· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 1211 7.7.28 What is the order of executing DML and DDL statements? · · · · · · · · · · 1211 7.7.29 How should I check whether the MySQL variables that TiDB is compatible with? · · · · · · · 5251 15.3.6 The order of results is different from MySQL when ORDER BY is omitted5251 15.3.7 Does TiDB support SELECT FOR UPDATE? · · · · · · automatically collect statistics. In future releases, the priority queue will be the only way to order tasks for automatically collecting statistics, so this system variable will be deprecated. 84 •

MySQL variables that TiDB is compatible with? · · · · · · · 5230 15.3.6 The order of results is different from MySQL when ORDER BY is omitted5230 22 15.3.7 Does TiDB support SELECT FOR UPDATE? · · · · automatically collect statistics. In future releases, the priority queue will be the only way to order tasks for automatically collecting statistics, so this system variable will be deprecated. 79 • fallback action when the memory limit is exceeded #56185 @xzhangxian1008 • Fix the issue that the ORDER BY column in the Sort operator is stuck if it contains a constant #55344 @xzhangxian1008 • Fix the

MySQL variables that TiDB is compatible with? · · · · · · · 5178 15.3.6 The order of results is different from MySQL when ORDER BY is omitted5178 15.3.7 Does TiDB support SELECT FOR UPDATE? · · · · · · automatically collect statistics. In future releases, the priority queue will be the only way to order tasks for automatically collecting statistics, so this system variable will be deprecated. • TiDB idx_col_2 < 20)) #54337 @ghazalfamilyusa • Use index order to avoid extra sorting operations for SQL queries like WHERE idx �→ _col_1 IS NULL ORDER BY idx_col_2 #54188 @ari-e • Display analyzed indexes

MySQL variables that TiDB is compatible with? · · · · · · · 5149 15.3.6 The order of results is different from MySQL when ORDER BY is omitted5149 15.3.7 Does TiDB support SELECT FOR UPDATE? · · · · · · following priority order: status, health, memory, CPU, location, and connection count. • location: the location priority policy performs load balancing based on the fol- lowing priority order: status, location minimum connection count priority policy performs load balanc- ing based on the following priority order: status and connection count. For more information, see documentation. 2.2.1.4 SQL • TiDB supports

MySQL variables that TiDB is compatible with? · · · · · · · 5103 15.3.6 The order of results is different from MySQL when ORDER BY is omitted5103 15.3.7 Does TiDB support SELECT FOR UPDATE? · · · · · · need to store a substantial number of tables. In �→ previous versions, handling table counts in the order of a million or �→ more was feasible, but it had the potential to degrade the overall �→ user experience downstream data inconsistencies caused by the potentially incor- rect order of UPDATE events received by TiCDC, which can lead to an incorrect order of split DELETE and INSERT events. For more information, see

MySQL variables that TiDB is compatible with? · · · · · · · 4878 15.3.6 The order of results is different from MySQL when ORDER BY is omitted4878 15.3.7 Does TiDB support SELECT FOR UPDATE? · · · · · · CTEStorageMap failed during the retry process #46522 @tiancaiamao • Fix the issue that LIMIT and ORDER BY might be invalid in nested UNION queries #49377 @AilinKid • Fix the issue that parsing invalid contains NULL #49823 @AilinKid • Fix the issue that executing queries containing the GROUP_CONCAT(ORDER BY) 68 syntax might return errors #49986 @AilinKid • Fix the issue that UPDATE, DELETE, and INSERT

MySQL variables that TiDB is compatible with? · · · · · · · 2345 13.2.2 The order of results is different from MySQL when ORDER BY is omitted2346 13.2.3 Does TiDB support SELECT FOR UPDATE? · · · · · · LEFT\|RIGHT [OUTER] JOIN Y Y Y Y UNION, UNION ALL Y Y Y Y EXCEPT and INTERSECT operators Y Y Y N GROUP BY, ORDER BY Y Y Y Y Window Functions Y Y Y Y Common Table Expressions (CTE) Y Y N N START TRANSACTION, COMMIT choice of indexes (Introduced in v5.0) – Extend the statistics feature by collecting the multi-column order dependency information. – Refactor the statistics module, including deleting the TopN value from

MySQL variables that TiDB is compatible with? · · · · · · · 3866 15.3.6 The order of results is different from MySQL when ORDER BY is omitted3866 15.3.7 Does TiDB support SELECT FOR UPDATE? · · · · · · under certain loads. User document, #95 • Support the join order hint syntax • The LEADING hint reminds the optimizer to use the specified order as the prefix of join operations. A good prefix of join can reminds the optimizer to join tables in an order that is consistent with the order of tables in the FROM clause. This provides a method for you to fix the order of table joins. A proper use of the hints

MySQL variables that TiDB is compatible with? · · · · · · · 4806 15.3.6 The order of results is different from MySQL when ORDER BY is omitted4806 15.3.7 Does TiDB support SELECT FOR UPDATE? · · · · · · to eliminate the �→ unnecessary I/O, CPU, and memory spikes caused by temporarily out-of- 36 �→ order data during data re-organization tasks. The global sorting �→ takes advantage of external shared object UNION, UNION ALL Y Y Y Y Y Y Y Y Y Y EXCEPT and INTERSECT operators Y Y Y Y Y Y Y Y Y N GROUP BY, ORDER BY Y Y Y Y Y Y Y Y Y Y Window Functions Y Y Y Y Y Y Y Y Y Y Common Table Expressions (CTE) Y Y Y

MySQL variables that TiDB is compatible with? · · · · · · · 2528 13.2.2 The order of results is different from MySQL when ORDER BY is omitted2528 13.2.3 Does TiDB support SELECT FOR UPDATE? · · · · · · [OUTER] JOIN Y Y Y Y Y UNION, UNION ALL Y Y Y Y Y EXCEPT and INTERSECT operators Y Y Y Y N GROUP BY, ORDER BY Y Y Y Y Y Window Functions Y Y Y Y Y Common Table Expressions (CTE) Y Y Y N N START TRANSACTION choice of indexes (Introduced in v5.0) – Extend the statistics feature by collecting the multi-column order dependency information. – Refactor the statistics module, including deleting the TopN value from