Problem:
=======
- InnoDB fails to find the foreign key index for the newly
added foreign key relation. This is caused by commit
5f09b53bdb (MDEV-31086).
FIX:
===
In check_col_is_in_fk_indexes(), while iterating through
the newly added foreign key relationship, InnoDB should
consider that foreign key relation may not have foreign index
when foreign key check is disabled.
Problem:
========
InnoDB fails to find the foreign key index for the
foreign key relation in the table while iterating the
foreign key constraints during alter operation. This is
caused by commit 5f09b53bdb
(MDEV-31086).
Fix:
====
In check_col_is_in_fk_indexes(), while iterating through
the foreign key relationship, InnoDB should consider that
foreign key relation may not have foreign index when
foreign key check is disabled.
While checking for altered column in foreign key constraints,
InnoDB fails to ignore virtual columns. This issue caused
by commit 5f09b53bdb4e973e7c7ec2c53a24c98321223f98(MDEV-31086).
- Server aborts when table doesn't have referenced index.
This is caused by 5f09b53bdb (MDEV-31086).
While iterating the foreign key constraints, we fail to
consider that InnoDB doesn't have referenced index for
it when foreign key check is disabled.
- InnoDB aborts when table is dropping the column. This is
caused by 5f09b53bdb (MDEV-31086).
While iterating the altered table fields, we fail to consider
the dropped columns.
- 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.
