From: Bruce Momjian <bruce@momjian.us>
To: Simon Riggs <simon@2ndquadrant.com>
Cc: Pavan Deolasee <pavan.deolasee@gmail.com>
Cc: Alexander Korotkov <a.korotkov@postgrespro.ru>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Pg Hackers <pgsql-hackers@postgresql.org>
Subject: Re: Indirect indexes
Date: Wed, 19 Oct 2016 13:04:16 -0400
Message-ID: <20161019170416.GR5087@momjian.us> (raw)
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On Wed, Oct 19, 2016 at 06:58:05PM +0200, Simon Riggs wrote:
> >> I agree. Also, I think the recheck mechanism will have to be something like
> >> what I wrote for WARM i.e. only checking for index quals won't be enough and we
> >> would actually need to verify that the heap tuple satisfies the key in the
> >> indirect index.
> >
> > I personally would like to see how far we get with WARM before adding
> > this feature that requires a DBA to evaluate and enable it.
>
> Assuming WARM is accepted, that *might* be fine.
First, I love WARM because everyone gets the benefits by default. For
example, a feature that improves performance by 10% but is only used by
1% of users has a usefulness of 0.1% --- at least that is how I think of
it.
> What we should ask is what is the difference between indirect indexes
> and WARM and to what extent they overlap.
>
> My current understanding is that WARM won't help you if you update
> parts of a JSON document and/or use GIN indexes, but is effective
> without needing to add a new index type and will be faster for
> retrieval than indirect indexes.
>
> So everybody please chirp in with benefits or comparisons.
I am not sure we have even explored all the limits of WARM with btree
indexes --- I haven't heard anyone talk about non-btree indexes yet.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ As you are, so once was I. As I am, so you will be. +
+ Ancient Roman grave inscription +
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Cc: bruce@momjian.us, simon@2ndquadrant.com, pavan.deolasee@gmail.com, a.korotkov@postgrespro.ru, robertmhaas@gmail.com, alvherre@2ndquadrant.com
Subject: Re: Indirect indexes
In-Reply-To: <20161019170416.GR5087@momjian.us>
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