optimizer_switch
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optimizer_switch is a server variable that one can use to enable/disable specific optimizations.
Syntax
To set or unset the various optimizations, use the following syntax:
SET [GLOBAL|SESSION] optimizer_switch='cmd[,cmd]...';
The cmd takes the following format:
| Syntax | Description |
|---|---|
| default | Reset all optimizations to their default values. |
| optimization_name=default | Set the specified optimization to its default value. |
| optimization_name=on | Enable the specified optimization. |
| optimization_name=off | Disable the specified optimization. |
There is no need to list all flags - only those that are specified in the command will be affected.
Available Flags
Below is a list of all optimizer_switch flags available in MariaDB:
- ↑ replaced split_grouping_derived, introduced in MariaDB 10.3.1
Defaults
| From version | Default optimizer_switch setting |
|---|---|
| MariaDB 11.7.0 | index_merge=on, index_merge_union=on, index_merge_sort_union=on, index_merge_intersection=on, index_merge_sort_intersection=off, index_condition_pushdown=on, derived_merge=on, derived_with_keys=on, firstmatch=on, loosescan=on, materialization=on, in_to_exists=on, semijoin=on, partial_match_rowid_merge=on, partial_match_table_scan=on, subquery_cache=on, mrr=off, mrr_cost_based=off, mrr_sort_keys=off, outer_join_with_cache=on, semijoin_with_cache=on, join_cache_incremental=on, join_cache_hashed=on, join_cache_bka=on, optimize_join_buffer_size=on, table_elimination=on, extended_keys=on, exists_to_in=on, orderby_uses_equalities=on, condition_pushdown_for_derived=on, split_materialized=on, condition_pushdown_for_subquery=on, rowid_filter=on, condition_pushdown_from_having=on, not_null_range_scan=off, hash_join_cardinality=on, cset_narrowing=on, sargable_casefold=on |
| MariaDB 11.3.1 | index_merge=on, index_merge_union=on, index_merge_sort_union=on, index_merge_intersection=on, index_merge_sort_intersection=off, index_condition_pushdown=on, derived_merge=on, derived_with_keys=on, firstmatch=on, loosescan=on, materialization=on, in_to_exists=on, semijoin=on, partial_match_rowid_merge=on, partial_match_table_scan=on, subquery_cache=on, mrr=off, mrr_cost_based=off, mrr_sort_keys=off, outer_join_with_cache=on, semijoin_with_cache=on, join_cache_incremental=on, join_cache_hashed=on, join_cache_bka=on, optimize_join_buffer_size=on, table_elimination=on, extended_keys=on, exists_to_in=on, orderby_uses_equalities=on, condition_pushdown_for_derived=on, split_materialized=on, condition_pushdown_for_subquery=on, rowid_filter=on, condition_pushdown_from_having=on, not_null_range_scan=off, hash_join_cardinality=on, cset_narrowing=off, sargable_casefold=on |
| MariaDB 10.6.16, MariaDB 10.11.6, MariaDB 11.0.4, MariaDB 11.1.3 and MariaDB 11.2.2 | index_merge=on, index_merge_union=on, index_merge_sort_union=on, index_merge_intersection=on, index_merge_sort_intersection=off, index_condition_pushdown=on, derived_merge=on, derived_with_keys=on, firstmatch=on, loosescan=on, materialization=on, in_to_exists=on, semijoin=on, partial_match_rowid_merge=on, partial_match_table_scan=on, subquery_cache=on, mrr=off, mrr_cost_based=off, mrr_sort_keys=off, outer_join_with_cache=on, semijoin_with_cache=on, join_cache_incremental=on, join_cache_hashed=on, join_cache_bka=on, optimize_join_buffer_size=on, table_elimination=on, extended_keys=on, exists_to_in=on, orderby_uses_equalities=on, condition_pushdown_for_derived=on, split_materialized=on, condition_pushdown_for_subquery=on, rowid_filter=on, condition_pushdown_from_having=on, not_null_range_scan=off, hash_join_cardinality=on, cset_narrowing=off |
| MariaDB 11.0.2 | index_merge=on, index_merge_union=on, index_merge_sort_union=on, index_merge_intersection=on, index_merge_sort_intersection=off, engine_condition_pushdown=off, index_condition_pushdown=on, derived_merge=on, derived_with_keys=on, firstmatch=on, loosescan=on, materialization=on, in_to_exists=on, semijoin=on, partial_match_rowid_merge=on, partial_match_table_scan=on, subquery_cache=on, mrr=off, mrr_cost_based=off, mrr_sort_keys=off, outer_join_with_cache=on, semijoin_with_cache=on, join_cache_incremental=on, join_cache_hashed=on, join_cache_bka=on, optimize_join_buffer_size=on, table_elimination=on, extended_keys=on, exists_to_in=on, orderby_uses_equalities=on, condition_pushdown_for_derived=on, split_materialized=on, condition_pushdown_for_subquery=on, rowid_filter=on,condition_pushdown_from_having=on, not_null_range_scan=off, hash_join_cardinality=on |
| MariaDB 10.6.13, MariaDB 10.11.3 | index_merge=on, index_merge_union=on, index_merge_sort_union=on, index_merge_intersection=on, index_merge_sort_intersection=off, engine_condition_pushdown=off, index_condition_pushdown=on, derived_merge=on, derived_with_keys=on, firstmatch=on, loosescan=on, materialization=on, in_to_exists=on, semijoin=on, partial_match_rowid_merge=on, partial_match_table_scan=on, subquery_cache=on, mrr=off, mrr_cost_based=off, mrr_sort_keys=off, outer_join_with_cache=on, semijoin_with_cache=on, join_cache_incremental=on, join_cache_hashed=on, join_cache_bka=on, optimize_join_buffer_size=on, table_elimination=on, extended_keys=on, exists_to_in=on, orderby_uses_equalities=on, condition_pushdown_for_derived=on, split_materialized=on, condition_pushdown_for_subquery=on, rowid_filter=on,condition_pushdown_from_having=on, not_null_range_scan=off, hash_join_cardinality=off |
| MariaDB 10.5.0 | index_merge=on, index_merge_union=on, index_merge_sort_union=on, index_merge_intersection=on, index_merge_sort_intersection=off, engine_condition_pushdown=off, index_condition_pushdown=on, derived_merge=on, derived_with_keys=on, firstmatch=on, loosescan=on, materialization=on, in_to_exists=on, semijoin=on, partial_match_rowid_merge=on, partial_match_table_scan=on, subquery_cache=on, mrr=off, mrr_cost_based=off, mrr_sort_keys=off, outer_join_with_cache=on, semijoin_with_cache=on, join_cache_incremental=on, join_cache_hashed=on, join_cache_bka=on, optimize_join_buffer_size=on, table_elimination=on, extended_keys=on, exists_to_in=on, orderby_uses_equalities=on, condition_pushdown_for_derived=on, split_materialized=on, condition_pushdown_for_subquery=on, rowid_filter=on,condition_pushdown_from_having=on, not_null_range_scan=off |
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