--optimizer-switch

This is a command-line option for the mariadbd & mysqld commands (arg: Required).

In 10.5 ES, 10.5 CS:

Fine-tune the optimizer behavior. Takes a comma-separated list of option=value pairs, where value is on, off, or default, and options are: index_merge, index_merge_union, index_merge_sort_union, index_merge_intersection, index_merge_sort_intersection, engine_condition_pushdown, index_condition_pushdown, derived_merge, derived_with_keys, firstmatch, loosescan, materialization, in_to_exists, semijoin, partial_match_rowid_merge, partial_match_table_scan, subquery_cache, mrr, mrr_cost_based, mrr_sort_keys, outer_join_with_cache, semijoin_with_cache, join_cache_incremental, join_cache_hashed, join_cache_bka, optimize_join_buffer_size, table_elimination, extended_keys, exists_to_in, orderby_uses_equalities, condition_pushdown_for_derived, split_materialized, condition_pushdown_for_subquery, rowid_filter, condition_pushdown_from_having, not_null_range_scan

In 10.4 ES, 10.4 CS:

Fine-tune the optimizer behavior. Takes a comma-separated list of option=value pairs, where value is on, off, or default, and options are: index_merge, index_merge_union, index_merge_sort_union, index_merge_intersection, index_merge_sort_intersection, engine_condition_pushdown, index_condition_pushdown, derived_merge, derived_with_keys, firstmatch, loosescan, materialization, in_to_exists, semijoin, partial_match_rowid_merge, partial_match_table_scan, subquery_cache, mrr, mrr_cost_based, mrr_sort_keys, outer_join_with_cache, semijoin_with_cache, join_cache_incremental, join_cache_hashed, join_cache_bka, optimize_join_buffer_size, table_elimination, extended_keys, exists_to_in, orderby_uses_equalities, condition_pushdown_for_derived, split_materialized, condition_pushdown_for_subquery, rowid_filter, condition_pushdown_from_having

In 10.3 ES, 10.3 CS:

Fine-tune the optimizer behavior. Takes a comma-separated list of option=value pairs, where value is on, off, or default, and options are: index_merge, index_merge_union, index_merge_sort_union, index_merge_intersection, index_merge_sort_intersection, engine_condition_pushdown, index_condition_pushdown, derived_merge, derived_with_keys, firstmatch, loosescan, materialization, in_to_exists, semijoin, partial_match_rowid_merge, partial_match_table_scan, subquery_cache, mrr, mrr_cost_based, mrr_sort_keys, outer_join_with_cache, semijoin_with_cache, join_cache_incremental, join_cache_hashed, join_cache_bka, optimize_join_buffer_size, table_elimination, extended_keys, exists_to_in, orderby_uses_equalities, condition_pushdown_for_derived, split_materialized

In 10.2 ES, 10.2 CS:

Fine-tune the optimizer behavior. Takes a comma-separated list of option=value pairs, where value is on, off, or default, and options are: index_merge, index_merge_union, index_merge_sort_union, index_merge_intersection, index_merge_sort_intersection, engine_condition_pushdown, index_condition_pushdown, derived_merge, derived_with_keys, firstmatch, loosescan, materialization, in_to_exists, semijoin, partial_match_rowid_merge, partial_match_table_scan, subquery_cache, mrr, mrr_cost_based, mrr_sort_keys, outer_join_with_cache, semijoin_with_cache, join_cache_incremental, join_cache_hashed, join_cache_bka, optimize_join_buffer_size, table_elimination, extended_keys, exists_to_in, orderby_uses_equalities, condition_pushdown_for_derived

See also: Options for mariadbd & mysqld in 10.5 ES, in 10.5 CS, in 10.4 ES, in 10.4 CS, in 10.3 ES, in 10.3 CS, in 10.2 ES, and in 10.2 CS