TiDB - v5.1.0

Improvements

• Support the built-in function VITESS_HASH() #23915
• Support pushing down data of the enumerated type to TiKV to improve performance when using enumerated types in WHERE clauses #23619
• Optimize the calculation of Window Function to solve TiDB OOM problems when paging data with ROW_NUMBER() #23807
• Optimize the calculation of UNION ALL to solve the TiDB OOM problems when using UNION ALL to join a large number of SELECT statements #21441
• Optimize the dynamic mode of partitioned tables to improve performance and stability #24150
• Fix the Region is Unavailable issue that occurs in multiple scenarios project#62
• Fix multiple Region is Unavailable issues that might occur in frequent scheduling situations
• Fix Region is Unavailable issue that might occur in some high stress write situations
• Avoid frequently reading the mysql.stats_histograms table if the cached statistics is up-to-date to avoid high CPU usage #24317

Bug Fixes

• Fix the issue that the execution result of project elimination might be wrong when the projection result is empty #23887
• Fix the issue of wrong query results when a column contains NULL values in some cases #23891
• Forbid generating MPP plans when the scan contains virtual columns #23886
• Fix the wrong reuse of PointGet and TableDual in Plan Cache #23187 #23144 #23304 #23290
• Fix the error that occurs when the optimizer builds the IndexMerge plan for clustered indexes #23906
• Fix the type inference of the BIT-type errors #23832
• Fix the issue that some optimizer hints do not take effect when the PointGet operator exists #23570
• Fix the issue that DDL operations might fail when rolling back due to an error #23893
• Fix the issue that the index range of the binary literal constant is incorrectly built #23672
• Fix the potential wrong results of the IN clause in some cases #23889
• Fix the wrong results of some string functions #23759
• Users now need both INSERT and DELETE privileges on a table to perform REPLACE operations #23909
• Users now need both INSERT and DELETE privileges on a table to perform REPLACE operations #24070
• Fix the wrong TableDual plans caused by incorrectly comparing binaries and bytes#23846
• Fix the panic issue caused by using the prefix index and index join in some cases #24547 #24716 #24717
• Fix the issue that the prepared plan cache of point get is incorrectly used by the point get statement in the transaction #24741
• Fix the issue of writing the wrong prefix index value when the collation is ascii_bin or latin1_bin #24569
• Fix the issue that the ongoing transaction might be interrupted by the GC worker #24591
• Fix a bug that the point query might get wrong on the clustered index when new-collation is enabled but new-row-format is disabled #24541
• Refactor the conversion of partition keys for shuffle hash join #24490
• Fix the panic issue that occurs when building the plan for queries that contain the HAVING clause #24045
• Fix the issue that the column pruning improvement causes the Apply and Join operators' results to go wrong #23887
• Fix a bug that the primary lock fallen back from async commit cannot be resolved #24384
• Fix a GC issue of statistics that might cause duplicated fm-sketch records #24357
• Avoid unnecessary pessimistic rollback when the pessimistic locking receives the ErrKeyExists error #23799
• Fix the issue that numeric literals cannot be recognized when the sql_mode contains ANSI_QUOTES #24429
• Forbid statements such as INSERT INTO table PARTITION (<partitions>) ... ON DUPLICATE KEY UPDATE to read data from non-listed partitions #24746
• Fix the potential index out of range error when a SQL statement contains both GROUP BY and UNION #24281
• Fix the issue that the CONCAT function incorrectly handles the collation #24296
• Fix the issue that the collation_server global variable does not take effect in new sessions #24156