Re: BUG #17220: ALTER INDEX ALTER COLUMN SET (..) with an optionless opclass makes index and table unusable

Michael Paquier <michael@paquier.xyz>

From: Michael Paquier <michael@paquier.xyz>
To: "Bossart, Nathan" <bossartn@amazon.com>
Cc: Vik Fearing <vik@postgresfriends.org>, "postgresql@zr40.nl" <postgresql@zr40.nl>, Alexander Korotkov <aekorotkov@gmail.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2021-10-13T03:42:00Z
Lists: pgsql-bugs, 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. Block ALTER INDEX/TABLE index_name ALTER COLUMN colname SET (options)

On Wed, Oct 13, 2021 at 12:06:32AM +0000, Bossart, Nathan wrote:
> At first glance, it looks like ALTER INDEX .. ALTER COLUMN ... SET
> uses the wrong validation function.  I've attached a patch where I've
> attempted to fix that and added some tests.

The gap is larger than than, because ALTER INDEX .. ALTER COLUMN
.. SET is supported by the parser but we don't document it.  The only
thing we document now is SET STATISTICS that applies to a column
*number*.

Anyway, specifying a column name for an ALTER INDEX is not right, no?
Just take for example the case of an expression which has a hardcoded
column name in pg_attribute.  So these are not specific to indexes,
which is why we apply column numbers for the statistics case.  I think
that we'd better just reject those cases until there is a proper
design done here.  As far as I can see, I guess that we should do
things  similarly to what we do for SET STATISTICS with column
numbers when it comes to indexes.
--
Michael