruning for the built-in IN expression in Range partition tables #26739
• Improve the accuracy of tracking memory usage when IndexJoin is executed #28650

Bug fixes

• Fix a memory leak bug that occurs when the system variable tidb_analyze_version is set to 2 #32499
• Fix the issue that the MaxDays and MaxBackups configurations do not take effect for the slow log #25716
• Fix the issue that executing the INSERT ... SELECT ... ON DUPLICATE KEY UPDATE statement gets panic #28078
• Fix the wrong result that might occur when performing JOIN on ENUM type columns #27831
• Fix the issue that INDEX HASH JOIN returns the send on closed channel error #31129
• Fix the issue that using the BatchCommands API might block sending TiDB requests to TiKV in some rare cases #32500
• Fix the issue of potential data index inconsistency in optimistic transaction mode #30410
• Fix the issue that window functions might return different results when using a transaction or not #29947
• Fix the issue that the length information is wrong when casting Decimal to String #29417
• Fix the issue that the GREATEST function returns incorrect result that occurs when setting the tidb_enable_vectorized_expression vectorized expression to off #29434
• Fix the issue that the optimizer might cache invalid plans for join in some cases #28087
• Fix wrong results of the microsecond and hour functions in vectorized expressions #29244 #28643
• Fix the TiDB panic when executing the ALTER TABLE.. ADD INDEX statement in some cases #27687
• 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

Compatibility changes

• Change the default value of the system variable tidb_analyze_version from 2 to 1 #31748
• Since v5.1.4, if TiKV is configured with storage.enable-ttl = true, the requests from TiDB are rejected, because the TTL feature of TiKV only supports the RawKV mode #27303

Feature enhancements

• Support partition pruning for the built-in IN expression in Range partition tables #26739
• Improve the accuracy of tracking memory usage when IndexJoin is executed #28650

Bug fixes

• Fix a memory leak bug that occurs when the system variable tidb_analyze_version is set to 2 #32499
• Fix the issue that the MaxDays and MaxBackups configurations do not take effect for the slow log #25716
• Fix the issue that executing the INSERT ... SELECT ... ON DUPLICATE KEY UPDATE statement gets panic #28078
• Fix the wrong result that might occur when performing JOIN on ENUM type columns #27831
• Fix the issue that INDEX HASH JOIN returns the send on closed channel error #31129
• Fix the issue that using the BatchCommands API might block sending TiDB requests to TiKV in some rare cases #32500
• Fix the issue of potential data index inconsistency in optimistic transaction mode #30410
• Fix the issue that window functions might return different results when using a transaction or not #29947
• Fix the issue that the length information is wrong when casting Decimal to String #29417
• Fix the issue that the GREATEST function returns incorrect result that occurs when setting the tidb_enable_vectorized_expression vectorized expression to off #29434
• Fix the issue that the optimizer might cache invalid plans for join in some cases #28087
• Fix wrong results of the microsecond and hour functions in vectorized expressions #29244 #28643
• Fix the TiDB panic when executing the ALTER TABLE.. ADD INDEX statement in some cases #27687
• 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

Improvements

• Add a new system variable tidb_enable_paging to determine whether to use paging to send Coprocessor requests. Enabling this feature can reduce the amount of data to process and to reduce latency and resource consumption #30578
• Support the ADMIN {SESSION | INSTANCE | GLOBAL} PLAN_CACHE syntax to clear the cached query plan #30370

Bug fixes

• Fix the issue of the tidb_analyze_version value change that occurs when upgrading the cluster from v4.x to v5.x #25422
• Fix the issue of the wrong result that occurs when using different collations in a subquery #30748
• Fix the issue that the result of concat(ifnull(time(3)) in TiDB is different from that in MySQL #29498
• Fix the issue of potential data index inconsistency in optimistic transaction mode #30410
• Fix the issue that the query execution plan of IndexMerge is wrong when an expression cannot be pushed down to TiKV #30200
• Fix the issue that concurrent column type change causes inconsistency between the schema and the data #31048
• Fix the issue that the IndexMerge query result is wrong when there is a subquery #30913
• Fix the panic issue that occurs when the FetchSize is set too large in the client #30896
• Fix the issue that LEFT JOIN might be mistakenly converted to INNER JOIN #20510
• Fix the issue that panic might occur when the CASE-WHEN expression and collation are used together #30245
• Fix the issue of wrong query result that occurs when the IN value contains a binary constant #31261
• Fix the issue of wrong query result that occurs when CTE has a subquery #31255
• Fix the issue that executing the INSERT ... SELECT ... ON DUPLICATE KEY UPDATE statement gets panic #28078
• Fix the issue that INDEX HASH JOIN returns the send on closed channel error #31129

Bug fixes

• Fix the panic that might occur when DML and DDL statements are executed concurrently #30940
• Fix the TiDB panic when executing the ALTER TABLE.. ADD INDEX statement in some cases #27687
• Fix the issue that the enforce-mpp configuration does not take effect in v5.0.4 #29252
• Fix the TiDB panic when inserting invalid date values concurrently #25393
• Fix the unexpected can not found column in Schema column error for queries in the MPP mode #30980
• Fix the unexpected index out of range error when the planner is doing join reorder #24095
• Fix the wrong result of CONCAT(IFNULL(TIME(3)) #29498
• Fix wrong results of GREATEST and LEAST when passing in unsigned BIGINT arguments #30101
• Fix the issue that a SQL operation is canceled when its JSON type column joins its CHAR type column #29401
• Fix the data inconsistency issue caused by incorrect usage of lazy existence check and untouched key optimization #30410
• Fix the issue that window functions might return different results when using a transaction or not #29947
• Fix the issue that the SQL statements that contain cast(integer as char) union string return wrong results #29513
• Fix the issue that the Column 'col_name' in field list is ambiguous error is reported unexpectedly when a SQL statement contains natural join #25041
• Fix the issue that the index out of range [1] with length 1 error is reported when a SQL statement evaluates an aggregation result on the result of join in some cases #1978

Improvements

• Upgrade the Grafana version from 7.5.7 to 7.5.11

Bug fixes

• Fix the query panic caused by overflow in the statistics module when converting a range to points for cost estimation #23625
• Fix wrong results of the control functions (such as IF and CASE WHEN) when using the ENUM type data as parameters of such functions #23114
• Fix the issue that the GREATEST function returns inconsistent results due to different values of tidb_enable_vectorized_expression (on or off) #29434
• Fix the panic when applying index join on prefix indexes in some cases #24547
• Fix the issue that planner might cache invalid plans for join in some cases #28087
• Fix a bug that TiDB cannot insert null into a non-null column when sql_mode is empty #11648
• Fix the wrong result type of the GREATEST and LEAST functions #29019
• Fix the privilege check fail error when performing the grant and revoke operations to grant and revoke global level privileges #29675
• Fix the panic when using the CASE WHEN function on the ENUM data type #29357
• Fix wrong results of the microsecond function in vectorized expressions #29244
• Fix wrong results of the hour function in vectorized expression #28643
• Fix the issue that optimistic transaction conflicts might cause transactions to block each other #11148
• Fix the issue of incomplete log information from the auto analyze result #29188
• Fix the issue that using an invalid default date does not report an error when the SQL_MODE is 'NO_ZERO_IN_DATE' #26766
• Fix the issue that the Coprocessor Cache panel in Grafana does not display metrics. Now, Grafana displays the number of hits/miss/evict #26338
• Fix the issue that concurrently truncating the same partition causes DDL statements to stuck #26229
• Fix the issue that when the CONCAT function has a negative float type argument, the last digit of the argument number is chopped in the result #29417
• Fix the issue of an extra column in the query result when NATURAL JOIN is used to join multiple tables #29481
• Fix the issue that TopN is wrongly pushed down to indexPlan when IndexScan uses a prefix index #29711
• Fix the issue that retrying transactions with the auto-increment columns of DOUBLE type causes data corruption #29892

Improvements

• 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
• Improve the default collection logic of ANALYZE when tidb_analyze_version is 2, which accelerates collection and reduces resource overhead
• Introduce the ANALYZE TABLE table_name COLUMNS col_1, col_2, ... , col_n syntax. The syntax allows collecting statistics only on a portion of the columns in wide tables, which improves the speed of statistics collection

Bug Fixes

• Fix an error that occurs during execution caused by the wrong execution plan. The wrong execution plan is caused by the shallow copy of schema columns when pushing down the aggregation operators on partitioned tables. #27797 #26554
• 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
• Fix the wrong default value of the plugin_dir configuration 28084

There is no release note for this version.

Improvements

• 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

Bug Fixes

• 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 may 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 may block sending requests in some rare cases #27688
• Fixed 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 can make tidb_snapshot unwork #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 theDATA RACE issue when assigningMPP 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 can not found column in Schema column for MPP queries #28149
• Fix the issue that TiDB might crash when TiFlash shuts down #28096
• Remove the support for insecure 3DES (Triple Data Encryption Algorithm) based TLS ciphersuites #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 issue that extract function gives wrong results when argument 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 log in production #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

There is no release note for this version.

Improvements

• Trigger auto-analyze by histogram row count, increase the accuracy of this trigger action #24237
• Push down mod() to TiFlash, increase the query performance. #2318

Bug Fixes

• Fix the potential wrong results of index hash join when the hash column is in the ENUM type #27893
• Fix a batch client bug that recycle idle connection may block sending requests in some rare cases #27678
• Fix the compatibility issue of the overflow check by keeping the same logic as MySQL #23897
• Fix the issue that TiDB returns an unknow error while it should return the pd is timeout error #26147
• Fix the error of the case when function caused by the wrong charset and collation #26662
• Fix the issue that greatest(datetime) union null returns an empty string #26532
• Fix the potential can not found column in Schema column error for MPP queries #28148
• Fix a bug that TiDB may panic when TiFlash is shutting down #28096
• Fix the issue of wrong range caused by using enum like 'x%' #27130
• Fix the issue that the between expression infers wrong collation. #27146
• Fix the Common Table Expression (CTE) dead lock issue when used with IndexLookupJoin #27410
• Fix a bug that retryable deadlocks are incorrectly recorded into the INFORMATION_SCHEMA.DEADLOCKS table #27400
• Fix a bug that GROUP_CONCAT function does not consider the collation #27429
• Fix a bug that the COUNT(DISTINCT) function on multiple columns returns wrong results when New Collation is on #27091
• Fix an issue that the TABLESAMPLE query result from partitioned tables is not sorted as expected #27349
• Fix a bug that the EXTRACT function returns wrong results when the argument is a negative duration #27236
• Remove the unused /debug/sub-optimal-plan HTTP API #27265
• Fix the issue that a wrong selection is pushed down when the HAVING condition is used in the aggregate function #26496
• Fix a bug that the query may return wrong results when the hash partition table deals with unsigned data #26569
• Fix the unexpected behavior when casting an invalid string to DATE #26762
• Fix a bug that creating partition fails if NO_UNSIGNED_SUBTRACTION is set #26765
• Fix the issue that the distinct flag is missing when Apply is converted to Join #26958
• Fix the issue that NO_ZERO_IN_DATE does not work on the default values #26766
• Set a block duration for the newly recovered TiFlash node to avoid blocking queries during this time #26897
• Fix a bug that might occur when the CTE is referenced more than once #26212
• Fix a CTE bug when MergeJoin is used #25474
• Fix a bug that the 'SELECT FOR UPDATE' statement does not correctly lock the data when a normal table joins a partition table #26251
• Fix the issue that the 'SELECT FOR UPDATE' statement returns an error when a normal table joins a partition table #26250
• Fix the issue that PointGet does not use the lite version of resolve lock #26562

Compatibility changes

• Fix the issue that executing SHOW VARIABLES in a new session is slow. This fix reverts some changes made in #21045 and might cause compatibility issues. #24326

Improvements

• Trigger auto-analyze based on the histogram row count #26706

Bug fixes

• Fix a bug that collation is incorrectly set for binary literals when building range 26455
• Fix the issue of wrong character set and collation for the case when expression #26671
• Fix the "index out of range" error that occurs when a query includes both GROUP BY and UNION 26553
• Fix the issue that TiDB might fail to send requests if TiKV has tombstone stores #25849
• Fix the issue of unexpected behavior when casting the invalid string to DATE #27935
• Fix the issue that column information is missed when converting the Apply operator to Join #27282
• Fix a bug that the count distinct result on multiple columns is wrong when the new collation is enabled #27830
• Fix the result wrong that occurs when the argument of the extract function is a negative duration #27236
• Fix the wrong execution results that occur when the column in the group_concat function has a non-bin collation #27429
• Fix the wrong execution results that occur when the collations around the between expression are different #27146
• Fix the issue that greatest(datetime) union null returns empty string #26564
• Fix the issue that the having clause might not work correctly #26496
• Remove the undocumented /debug/sub-optimal-plan HTTP API #27264

Bug Fixes

• Fix an error that occurs during execution caused by the wrong execution plan. The wrong execution plan is caused by the shallow copy of schema columns when pushing down the aggregation operators on partitioned tables. #27797 #26554