MDEV-32688 Add innodb_foreign_key_errors status variable

mysql-test/suite/innodb/r/foreign_key_errors.result

@@ -0,0 +1,85 @@
+#
+# MDEV-32688: Test innodb_foreign_key_errors status variable
+#
+# Setup
+CREATE TABLE parent (id INT PRIMARY KEY) ENGINE=InnoDB;
+CREATE TABLE child (
+id INT PRIMARY KEY,
+parent_id INT,
+FOREIGN KEY (parent_id) REFERENCES parent(id)
+) ENGINE=InnoDB;
+INSERT INTO parent VALUES (1), (2), (3);
+INSERT INTO child VALUES (1, 1), (2, 2);
+# Counter starts at 0
+SHOW GLOBAL STATUS LIKE 'innodb_foreign_key_errors';
+Variable_name	Value
+Innodb_foreign_key_errors	0
+# Child-side violations (INSERT, UPDATE, REPLACE, INSERT...SELECT)
+INSERT INTO child VALUES (10, 999);
+ERROR 23000: Cannot add or update a child row: a foreign key constraint fails (`test`.`child`, CONSTRAINT `1` FOREIGN KEY (`parent_id`) REFERENCES `parent` (`id`))
+UPDATE child SET parent_id = 888 WHERE id = 1;
+ERROR 23000: Cannot add or update a child row: a foreign key constraint fails (`test`.`child`, CONSTRAINT `1` FOREIGN KEY (`parent_id`) REFERENCES `parent` (`id`))
+REPLACE INTO child VALUES (30, 777);
+ERROR 23000: Cannot add or update a child row: a foreign key constraint fails (`test`.`child`, CONSTRAINT `1` FOREIGN KEY (`parent_id`) REFERENCES `parent` (`id`))
+INSERT INTO child (id, parent_id) SELECT 40, 555;
+ERROR 23000: Cannot add or update a child row: a foreign key constraint fails (`test`.`child`, CONSTRAINT `1` FOREIGN KEY (`parent_id`) REFERENCES `parent` (`id`))
+# Parent-side violations (DELETE, UPDATE)
+DELETE FROM parent WHERE id = 1;
+ERROR 23000: Cannot delete or update a parent row: a foreign key constraint fails (`test`.`child`, CONSTRAINT `1` FOREIGN KEY (`parent_id`) REFERENCES `parent` (`id`))
+UPDATE parent SET id = 100 WHERE id = 1;
+ERROR 23000: Cannot delete or update a parent row: a foreign key constraint fails (`test`.`child`, CONSTRAINT `1` FOREIGN KEY (`parent_id`) REFERENCES `parent` (`id`))
+# Counter after 6 violations
+SHOW GLOBAL STATUS LIKE 'innodb_foreign_key_errors';
+Variable_name	Value
+Innodb_foreign_key_errors	6
+# Successful operations should NOT increment
+INSERT INTO child VALUES (50, 3);
+UPDATE child SET parent_id = 1 WHERE id = 50;
+DELETE FROM child WHERE id = 50;
+INSERT INTO child VALUES (60, NULL);
+DELETE FROM child WHERE id = 60;
+# Counter unchanged after successful operations
+SHOW GLOBAL STATUS LIKE 'innodb_foreign_key_errors';
+Variable_name	Value
+Innodb_foreign_key_errors	6
+# FOREIGN_KEY_CHECKS=0 should NOT increment
+SET FOREIGN_KEY_CHECKS = 0;
+INSERT INTO child VALUES (70, 999);
+SET FOREIGN_KEY_CHECKS = 1;
+DELETE FROM child WHERE id = 70;
+# Counter unchanged with FK checks disabled
+SHOW GLOBAL STATUS LIKE 'innodb_foreign_key_errors';
+Variable_name	Value
+Innodb_foreign_key_errors	6
+# CASCADE chain failure
+CREATE TABLE grandparent (id INT PRIMARY KEY) ENGINE=InnoDB;
+CREATE TABLE parent_cascade (
+id INT PRIMARY KEY,
+gp_id INT,
+FOREIGN KEY (gp_id) REFERENCES grandparent(id) ON DELETE RESTRICT
+) ENGINE=InnoDB;
+CREATE TABLE child_cascade (
+id INT PRIMARY KEY,
+parent_id INT,
+FOREIGN KEY (parent_id) REFERENCES parent_cascade(id) ON DELETE CASCADE
+) ENGINE=InnoDB;
+INSERT INTO grandparent VALUES (1);
+INSERT INTO parent_cascade VALUES (1, 1);
+INSERT INTO child_cascade VALUES (1, 1);
+DELETE FROM grandparent WHERE id = 1;
+ERROR 23000: Cannot delete or update a parent row: a foreign key constraint fails (`test`.`parent_cascade`, CONSTRAINT `1` FOREIGN KEY (`gp_id`) REFERENCES `grandparent` (`id`))
+# Counter after CASCADE chain failure
+SHOW GLOBAL STATUS LIKE 'innodb_foreign_key_errors';
+Variable_name	Value
+Innodb_foreign_key_errors	7
+DROP TABLE child_cascade;
+DROP TABLE parent_cascade;
+DROP TABLE grandparent;
+# Counter resets after restart
+# restart
+SHOW GLOBAL STATUS LIKE 'innodb_foreign_key_errors';
+Variable_name	Value
+Innodb_foreign_key_errors	0
+# Cleanup
+DROP TABLE child;
+DROP TABLE parent;

mysql-test/suite/innodb/r/innodb_status_variables.result

@@ -56,6 +56,7 @@ INNODB_DATA_WRITTEN
 INNODB_DBLWR_PAGES_WRITTEN
 INNODB_DBLWR_WRITES
 INNODB_DEADLOCKS
+INNODB_FOREIGN_KEY_ERRORS
 INNODB_HISTORY_LIST_LENGTH
 INNODB_LOG_WAITS
 INNODB_LOG_WRITE_REQUESTS

mysql-test/suite/innodb/t/foreign_key_errors.test

@@ -0,0 +1,97 @@
+--source include/have_innodb.inc
+
+--echo #
+--echo # MDEV-32688: Test innodb_foreign_key_errors status variable
+--echo #
+
+--echo # Setup
+CREATE TABLE parent (id INT PRIMARY KEY) ENGINE=InnoDB;
+CREATE TABLE child (
+    id INT PRIMARY KEY,
+    parent_id INT,
+    FOREIGN KEY (parent_id) REFERENCES parent(id)
+) ENGINE=InnoDB;
+
+INSERT INTO parent VALUES (1), (2), (3);
+INSERT INTO child VALUES (1, 1), (2, 2);
+
+--echo # Counter starts at 0
+SHOW GLOBAL STATUS LIKE 'innodb_foreign_key_errors';
+
+--echo # Child-side violations (INSERT, UPDATE, REPLACE, INSERT...SELECT)
+--error ER_NO_REFERENCED_ROW_2
+INSERT INTO child VALUES (10, 999);
+
+--error ER_NO_REFERENCED_ROW_2
+UPDATE child SET parent_id = 888 WHERE id = 1;
+
+--error ER_NO_REFERENCED_ROW_2
+REPLACE INTO child VALUES (30, 777);
+
+--error ER_NO_REFERENCED_ROW_2
+INSERT INTO child (id, parent_id) SELECT 40, 555;
+
+--echo # Parent-side violations (DELETE, UPDATE)
+--error ER_ROW_IS_REFERENCED_2
+DELETE FROM parent WHERE id = 1;
+
+--error ER_ROW_IS_REFERENCED_2
+UPDATE parent SET id = 100 WHERE id = 1;
+
+--echo # Counter after 6 violations
+SHOW GLOBAL STATUS LIKE 'innodb_foreign_key_errors';
+
+--echo # Successful operations should NOT increment
+INSERT INTO child VALUES (50, 3);
+UPDATE child SET parent_id = 1 WHERE id = 50;
+DELETE FROM child WHERE id = 50;
+INSERT INTO child VALUES (60, NULL);
+DELETE FROM child WHERE id = 60;
+
+--echo # Counter unchanged after successful operations
+SHOW GLOBAL STATUS LIKE 'innodb_foreign_key_errors';
+
+--echo # FOREIGN_KEY_CHECKS=0 should NOT increment
+SET FOREIGN_KEY_CHECKS = 0;
+INSERT INTO child VALUES (70, 999);
+SET FOREIGN_KEY_CHECKS = 1;
+DELETE FROM child WHERE id = 70;
+
+--echo # Counter unchanged with FK checks disabled
+SHOW GLOBAL STATUS LIKE 'innodb_foreign_key_errors';
+
+--echo # CASCADE chain failure
+CREATE TABLE grandparent (id INT PRIMARY KEY) ENGINE=InnoDB;
+CREATE TABLE parent_cascade (
+    id INT PRIMARY KEY,
+    gp_id INT,
+    FOREIGN KEY (gp_id) REFERENCES grandparent(id) ON DELETE RESTRICT
+) ENGINE=InnoDB;
+CREATE TABLE child_cascade (
+    id INT PRIMARY KEY,
+    parent_id INT,
+    FOREIGN KEY (parent_id) REFERENCES parent_cascade(id) ON DELETE CASCADE
+) ENGINE=InnoDB;
+
+INSERT INTO grandparent VALUES (1);
+INSERT INTO parent_cascade VALUES (1, 1);
+INSERT INTO child_cascade VALUES (1, 1);
+
+--error ER_ROW_IS_REFERENCED_2
+DELETE FROM grandparent WHERE id = 1;
+
+--echo # Counter after CASCADE chain failure
+SHOW GLOBAL STATUS LIKE 'innodb_foreign_key_errors';
+
+DROP TABLE child_cascade;
+DROP TABLE parent_cascade;
+DROP TABLE grandparent;
+
+--echo # Counter resets after restart
+--source include/restart_mysqld.inc
+
+SHOW GLOBAL STATUS LIKE 'innodb_foreign_key_errors';
+
+--echo # Cleanup
+DROP TABLE child;
+DROP TABLE parent;

storage/innobase/dict/dict0dict.cc

@@ -172,6 +172,8 @@ and unique key errors. Only created if !srv_read_only_mode */
 FILE*	dict_foreign_err_file		= NULL;
 /* mutex protecting the foreign and unique error buffers */
 mysql_mutex_t dict_foreign_err_mutex;
+/** Number of foreign key constraint violations */
+ulint	dict_foreign_key_errors		= 0;
 
 /********************************************************************//**
 Checks if the database name in two table names is the same.

storage/innobase/handler/ha_innodb.cc

@@ -73,6 +73,7 @@ this program; if not, write to the Free Software Foundation, Inc.,
 #include "buf0flu.h"
 #include "buf0lru.h"
 #include "dict0boot.h"
+#include "dict0dict.h"
 #include "dict0load.h"
 #include "dict0crea.h"
 #include "dict0stats.h"
@@ -993,6 +994,7 @@ static SHOW_VAR innodb_status_variables[]= {
   {"dblwr_pages_written", &export_vars.innodb_dblwr_pages_written,SHOW_SIZE_T},
   {"dblwr_writes", &export_vars.innodb_dblwr_writes, SHOW_SIZE_T},
   {"deadlocks", &lock_sys.deadlocks, SHOW_SIZE_T},
+  {"foreign_key_errors", &dict_foreign_key_errors, SHOW_SIZE_T},
   {"history_list_length", &export_vars.innodb_history_list_length,SHOW_SIZE_T},
   {"log_waits", &log_sys.waits, SHOW_SIZE_T},
   {"log_write_requests", &log_sys.write_to_buf, SHOW_SIZE_T},

storage/innobase/include/dict0dict.h

@@ -1276,6 +1276,8 @@ constraint */
 and unique key errors */
 extern FILE*		dict_foreign_err_file;
 extern mysql_mutex_t dict_foreign_err_mutex;
+/** Number of foreign key constraint violations */
+extern ulint 		dict_foreign_key_errors;
 
 /** InnoDB data dictionary cache */
 class dict_sys_t

storage/innobase/row/row0ins.cc

@@ -760,6 +760,8 @@ row_ins_foreign_report_err(
 
 	row_ins_foreign_trx_print(trx);
 
+	dict_foreign_key_errors++;
+
 	fputs("Foreign key constraint fails for table ", ef);
 	ut_print_name(ef, trx, foreign->foreign_table_name);
 	fputs(":\n", ef);
@@ -816,6 +818,8 @@ row_ins_foreign_report_add_err(
 
 	row_ins_foreign_trx_print(trx);
 
+	dict_foreign_key_errors++;
+
 	fputs("Foreign key constraint fails for table ", ef);
 	ut_print_name(ef, trx, foreign->foreign_table_name);
 	fputs(":\n", ef);