Re: doc: improve the restriction description of using indexes on REPLICA IDENTITY FULL table.

Masahiko Sawada <sawada.mshk@gmail.com>

From: Masahiko Sawada <sawada.mshk@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Önder Kalacı <onderkalaci@gmail.com>, Peter Smith <smithpb2250@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-07-25T07:44:34Z
Lists: pgsql-hackers
On Mon, Jul 24, 2023 at 12:05 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Mon, Jul 24, 2023 at 6:39 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> >
> > On Sat, Jul 22, 2023 at 7:32 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> > >
> > >
> > > You have moved most of the comments related to the restriction of
> > > which index can be picked atop IsIndexUsableForReplicaIdentityFull().
> > > Now, the comments related to limitation atop
> > > FindUsableIndexForReplicaIdentityFull() look slightly odd as it refers
> > > to limitations but those limitation were not stated. The comments I am
> > > referring to are: "Note that the limitations of index scans for
> > > replica identity full only .... might not be a good idea in some
> > > cases". Shall we move these as well atop
> > > IsIndexUsableForReplicaIdentityFull()?
> >
> > Good point.
> >
> > Looking at neighbor comments, the following comment looks slightly odd to me:
> >
> >  * XXX: See IsIndexUsableForReplicaIdentityFull() to know the challenges in
> >  * supporting indexes other than btree and hash. For partial indexes, the
> >  * required changes are likely to be larger. If none of the tuples satisfy
> >  * the expression for the index scan, we fall-back to sequential execution,
> >  * which might not be a good idea in some cases.
> >
> > Are the first and second sentences related actually?
> >
>
> Not really.
>
> > I think we can move it as well to
> > IsIndexUsableForReplicaIdentityFull() with some adjustments. I've
> > attached the updated patch that incorporated your comment and included
> > my idea to update the comment.
> >
>
> LGTM.

Pushed.

Regards,

-- 
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com



Commits

  1. Remove unnecessary checks for indexes for REPLICA IDENTITY FULL tables.

  2. Allow the use of a hash index on the subscriber during replication.

  3. Doc: clarify the conditions of usable indexes for REPLICA IDENTITY FULL tables.

  4. Allow the use of indexes other than PK and REPLICA IDENTITY on the subscriber.