Constraints

Table 1 describes the query statements that cannot be executed in parallel.

**Table 1** Query statements that cannot be executed in parallel
Statement Type	Description
Table	System table Temporary table Non-InnoDB table Partition table const table
Data	BLOB TEXT JSON GEOMETRY
Index	Spatial index Full-text index Index merge
Function	Window functions with rollup Spatial functions (such as SP_WITHIN_FUNC) distinct User-defined functions GROUP_CONCAT JSON functions XML functions STD/STDDEV/STDDEV_POP ARIANCE/VAR_POP/VAR_SAMP BIT_AND, BIT_OR, BIT_XOR rand st_distance get_lock is_free_lock, is_used_lock, release_lock, release_all_locks sleep weight_string SHA, SHA1, SHA2, MD5 row_count round VARIANCE
Others	Subqueries union Stored procedure Triggers Lock queries, such as the serializable isolation level and "for update/share lock" Prepared Statements generated column Not compliant with the only_full_group_by condition No line of data returned in the execution result (The execution plan displays Zero limit, Impossible WHERE, Impossible HAVING, No matching min/max row, Select tables optimized away, Impossible HAVING noticed after reading const tables, no matching row in const table, etc.)