v.20.8Improvement

Disallow CODEC on ALIAS column type

Disallows CODEC on ALIAS column type. Fixes #13911. #14263 (Bharat Nallan).
Disallows applying CODEC compression on columns of type ALIAS in ClickHouse.

Why it matters

This feature prevents the usage of compression codecs on ALIAS columns, resolving an issue where such usage was invalid and caused errors. It ensures data integrity and consistency by forbidding an unsupported combination of column type and codec application, as reported in issue #13911.

How to use it

Users do not need to take any explicit action; the system now automatically disallows specifying CODEC options on ALIAS columns during table creation or alteration. Attempts to apply codecs on ALIAS columns will result in an error.