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CREATE TABLE t1 (f1 VARCHAR(8000)) ENGINE=InnoDB;
INSERT INTO t1 VALUES (NULL),(CONCAT(REPEAT('x', 7999), 'a'));
SELECT LENGTH(f1) FROM t1;
LENGTH(f1)
NULL
8000
DELETE FROM t1 WHERE f1 IS NULL;
UPDATE t1 SET f1 = CONCAT(REPEAT('x', 7999), 'b') WHERE f1 = CONCAT(REPEAT('x', 7999), 'a');
SELECT COUNT(*) = 1 FROM t1;
COUNT(*) = 1
1
SELECT LENGTH(f1) = 8000 FROM t1;
LENGTH(f1) = 8000
1
SELECT f1 = CONCAT(REPEAT('x', 7999), 'b') FROM t1;
f1 = CONCAT(REPEAT('x', 7999), 'b')
1
CREATE TABLE t2 (f1 BLOB) ENGINE=InnoDB;
INSERT INTO t2 VALUES (CONCAT(REPEAT('x', 7999), 'a'));
SET AUTOCOMMIT=OFF;
START TRANSACTION;
UPDATE t2 SET f1 = 'abc' WHERE f1 = CONCAT(REPEAT('x', 7999), 'a');
SET AUTOCOMMIT=OFF;
START TRANSACTION;
UPDATE t2 SET f1 = 'xyz' WHERE f1 = CONCAT(REPEAT('x', 7999), 'a');
COMMIT;
COMMIT;
ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
DROP TABLE t1;
DROP TABLE t2;
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