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BOGUS "THE TABLE MYSQL.PROC IS MISSING,..." There was a race condition between loading a stored routine (function/procedure/trigger) specified by fully qualified name SCHEMA_NAME.PROC_NAME and dropping the stored routine database. The problem was that there is a window for race condition when one server thread tries to load a stored routine being executed and the other thread tries to drop the stored routine schema. This condition race window exists in implementation of function mysql_change_db() called by db_load_routine() during loading of stored routine to cache. Function mysql_change_db() calls check_db_dir_existence() that might failed because specified database was dropped during concurrent execution of DROP SCHEMA statement. db_load_routine() calls mysql_change_db() with flag 'force_switch' set to 'true' value so when referenced db is not found then my_error() is not called and function mysql_change_db() returns ok. This shadows information about schema opening error in db_load_routine(). Then db_load_routine() makes attempt to parse stored routine that is failed. This makes to return error to sp_cache_routines_and_add_tables_aux() but since during error generation a call to my_error wasn't made and hence THD::main_da wasn't set we set the generic "mysql.proc table corrupt" error when running sp_cache_routines_and_add_tables_aux(). The fix is to install an error handler inside db_load_routine() for the mysql_op_change_db() call, and check later if the ER_BAD_DB_ERROR was caught. sql/sql_db.cc: Added synchronization point "before_db_dir_check" to emulate a race condition during processing of CALL/DROP SCHEMA.
35 lines
1.1 KiB
Text
35 lines
1.1 KiB
Text
Tests of synchronization of stored procedure execution.
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#
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# Bug#48157: crash in Item_field::used_tables
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#
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CREATE TABLE t1 AS SELECT 1 AS a, 1 AS b;
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CREATE TABLE t2 AS SELECT 1 AS a, 1 AS b;
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CREATE PROCEDURE p1()
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BEGIN
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UPDATE t1 JOIN t2 USING( a, b ) SET t1.b = 1, t2.b = 1;
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END|
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LOCK TABLES t1 WRITE, t2 WRITE;
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SET DEBUG_SYNC = 'multi_update_reopen_tables SIGNAL parked WAIT_FOR go';
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CALL p1();
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DROP TABLE t1, t2;
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SET DEBUG_SYNC = 'now WAIT_FOR parked';
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CREATE TABLE t1 AS SELECT 1 AS a, 1 AS b;
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CREATE TABLE t2 AS SELECT 1 AS a, 1 AS b;
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SET DEBUG_SYNC = 'now SIGNAL go';
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# Without the DEBUG_SYNC supplied in the same patch as this test in the
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# code, this test statement will hang.
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DROP TABLE t1, t2;
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DROP PROCEDURE p1;
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#
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# test for bug#11756013
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#
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DROP SCHEMA IF EXISTS s1;
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CREATE SCHEMA s1;
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CREATE PROCEDURE s1.p1() BEGIN END;
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SET DEBUG_SYNC='before_db_dir_check SIGNAL check_db WAIT_FOR dropped_schema';
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CALL s1.p1;
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SET DEBUG_SYNC='now WAIT_FOR check_db';
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DROP SCHEMA s1;
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SET DEBUG_SYNC='now SIGNAL dropped_schema';
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ERROR 42000: Unknown database 's1'
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SET DEBUG_SYNC = 'RESET';
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