Re: Proposal: Local indexes for partitioned table

From: Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, Maksim Milyutin <m(dot)milyutin(at)postgrespro(dot)ru>
Subject: Re: Proposal: Local indexes for partitioned table
Date: 2017-10-23 16:15:03
Message-ID: 20171023161503.ohkybquxrlech7d7@alvherre.pgsql
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Robert Haas wrote:
> On Mon, Oct 23, 2017 at 11:12 AM, Alvaro Herrera
> <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
> > I started with Maksim's submitted code, and developed according to the
> > ideas discussed in this thread. Attached is a very WIP patch series for
> > this feature.
> >
> > Many things remain to be done before this is committable: pg_dump
> > support needs to be written. ALTER INDEX ATTACH/DETACH not yet
> > implemented. No REINDEX support yet. Docs not updated (but see the
> > regression test as a guide for how this is supposed to work; see patch
> > 0005). CREATE INDEX CONCURRENTLY not done yet.
> >
> > I'm now working on the ability to build unique indexes (and unique
> > constraints) on top of this.
>
> Cool. Are you planning to do that by (a) only allowing the special
> case where the partition key columns/expressions are included in the
> indexed columns/expressions, (b) trying to make every insert to any
> index check all of the indexes for uniqueness conflicts, or (c)
> implementing global indexes? Because (b) sounds complex - think about
> attach operations, for example - and (c) sounds super-hard. I'd
> suggest doing (a) first, just on the basis of complexity.

Yes, I think (a) is a valuable thing to have -- not planning on doing
(c) at all because I fear it'll be a huge time sink. I'm not sure about
(b), but it's not currently on my plan.

> I hope that you don't get so involved in making this unique index
> stuff work that we don't get the cascading index feature, at least,
> committed to v11. That's already a considerable step forward in terms
> of ease of use, and I'd really like to have it.

Absolutely -- I do plan to get this one finished regardless of unique
indexes.

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

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