From fce11a8bb1df6a0c3ba5bbb3aa89a8ee031a1f0e Mon Sep 17 00:00:00 2001 From: Staale Smedseng Date: Fri, 27 Mar 2009 12:09:15 +0100 Subject: [PATCH] Bug#39953 Triggers are not working properly with multi table updates Attempt to execute trigger or stored function with multi-UPDATE which used - but didn't update - a table that was also used by the calling statement led to an error. Read-only reference to tables used in the calling statement should be allowed. This problem was caused by the fact that check for conflicting use of tables in SP/triggers was performed in open_tables(), and in case of multi-UPDATE we didn't know exact lock type at this stage. We solve the problem by moving this check to lock_tables(), so it can be performed after exact lock types for tables used by multi-UPDATE are determined. --- mysql-test/r/trigger.result | 20 ++++++++++++ mysql-test/t/trigger.test | 33 +++++++++++++++++++ sql/sql_base.cc | 64 ++++++++++++++++++++++--------------- 3 files changed, 91 insertions(+), 26 deletions(-) diff --git a/mysql-test/r/trigger.result b/mysql-test/r/trigger.result index a07318435f6..a88a6973d61 100644 --- a/mysql-test/r/trigger.result +++ b/mysql-test/r/trigger.result @@ -1961,4 +1961,24 @@ select * from t2; s1 drop table t1; drop temporary table t2; +#------------------------------------------------------------------------ +# Bug#39953 Triggers are not working properly with multi table updates +#------------------------------------------------------------------------ +DROP TABLE IF EXISTS t1; +DROP TRIGGER IF EXISTS t_insert; +DROP TABLE IF EXISTS t2; +CREATE TABLE t1 (a int, date_insert timestamp, PRIMARY KEY (a)); +INSERT INTO t1 (a) VALUES (2),(5); +CREATE TABLE t2 (a int, b int, PRIMARY KEY (a)); +CREATE TRIGGER t_insert AFTER INSERT ON t2 FOR EACH ROW BEGIN UPDATE t1,t2 SET +date_insert=NOW() WHERE t1.a=t2.b AND t2.a=NEW.a; END | +INSERT INTO t2 (a,b) VALUES (1,2); +DROP TRIGGER t_insert; +CREATE TRIGGER t_insert AFTER INSERT ON t2 FOR EACH ROW BEGIN UPDATE t1,t2 SET +date_insert=NOW(),b=b+1 WHERE t1.a=t2.b AND t2.a=NEW.a; END | +INSERT INTO t2 (a,b) VALUES (3,5); +ERROR HY000: Can't update table 't2' in stored function/trigger because it is already used by statement which invoked this stored function/trigger. +DROP TABLE t1; +DROP TRIGGER t_insert; +DROP TABLE t2; End of 5.0 tests diff --git a/mysql-test/t/trigger.test b/mysql-test/t/trigger.test index 2f62ad38621..9a0277a98c2 100644 --- a/mysql-test/t/trigger.test +++ b/mysql-test/t/trigger.test @@ -2217,4 +2217,37 @@ select * from t1; select * from t2; drop table t1; drop temporary table t2; + +--echo #------------------------------------------------------------------------ +--echo # Bug#39953 Triggers are not working properly with multi table updates +--echo #------------------------------------------------------------------------ + +--disable_warnings +DROP TABLE IF EXISTS t1; +DROP TRIGGER IF EXISTS t_insert; +DROP TABLE IF EXISTS t2; +--enable_warnings + +CREATE TABLE t1 (a int, date_insert timestamp, PRIMARY KEY (a)); +INSERT INTO t1 (a) VALUES (2),(5); +CREATE TABLE t2 (a int, b int, PRIMARY KEY (a)); +DELIMITER |; +CREATE TRIGGER t_insert AFTER INSERT ON t2 FOR EACH ROW BEGIN UPDATE t1,t2 SET +date_insert=NOW() WHERE t1.a=t2.b AND t2.a=NEW.a; END | +DELIMITER ;| +INSERT INTO t2 (a,b) VALUES (1,2); + +DROP TRIGGER t_insert; + +DELIMITER |; +CREATE TRIGGER t_insert AFTER INSERT ON t2 FOR EACH ROW BEGIN UPDATE t1,t2 SET +date_insert=NOW(),b=b+1 WHERE t1.a=t2.b AND t2.a=NEW.a; END | +DELIMITER ;| +--error ER_CANT_UPDATE_USED_TABLE_IN_SF_OR_TRG +INSERT INTO t2 (a,b) VALUES (3,5); + +DROP TABLE t1; +DROP TRIGGER t_insert; +DROP TABLE t2; + --echo End of 5.0 tests diff --git a/sql/sql_base.cc b/sql/sql_base.cc index 0cf3e023be9..b43085436e5 100644 --- a/sql/sql_base.cc +++ b/sql/sql_base.cc @@ -1596,27 +1596,11 @@ TABLE *open_table(THD *thd, TABLE_LIST *table_list, MEM_ROOT *mem_root, { // Using table locks TABLE *best_table= 0; int best_distance= INT_MIN; - bool check_if_used= thd->prelocked_mode && - ((int) table_list->lock_type >= - (int) TL_WRITE_ALLOW_WRITE); for (table=thd->open_tables; table ; table=table->next) { if (table->s->key_length == key_length && !memcmp(table->s->table_cache_key, key, key_length)) { - if (check_if_used && table->query_id && - table->query_id != thd->query_id) - { - /* - If we are in stored function or trigger we should ensure that - we won't change table that is already used by calling statement. - So if we are opening table for writing, we should check that it - is not already open by some calling stamement. - */ - my_error(ER_CANT_UPDATE_USED_TABLE_IN_SF_OR_TRG, MYF(0), - table->s->table_name); - DBUG_RETURN(0); - } if (!my_strcasecmp(system_charset_info, table->alias, alias) && table->query_id != thd->query_id && /* skip tables already used */ !(thd->prelocked_mode && table->query_id)) @@ -1640,13 +1624,13 @@ TABLE *open_table(THD *thd, TABLE_LIST *table_list, MEM_ROOT *mem_root, { best_distance= distance; best_table= table; - if (best_distance == 0 && !check_if_used) + if (best_distance == 0) { /* - If we have found perfect match and we don't need to check that - table is not used by one of calling statements (assuming that - we are inside of function or trigger) we can finish iterating - through open tables list. + We have found a perfect match and can finish iterating + through open tables list. Check for table use conflict + between calling statement and SP/trigger is done in + lock_tables(). */ break; } @@ -2944,9 +2928,9 @@ static bool check_lock_and_start_stmt(THD *thd, TABLE *table, lock_type Lock to use for open NOTE - This function don't do anything like SP/SF/views/triggers analysis done - in open_tables(). It is intended for opening of only one concrete table. - And used only in special contexts. + This function doesn't do anything like SP/SF/views/triggers analysis done + in open_tables()/lock_tables(). It is intended for opening of only one + concrete table. And used only in special contexts. RETURN VALUES table Opened table @@ -3262,8 +3246,36 @@ int lock_tables(THD *thd, TABLE_LIST *tables, uint count, bool *need_reopen) TABLE_LIST *first_not_own= thd->lex->first_not_own_table(); for (table= tables; table != first_not_own; table= table->next_global) { - if (!table->placeholder() && - check_lock_and_start_stmt(thd, table->table, table->lock_type)) + if (table->placeholder()) + continue; + + /* + In a stored function or trigger we should ensure that we won't change + a table that is already used by the calling statement. + */ + if (thd->prelocked_mode && + table->lock_type >= TL_WRITE_ALLOW_WRITE) + { + for (TABLE* opentab= thd->open_tables; opentab; opentab= opentab->next) + { + /* + issue an error if the tables are the same (by key comparison), + but query_id isn't + */ + if (opentab->query_id && + table->table->query_id != opentab->query_id && + table->table->s->key_length == opentab->s->key_length && + !memcmp(table->table->s->table_cache_key, + opentab->s->table_cache_key, opentab->s->key_length)) + { + my_error(ER_CANT_UPDATE_USED_TABLE_IN_SF_OR_TRG, MYF(0), + table->table->s->table_name); + DBUG_RETURN(-1); + } + } + } + + if (check_lock_and_start_stmt(thd, table->table, table->lock_type)) { ha_rollback_stmt(thd); DBUG_RETURN(-1);