Subject: Re: BUG #17220: ALTER INDEX ALTER COLUMN SET (..) with an optionless
 opclass makes index and table unusable
To: "Bossart, Nathan" <bossartn@amazon.com>,
 "postgresql@zr40.nl" <postgresql@zr40.nl>,
 Alexander Korotkov <aekorotkov@gmail.com>
Cc: "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
References: <17220-15d684c6c2171a83@postgresql.org>
 <9b91d241-4d05-e5a4-67da-5b8acdb9a2f1@postgresfriends.org>
 <E29EF33B-CA1A-4146-BFCF-C8EC08FB91A8@amazon.com>
From: Vik Fearing <vik@postgresfriends.org>
Message-ID: <706b30e0-2bfc-7e1c-6149-a36ff7a5096a@postgresfriends.org>
Date: Wed, 13 Oct 2021 02:30:09 +0200
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On 10/13/21 2:06 AM, Bossart, Nathan wrote:
> On 10/11/21, 11:03 AM, "Vik Fearing" <vik@postgresfriends.org> wrote:
>> On 10/11/21 5:25 PM, PG Bug reporting form wrote:
>>>
>>> User 'musttu' on IRC reported the following bug: After running "ALTER INDEX
>>> some_idx ALTER COLUMN expr SET (n_distinct=100)", the index and table become
>>> unusable. All further statements involving the table result in: "ERROR:
>>> operator class text_ops has no options".
>>>
>>> They reported this on the RDS version of 13.3, but I've been able to
>>> reproduce this on Debian with 13.4 and 14.0. It does not reproduce on 12.8,
>>> all statements succeed on that version.
>>
>> This was broken by 911e702077 (Implement operator class parameters).
> 
> Moving to pgsql-hackers@.
> 
> 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.

Ah, thank you.  I was in the (slow) process of writing basically this
exact patch.  So I'll stop now and endorse yours.
-- 
Vik Fearing