From:
"Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To:
"Hitoshi Harada" <umi(dot)tanuki(at)gmail(dot)com>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc:
"David Fetter" <david(at)fetter(dot)org>, "Pavel Stehule" <pavel(dot)stehule(at)gmail(dot)com>, "PostgreSQL Hackers" <pgsql-hackers(at)postgresql(dot)org>
Subject:
Re: wip: functions median and percentile
Date:
2010-10-01 15:15:03
Message-ID:
4CA5B4A70200002500036331@gw.wicourts.gov (view raw or flat )
Thread:
2010-08-19 10:59:33 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-08-19 14:50:23 from Greg Stark <gsstark(at)mit(dot)edu>
2010-08-19 15:33:13 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-08-19 16:49:45 from Robert Haas <robertmhaas(at)gmail(dot)com>
2010-08-19 17:03:20 from David Fetter <david(at)fetter(dot)org>
2010-08-19 17:12:12 from "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
2010-08-19 17:14:58 from David Fetter <david(at)fetter(dot)org>
2010-08-19 17:25:36 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-08-19 17:47:59 from David Fetter <david(at)fetter(dot)org>
2010-08-19 18:17:42 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-08-19 17:41:57 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-08-19 18:17:28 from "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
2010-08-19 17:38:14 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-09-20 03:47:09 from Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
2010-09-20 05:11:02 from David Fetter <david(at)fetter(dot)org>
2010-09-20 06:22:29 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-09-21 20:28:15 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-09-21 20:44:16 from Robert Haas <robertmhaas(at)gmail(dot)com>
2010-09-21 21:03:31 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-09-22 02:21:01 from Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
2010-09-22 04:36:24 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-09-22 03:06:51 from Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
2010-09-22 04:44:58 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-09-23 09:35:47 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-09-23 17:45:36 from Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
2010-09-23 18:27:38 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-09-23 18:48:47 from David Fetter <david(at)fetter(dot)org>
2010-09-23 18:56:53 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-09-26 10:39:21 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-10-01 08:17:19 from Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
2010-10-01 08:46:45 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-10-01 13:05:43 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-10-01 13:19:57 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-10-01 14:11:08 from Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
2010-10-01 14:43:47 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-10-01 15:00:35 from Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
2010-10-01 15:08:00 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-10-01 15:15:03 from "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
2010-10-01 15:35:03 from Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
2010-10-01 15:16:03 from Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
2010-10-01 15:22:46 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-10-01 15:32:03 from Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
2010-10-01 17:37:03 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-10-01 19:17:08 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-10-03 14:06:25 from Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
2010-10-03 15:49:37 from Greg Stark <gsstark(at)mit(dot)edu>
2010-10-04 06:36:48 from Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
2010-10-04 06:58:44 from Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
2010-10-04 16:14:06 from Greg Stark <gsstark(at)mit(dot)edu>
2010-10-04 17:22:39 from Robert Haas <robertmhaas(at)gmail(dot)com>
2010-10-04 19:20:28 from Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
2010-10-05 06:04:31 from Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
2010-10-05 08:47:52 from Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
2010-10-05 12:14:24 from Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
2010-10-05 13:08:59 from Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
2010-10-10 21:16:59 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-10-11 06:58:53 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-10-11 09:35:13 from Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
2010-10-11 09:55:16 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-10-11 10:33:11 from Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
2010-10-11 14:03:40 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-10-11 15:30:46 from Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
2010-10-11 15:44:08 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-10-11 17:34:51 from Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
2010-10-11 17:37:11 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-10-11 17:42:10 from Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
2010-10-11 17:48:12 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-10-11 17:55:32 from Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
2010-10-11 18:05:11 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-10-11 18:23:25 from Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
2010-10-11 10:33:12 from Robert Haas <robertmhaas(at)gmail(dot)com>
2010-10-11 14:08:53 from Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
2010-10-11 14:29:38 from Robert Haas <robertmhaas(at)gmail(dot)com>
2010-10-11 18:27:13 from Greg Stark <gsstark(at)mit(dot)edu>
2010-10-11 18:30:39 from Josh Berkus <josh(at)agliodbs(dot)com>
2010-10-11 18:46:47 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-10-12 03:08:32 from Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
2010-10-12 08:44:20 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-10-13 10:36:59 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-10-13 10:48:17 from Peter Eisentraut <peter_e(at)gmx(dot)net>
2010-10-13 10:51:51 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-10-13 10:56:06 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-10-14 00:54:42 from Robert Haas <robertmhaas(at)gmail(dot)com>
2010-10-14 02:37:37 from Greg Stark <gsstark(at)mit(dot)edu>
2010-10-14 12:17:54 from Robert Haas <robertmhaas(at)gmail(dot)com>
2010-10-14 04:53:57 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-10-03 17:31:18 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-10-01 14:44:44 from Robert Haas <robertmhaas(at)gmail(dot)com>
2010-09-23 13:22:39 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
2010-09-23 13:25:32 from Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
Lists:
pgsql-hackers pgsql-rrreviewers
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com> writes:
>> Another suggestion?
>
> The implementation I would've expected to see is to do the sort
> and then have two code paths for retrieving the median, depending
> on whether the sort result is all in memory or not.
Would it make sense to accumulate value/count pairs in a hash table,
along with a total count, as the tuples are encountered, and sort
the (potentially smaller) hash table at the end? (Not that this
helps with the memory management questions...) Large sets with any
significant degree of duplication in values (say the age in years of
residents of a state) would probably run significantly faster this
way.
-Kevin
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