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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.
63 lines
1.6 KiB
Text
63 lines
1.6 KiB
Text
-- source include/have_log_bin.inc
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-- source include/have_innodb.inc
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-- source include/not_binlog_format_row.inc
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--echo #
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--echo # Bug #39022: Mysql randomly crashing in lock_sec_rec_cons_read_sees
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--echo #
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CREATE TABLE t1(a TINYINT NOT NULL,b TINYINT,PRIMARY KEY(b)) ENGINE=innodb;
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CREATE TABLE t2(d TINYINT NOT NULL,UNIQUE KEY(d)) ENGINE=innodb;
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INSERT INTO t1 VALUES (13,0),(8,1),(9,2),(6,3),
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(11,5),(11,6),(7,7),(7,8),(4,9),(6,10),(3,11),(11,12),
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(12,13),(7,14);
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INSERT INTO t2 VALUES (0),(1),(2),(3),(4),(5),(6),(7),(8),(9),(10),
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(11),(12),(13),(14);
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connect (thread1, localhost, root,,);
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connect (thread2, localhost, root,,);
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connection thread1;
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--echo # in thread1
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START TRANSACTION;
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connection thread2;
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--echo # in thread2
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REPLACE INTO t2 VALUES (-17);
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SELECT d FROM t2,t1 WHERE d=(SELECT MAX(a) FROM t1 WHERE t1.a > t2.d) LOCK IN SHARE MODE;
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connection thread1;
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--echo # in thread1
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REPLACE INTO t1(a,b) VALUES (67,20);
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connection thread2;
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--echo # in thread2
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COMMIT;
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START TRANSACTION;
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REPLACE INTO t1(a,b) VALUES (65,-50);
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REPLACE INTO t2 VALUES (-91);
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send;
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SELECT d FROM t2,t1 WHERE d=(SELECT MAX(a) FROM t1 WHERE t1.a > t2.d) LOCK IN SHARE MODE; #waits
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connection thread1;
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--echo # in thread1
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--echo # should not crash
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--error ER_LOCK_DEADLOCK
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SELECT d FROM t2,t1 WHERE d=(SELECT MAX(a) FROM t1 WHERE t1.a > t2.d) LOCK IN SHARE MODE; #crashes
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connection thread2;
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--echo # in thread2
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REAP;
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disconnect thread2;
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--source include/wait_until_disconnected.inc
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connection thread1;
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--echo # in thread1;
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disconnect thread1;
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--source include/wait_until_disconnected.inc
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connection default;
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DROP TABLE t1,t2;
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