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MDEV-12669 Circular foreign keys cause a loop and OOM upon LOCK TABLE

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table_already_fk_prelocked() was looking for a table in the wrong
list (not the complete list of prelocked tables, but only in its tail,
starting from the current table - which is always empty for the last
added table), so for circular FKs it kept adding same tables to the list
indefinitely.
This commit is contained in:
Sergei Golubchik
2017-05-03 15:42:35 +02:00
parent 2b29c52ea8
commit d6d7e169fb
3 changed files with 46 additions and 2 deletions
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19
mysql-test/suite/innodb/r/foreign_key.result
View File

@ -150,3 +150,22 @@ unique_constraint_name
PRIMARY PRIMARY
DROP TABLE t2; DROP TABLE t2;
DROP TABLE t1; DROP TABLE t1;
SET FOREIGN_KEY_CHECKS=0;
CREATE TABLE staff (
staff_id TINYINT UNSIGNED NOT NULL AUTO_INCREMENT,
store_id TINYINT UNSIGNED NOT NULL,
PRIMARY KEY (staff_id),
KEY idx_fk_store_id (store_id),
CONSTRAINT fk_staff_store FOREIGN KEY (store_id) REFERENCES store (store_id) ON DELETE RESTRICT ON UPDATE CASCADE
) ENGINE=InnoDB;
CREATE TABLE store (
store_id TINYINT UNSIGNED NOT NULL AUTO_INCREMENT,
manager_staff_id TINYINT UNSIGNED NOT NULL,
PRIMARY KEY (store_id),
UNIQUE KEY idx_unique_manager (manager_staff_id),
CONSTRAINT fk_store_staff FOREIGN KEY (manager_staff_id) REFERENCES staff (staff_id) ON DELETE RESTRICT ON UPDATE CASCADE
) ENGINE=InnoDB;
SET FOREIGN_KEY_CHECKS=DEFAULT;
LOCK TABLE staff WRITE;
UNLOCK TABLES;
DROP TABLES staff, store;

24
mysql-test/suite/innodb/t/foreign_key.test
View File

@ -113,3 +113,27 @@ WHERE table_name = 't2';
DROP TABLE t2; DROP TABLE t2;
DROP TABLE t1; DROP TABLE t1;
#
# MDEV-12669 Circular foreign keys cause a loop and OOM upon LOCK TABLE
#
SET FOREIGN_KEY_CHECKS=0;
CREATE TABLE staff (
staff_id TINYINT UNSIGNED NOT NULL AUTO_INCREMENT,
store_id TINYINT UNSIGNED NOT NULL,
PRIMARY KEY (staff_id),
KEY idx_fk_store_id (store_id),
CONSTRAINT fk_staff_store FOREIGN KEY (store_id) REFERENCES store (store_id) ON DELETE RESTRICT ON UPDATE CASCADE
) ENGINE=InnoDB;
CREATE TABLE store (
store_id TINYINT UNSIGNED NOT NULL AUTO_INCREMENT,
manager_staff_id TINYINT UNSIGNED NOT NULL,
PRIMARY KEY (store_id),
UNIQUE KEY idx_unique_manager (manager_staff_id),
CONSTRAINT fk_store_staff FOREIGN KEY (manager_staff_id) REFERENCES staff (staff_id) ON DELETE RESTRICT ON UPDATE CASCADE
) ENGINE=InnoDB;
SET FOREIGN_KEY_CHECKS=DEFAULT;
LOCK TABLE staff WRITE;
UNLOCK TABLES;
DROP TABLES staff, store;

5
sql/sql_base.cc
View File

@ -4255,8 +4255,9 @@ handle_table(THD *thd, Query_tables_list *prelocking_ctx,
else else
lock_type= TL_READ; lock_type= TL_READ;
if (table_already_fk_prelocked(table_list, fk->foreign_db, if (table_already_fk_prelocked(prelocking_ctx->query_tables,
fk->foreign_table, lock_type)) fk->foreign_db, fk->foreign_table,
lock_type))
continue; continue;
TABLE_LIST *tl= (TABLE_LIST *) thd->alloc(sizeof(TABLE_LIST)); TABLE_LIST *tl= (TABLE_LIST *) thd->alloc(sizeof(TABLE_LIST));