From 14dc91ff83001809fc40380ab22fc4e606f611de Mon Sep 17 00:00:00 2001 From: Sergey Glukhov Date: Wed, 5 Oct 2011 13:28:20 +0400 Subject: Bug#11747970 34660: CRASH WHEN FEDERATED TABLE LOSES CONNECTION DURING INSERT ... SELECT Problematic query: insert ignore into `t1_federated` (`c1`) select `c1` from `t1_local` a where not exists (select 1 from `t1_federated` b where a.c1 = b.c1); When this query is killed in another connection it could lead to crash. The problem is follwing: An attempt to obtain table statistics for subselect table in killed query fails with an error. So JOIN::optimize() for subquery is failed but it does not prevent further subquery evaluation. At the first subquery execution JOIN::optimize() is called (see subselect_single_select_engine::exec()) and fails with an error. 'executed' flag is set to TRUE and it prevents further subquery evaluation. At the second call JOIN::optimize() does not happen as 'JOIN::optimized' is TRUE and in case of uncacheable subquery the 'executed' flag is set to FALSE before subquery evaluation. So we loose 'optimize stage' error indication (see subselect_single_select_engine::exec()). In other words 'executed' flag is used for two purposes, for error indication at JOIN::optimize() stage and for an indication of subquery execution. And it seems it's wrong as the flag could be reset. mysql-test/r/error_simulation.result: test case mysql-test/t/error_simulation.test: test case sql/item_subselect.cc: added new flag subselect_single_select_engine::optimize_error which is used for error detection which could happen at optimize stage. sql/item_subselect.h: added new flag subselect_single_select_engine::optimize_error sql/sql_select.cc: test case --- sql/item_subselect.h | 1 + 1 file changed, 1 insertion(+) (limited to 'sql/item_subselect.h') diff --git a/sql/item_subselect.h b/sql/item_subselect.h index 74bbec626c1..65b415b44e9 100644 --- a/sql/item_subselect.h +++ b/sql/item_subselect.h @@ -419,6 +419,7 @@ class subselect_single_select_engine: public subselect_engine my_bool prepared; /* simple subselect is prepared */ my_bool optimized; /* simple subselect is optimized */ my_bool executed; /* simple subselect is executed */ + my_bool optimize_error; ///< simple subselect optimization failed st_select_lex *select_lex; /* corresponding select_lex */ JOIN * join; /* corresponding JOIN structure */ public: -- cgit v1.2.1