Submitted by: @ibaseru

Is related to QA576

Alterting char/varchar columns to lower size produces error

New size specified for column fff must be at least NN characters.

where NN is bytes per character, not character size of field/domain itself.

Example to reproduce (employee):

ALTER TABLE EMPLOYEE ADD UTF VARCHAR(100) CHARACTER SET UTF8;
commit;
ALTER TABLE EMPLOYEE ALTER COLUMN UTF8 TYPE VARCHAR(90);

error message says

This operation is not defined for system tables.
unsuccessful metadata update.
New size specified for column UTF must be at least 400 characters.

where, as you see, 400 is rdb$field_length, not rdb$character_length (100).

So, correct error message must be
New size specified for column UTF must be at least 100 characters.

Commits: 94a9c6d