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#
# TRUNCATE TABLE
#
# Truncating is disallowed for parent tables unless such table
# participates in self-referencing foreign keys only.
#
CREATE TABLE t1 (pk INT PRIMARY KEY) ENGINE=INNODB;
CREATE TABLE t2 (fk INT NOT NULL, FOREIGN KEY (fk) REFERENCES t1 (pk)) ENGINE=INNODB;
TRUNCATE TABLE t1;
ERROR 42000: Cannot truncate a table referenced in a foreign key constraint (`test`.`t2`, CONSTRAINT `t2_ibfk_1` FOREIGN KEY (`fk`) REFERENCES `test`.`t1` (`pk`))
# Truncation of child should succeed.
TRUNCATE TABLE t2;
DROP TABLE t2;
DROP TABLE t1;
CREATE TABLE t1 (pk INT PRIMARY KEY, fk INT,
FOREIGN KEY (fk) REFERENCES t1 (pk)) ENGINE=INNODB;
# Truncation of self-referencing table should succeed.
TRUNCATE TABLE t1;
DROP TABLE t1;
#
# Also, truncating such tables is allowed if foreign key
# checks are disabled.
#
SET @old_foreign_key_checks = @@SESSION.foreign_key_checks;
CREATE TABLE t1 (pk INT PRIMARY KEY) ENGINE=INNODB;
CREATE TABLE t2 (fk INT NOT NULL, FOREIGN KEY (fk) REFERENCES t1 (pk)) ENGINE=INNODB;
CREATE TABLE t3 (pk INT PRIMARY KEY, fk INT,
FOREIGN KEY (fk) REFERENCES t1 (pk)) ENGINE=INNODB;
SET @@SESSION.foreign_key_checks = 0;
TRUNCATE TABLE t1;
TRUNCATE TABLE t2;
TRUNCATE TABLE t3;
SET @@SESSION.foreign_key_checks = 1;
TRUNCATE TABLE t1;
ERROR 42000: Cannot truncate a table referenced in a foreign key constraint (`test`.`t2`, CONSTRAINT `t2_ibfk_1` FOREIGN KEY (`fk`) REFERENCES `test`.`t1` (`pk`))
TRUNCATE TABLE t2;
TRUNCATE TABLE t3;
LOCK TABLES t1 WRITE;
SET @@SESSION.foreign_key_checks = 0;
TRUNCATE TABLE t1;
SET @@SESSION.foreign_key_checks = 1;
TRUNCATE TABLE t1;
ERROR 42000: Cannot truncate a table referenced in a foreign key constraint (`test`.`t2`, CONSTRAINT `t2_ibfk_1` FOREIGN KEY (`fk`) REFERENCES `test`.`t1` (`pk`))
UNLOCK TABLES;
DROP TABLE t3,t2,t1;
SET @@SESSION.foreign_key_checks = @old_foreign_key_checks;
#
# Test that TRUNCATE resets auto-increment.
#
CREATE TABLE t1 (a INT PRIMARY KEY NOT NULL AUTO_INCREMENT,
b INT, c INT, d INT, e INT, f INT, g INT, h INT, i INT, j INT, k INT,
l INT, m INT, n INT, o INT, p INT, q INT, r INT, s INT, t INT, u INT,
KEY(b),KEY(c),KEY(d),KEY(e),KEY(f),KEY(g),KEY(h),KEY(i),KEY(j),KEY(k),
KEY(l),KEY(m),KEY(n),KEY(o),KEY(p),KEY(q),KEY(r),KEY(s),KEY(t),KEY(u),
KEY(c,b),KEY(d,b),KEY(e,b),KEY(f,b),KEY(g,b),KEY(h,b),KEY(i,b),KEY(j,b),
KEY(k,b),KEY(l,b),KEY(m,b),KEY(n,b),KEY(o,b),KEY(p,b),KEY(q,b),KEY(r,b),
KEY(s,b),KEY(t,b),KEY(u,b),
KEY(d,c),KEY(e,c),KEY(f,c),KEY(g,c),KEY(h,c),KEY(i,c),KEY(j,c),
KEY(k,c),KEY(l,c),KEY(m,c),KEY(n,c),KEY(o,c),KEY(p,c),KEY(q,c),KEY(r,c),
KEY(s,c),KEY(t,c),KEY(u,c),
KEY(e,d),KEY(f,d),KEY(g,d),KEY(h,d),KEY(i,d),KEY(j,d)
) ENGINE=InnoDB;
INSERT INTO t1 () VALUES (), ();
SELECT AUTO_INCREMENT FROM INFORMATION_SCHEMA.TABLES WHERE table_name = 't1';
AUTO_INCREMENT
3
SELECT a FROM t1 ORDER BY a;
a
1
2
TRUNCATE TABLE t1;
SELECT AUTO_INCREMENT FROM INFORMATION_SCHEMA.TABLES WHERE table_name = 't1';
AUTO_INCREMENT
1
INSERT INTO t1 () VALUES (), ();
SELECT a FROM t1 ORDER BY a;
a
1
2
DROP TABLE t1;
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