From:
"Stephen R(dot) van den Berg" <srb(at)cuci(dot)nl>
To:
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc:
Gregory Stark <stark(at)enterprisedb(dot)com>,Alex Hunsaker <badalex(at)gmail(dot)com>,Robert Haas <robertmhaas(at)gmail(dot)com>,PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject:
Re: Significantly larger toast tables on 8.4?
Date:
2009-01-03 10:46:53
Message-ID:
20090103104653.GA14952@cuci.nl (view raw or flat )
Thread:
2009-01-02 04:30:59 from "Alex Hunsaker" <badalex(at)gmail(dot)com>
2009-01-02 04:49:55 from "Alex Hunsaker" <badalex(at)gmail(dot)com>
2009-01-02 05:44:49 from "Alex Hunsaker" <badalex(at)gmail(dot)com>
2009-01-02 06:09:35 from "Alex Hunsaker" <badalex(at)gmail(dot)com>
2009-01-02 14:57:46 from "Stephen R(dot) van den Berg" <srb(at)cuci(dot)nl>
2009-01-02 16:01:56 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2009-01-02 17:44:38 from "Robert Haas" <robertmhaas(at)gmail(dot)com>
2009-01-02 18:44:48 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2009-01-02 19:50:34 from "Alex Hunsaker" <badalex(at)gmail(dot)com>
2009-01-03 01:30:30 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2009-01-03 02:27:46 from "Alex Hunsaker" <badalex(at)gmail(dot)com>
2009-01-03 09:46:30 from Simon Riggs <simon(at)2ndQuadrant(dot)com>
2009-01-02 19:42:56 from "Alex Hunsaker" <badalex(at)gmail(dot)com>
2009-01-02 20:23:13 from "Stephen R(dot) van den Berg" <srb(at)cuci(dot)nl>
2009-01-02 20:35:18 from "Robert Haas" <robertmhaas(at)gmail(dot)com>
2009-01-02 21:19:00 from "Stephen R(dot) van den Berg" <srb(at)cuci(dot)nl>
2009-01-02 21:43:40 from "Robert Haas" <robertmhaas(at)gmail(dot)com>
2009-01-03 01:36:16 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2009-01-03 02:37:31 from "Robert Haas" <robertmhaas(at)gmail(dot)com>
2009-01-03 03:30:31 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2009-01-03 04:34:11 from "Robert Haas" <robertmhaas(at)gmail(dot)com>
2009-01-03 05:17:16 from Andrew Chernow <ac(at)esilo(dot)com>
2009-01-03 06:16:58 from "Alex Hunsaker" <badalex(at)gmail(dot)com>
2009-01-03 22:56:13 from Peter Eisentraut <peter_e(at)gmx(dot)net>
2009-01-02 22:48:15 from Martijn van Oosterhout <kleptog(at)svana(dot)org>
2009-01-07 14:44:51 from "Gregory Maxwell" <gmaxwell(at)gmail(dot)com>
2009-01-02 20:59:35 from Gregory Stark <stark(at)enterprisedb(dot)com>
2009-01-03 01:46:21 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2009-01-03 06:32:00 from "Alex Hunsaker" <badalex(at)gmail(dot)com>
2009-01-05 15:57:21 from "Merlin Moncure" <mmoncure(at)gmail(dot)com>
2009-01-03 10:46:53 from "Stephen R(dot) van den Berg" <srb(at)cuci(dot)nl>
2009-01-04 03:47:23 from Philip Warner <pjw(at)rhyme(dot)com(dot)au>
2009-01-04 04:29:02 from "Alex Hunsaker" <badalex(at)gmail(dot)com>
2009-01-04 04:56:57 from Philip Warner <pjw(at)rhyme(dot)com(dot)au>
2009-01-04 05:15:09 from "Alex Hunsaker" <badalex(at)gmail(dot)com>
2009-01-03 22:45:44 from Peter Eisentraut <peter_e(at)gmx(dot)net>
2009-01-04 22:42:05 from James Mansion <james(at)mansionfamily(dot)plus(dot)com>
2009-01-05 01:34:07 from "Stephen R(dot) van den Berg" <srb(at)cuci(dot)nl>
2009-01-05 07:38:21 from Peter Eisentraut <peter_e(at)gmx(dot)net>
2009-01-05 16:45:49 from Alvaro Herrera <alvherre(at)commandprompt(dot)com>
2009-01-05 16:55:03 from "Merlin Moncure" <mmoncure(at)gmail(dot)com>
2009-01-06 18:10:31 from Peter Eisentraut <peter_e(at)gmx(dot)net>
2009-01-06 19:57:41 from "Stephen R(dot) van den Berg" <srb(at)cuci(dot)nl>
2009-01-06 20:30:11 from "Alex Hunsaker" <badalex(at)gmail(dot)com>
2009-01-02 18:56:47 from "Alex Hunsaker" <badalex(at)gmail(dot)com>
Lists:
pgsql-hackers
Tom Lane wrote:
>and I'm still pretty worried about the longevity of any knob we put in
>here. But we might not have a lot of choice.
>It would be fairly easy, I think, to add some reloption fields that
>would let these parameters be controlled on a per-table level.
>Per-column would be much more painful; do we really need that?
+1
Per table sounds fine for now. Per column would be nice, but can be worked
around if absolutely necessary by splitting tables.
To avoid having to add another parameter later, I *would* suggest to use
something like:
ALTER TABLE mytable SET COMPRESSIONLEVEL = 9;
Where it can range from 0 (= no compression), to 9 (= maximum compression).
The current algorithm could then either be as simplistic as to kick in
anytime COMPRESSIONLEVEL>=1, and not to compress when COMPRESSIONLEVEL==0.
More advanced algorithms and decisions can be implemented later.
Obviously the algorithm should ideally use the one-dimensional knob to
more or less deliver IO-bound (de)compression at level one, and CPU-bound
(de)compression at level nine.
This kind of one-dimensional knob is well understood by many compression
tools and libraries and users, so it'd make sense to provide something similar
to the DBA.
--
Sincerely,
Stephen R. van den Berg.
Expect the unexpected!
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