TiDB - v5.0.3

Compatibility Changes

• After a v4.0 cluster is upgraded to v5.0 or a later version (dev or v5.1), the default value of the tidb_multi_statement_mode variable changes from WARN to OFF
• TiDB is now compatible with MySQL 5.7's noop variable innodb_default_row_format #23541

Improvements

• Support pushing down the TopN operator to TiFlash #25162
• Support pushing down the built-in function json_unquote() to TiKV #24415
• Support removing the union branch from the dual table #25614
• Support pushing down the built-in function replace() to TiFlash #25565
• Support pushing down the built-in functions unix_timestamp(), concat(), year(), day(), datediff(), datesub(), and concat_ws() to TiFlash #25564
• Optimize the aggregate operator's cost factor #25241
• Support pushing down the Limit operator to TiFlash #25159
• Support pushing down the built-in function str_to_date to TiFlash #25148
• Allow the MPP outer join to choose the build table based on the table row count #25142
• Support pushing down the built-in functions left(), right(), and abs() to TiFlash #25133
• Support pushing down the Broadcast Cartesian join to TiFlash #25106
• Support pushing down the Union All operator to TiFlash #25051
• Support balancing the MPP query workload among different TiFlash nodes based on Regions #24724
• Support invalidating stale Regions in the cache after the MPP query is executed #24432
• Improve the MySQL compatibility of the built-in function str_to_date for the format specifiers %b/%M/%r/%T #25767

Bug Fixes

• Fix the issue that an incorrect result is returned when using merge join on the SET type column #25669
• Fix the data corruption issue in the IN expression's arguments #25591
• Avoid the sessions of GC being affected by global variables #24976
• Fix the panic issue that occurs when using limit in the window function queries #25344
• Fix the wrong value returned when querying a partitioned table using Limit #24636
• Fix the issue that IFNULL does not correctly take effect on the ENUM or SET type column #24944
• Fix the wrong results caused by changing the count in the join subqueries to first_row #24865
• Fix the query hang issue that occurs when ParallelApply is used under the TopN operator #24930
• Fix the issue that more results than expected are returned when executing SQL statements using multi-column prefix indexes #24356
• Fix the issue that the <=> operator cannot correctly take effect #24477
• Fix the data race issue of the parallel Apply operator #23280
• Fix the issue that the index out of range error is reported when sorting the IndexMerge results of the PartitionUnion operator #23919
• Fix the issue that setting the tidb_snapshot variable to an unexpectedly large value might damage the transaction isolation #25680
• Fix the issue that the ODBC-styled constant (for example, {d '2020-01-01'}) cannot be used as the expression #25531
• Fix the issue that SELECT DISTINCT converted to Batch Get causes incorrect results #25320
• Fix the issue that backing off queries from TiFlash to TiKV cannot be triggered #23665 #24421
• Fix the index-out-of-range error that occurs when checking only_full_group_by #23839)
• Fix the issue that queries with TABLESAMPLE on an empty table returns unexpected rows #25257
• Fix the issue that the result of index join in correlated subqueries is wrong #25799