diff options
Diffstat (limited to 'sql/sql_lex.cc')
| -rw-r--r-- | sql/sql_lex.cc | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/sql/sql_lex.cc b/sql/sql_lex.cc index c30fcd95d73..a7215053a58 100644 --- a/sql/sql_lex.cc +++ b/sql/sql_lex.cc @@ -3502,6 +3502,8 @@ bool st_select_lex::optimize_unflattened_subqueries(bool const_only) bool empty_union_result= true; bool is_correlated_unit= false; + bool first= true; + bool union_plan_saved= false; /* If the subquery is a UNION, optimize all the subqueries in the UNION. If there is no UNION, then the loop will execute once for the subquery. @@ -3509,6 +3511,17 @@ bool st_select_lex::optimize_unflattened_subqueries(bool const_only) for (SELECT_LEX *sl= un->first_select(); sl; sl= sl->next_select()) { JOIN *inner_join= sl->join; + if (first) + first= false; + else + { + if (!union_plan_saved) + { + union_plan_saved= true; + if (un->save_union_explain(un->thd->lex->explain)) + return true; /* Failure */ + } + } if (!inner_join) continue; SELECT_LEX *save_select= un->thd->lex->current_select; @@ -4331,6 +4344,10 @@ void LEX::restore_set_statement_var() int st_select_lex_unit::save_union_explain(Explain_query *output) { SELECT_LEX *first= first_select(); + + if (output->get_union(first->select_number)) + return 0; /* Already added */ + Explain_union *eu= new (output->mem_root) Explain_union(output->mem_root); if (derived) |