diff options
Diffstat (limited to 'sql/item_subselect.cc')
| -rw-r--r-- | sql/item_subselect.cc | 27 |
1 files changed, 14 insertions, 13 deletions
diff --git a/sql/item_subselect.cc b/sql/item_subselect.cc index 83c7e3e1529..ab77bb0e59c 100644 --- a/sql/item_subselect.cc +++ b/sql/item_subselect.cc @@ -49,7 +49,7 @@ Item_subselect::Item_subselect(): used_tables_cache(0), have_to_be_excluded(0), const_item_cache(1), inside_first_fix_fields(0), done_first_fix_fields(FALSE), expr_cache(0), forced_const(FALSE), substitution(0), engine(0), eliminated(FALSE), - engine_changed(0), changed(0), is_correlated(FALSE) + changed(0), is_correlated(FALSE) { DBUG_ENTER("Item_subselect::Item_subselect"); DBUG_PRINT("enter", ("this: 0x%lx", (ulong) this)); @@ -623,6 +623,8 @@ bool Item_subselect::walk(Item_processor processor, bool walk_subquery, bool Item_subselect::exec() { + subselect_engine *org_engine= engine; + DBUG_ENTER("Item_subselect::exec"); /* @@ -644,11 +646,14 @@ bool Item_subselect::exec() #ifndef DBUG_OFF ++exec_counter; #endif - if (engine_changed) + if (engine != org_engine) { - engine_changed= 0; - res= exec(); - DBUG_RETURN(res); + /* + If the subquery engine changed during execution due to lazy subquery + optimization, or because the original engine found a more efficient other + engine, re-execute the subquery with the new engine. + */ + DBUG_RETURN(exec()); } DBUG_RETURN(res); } @@ -1063,11 +1068,9 @@ Item_singlerow_subselect::select_transformer(JOIN *join) } substitution= select_lex->item_list.head(); /* - as far as we moved content to upper level, field which depend of - 'upper' select is not really dependent => we remove this dependence + as far as we moved content to upper level we have to fix dependences & Co */ - substitution->walk(&Item::remove_dependence_processor, 0, - (uchar *) select_lex->outer_select()); + substitution->fix_after_pullout(select_lex->outer_select(), &substitution); } DBUG_RETURN(false); } @@ -2003,7 +2006,7 @@ Item_in_subselect::create_single_in_to_exists_cond(JOIN * join, } else { - Item *item= (Item*) select_lex->item_list.head(); + Item *item= (Item*) select_lex->item_list.head()->real_item(); if (select_lex->table_list.elements) { @@ -3143,10 +3146,8 @@ int subselect_single_select_engine::exec() DBUG_RETURN(1); /* purecov: inspected */ } } - if (item->engine_changed) - { + if (item->engine_changed(this)) DBUG_RETURN(1); - } } if (select_lex->uncacheable && select_lex->uncacheable != UNCACHEABLE_EXPLAIN |