- InnoDB throws ASAN error while adding the index on virtual column
of system versioned table. InnoDB wrongly assumes that virtual
column collation type changes, creates new column with different
character set. This leads to failure while detaching the column
from indexes.
- Newly created InnoDB fulltext index does have only one column
and doesn't associate with primary key fields during DDL.
init_change_cols() has strict assertion that number of fields
should be greater than number of collation change columns.
Problem:
=======
ALTER TABLE in InnoDB fails to detect duplicate entries
for the unique index when the character set or collation of
an indexed column is changed in such a way that the character
encoding is compatible with the old table definition.
In this case, any secondary indexes on the changed columns
would be rebuilt (DROP INDEX, ADD INDEX).
Solution:
========
During ALTER TABLE, InnoDB keeps track of columns whose collation
changed, and will fill in the correct metadata when sorting the
index records, or applying changes from concurrent DML.
This metadata will be allocated in the dict_index_t::heap of
the being-created secondary indexes.
The fix was developed by Thirunarayanan Balathandayuthapani
and simplified by me.
ha_innobase::check_if_supported_inplace_alter(): Refuse to change the
collation of a column that would become or remain indexed as part of
the ALTER TABLE operation.
In MariaDB Server 10.6, we will allow this type of operation;
that fix depends on MDEV-15250.
