diff options
Diffstat (limited to 'sql/sql_join_cache.cc')
| -rw-r--r-- | sql/sql_join_cache.cc | 35 |
1 files changed, 29 insertions, 6 deletions
diff --git a/sql/sql_join_cache.cc b/sql/sql_join_cache.cc index 620c52a3f40..c7b6a0bf6e4 100644 --- a/sql/sql_join_cache.cc +++ b/sql/sql_join_cache.cc @@ -2293,11 +2293,7 @@ enum_nested_loop_state JOIN_CACHE::join_matching_records(bool skip_last) int error; enum_nested_loop_state rc= NESTED_LOOP_OK; join_tab->table->null_row= 0; - bool check_only_first_match= - join_tab->check_only_first_match() && - (!join_tab->first_inner || // semi-join case - join_tab->first_inner == join_tab->first_unmatched); // outer join case - bool outer_join_first_inner= join_tab->is_first_inner_for_outer_join(); + bool check_only_first_match= join_tab->check_only_first_match(); DBUG_ENTER("JOIN_CACHE::join_matching_records"); /* Return at once if there are no records in the join buffer */ @@ -2363,7 +2359,34 @@ enum_nested_loop_state JOIN_CACHE::join_matching_records(bool skip_last) Also those records that must be null complemented are not considered as candidates for matches. */ - if ((!check_only_first_match && !outer_join_first_inner) || + + bool not_exists_opt_is_applicable= true; + if (check_only_first_match && join_tab->first_inner) + { + /* + This is the case with not_exists optimization for nested outer join + when join_tab is the last inner table for one or more embedding outer + joins. To safely use 'not_exists' optimization in this case we have + to check that the match flags for all these embedding outer joins are + in the 'on' state. + (See also a similar check in evaluate_join_record() for the case when + join buffer are not used.) + */ + for (JOIN_TAB *tab= join_tab->first_inner; + tab && tab->first_inner && tab->last_inner == join_tab; + tab= tab->first_inner->first_upper) + { + if (get_match_flag_by_pos_from_join_buffer(rec_ptr, tab) != + MATCH_FOUND) + { + not_exists_opt_is_applicable= false; + break; + } + } + } + + if (!check_only_first_match || + (join_tab->first_inner && !not_exists_opt_is_applicable) || !skip_next_candidate_for_match(rec_ptr)) { read_next_candidate_for_match(rec_ptr); |