MDEV-22934 Table disappear after two alter table commandbb-10.2-MDEV-22934

Problem:
=======
InnoDB drops the column which has foreign key relations on it. So it
tries to load the foreign key during rename process of copy algorithm
even though the foreign_key_check is disabled.

Solution:
========
Rename operation shouldn't load foreign key constraints during
copy operation when foreign_key_check is disabled.

3 files changed, 53 insertions, 0 deletions

diff --git a/mysql-test/suite/innodb/r/foreign_key.result b/mysql-test/suite/innodb/r/foreign_key.result
index b0b4635157e..b530b3270f0 100644
--- a/mysql-test/suite/innodb/r/foreign_key.result
+++ b/mysql-test/suite/innodb/r/foreign_key.result
@@ -714,4 +714,30 @@ drop table t1,t2;
 ERROR 23000: Cannot delete or update a parent row: a foreign key constraint fails
 drop table t1,t2;
 ERROR 42S02: Unknown table 'test.t2'
+#
+# MDEV-22934 Table disappear after two alter table command
+#
+CREATE TABLE t1(f1 INT NOT NULL AUTO_INCREMENT,
+f2 INT NOT NULL,
+PRIMARY KEY (f1), INDEX (f2))ENGINE=InnoDB;
+CREATE TABLE t2(f1 INT NOT NULL,
+f2 INT NOT NULL, f3 INT NOT NULL,
+PRIMARY KEY(f1, f2), UNIQUE KEY(f2),
+CONSTRAINT `t2_ibfk_1` FOREIGN KEY (f2) REFERENCES t1(f2) ON DELETE CASCADE,
+CONSTRAINT `t2_ibfk_2` FOREIGN KEY (f1) REFERENCES t1(f1) ON DELETE CASCADE
+) ENGINE=InnoDB;
+SET FOREIGN_KEY_CHECKS=0;
+ALTER TABLE t2 DROP PRIMARY KEY, ADD PRIMARY KEY(f3), ALGORITHM=INPLACE;
+ALTER TABLE t2 DROP INDEX `f2`, ALGORITHM=COPY;
+SHOW CREATE TABLE t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `f1` int(11) NOT NULL,
+  `f2` int(11) NOT NULL,
+  `f3` int(11) NOT NULL,
+  PRIMARY KEY (`f3`)
+) ENGINE=InnoDB DEFAULT CHARSET=latin1
+CREATE TABLE t2 (f1 INT NOT NULL)ENGINE=InnoDB;
+ERROR 42S01: Table 't2' already exists
+DROP TABLE t2, t1;
 # End of 10.2 tests
diff --git a/mysql-test/suite/innodb/t/foreign_key.test b/mysql-test/suite/innodb/t/foreign_key.test
index 27fa63f144e..92a804a18a6 100644
--- a/mysql-test/suite/innodb/t/foreign_key.test
+++ b/mysql-test/suite/innodb/t/foreign_key.test
@@ -698,6 +698,27 @@ drop table t1,t2;
 --error ER_BAD_TABLE_ERROR
 drop table t1,t2;
 
+--echo #
+--echo # MDEV-22934 Table disappear after two alter table command
+--echo #
+CREATE TABLE t1(f1 INT NOT NULL AUTO_INCREMENT,
+		f2 INT NOT NULL,
+		PRIMARY KEY (f1), INDEX (f2))ENGINE=InnoDB;
+CREATE TABLE t2(f1 INT NOT NULL,
+		f2 INT NOT NULL, f3 INT NOT NULL,
+		PRIMARY KEY(f1, f2), UNIQUE KEY(f2),
+CONSTRAINT `t2_ibfk_1` FOREIGN KEY (f2) REFERENCES t1(f2) ON DELETE CASCADE,
+CONSTRAINT `t2_ibfk_2` FOREIGN KEY (f1) REFERENCES t1(f1) ON DELETE CASCADE
+) ENGINE=InnoDB;
+
+SET FOREIGN_KEY_CHECKS=0;
+ALTER TABLE t2 DROP PRIMARY KEY, ADD PRIMARY KEY(f3), ALGORITHM=INPLACE;
+ALTER TABLE t2 DROP INDEX `f2`, ALGORITHM=COPY;
+SHOW CREATE TABLE t2;
+--error ER_TABLE_EXISTS_ERROR
+CREATE TABLE t2 (f1 INT NOT NULL)ENGINE=InnoDB;
+DROP TABLE t2, t1;
+
 --echo # End of 10.2 tests
 
 --source include/wait_until_count_sessions.inc
diff --git a/storage/innobase/row/row0mysql.cc b/storage/innobase/row/row0mysql.cc
index 7c61ad9b45b..5203e26679a 100644
--- a/storage/innobase/row/row0mysql.cc
+++ b/storage/innobase/row/row0mysql.cc
@@ -4524,6 +4524,12 @@ end:
 			innobase_rename_vc_templ(table);
 		}
 
+		/* Avoid renaming of foreign key constraints
+		if foreign_key_check is disabled */
+		if (!trx->check_foreigns) {
+			goto funct_exit;
+		}
+
 		/* We only want to switch off some of the type checking in
 		an ALTER TABLE...ALGORITHM=COPY, not in a RENAME. */
 		dict_names_t	fk_tables;