Force InnoDB to recheck foreign keys on a table/tables?

mysql foreign-keys innodb 
DELIMITER $$

DROP PROCEDURE IF EXISTS ANALYZE_INVALID_FOREIGN_KEYS$$

CREATE
    PROCEDURE `ANALYZE_INVALID_FOREIGN_KEYS`(
        checked_database_name VARCHAR(64), 
        checked_table_name VARCHAR(64), 
        temporary_result_table ENUM('Y', 'N'))

    LANGUAGE SQL
    NOT DETERMINISTIC
    READS SQL DATA

    BEGIN
        DECLARE TABLE_SCHEMA_VAR VARCHAR(64);
        DECLARE TABLE_NAME_VAR VARCHAR(64);
        DECLARE COLUMN_NAME_VAR VARCHAR(64); 
        DECLARE CONSTRAINT_NAME_VAR VARCHAR(64);
        DECLARE REFERENCED_TABLE_SCHEMA_VAR VARCHAR(64);
        DECLARE REFERENCED_TABLE_NAME_VAR VARCHAR(64);
        DECLARE REFERENCED_COLUMN_NAME_VAR VARCHAR(64);
        DECLARE KEYS_SQL_VAR VARCHAR(1024);

        DECLARE done INT DEFAULT 0;

        DECLARE foreign_key_cursor CURSOR FOR
            SELECT
                `TABLE_SCHEMA`,
                `TABLE_NAME`,
                `COLUMN_NAME`,
                `CONSTRAINT_NAME`,
                `REFERENCED_TABLE_SCHEMA`,
                `REFERENCED_TABLE_NAME`,
                `REFERENCED_COLUMN_NAME`
            FROM 
                information_schema.KEY_COLUMN_USAGE 
            WHERE 
                `CONSTRAINT_SCHEMA` LIKE checked_database_name AND
                `TABLE_NAME` LIKE checked_table_name AND
                `REFERENCED_TABLE_SCHEMA` IS NOT NULL;

        DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;

        IF temporary_result_table = 'N' THEN
            DROP TEMPORARY TABLE IF EXISTS INVALID_FOREIGN_KEYS;
            DROP TABLE IF EXISTS INVALID_FOREIGN_KEYS;

            CREATE TABLE INVALID_FOREIGN_KEYS(
                `TABLE_SCHEMA` VARCHAR(64), 
                `TABLE_NAME` VARCHAR(64), 
                `COLUMN_NAME` VARCHAR(64), 
                `CONSTRAINT_NAME` VARCHAR(64),
                `REFERENCED_TABLE_SCHEMA` VARCHAR(64),
                `REFERENCED_TABLE_NAME` VARCHAR(64),
                `REFERENCED_COLUMN_NAME` VARCHAR(64),
                `INVALID_KEY_COUNT` INT,
                `INVALID_KEY_SQL` VARCHAR(1024)
            );
        ELSEIF temporary_result_table = 'Y' THEN
            DROP TEMPORARY TABLE IF EXISTS INVALID_FOREIGN_KEYS;
            DROP TABLE IF EXISTS INVALID_FOREIGN_KEYS;

            CREATE TEMPORARY TABLE INVALID_FOREIGN_KEYS(
                `TABLE_SCHEMA` VARCHAR(64), 
                `TABLE_NAME` VARCHAR(64), 
                `COLUMN_NAME` VARCHAR(64), 
                `CONSTRAINT_NAME` VARCHAR(64),
                `REFERENCED_TABLE_SCHEMA` VARCHAR(64),
                `REFERENCED_TABLE_NAME` VARCHAR(64),
                `REFERENCED_COLUMN_NAME` VARCHAR(64),
                `INVALID_KEY_COUNT` INT,
                `INVALID_KEY_SQL` VARCHAR(1024)
            );
        END IF;


        OPEN foreign_key_cursor;
        foreign_key_cursor_loop: LOOP
            FETCH foreign_key_cursor INTO 
            TABLE_SCHEMA_VAR, 
            TABLE_NAME_VAR, 
            COLUMN_NAME_VAR, 
            CONSTRAINT_NAME_VAR, 
            REFERENCED_TABLE_SCHEMA_VAR, 
            REFERENCED_TABLE_NAME_VAR, 
            REFERENCED_COLUMN_NAME_VAR;
            IF done THEN
                LEAVE foreign_key_cursor_loop;
            END IF;


            SET @from_part = CONCAT('FROM ', '`', TABLE_SCHEMA_VAR, '`.`', TABLE_NAME_VAR, '`', ' AS REFERRING ', 
                 'LEFT JOIN `', REFERENCED_TABLE_SCHEMA_VAR, '`.`', REFERENCED_TABLE_NAME_VAR, '`', ' AS REFERRED ', 
                 'ON (REFERRING', '.`', COLUMN_NAME_VAR, '`', ' = ', 'REFERRED', '.`', REFERENCED_COLUMN_NAME_VAR, '`', ') ', 
                 'WHERE REFERRING', '.`', COLUMN_NAME_VAR, '`', ' IS NOT NULL ',
                 'AND REFERRED', '.`', REFERENCED_COLUMN_NAME_VAR, '`', ' IS NULL');
            SET @full_query = CONCAT('SELECT COUNT(*) ', @from_part, ' INTO @invalid_key_count;');
            PREPARE stmt FROM @full_query;

            EXECUTE stmt;
            IF @invalid_key_count > 0 THEN
                INSERT INTO 
                    INVALID_FOREIGN_KEYS 
                SET 
                    `TABLE_SCHEMA` = TABLE_SCHEMA_VAR, 
                    `TABLE_NAME` = TABLE_NAME_VAR, 
                    `COLUMN_NAME` = COLUMN_NAME_VAR, 
                    `CONSTRAINT_NAME` = CONSTRAINT_NAME_VAR, 
                    `REFERENCED_TABLE_SCHEMA` = REFERENCED_TABLE_SCHEMA_VAR, 
                    `REFERENCED_TABLE_NAME` = REFERENCED_TABLE_NAME_VAR, 
                    `REFERENCED_COLUMN_NAME` = REFERENCED_COLUMN_NAME_VAR, 
                    `INVALID_KEY_COUNT` = @invalid_key_count,
                    `INVALID_KEY_SQL` = CONCAT('SELECT ', 
                        'REFERRING.', '`', COLUMN_NAME_VAR, '` ', 'AS "Invalid: ', COLUMN_NAME_VAR, '", ', 
                        'REFERRING.* ', 
                        @from_part, ';');
            END IF;
            DEALLOCATE PREPARE stmt; 

        END LOOP foreign_key_cursor_loop;
    END$$

DELIMITER ;

CALL ANALYZE_INVALID_FOREIGN_KEYS('%', '%', 'Y');
DROP PROCEDURE IF EXISTS ANALYZE_INVALID_FOREIGN_KEYS;

SELECT * FROM INVALID_FOREIGN_KEYS;

You can use this stored procedure to check the all database for invalid foreign keys. The result will be loaded into INVALID_FOREIGN_KEYS table. Parameters of ANALYZE_INVALID_FOREIGN_KEYS:

  1. Database name pattern (LIKE style)
  2. Table name pattern (LIKE style)

  3. Whether the result will be temporary. It can be: 'Y', 'N', NULL.

    • In case of 'Y' the ANALYZE_INVALID_FOREIGN_KEYS result table will be temporary table. The temporary table won't be visible for other sessions. You can execute multiple ANALYZE_INVALID_FOREIGN_KEYS(...) stored procedure parallelly with temporary result table.
    • But if you are interested in the partial result from an other session, then you must use 'N', then execute SELECT * FROM INVALID_FOREIGN_KEYS; from an other session.

    • You must use NULL to skip result table creation in transaction, because MySQL executes implicit commit in transaction for CREATE TABLE ... and DROP TABLE ..., so the creation of result table would cause problem in transaction. In this case you must create the result table yourself out of BEGIN; COMMIT/ROLLBACK; block:

      CREATE TABLE INVALID_FOREIGN_KEYS(
    `TABLE_SCHEMA` VARCHAR(64), 
    `TABLE_NAME` VARCHAR(64), 
    `COLUMN_NAME` VARCHAR(64), 
    `CONSTRAINT_NAME` VARCHAR(64),
    `REFERENCED_TABLE_SCHEMA` VARCHAR(64),
    `REFERENCED_TABLE_NAME` VARCHAR(64),
    `REFERENCED_COLUMN_NAME` VARCHAR(64),
    `INVALID_KEY_COUNT` INT,
    `INVALID_KEY_SQL` VARCHAR(1024)
);

      Visit MySQL site about implicit commit: http://dev.mysql.com/doc/refman/5.6/en/implicit-commit.html

The INVALID_FOREIGN_KEYS rows will contain only the name of invalid database, table, column. But you can see the invalid referring rows with the execution of value of INVALID_KEY_SQL column of INVALID_FOREIGN_KEYS if there is any.

This stored procedure will be very fast if there are indexes on the referring columns (aka. foreign index) and on the referred columns (usually primary key).


Thanks for this great answer - this is a very handy tool. Here is a slightly modified version of the procedure that includes SQL in the output table to delete keys with invalid keys - handy for the cases where you have confirmed that these rows are simply orphans from missing/disabled delete cascade rules (and not orphans from primary key changes or other more complex cases).

DELIMITER $$

DROP PROCEDURE IF EXISTS ANALYZE_INVALID_FOREIGN_KEYS$$

CREATE
    PROCEDURE `ANALYZE_INVALID_FOREIGN_KEYS`(
        checked_database_name VARCHAR(64), 
        checked_table_name VARCHAR(64), 
        temporary_result_table ENUM('Y', 'N'))

    LANGUAGE SQL
    NOT DETERMINISTIC
    READS SQL DATA

    BEGIN
        DECLARE TABLE_SCHEMA_VAR VARCHAR(64);
        DECLARE TABLE_NAME_VAR VARCHAR(64);
        DECLARE COLUMN_NAME_VAR VARCHAR(64); 
        DECLARE CONSTRAINT_NAME_VAR VARCHAR(64);
        DECLARE REFERENCED_TABLE_SCHEMA_VAR VARCHAR(64);
        DECLARE REFERENCED_TABLE_NAME_VAR VARCHAR(64);
        DECLARE REFERENCED_COLUMN_NAME_VAR VARCHAR(64);
        DECLARE KEYS_SQL_VAR VARCHAR(1024);

        DECLARE done INT DEFAULT 0;

        DECLARE foreign_key_cursor CURSOR FOR
            SELECT
                `TABLE_SCHEMA`,
                `TABLE_NAME`,
                `COLUMN_NAME`,
                `CONSTRAINT_NAME`,
                `REFERENCED_TABLE_SCHEMA`,
                `REFERENCED_TABLE_NAME`,
                `REFERENCED_COLUMN_NAME`
            FROM 
                information_schema.KEY_COLUMN_USAGE 
            WHERE 
                `CONSTRAINT_SCHEMA` LIKE checked_database_name AND
                `TABLE_NAME` LIKE checked_table_name AND
                `REFERENCED_TABLE_SCHEMA` IS NOT NULL;

        DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;

        IF temporary_result_table = 'N' THEN
            DROP TEMPORARY TABLE IF EXISTS INVALID_FOREIGN_KEYS;
            DROP TABLE IF EXISTS INVALID_FOREIGN_KEYS;

            CREATE TABLE INVALID_FOREIGN_KEYS(
                `TABLE_SCHEMA` VARCHAR(64), 
                `TABLE_NAME` VARCHAR(64), 
                `COLUMN_NAME` VARCHAR(64), 
                `CONSTRAINT_NAME` VARCHAR(64),
                `REFERENCED_TABLE_SCHEMA` VARCHAR(64),
                `REFERENCED_TABLE_NAME` VARCHAR(64),
                `REFERENCED_COLUMN_NAME` VARCHAR(64),
                `INVALID_KEY_COUNT` INT,
                `INVALID_KEY_SQL` VARCHAR(1024),
                `INVALID_KEY_DELETE_SQL` VARCHAR(1024)
            );
        ELSEIF temporary_result_table = 'Y' THEN
            DROP TEMPORARY TABLE IF EXISTS INVALID_FOREIGN_KEYS;
            DROP TABLE IF EXISTS INVALID_FOREIGN_KEYS;

            CREATE TEMPORARY TABLE INVALID_FOREIGN_KEYS(
                `TABLE_SCHEMA` VARCHAR(64), 
                `TABLE_NAME` VARCHAR(64), 
                `COLUMN_NAME` VARCHAR(64), 
                `CONSTRAINT_NAME` VARCHAR(64),
                `REFERENCED_TABLE_SCHEMA` VARCHAR(64),
                `REFERENCED_TABLE_NAME` VARCHAR(64),
                `REFERENCED_COLUMN_NAME` VARCHAR(64),
                `INVALID_KEY_COUNT` INT,
                `INVALID_KEY_SQL` VARCHAR(1024),
                `INVALID_KEY_DELETE_SQL` VARCHAR(1024)
            );
        END IF;


        OPEN foreign_key_cursor;
        foreign_key_cursor_loop: LOOP
            FETCH foreign_key_cursor INTO 
            TABLE_SCHEMA_VAR, 
            TABLE_NAME_VAR, 
            COLUMN_NAME_VAR, 
            CONSTRAINT_NAME_VAR, 
            REFERENCED_TABLE_SCHEMA_VAR, 
            REFERENCED_TABLE_NAME_VAR, 
            REFERENCED_COLUMN_NAME_VAR;
            IF done THEN
                LEAVE foreign_key_cursor_loop;
            END IF;


            SET @from_part = CONCAT('FROM ', '`', TABLE_SCHEMA_VAR, '`.`', TABLE_NAME_VAR, '`', ' AS REFERRING ', 
                 'LEFT JOIN `', REFERENCED_TABLE_SCHEMA_VAR, '`.`', REFERENCED_TABLE_NAME_VAR, '`', ' AS REFERRED ', 
                 'ON (REFERRING', '.`', COLUMN_NAME_VAR, '`', ' = ', 'REFERRED', '.`', REFERENCED_COLUMN_NAME_VAR, '`', ') ', 
                 'WHERE REFERRING', '.`', COLUMN_NAME_VAR, '`', ' IS NOT NULL ',
                 'AND REFERRED', '.`', REFERENCED_COLUMN_NAME_VAR, '`', ' IS NULL');
            SET @full_query = CONCAT('SELECT COUNT(*) ', @from_part, ' INTO @invalid_key_count;');
            PREPARE stmt FROM @full_query;

            EXECUTE stmt;
            IF @invalid_key_count > 0 THEN
                INSERT INTO 
                    INVALID_FOREIGN_KEYS 
                SET 
                    `TABLE_SCHEMA` = TABLE_SCHEMA_VAR, 
                    `TABLE_NAME` = TABLE_NAME_VAR, 
                    `COLUMN_NAME` = COLUMN_NAME_VAR, 
                    `CONSTRAINT_NAME` = CONSTRAINT_NAME_VAR, 
                    `REFERENCED_TABLE_SCHEMA` = REFERENCED_TABLE_SCHEMA_VAR, 
                    `REFERENCED_TABLE_NAME` = REFERENCED_TABLE_NAME_VAR, 
                    `REFERENCED_COLUMN_NAME` = REFERENCED_COLUMN_NAME_VAR, 
                    `INVALID_KEY_COUNT` = @invalid_key_count,
                    `INVALID_KEY_SQL` = CONCAT('SELECT ', 
                        'REFERRING.', '`', COLUMN_NAME_VAR, '` ', 'AS "Invalid: ', COLUMN_NAME_VAR, '", ', 
                        'REFERRING.* ', 
                        @from_part, ';'),
                    `INVALID_KEY_DELETE_SQL` = CONCAT('DELETE ', '`', TABLE_SCHEMA_VAR, '`.`', TABLE_NAME_VAR, '` ',
                        'FROM ', '`', TABLE_SCHEMA_VAR, '`.`', TABLE_NAME_VAR, '`', ' ', 
                        'LEFT JOIN `', REFERENCED_TABLE_SCHEMA_VAR, '`.`', REFERENCED_TABLE_NAME_VAR, '`', ' ', 
                        'ON (', '`', TABLE_SCHEMA_VAR, '`.`', TABLE_NAME_VAR, '`', '.`', COLUMN_NAME_VAR, '`', ' = ', '`', REFERENCED_TABLE_SCHEMA_VAR, '`.`', REFERENCED_TABLE_NAME_VAR, '`', '.`', REFERENCED_COLUMN_NAME_VAR, '`', ') ', 
                        'WHERE ', '`', TABLE_SCHEMA_VAR, '`.`', TABLE_NAME_VAR, '`', '.`', COLUMN_NAME_VAR, '`', ' IS NOT NULL ',
                        'AND ', '`', REFERENCED_TABLE_SCHEMA_VAR, '`.`', REFERENCED_TABLE_NAME_VAR, '`', '.`', REFERENCED_COLUMN_NAME_VAR, '`', ' IS NULL', ';');
            END IF;
            DEALLOCATE PREPARE stmt; 

        END LOOP foreign_key_cursor_loop;
    END$$

DELIMITER ;

CALL ANALYZE_INVALID_FOREIGN_KEYS('%', '%', 'Y');
DROP PROCEDURE IF EXISTS ANALYZE_INVALID_FOREIGN_KEYS;

SELECT * FROM INVALID_FOREIGN_KEYS;

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