From:
Noah Misch <noah(at)leadboat(dot)com>
To:
Alvaro Herrera <alvherre(at)commandprompt(dot)com>
Cc:
Jaime Casanova <jaime(at)2ndquadrant(dot)com>,Bernd Helmle <mailings(at)oopsware(dot)de>,Greg Smith <greg(at)2ndquadrant(dot)com>,Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject:
Re: Measuring relation free space
Date:
2012-01-24 00:18:59
Message-ID:
20120124001859.GA31986@tornado.leadboat.com (view raw or flat )
Thread:
2011-11-06 03:08:11 from Greg Smith <greg(at)2ndQuadrant(dot)com>
2011-11-06 10:38:54 from Magnus Hagander <magnus(at)hagander(dot)net>
2011-11-08 21:12:25 from Jaime Casanova <jaime(at)2ndquadrant(dot)com>
2011-11-09 12:58:47 from Alvaro Herrera <alvherre(at)commandprompt(dot)com>
2011-11-14 22:02:04 from Jaime Casanova <jaime(at)2ndquadrant(dot)com>
2011-11-26 00:42:31 from Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
2011-11-28 10:40:39 from Greg Smith <greg(at)2ndQuadrant(dot)com>
2011-12-07 16:22:41 from Jaime Casanova <jaime(at)2ndquadrant(dot)com>
2011-12-15 12:26:57 from Greg Smith <greg(at)2ndQuadrant(dot)com>
2011-11-06 21:20:49 from Bernd Helmle <mailings(at)oopsware(dot)de>
2011-11-07 04:55:48 from Mark Kirkwood <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz>
2011-11-08 18:07:02 from Greg Smith <greg(at)2ndQuadrant(dot)com>
2011-11-08 22:07:58 from Robert Treat <rob(at)xzilla(dot)net>
2011-11-09 00:19:00 from Greg Smith <greg(at)2ndQuadrant(dot)com>
2011-11-09 16:34:03 from Robert Treat <rob(at)xzilla(dot)net>
2011-12-15 21:11:21 from Noah Misch <noah(at)leadboat(dot)com>
2011-12-16 07:02:03 from Greg Smith <greg(at)2ndQuadrant(dot)com>
2011-12-18 16:56:25 from Noah Misch <noah(at)leadboat(dot)com>
2012-01-14 09:41:57 from Jaime Casanova <jaime(at)2ndquadrant(dot)com>
2012-01-14 11:26:51 from Noah Misch <noah(at)leadboat(dot)com>
2012-01-14 19:40:46 from Jaime Casanova <jaime(at)2ndquadrant(dot)com>
2012-01-16 10:09:31 from Noah Misch <noah(at)leadboat(dot)com>
2012-01-18 14:46:20 from Jaime Casanova <jaime(at)2ndquadrant(dot)com>
2012-01-19 00:01:05 from Noah Misch <noah(at)leadboat(dot)com>
2012-01-21 00:03:22 from Jaime Casanova <jaime(at)2ndquadrant(dot)com>
2012-01-21 01:33:30 from Noah Misch <noah(at)leadboat(dot)com>
2012-01-23 19:56:24 from Alvaro Herrera <alvherre(at)commandprompt(dot)com>
2012-01-24 00:18:59 from Noah Misch <noah(at)leadboat(dot)com>
2012-01-24 16:24:08 from Jaime Casanova <jaime(at)2ndquadrant(dot)com>
2012-01-26 02:47:29 from Noah Misch <noah(at)leadboat(dot)com>
2012-02-14 07:04:26 from Jaime Casanova <jaime(at)2ndquadrant(dot)com>
2012-02-22 05:27:47 from Noah Misch <noah(at)leadboat(dot)com>
2012-03-09 07:18:02 from Jaime Casanova <jaime(at)2ndquadrant(dot)com>
2012-03-13 02:41:49 from Noah Misch <noah(at)leadboat(dot)com>
2012-03-13 03:10:37 from Jaime Casanova <jaime(at)2ndquadrant(dot)com>
2012-03-13 13:53:13 from Robert Haas <robertmhaas(at)gmail(dot)com>
Lists:
pgsql-hackers
On Mon, Jan 23, 2012 at 04:56:24PM -0300, Alvaro Herrera wrote:
> Excerpts from Noah Misch's message of vie ene 20 22:33:30 -0300 2012:
> > pgstattuple() figures the free_percent by adding up all space available to
> > hold tuples and dividing that by the simple size of the relation. Non-leaf
> > pages and the meta page get identical treatment: both never hold tuples, so
> > they do not contribute to the free space.
>
> Hm. Leaf pages hold as much tuples as non-leaf pages, no? I mean
> for each page element there's a value and a CTID. In non-leaf those
> CTIDs point to other index pages, one level down the tree; in leaf pages
> they point to the heap.
That distinction seemed important when I sent my last message, but now I agree
that it's largely irrelevant for free space purposes. If someone feels like
doing it, +1 for making pgstattuple() count non-leaf free space.
Thanks,
nm
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