--On Dienstag, Februar 14, 2006 10:35:12 -0600 hector Corrada Bravo
[EMAIL PROTECTED] wrote:
Before I start trying this (creating aggregate paths seems the
reasonable thing to do) I would like your counsel.
1) Regardless of the optimization problem, is the executor able to
execute aggregate
On Tue, Feb 14, 2006 at 05:28:54PM -0500, Tom Lane wrote:
Simon Riggs [EMAIL PROTECTED] writes:
How much time would you need? I think having every patch built before
anyone even looks at the code would sort out most of the issues I
mentioned.
If I ran a buildfarm machine, I'd turn it
On Tue, 2006-02-14 at 21:47 -0500, Neil Conway wrote:
On Tue, 2006-02-14 at 22:54 +, Simon Riggs wrote:
On Tue, 2006-02-14 at 17:28 -0500, Tom Lane wrote:
IMHO the thing we are really seriously short of is patch reviewers.
[...]
Well that was the basis of my original suggestion.
[EMAIL PROTECTED] (Robert Treat) writes:
On Tuesday 14 February 2006 16:00, Martijn van Oosterhout wrote:
I would like to suggest that we increase substantially the FAQ entries
relating to patch submission. By we, I actually mean please could the
committers sit down and agree some
Gary Doades [EMAIL PROTECTED] writes:
If I run the script again, it is not always the first case that is slow,
it varies from run to run, which is why I repeated it quite a few times
for the test.
For some reason I hadn't immediately twigged to the fact that your test
script is just N
Tom Lane wrote:
For some reason I hadn't immediately twigged to the fact that your test
script is just N repetitions of the exact same structure with random data.
So it's not so surprising that you get random variations in behavior
with different test data sets.
It seems clear that our
Gary Doades [EMAIL PROTECTED] writes:
Is this likely to hit me in a random fashion during normal operation,
joins, sorts, order by for example?
Yup, anytime you're passing data with that kind of distribution
through a sort.
So the options are:
1) Fix the included qsort.c code and use that
Gary Doades [EMAIL PROTECTED] writes:
Ouch! That confirms my problem. I generated the random test case because
it was easier than including the dump of my tables, but you can
appreciate that tables 20 times the size are basically crippled when it
comes to creating an index on them.
This behavior is consistent with the pivot choosing algorithm
assuming certain distribution(s) for the data. For instance,
median-of-three partitioning is known to be pessimal when the data is
geometrically or hyper-geometrically distributed. Also, care must be
taken that sometimes is not
I wrote:
Gary Doades [EMAIL PROTECTED] writes:
Ouch! That confirms my problem. I generated the random test case because
it was easier than including the dump of my tables, but you can
appreciate that tables 20 times the size are basically crippled when it
comes to creating an index on
Ron [EMAIL PROTECTED] writes:
How are we choosing our pivots?
See qsort.c: it looks like median of nine equally spaced inputs (ie,
the 1/8th points of the initial input array, plus the end points),
implemented as two rounds of median-of-three choices. With half of the
data inputs zero, it's not
We are currently maintaining information about configuration parameters
in at least three places: the documentation, guc.c, and
postgresql.conf.sample. I would like to generate these from a single
source. Computationally, this is not very challenging, it's just a bit
of work. I imagine as
-Original Message-
From: [EMAIL PROTECTED] [mailto:pgsql-hackers-
[EMAIL PROTECTED] On Behalf Of Tom Lane
Sent: Wednesday, February 15, 2006 5:22 PM
To: Ron
Cc: pgsql-performance@postgresql.org; pgsql-hackers@postgresql.org
Subject: Re: [HACKERS] qsort again (was Re: [PERFORM]
Ouch! That confirms my problem. I generated the random test case because
it was easier than including the dump of my tables, but you can
appreciate that tables 20 times the size are basically crippled when it
comes to creating an index on them.
I have to say that I restored a few gigabyte
On Wed, 2006-02-15 at 19:59 -0500, Tom Lane wrote:
I get
amazingly stable runtimes now --- I didn't have the patience to run 100
trials, but in 30 trials I have slowest 11538 msec and fastest 11144 msec.
So this code path is definitely not very sensitive to this data
distribution.
The
On Wed, 2006-02-15 at 18:28 -0500, Tom Lane wrote:
It seems clear that our qsort.c is doing a pretty awful job of picking
qsort pivots, while glibc is mostly managing not to make that mistake.
I haven't looked at the glibc code yet to see what they are doing
differently.
glibc qsort is
Tom Lane [EMAIL PROTECTED] wrote
I did this 100 times and sorted the reported runtimes.
I'd say this puts a considerable damper on my enthusiasm for using our
qsort all the time, as was recently debated in this thread:
http://archives.postgresql.org/pgsql-hackers/2005-12/msg00610.php
100
Qingqing Zhou [EMAIL PROTECTED] writes:
By did this 100 times do you mean generate a sequence of at most
20*100 numbers, and for every 20 numbers, the first half are all
zeros and the other half are uniform random numbers?
No, I mean I ran the bit of SQL script I gave 100 separate
Tom Lane [EMAIL PROTECTED] wrote
Qingqing Zhou [EMAIL PROTECTED] writes:
By did this 100 times do you mean generate a sequence of at most
20*100 numbers, and for every 20 numbers, the first half are all
zeros and the other half are uniform random numbers?
No, I mean I ran the bit
Qingqing Zhou [EMAIL PROTECTED] wrote
I must misunderstand something here -- I can't figure out that why the
cost
of the same procedure keep climbing?
Ooops, I mis-intepret the sentence -- you sorted the results ...
Regards,
Qingqing
---(end of
Qingqing Zhou [EMAIL PROTECTED] writes:
Tom Lane [EMAIL PROTECTED] wrote
No, I mean I ran the bit of SQL script I gave 100 separate times.
I must misunderstand something here -- I can't figure out that why the cost
of the same procedure keep climbing?
No, the run cost varies randomly
At 08:21 PM 2/15/2006, Tom Lane wrote:
Ron [EMAIL PROTECTED] writes:
How are we choosing our pivots?
See qsort.c: it looks like median of nine equally spaced inputs (ie,
the 1/8th points of the initial input array, plus the end points),
implemented as two rounds of median-of-three choices.
http://www.flamingspork.com/blog/2006/02/16/enterprisedb-where-is-the-source/
Any comments on this? Is he referring to EnterpriseDB extensions that
they don't make public?
Chris
---(end of broadcast)---
TIP 1: if posting/reading through
23 matches
Mail list logo