Unix Technical Forum

Re: How to interpret this explain analyse?

This is a discussion on Re: How to interpret this explain analyse? within the Pgsql Performance forums, part of the PostgreSQL category; --> "Joost Kraaijeveld" <J.Kraaijeveld@Askesis.nl> writes: > I cannot change the query (it is geneated by a tool called Clarion) but ...


Go Back   Unix Technical Forum > Database Server Software > PostgreSQL > Pgsql Performance

Register FAQ Members List Calendar Search Today's Posts Mark Forums Read
  #1 (permalink)  
Old 04-18-2008, 11:07 AM
Tom Lane
 
Posts: n/a
Default Re: How to interpret this explain analyse?

"Joost Kraaijeveld" <J.Kraaijeveld@Askesis.nl> writes:
> I cannot change the query (it is geneated by a tool called Clarion) but it something like (from the psqlodbc_xxx.log):
> "...
> declare SQL_CUR01 cursor for
> SELECT A.ordernummer, B.klantnummer FROM "orders" A LEFT OUTER JOIN "klt_alg" B ON A.Klantnummer=B.Klantnummer ORDER BY A.klantnummer;
> fetch 100 in SQL_CUR01;
> ..."


Well, the planner does put some emphasis on startup time when dealing
with a DECLARE CURSOR plan; the problem you face is just that that
correction isn't large enough. (From memory, I think it optimizes on
the assumption that 10% of the estimated rows will actually be fetched;
you evidently want a setting of 1% or even less.)

We once talked about setting up a GUC variable to control the percentage
of a cursor that is estimated to be fetched:
http://archives.postgresql.org/pgsql...0/msg01108.php
It never got done but that seems like the most reasonable solution to
me.

regards, tom lane

---------------------------(end of broadcast)---------------------------
TIP 5: Have you checked our extensive FAQ?

http://www.postgresql.org/docs/faq

Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On
Forum Jump


All times are GMT. The time now is 03:36 AM.


Powered by vBulletin® Version 3.6.5
Copyright ©2000 - 2008, Jelsoft Enterprises Ltd.
SEO by vBSEO 3.2.0
www.UnixAdminTalk.com