From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
---|---|
To: | David Rowley <dgrowleyml(at)gmail(dot)com> |
Cc: | Andreas Karlsson <andreas(at)proxel(dot)se>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Using 128-bit integers for sum, avg and statistics aggregates |
Date: | 2014-12-31 05:20:24 |
Message-ID: | CA+TgmoZJWHCqCtrEXvAo6_cVRTZMpWiqAC0eUv4MOtS1=Bb4ag@mail.gmail.com |
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Lists: | pgsql-hackers |
On Fri, Dec 26, 2014 at 7:57 AM, David Rowley <dgrowleyml(at)gmail(dot)com> wrote:
> 1. Do we need to keep the 128 byte aggregate state size for machines without
> 128 bit ints? This has been reduced to 48 bytes in the patch, which is in
> favour code being compiled with a compiler which has 128 bit ints. I kind
> of think that we need to keep the 128 byte estimates for compilers that
> don't support int128, but I'd like to hear any counter arguments.
I think you're referring to the estimated state size in pg_aggregate
here, and I'd say it's probably not a big deal one way or the other.
Presumably, at some point, 128-bit arithmetic will become common
enough that we'll want to change that estimate, but I don't know
whether we've reached that point or not.
> 2. References to int16 meaning 16 bytes. I'm really in two minds about this,
> it's quite nice to keep the natural flow, int4, int8, int16, but I can't
> help think that this will confuse someone one day. I think it'll be a long
> time before it confused anyone if we called it int128 instead, but I'm not
> that excited about seeing it renamed either. I'd like to hear what others
> have to say... Is there a chance that some sql standard in the distant
> future will have HUGEINT and we might regret not getting the internal names
> nailed down?
Yeah, I think using int16 to mean 16-bytes will be confusing to
someone almost immediately.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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