Re: jsonb format is pessimal for toast compression

From: Arthur Silva <arthurprs(at)gmail(dot)com>
To: Peter Geoghegan <pg(at)heroku(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Josh Berkus <josh(at)agliodbs(dot)com>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Larry White <ljw1001(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Kevin Grittner <kgrittn(at)ymail(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, Bruce Momjian <bruce(at)momjian(dot)us>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, Gavin Flower <GavinFlower(at)archidevsys(dot)co(dot)nz>
Subject: Re: jsonb format is pessimal for toast compression
Date: 2014-08-27 04:09:43
Message-ID: CAO_YK0W1pS35b6SkB08Pcqh28pikSagHWRGYrLDnGsQE03z8Eg@mail.gmail.com
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It won't be faster by any means, but it should definitely be incorporated
if any format changes are made (like Tom already suggested).

I think it's important we gather at least 2 more things before making any
calls:
* Josh tests w/ cache aware patch, which should confirm cache aware is
indeed prefered
* Tests with toast hacked to use lz4 instead, which might ease any decisions

--
Arthur Silva

On Wed, Aug 27, 2014 at 12:53 AM, Peter Geoghegan <pg(at)heroku(dot)com> wrote:

> On Tue, Aug 26, 2014 at 8:41 PM, Arthur Silva <arthurprs(at)gmail(dot)com> wrote:
> > The difference is small but I's definitely faster, which makes sense
> since
> > cache line misses are probably slightly reduced.
> > As in the previous runs, I ran the query a dozen times and took the
> average
> > after excluding runs with a high deviation.
>
> I'm not surprised that it hasn't beaten HEAD. I haven't studied the
> problem in detail, but I don't think that the "cache awareness" of the
> new revision is necessarily a distinct advantage.
>
> --
> Peter Geoghegan
>

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