pingcap/tidb v4.0.14 on GitHub

Compatibility changes

Change the default value of tidb_multi_statement_mode from WARN to OFF in v4.0. It is recommended to use the multi-statement feature of your client library instead. See the documentation on tidb_multi_statement_mode for details. #25749
Upgrade Grafana dashboard from v6.1.16 to v7.5.7 to solve two security vulnerabilities. See the Grafana blog post for details.
Change the default value of the tidb_stmt_summary_max_stmt_count variable from 200 to 3000 #25872

Change the LOCK record into the PUT record for the index keys using point get or batch point get for UPDATE reads #26223
Support the MySQL system variable init_connect and its associated features #26031
Support the stable result mode to make the query results more stable #26003
Support pushing down the built-in function json_unquote() to TiKV #25721
Make the SQL Plan Management (SPM) not affected by the character set #23295

Fix the issue that the SELECT result is incompatible with MySQL when joining a subquery with a WHERE clause evaluated to false #24865
Fix the calculation error of the ifnull function that occurs when the argument is the ENUM or SET type #24944
Fix the wrong aggregate pruning in some cases #25202
Fix the incorrect result of the merge join operation that might occur when the column is the SET type #25669
Fix the issue that TiDB returns wrong results for cartesian join #25591
Fix the panic issue that occurs when SELECT ... FOR UPDATE works on a join operation and the join uses a partitioned table #20028
Fix the issue that the cached prepared plan is incorrectly used for point get #24741
Fix the issue that the LOAD DATA statement can abnormally import non-utf8 data #25979
Fix a potential memory leak issue that occurs when accessing the statistics via an HTTP API #24650
Fix a security issue that occurs when executing the ALTER USER statement #25225
Fix a bug that the TIKV_REGION_PEERS table cannot correctly handle the DOWN status #24879
Fix the issue that invalid strings are not truncated when parsing DateTime #22231
Fix the issue that the select into outfile statement might have no result when the column type is YEAR #22159
Fix the issue that the query result might be wrong when NULL is in the UNION subquery #26532
Fix the issue that the projection operator in execution might cause panic in some cases #26534