semijoin_with_cache , outer_join_with_cache, mrr, mrr_sort_keys, mrr_cost_based are missing from some representations of optimizer_switch

[Philip Stoev]

The outer_join_with_cache and semijoin_with_cache options are missing from @@optimizer_switch . I thought that this was because those options were deprecated and removed on purpose, but now I see that they are still valid if specified manually.

To repeat:

mysqld --verbose --help | grep optimizer_switch | grep join_with_cache

Maybe there are other such options. Ideally, there should be one unified list of allowable optimizer_switches.

[Sergey Petrunia (sergefp)]

grepping for optimizer_switch and join_with_cache on the same line produces nothing, because the help text looks like this:

  --optimizer_switch=name
                      optimizer_switch=option=val[,option=val...], where
                      option={index_merge, index_merge_union,
                      index_merge_sort_union, index_merge_intersection,
                      index_merge_sort_intersection, 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, outer_join_with_cache,
                      semijoin_with_cache, join_cache_incremental,
                      join_cache_hashed, join_cache_bka,
                      optimize_join_buffer_size, table_elimination} and
                      val={on, off, default}.

one can see that semijoin_with_cache and outerjoin_with_cache are present there.

Everything seems to work as it should.

[Philip Stoev (pstoev-askmonty)]

Those are the two lists from mysqld --verbose --help:

index_merge=xx,index_merge_union=xx,index_merge_sort_union=xx,index_merge_intersection=xx,index_merge_sort_intersection=xxx,index_condition_pushdown=xxx,derived_merge=xxx,derived_with_keys=xxx,firstmatch=xx,loosescan=xx,materialization=xxx,in_to_exists=xx,semijoin=xx,partial_match_rowid_merge=xx,partial_match_table_scan=xx,subquery_cache=xx, outer_join_with_cache=xxx,semijoin_with_cache=xxx,join_cache_incremental=xx,join_cache_hashed=xx,join_cache_bka=xx,optimize_join_buffer_size=xxx,table_elimination=xx

optimizer_switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,index_condition_pushdown=off,derived_merge=off,derived_with_keys=off,firstmatch=on,loosescan=on,materialization=off,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,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=off,table_elimination=on

and this is from SHOW VARIABLES on a running server:

index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,index_condition_pushdown=off,derived_merge=off,derived_with_keys=off,firstmatch=on,loosescan=on,materialization=off,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=off,semijoin_with_cache=off,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=off,table_elimination=on

Those three lists are different. The first list from mysqld --verbose --help is missing mrr,mrr_cost_based,mrr_sort keys. The second list is missing outer_join_with_cache, semijoin_with_cache.