Re: range_agg

From: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
To: Paul Jungwirth <pj(at)illuminatedcomputing(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Jeff Davis <pgsql(at)j-davis(dot)com>, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, David Fetter <david(at)fetter(dot)org>
Subject: Re: range_agg
Date: 2020-04-04 23:10:18
Message-ID: 20200404231018.GA4570@alvherre.pgsql
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On 2020-Mar-23, Paul Jungwirth wrote:

> On Mon, Mar 23, 2020 at 4:33 PM Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
> wrote:
> >
> > Thinking about the on-disk representation, can we do better than putting
> > the contained ranges in long-varlena format, including padding; also we
> > include the type OID with each element.  Sounds wasteful.  A more
> > compact representation might be to allow short varlenas and doing away
> > with the alignment padding, put the the type OID just once.  This is
> > important because we cannot change it later.
>
> Can you give me some guidance on this? I don't know how to make the on-disk
> format different from the in-memory format. (And for the in-memory format, I
> think it's important to have actual RangeTypes inside the multirange.) Is
> there something in the documentation, or a README in the repo, or even
> another type I can follow?

Sorry I didn't reply earlier, but I didn't know the answer then and I
still don't know the answer now.

Anyway, I rebased this to verify that the code hasn't broken, and it
hasn't -- the tests still pass. There was a minor conflict in
pg_operator.dat which I fixed.

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

Attachment Content-Type Size
v16-multirange.patch text/x-diff 332.2 KB

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