Re: speed of querry? - Mailing list pgsql-performance

From Joel Fradkin
Subject Re: speed of querry?
Date
Msg-id 000001c540f9$311dd440$797ba8c0@jfradkin
Whole thread Raw
In response to Re: speed of querry?  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: speed of querry?  (Dawid Kuroczko <qnex42@gmail.com>)
List pgsql-performance
I have done a vacuum and a vacuum analyze.
I can try again for kicks, but it is not in production so no new records are
added and vacuum analyze is ran after any mods to the indexes.

I am still pursuing Dell on why the monster box is so much slower then the
desktop as well.

Joel Fradkin

Wazagua, Inc.
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Tel.  941-753-7111 ext 305

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-----Original Message-----
From: Tom Lane [mailto:tgl@sss.pgh.pa.us]
Sent: Thursday, April 14, 2005 1:47 AM
To: Richard Huxton
Cc: Joel Fradkin; PostgreSQL Perform
Subject: Re: [PERFORM] speed of querry?

Richard Huxton <dev@archonet.com> writes:
> In the first, we match outer.clientnum to inner.clientnum, in the second
> it's "?column10?" - are you sure the query was identical in each case.
> I'm guessing the unidentified column in query 2 is the reason for the
> sort a couple of lines below it, which seems to take up a large chunk of
> time.

The "?column10?" is because EXPLAIN isn't excessively bright about
reporting references to outputs of lower plan nodes.  (Gotta fix that
sometime.)  The real point here is that the planner thought that a scan
plus sort would be faster than scanning an index that exactly matched
the sort order the Merge Join needed ... and it was wrong :-(

So this is just the usual sort of question of "are your stats up to
date, maybe you need to increase stats targets, or else play with
random_page_cost, etc" ...

            regards, tom lane


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