Horton

Re: ALTER tbl rewrite loses CLUSTER ON index

Justin Pryzby <pryzby@telsasoft.com>

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From: Justin Pryzby <pryzby@telsasoft.com>
To: Amit Langote <amitlangote09@gmail.com>
Cc: pgsql-hackers@postgresql.org
Date: 2020-02-06T14:44:26Z
Lists: pgsql-hackers 
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.

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. */

Commits

  1. Refactor cluster.c to use new routine get_index_isclustered()

  2. Preserve clustered index after rewrites with ALTER TABLE

  3. Preserve replica identity index across ALTER TABLE rewrite

  4. Remove RangeIOData->typiofunc

  5. Preserve pg_index.indisclustered across REINDEX CONCURRENTLY