Re: Memory Alignment in Postgres

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Arthur Silva <arthurprs(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Memory Alignment in Postgres
Date: 2014-09-10 20:29:29
Message-ID: 20140910202929.GB21173@momjian.us
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On Wed, Sep 10, 2014 at 11:43:52AM -0400, Robert Haas wrote:
> But there are a couple of obvious problems with this idea, too, such as:
>
> 1. It's really complicated and a ton of work.
> 2. It would break pg_upgrade pretty darn badly unless we employed some
> even-more-complex strategy to mitigate that.
> 3. The savings might not be enough to justify the effort.
>
> It might be interesting for someone to develop a tool measuring the
> number of bytes of alignment padding we lose per tuple or per page and
> gather some statistics on it on various databases. That would give us
> some sense as to the possible savings.

And will we ever implement a logical attribute system so we can reorder
the stored attribtes to minimize wasted space?

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ Everyone has their own god. +

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