Horton

Re: ALTER COLUMN ... SET EXPRESSION to alter stored generated column's expression

Ajit Awekar <ajitpostgres@gmail.com>

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From: ajitpostgres awekar <ajitpostgres@gmail.com>
To: pgsql-hackers@lists.postgresql.org
Cc: Amul Sul <sulamul@gmail.com>
Date: 2023-08-22T07:14:54Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. ALTER TABLE command to change generation expression

  2. Refactor: separate function to find all objects depending on a column

  3. Turn AT_PASS_* macros into an enum

The following review has been posted through the commitfest application:
make installcheck-world:  tested, passed
Implements feature:       tested, passed
Spec compliant:           tested, passed
Documentation:            tested, passed

Hi Amul,
Patch changes look fine.
Below are some of my observations as soon as we alter default expression on column

1. Materialized view becomes stale and starts giving incorrect results. We need to refresh the materialized view to get correct results.
2. Index on generated column need to be reindexed in order to use new expression.
3. Column Stats become stale and plan may be impacted due to outdated stats.

These things also happen as soon as we delete default expression or set default expression on column.

Thanks & Best Regards,
Ajit