v.22.3Improvement

ALTER TABLE DROP COLUMN Now Instantly Supports ALIAS Columns in MergeTree

Official CH changelog text
Now ALTER TABLE DROP COLUMN columnX queries for MergeTree table engines will work instantly when columnX is an ALIAS column. Fixes #34660. #34786 (alesapin).
Instant execution of ALTER TABLE DROP COLUMN queries for ALIAS columns in MergeTree table engines.

Why it matters

Previously, dropping an ALIAS column in a MergeTree table using ALTER TABLE DROP COLUMN could be slow or cause delays. This feature makes dropping ALIAS columns instantaneous, improving usability and efficiency when modifying table schemas.

How to use it

Simply use the ALTER TABLE table_name DROP COLUMN alias_column_name command on a MergeTree table where the column is defined as an ALIAS. The operation will complete instantly without additional delays.

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