Marko Mäkelä 4a1c66290d MDEV-18775 Fix ALTER TABLE error handling for DROP INDEX ...

On an error (such as when an index cannot be dropped due to
FOREIGN KEY constraints), the field dict_index_t::to_be_dropped
was only being cleared in debug builds, even though the field
is available and being used also in non-debug builds.

This was a regression that was introduced by myself originally
in MySQL 5.7.6 and later merged to MariaDB 10.2.2, in
d39898de8e

An error manifested itself in the MariaDB Server 10.4 non-debug build,
involving instant ADD or DROP column. Because an earlier failed
ALTER TABLE operation incorrectly left the dict_index_t::to_be_dropped
flag set, the column pointers of the index fields would fail to be
adjusted for instant ADD or DROP column (MDEV-15562). The instant
ADD COLUMN in MariaDB Server 10.3 is unlikely to be affected by a
similar scenario, because dict_table_t::instant_add_column() in 10.3
is applying the transformations to all indexes, not skipping
to-be-dropped ones.

2019-03-01 12:16:12 +02:00

1.7 KiB

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