Re: [PERFORM] Appending "LIMIT" to query drastically decreases performance

2007-11-30 Thread cluster
Please post EXPLAIN ANALYZE output for the two queries. As I wrote in my first post, I pasted this together with the two queries at pastebin.com: http://pastebin.com/m3c0d1896 ---(end of broadcast)--- TIP 9: In versions below 8.0, the planner

Re: [PERFORM] TB-sized databases

2007-11-30 Thread Luke Lonergan
Hi Peter, If you run into a scaling issue with PG (you will at those scales 1TB+), you can deploy Greenplum DB which is PG 8.2.5 compatible. A large internet company (look for press soon) is in production with a 150TB database on a system capable of doing 400TB and we have others in production at

Re: [PERFORM] Appending "LIMIT" to query drastically decreases performance

2007-11-30 Thread Bill Moran
In response to Matthew <[EMAIL PROTECTED]>: > On Fri, 30 Nov 2007, cluster wrote: > > Can anyone explain the following odd behavior? > > I have a query that completes in about 90 ms. If I append LIMIT to the > > very end, eg. "LIMIT 500" the evaluation time increases to about 800 ms. > > How can p

Re: [PERFORM] GiST indexing tuples

2007-11-30 Thread Matthew
On Thu, 29 Nov 2007, Matthew T. O'Connor wrote: > Matthew wrote: > > For instance, the normal B-tree index on (a, b) is able to answer queries > > like "a = 5 AND b > 1" or "a > 5". An R-tree would be able to index these, > > plus queries like "a > 5 AND b < 1". > > Sorry in advance if this is a st

Re: [PERFORM] Appending "LIMIT" to query drastically decreases performance

2007-11-30 Thread Matthew
On Fri, 30 Nov 2007, cluster wrote: > Can anyone explain the following odd behavior? > I have a query that completes in about 90 ms. If I append LIMIT to the > very end, eg. "LIMIT 500" the evaluation time increases to about 800 ms. > How can performance get *worse* by giving the database the optio

[PERFORM] Appending "LIMIT" to query drastically decreases performance

2007-11-30 Thread cluster
Can anyone explain the following odd behavior? I have a query that completes in about 90 ms. If I append LIMIT to the very end, eg. "LIMIT 500" the evaluation time increases to about 800 ms. How can performance get *worse* by giving the database the option to stop the evaluation earlier (when it

Re: [PERFORM] TB-sized databases

2007-11-30 Thread Csaba Nagy
> Isn't that what statement_timeout is for? Since this is entirely based > on estimates, using arbitrary fuzzy numbers for this seems fine to me; > precision isn't really the goal. There's an important difference to statement_timeout: this proposal would avoid completely taking any resources if it

Re: [PERFORM] TB-sized databases

2007-11-30 Thread Trevor Talbot
On 11/29/07, Gregory Stark <[EMAIL PROTECTED]> wrote: > "Simon Riggs" <[EMAIL PROTECTED]> writes: > > On Wed, 2007-11-28 at 14:48 +0100, Csaba Nagy wrote: > >> In fact an even more useful option would be to ask the planner to throw > >> error if the expected cost exceeds a certain threshold... >

Re: [PERFORM] Training Recommendations

2007-11-30 Thread Robert Treat
On Wednesday 28 November 2007 11:20, Usama Munir Dar wrote: > EnterpriseDB (www.enterprisedb.com), ofcourse > lame :-P > Campbell, Lance wrote: > > PostgreSQL: 8.2.4 > > > > > > > > Does anyone have any companies they would recommend using for > > performance tuning training of PostgreSQL for Lin

Re: [PERFORM] TB-sized databases

2007-11-30 Thread Simon Riggs
On Fri, 2007-11-30 at 17:41 +1100, Russell Smith wrote: > Simon Riggs wrote: > > On Tue, 2007-11-27 at 18:06 -0500, Pablo Alcaraz wrote: > > > >> Simon Riggs wrote: > >> > >>> All of those responses have cooked up quite a few topics into one. Large > >>> databases might mean text warehouses