Server System Variables For more information about memory use during different operations, see Section 8.12.3.1, “How MySQL Uses Memory” . For information about Multi-Range Read optimization, see Section 8.2.1.11, “Multi- Range Read Optimization” . • regexp_stack_limit • regexp_time_limit • require_row_format 868 The maximum available memory in bytes for the internal stack used for regular expression matching operations performed by  REGEXP_LIKE()  and similar functions (see Section 12.8.2, “Regular Expressions” ). The time limit for regular expression matching operations performed by  REGEXP_LIKE()  and similar functions (see Section 12.8.2, “Regular Expressions” ). This limit is expressed as the maximum permitted number of steps performed by the match engine, and thus affects execution time only indirectly. Typically, it is on the order of milliseconds. Command-Line Format --regexp-stack-limit=# System Variable regexp_stack_limit Scope Global Dynamic Yes SET_VAR  Hint Applies No Type Integer Default Value 8000000 Minimum Value 0 Maximum Value 2147483647 Command-Line Format --regexp-time-limit=# System Variable regexp_time_limit Scope Global Dynamic Yes SET_VAR  Hint Applies No Type Integer Default Value 32 Minimum Value 0 Maximum Value 2147483647 Introduced 8.0.19 System Variable require_row_format Scope Session Dynamic Yes SET_VAR  Hint Applies No Type Boolean