Server System Variables Type Integer Default Value 16777216 Minimum Value 16384 Maximum Value (64-bit platforms) 18446744073709547520 Maximum Value (32-bit platforms) 4294967295 Block Size 1024 Deprecated Yes System Variable max_insert_delayed_threads Scope Global, Session Dynamic Yes SET_VAR  Hint Applies No Type Integer Command-Line Format --max-join-size=# System Variable max_join_size Scope Global, Session Dynamic Yes SET_VAR  Hint Applies Yes Type Integer Default Value 18446744073709551615 This variable sets the maximum size to which user-created  MEMORY  tables are permitted to grow. The value of the variable is used to calculate  MEMORY  table  MAX_ROWS  values. Setting this variable has no effect on any existing  MEMORY  table, unless the table is re-created with a statement such as  CREATE TABLE  or altered with  ALTER TABLE  or  TRUNCATE TABLE . A server restart also sets the maximum size of existing  MEMORY  tables to the global  max_heap_table_size  value. This variable is also used in conjunction with  tmp_table_size  to limit the size of internal in-memory tables. See Section 8.4.4, “Internal Temporary Table Use in MySQL” . max_heap_table_size  is not replicated. See Section 17.5.1.21, “Replication and MEMORY Tables” , and Section 17.5.1.39, “Replication and Variables” , for more information. As of MySQL 8.0.26, setting the session value of this system variable is a restricted operation. The session user must have privileges sufficient to set restricted session variables. See Section 5.1.9.1, “System Variable Privileges” . • max_insert_delayed_threads • max_join_size This variable is a synonym for  max_delayed_threads . Like  max_delayed_threads , it is deprecated (because  DELAYED  inserts are not supported) and subject to removal in a future MySQL release. As of MySQL 8.0.26, setting the session value of this system variable is a restricted operation. The session user must have privileges sufficient to set restricted session variables. See Section 5.1.9.1, “System Variable Privileges” . 832