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35a9c90fff
When the transaction isolation level is SERIALIZABLE, or when a locking read is performed in the REPEATABLE READ isolation level, InnoDB must lock delete-marked records in order to prevent another transaction from inserting something. However, at READ UNCOMMITTED or READ COMMITTED isolation level or when the parameter innodb_locks_unsafe_for_binlog is set, the repeatability of the reads does not matter, and there is no need to lock any records. row_search_for_mysql(): Skip locks on delete-marked committed records upfront, instead of invoking row_unlock_for_mysql() afterwards. The unlocking never worked for secondary index records.
41 lines
1.3 KiB
Plaintext
41 lines
1.3 KiB
Plaintext
START TRANSACTION WITH CONSISTENT SNAPSHOT;
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CREATE TABLE t1(a INT PRIMARY KEY, b INT UNIQUE) ENGINE=InnoDB;
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INSERT INTO t1 VALUES(1,1);
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DELETE FROM t1;
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SET DEBUG_SYNC='row_ins_sec_index_unique SIGNAL inserted WAIT_FOR locked';
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BEGIN;
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INSERT INTO t1 VALUES(1,1);
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SET DEBUG_SYNC='now WAIT_FOR inserted';
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SET DEBUG_SYNC='innodb_row_search_for_mysql_exit SIGNAL locked';
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SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED;
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BEGIN;
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DELETE FROM t1 WHERE b=1;
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COMMIT;
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SET DEBUG_SYNC='RESET';
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ROLLBACK;
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SET DEBUG_SYNC='row_ins_sec_index_unique SIGNAL inserted WAIT_FOR locked';
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BEGIN;
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INSERT INTO t1 VALUES(1,1);
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SET DEBUG_SYNC='now WAIT_FOR inserted';
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SET DEBUG_SYNC='innodb_row_search_for_mysql_exit SIGNAL locked';
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SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
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BEGIN;
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DELETE FROM t1 WHERE b=1;
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COMMIT;
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SET DEBUG_SYNC='RESET';
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ROLLBACK;
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SET DEBUG_SYNC='row_ins_sec_index_unique SIGNAL inserted WAIT_FOR locked';
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BEGIN;
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SET innodb_lock_wait_timeout=1;
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INSERT INTO t1 VALUES(1,1);
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SET DEBUG_SYNC='now WAIT_FOR inserted';
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SET DEBUG_SYNC='innodb_row_search_for_mysql_exit SIGNAL locked';
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SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ;
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BEGIN;
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DELETE FROM t1 WHERE b=1;
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ERROR HY000: Lock wait timeout exceeded; try restarting transaction
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COMMIT;
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SET DEBUG_SYNC='RESET';
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COMMIT;
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DROP TABLE t1;
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