Обсуждение: plan-reading extensive tutorial?
In the docs it says "Plan-reading is an art that deserves an extensive tutorial, which this is not". Is there one? I've gone beyond simple queries (which are performing well) to the more difficult queries (which aren't). e.g. 4 generation family tree implemented as a view using 14 left outer joins back into the same table. If I select only from it, the optimizer uses the primary key (single int4 field) in nested loop left join on all 14. If I join the view to another table, it wants to do it sequentially (the other table is just a single int4 field with 1 row. the field is the primary key and also has a foreign key constraint to the main table). I dont want exact help on this particular query. Posting every query I'm having a problem with to the mailing list is a waste of both my time and yours (and not really feasable since it requires all the table structures and data). I have tried the obvious with vacuum full analyze, and changing the settings (like enable_seqscan, join_collapse_limit, from_collapse_limit...). klint. +---------------------------------------+-----------------+ : Klint Gore : "Non rhyming : : EMail : kg@kgb.une.edu.au : slang - the : : Snail : A.B.R.I. : possibilities : : Mail University of New England : are useless" : : Armidale NSW 2351 Australia : L.J.J. : : Fax : +61 2 6772 5376 : : +---------------------------------------+-----------------+
On Mon, 2004-04-19 at 08:35, Klint Gore wrote: > In the docs it says "Plan-reading is an art that deserves an extensive > tutorial, which this is not". Is there one? I've gone beyond simple > queries (which are performing well) to the more difficult queries (which > aren't). Red Hat has a tool called "Visual explain" that shows explain output graphically: http://sources.redhat.com/rhdb/ It might help understand what's going on. Bye, Chris.
Klint Gore wrote: > In the docs it says "Plan-reading is an art that deserves an extensive > tutorial, which this is not". Is there one? I've gone beyond simple > queries (which are performing well) to the more difficult queries (which > aren't). Try this one.. http://www.gtsm.com/oscon2003/toc.html Shridhar
FWIW, this site gives:
404 - File Not Found
"These aren't the droids files you're looking for."
Sorry, but that file could not be found. And believe you me, we looked! We checked all the likely directories, then all
theunlikely directories, and even grepped
through the RAM. We broke into all the computers on our nearby subnet and checked their directories, but still could
notfind anything. We checked underneath the
cushions, but all we turned up was that remote we've been looking for since last year. We searched through the laundry
bin,rummaged through the junk drawer, and
even asked the neighbor if they had a copy (like they would tell us anyway - they still haven't returned that
index.htmlwe loaned them 3 weeks ago!) Are you really,
really sure that's the correct file?
[which is a lot better than the usual 404 message, you have to admit!]
Greg Williamson
DBA
GLobeXplorer LLC
-----Original Message-----
From: Shridhar Daithankar [mailto:shridhar@frodo.hserus.net]
Sent: Monday, April 19, 2004 1:39 AM
To: Klint Gore
Cc: pgsql-general@postgresql.org
Subject: Re: [GENERAL] plan-reading extensive tutorial?
Klint Gore wrote:
> In the docs it says "Plan-reading is an art that deserves an extensive
> tutorial, which this is not". Is there one? I've gone beyond simple
> queries (which are performing well) to the more difficult queries (which
> aren't).
Try this one..
http://www.gtsm.com/oscon2003/toc.html
Shridhar
---------------------------(end of broadcast)---------------------------
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Gregory S. Williamson schrieb: >FWIW, this site gives: >404 - File Not Found >[...] >[which is a lot better than the usual 404 message, you have to admit!] > > No doubt :) ... but simply clicking on the url you provided in your mail led to the document. > <>[...] > http://www.gtsm.com/oscon2003/toc.html
On Mon, 19 Apr 2004, Gregory S. Williamson wrote: > FWIW, this site gives: > 404 - File Not Found > > "These aren't the droids files you're looking for." > > Sorry, but that file could not be found. And believe you me, we looked! We checked all the likely directories, then allthe unlikely directories, and even grepped > through the RAM. We broke into all the computers on our nearby subnet and checked their directories, but still could notfind anything. We checked underneath the > cushions, but all we turned up was that remote we've been looking for since last year. We searched through the laundrybin, rummaged through the junk drawer, and > even asked the neighbor if they had a copy (like they would tell us anyway - they still haven't returned that index.htmlwe loaned them 3 weeks ago!) Are you really, > really sure that's the correct file? > > [which is a lot better than the usual 404 message, you have to admit!] My favorite is: http://www.shartwell.freeserve.co.uk/humor-site/404server.htm
Chris wrote: > Red Hat has a tool called "Visual explain" that shows explain output > graphically: > > http://sources.redhat.com/rhdb/ > I'm having a devil of a time getting this installed on my system ... anybody here willing to give me a walk-through? -- Jeff Boes vox 269.226.9550 ext 24 Database Engineer fax 269.349.9076 Nexcerpt, Inc. http://www.nexcerpt.com ...Nexcerpt... Extend your Expertise
On Tue, Apr 20, 2004 at 05:44:53PM +0000, Jeff Boes wrote: > > I'm having a devil of a time getting this installed on my system ... > anybody here willing to give me a walk-through? I did it just yesterday, to show it to someone. What's the problem? Do you have the proper jdk and ant? Are they first in your $PATH? I know that on debian, for instance, when you type 'java' you get something that's free but which doesn't always work. -- Andrew Sullivan | ajs@crankycanuck.ca