Thirunarayanan Balathandayuthapani 5f09b53bdb MDEV-31086 MODIFY COLUMN can break FK constraints, and lead to unrestorable dumps ... - When foreign_key_check is disabled, allowing to modify the column which is part of foreign key constraint can lead to refusal of TRUNCATE TABLE, OPTIMIZE TABLE later. So it make sense to block the column modify operation when foreign key is involved irrespective of foreign_key_check variable. Correct way to modify the charset of the column when fk is involved: SET foreign_key_checks=OFF; ALTER TABLE child DROP FOREIGN KEY fk, MODIFY m VARCHAR(200) CHARSET utf8mb4; ALTER TABLE parent MODIFY m VARCHAR(200) CHARSET utf8mb4; ALTER TABLE child ADD CONSTRAINT FOREIGN KEY (m) REFERENCES PARENT(m); SET foreign_key_checks=ON; fk_check_column_changes(): Remove the FOREIGN_KEY_CHECKS while checking the column change for foreign key constraint. This is the partial revert of commit 5f1f2fc0e4 and it changes the behaviour of copy alter algorithm ha_innobase::prepare_inplace_alter_table(): Find the modified column and check whether it is part of existing and newly added foreign key constraint.		2023-06-27 16:58:22 +05:30
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r	MDEV-31086 MODIFY COLUMN can break FK constraints, and lead to unrestorable dumps	2023-06-27 16:58:22 +05:30
t	MDEV-31086 MODIFY COLUMN can break FK constraints, and lead to unrestorable dumps	2023-06-27 16:58:22 +05:30
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