Date: Thu, 6 Feb 2020 14:24:47 -0300
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: Amit Langote <amitlangote09@gmail.com>, pgsql-hackers@postgresql.org
Subject: Re: ALTER tbl rewrite loses CLUSTER ON index
Message-ID: <20200206172447.GA28041@alvherre.pgsql>
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On 2020-Feb-06, Justin Pryzby wrote:

> I wondered if it wouldn't be better if CLUSTER ON was stored in pg_class as the
> Oid of a clustered index, rather than a boolean in pg_index.

Maybe.  Do you want to try a patch?

> That likely would've avoided (or at least exposed) this issue.
> And avoids the possibility of having two indices marked as "clustered".
> These would be more trivial:
> mark_index_clustered
> /* We need to find the index that has indisclustered set. */

You need to be careful when dropping the index ...

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services