delta/mariadb-git.git - github.com: MariaDB/server.git

	Commit message (Collapse)	Author	Age	Files	Lines
*	Bug# 11763784 (former 56541)	Jon Olav Hauglid	2011-03-29	1	-0/+54
\| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \|	ASSERTION TABLE->DB_STAT FAILED IN SQL_BASE.CC::OPEN_TABLE() DURING I_S Q This assert could be triggered if a statement requiring a name lock on a table (e.g. DROP TRIGGER) executed concurrently with an I_S query which also used the table. One connection first started an I_S query that opened a given table. Then another connection started a statement requiring a name lock on the same table. This statement was blocked since the table was in use by the I_S query. When the I_S query resumed and tried to open the table again as part of get_all_tables(), it would encounter a table instance with an old version number representing the pending name lock. Since I_S queries ignore version checks and thus pending name locks, it would try to continue. This caused it to encounter the assert. The assert checked that the TABLE instance found with a different version, was a real, open table. However, since this TABLE instance instead represented a pending name lock, the check would fail and trigger the assert. This patch fixes the problem by removing the assert. It is ok for TABLE::db_stat to be 0 in this case since the TABLE instance can represent a pending name lock. Test case added to lock_sync.test.
*	A 5.1-only version of fix for bug #46947 "Embedded SELECT	Dmitry Lenev	2010-05-28	1	-0/+867
	without FOR UPDATE is causing a lock". SELECT statements with subqueries referencing InnoDB tables were acquiring shared locks on rows in these tables when they were executed in REPEATABLE-READ mode and with statement or mixed mode binary logging turned on. This was a regression which were introduced when fixing bug 39843. The problem was that for tables belonging to subqueries parser set TL_READ_DEFAULT as a lock type. In cases when statement/mixed binary logging at open_tables() time this type of lock was converted to TL_READ_NO_INSERT lock at open_tables() time and caused InnoDB engine to acquire shared locks on reads from these tables. Although in some cases such behavior was correct (e.g. for subqueries in DELETE) in case of SELECT it has caused unnecessary locking. This patch implements minimal version of the fix for the specific problem described in the bug-report which supposed to be not too risky for pushing into 5.1 tree. The 5.5 tree already contains a more appropriate solution which also addresses other related issues like bug 53921 "Wrong locks for SELECTs used stored functions may lead to broken SBR". This patch tries to solve the problem by ensuring that TL_READ_DEFAULT lock which is set in the parser for tables participating in subqueries at open_tables() time is interpreted as TL_READ_NO_INSERT or TL_READ. TL_READ is used only if we know that this is a SELECT and that this particular table is not used by a stored function. Test coverage is added for both InnoDB and MyISAM. This patch introduces an "incompatible" change in locking scheme for subqueries used in SELECT ... FOR UPDATE and SELECT .. IN SHARE MODE. In 4.1 (as well as in 5.0 and 5.1 before fix for bug 39843) the server would use a snapshot InnoDB read for subqueries in SELECT FOR UPDATE and SELECT .. IN SHARE MODE statements, regardless of whether the binary log is on or off. If the user required a different type of read (i.e. locking read), he/she could request so explicitly by providing FOR UPDATE/IN SHARE MODE clause for each individual subquery. The patch for bug 39843 broke this behaviour (which was not documented or tested), and started to use locking reads for all subqueries in SELECT ... FOR UPDATE/IN SHARE MODE. This patch restores 4.1 behaviour. This patch should be mostly null-merged into 5.5 tree. mysql-test/include/check_concurrent_insert.inc: Added auxiliary script which allows to check if statement reading table allows concurrent inserts in it. mysql-test/include/check_no_concurrent_insert.inc: Added auxiliary script which allows to check that statement reading table doesn't allow concurrent inserts in it. mysql-test/include/check_no_row_lock.inc: Added auxiliary script which allows to check if statement reading table doesn't take locks on its rows. mysql-test/include/check_shared_row_lock.inc: Added auxiliary script which allows to check if statement reading table takes shared locks on some of its rows. mysql-test/r/bug39022.result: After bug #46947 'Embedded SELECT without FOR UPDATE is causing a lock' was fixed test case for bug 39022 has to be adjusted in order to trigger execution path on which original problem was encountered. mysql-test/r/innodb_mysql_lock2.result: Added coverage for handling of locking in various cases when we read data from InnoDB tables (includes test case for bug #46947 'Embedded SELECT without FOR UPDATE is causing a lock'). mysql-test/r/lock_sync.result: Added coverage for handling of locking in various cases when we read data from MyISAM tables. mysql-test/t/bug39022.test: After bug #46947 'Embedded SELECT without FOR UPDATE is causing a lock' was fixed test case for bug 39022 has to be adjusted in order to trigger execution path on which original problem was encountered. mysql-test/t/innodb_mysql_lock2.test: Added coverage for handling of locking in various cases when we read data from InnoDB tables (includes test case for bug #46947 'Embedded SELECT without FOR UPDATE is causing a lock'). mysql-test/t/lock_sync.test: Added coverage for handling of locking in various cases when we read data from MyISAM tables. sql/mysql_priv.h: Function read_lock_type_for_table() now takes pointers to LEX and TABLE_LIST elements as its arguments since to correctly determine lock type it needs to know what statement is being performed and whether table element for which lock type to be determined belongs to prelocking list. sql/sql_base.cc: Changed read_lock_type_for_table() to return a weak TL_READ type of lock in cases when we are executing SELECT (and so won't update tables directly) and table doesn't belong to statement's prelocking list and thus can't be used by a stored function. It is OK to do so since in this case table won't be used by statement or function call which will be written to the binary log, so serializability requirements for it can be relaxed. One of results from this change is that SELECTs on InnoDB tables no longer takes shared row locks for tables which are used in subqueries (i.e. bug #46947 is fixed). Another result is that for similar SELECTs on MyISAM tables concurrent inserts are allowed. In order to implement this change signature of read_lock_type_for_table() function was changed to take pointers to LEX and TABLE_LIST objects. sql/sql_update.cc: Function read_lock_type_for_table() now takes pointers to LEX and TABLE_LIST elements as its arguments since to correctly determine lock type it needs to know what statement is being performed and whether table element for which lock type to be determined belongs to prelocking list.