Re: [PERFORM] how to plan for vacuum?

2007-01-23 Thread Galy Lee
Just have one example here: workload: run pgbench in 365x24x7 database size: 100GB the workload distribution: 06:00-24:00 100tps 00:00-06:00 20tps how should we plan vacuum for this situation to get the highest performance? Best regards Galy Galy Lee wrote: > Hi, > > For I can no

Re: [PERFORM] Bad Row Count Estimate on View with 8.2

2007-01-23 Thread Tom Lane
"Dave Dutcher" <[EMAIL PROTECTED]> writes: > I discovered a query which is taking 70 seconds on 8.2.1 which used to take > under a second on 8.1.2. I was digging into what was causing it and I > believe the problem is a view which the planner estimates will return 1 row > when it actually returns

[PERFORM] how to plan for vacuum?

2007-01-23 Thread Galy Lee
Hi, For I can not find too much information about how to use vacuum, I want to ask some general information about the guideline of vacuum planning. 1. How do we know if autovacuum is enough for my application, or should I setup a vacuum manually from cron for my application? 2. How to set t

Re: [PERFORM] extract(field from timestamp) vs date dimension

2007-01-23 Thread Mark Kirkwood
Tobias Brox wrote: I suppose the strongest argument for introducing date dimensions already now is that I probably will benefit from having conform and well-designed dimensions when I will be introducing more data marts. As for now I have only one fact table and some few dimensions in the syst

Re: [PERFORM] slow result

2007-01-23 Thread Mark Kirkwood
Laurent Manchon wrote: Hi, I have a slow response of my PostgreSQL database 7.4 using this query below on a table with 80 rows: select count(*)from tbl; PostgreSQL return result in 28 sec every time. Can you post the results of: analyze verbose tbl; explain analyze select count(*) from

[PERFORM] Bad Row Count Estimate on View with 8.2

2007-01-23 Thread Dave Dutcher
Hello, I discovered a query which is taking 70 seconds on 8.2.1 which used to take under a second on 8.1.2. I was digging into what was causing it and I believe the problem is a view which the planner estimates will return 1 row when it actually returns 3500. When I join with the view, the plann

Re: [PERFORM] slow result

2007-01-23 Thread Bruno Wolff III
On Tue, Jan 23, 2007 at 11:34:52 +0100, Laurent Manchon <[EMAIL PROTECTED]> wrote: > Hi, > > I have a slow response of my PostgreSQL database 7.4 using this query below > on a table with 80 rows: > > select count(*)from tbl; > > PostgreSQL return result in 28 sec every time. > although MS-

Re: [PERFORM] extract(field from timestamp) vs date dimension

2007-01-23 Thread Merlin Moncure
On 1/23/07, Tobias Brox <[EMAIL PROTECTED]> wrote: Does anyone have experience with using postgres for data warehousing? Right, I saw one post suggestion to use mysql for a mostly read-only database ... but anyway, I think it's not a question to change the database platform for this project, at l

[PERFORM] Postgres processes have a burst of CPU usage

2007-01-23 Thread Subramaniam Aiylam
Hello all, I have a setup in which four client machines access a Postgres database (8.1.1) (on a Linux box). So, there are connections from each machine to the database; hence, the Linux box has about 2 postgres processes associated with each machine. I am using the JDBC driver (postgresql-8.

Re: [PERFORM] slow result

2007-01-23 Thread Ron
At 07:34 AM 1/23/2007, Laurent Manchon wrote: Hi, I have a slow response of my PostgreSQL database 7.4 using this query below on a table with 80 rows: 1= Upgrade to the latest stable version of pg. That would be 8.2.x You are very much in the Dark Ages pg version wise. pg 8.x has sign

Re: [PERFORM] slow result

2007-01-23 Thread Bill Moran
In response to Laurent Manchon <[EMAIL PROTECTED]>: > > I have a slow response of my PostgreSQL database 7.4 using this query below > on a table with 80 rows: > > select count(*)from tbl; > > PostgreSQL return result in 28 sec every time. > although MS-SQL return result in 0.02 sec every tim

Re: [PERFORM] extract(field from timestamp) vs date dimension

2007-01-23 Thread Tobias Brox
[Chad Wagner - Tue at 08:24:34AM -0500] > I guess go with your gut, but at some point the expressions are going to be > too complicated to maintain, and inefficient. The layout of my system is quite flexible, so it should eventually be fairly trivial to throw in a date dimension at a later stage.

Re: [PERFORM] extract(field from timestamp) vs date dimension

2007-01-23 Thread Chad Wagner
On 1/23/07, Tobias Brox <[EMAIL PROTECTED]> wrote: Ralph Kimball seems to be some kind of guru on data warehousing, and in his books he's strongly recommending to have a date dimension - simply a table describing all dates in the system, and having I would tend to agree with this line of thou

[PERFORM] extract(field from timestamp) vs date dimension

2007-01-23 Thread Tobias Brox
Does anyone have experience with using postgres for data warehousing? Right, I saw one post suggestion to use mysql for a mostly read-only database ... but anyway, I think it's not a question to change the database platform for this project, at least not today ;-) Ralph Kimball seems to be some ki

Re: [PERFORM] slow result

2007-01-23 Thread A. Kretschmer
am Tue, dem 23.01.2007, um 13:34:19 +0100 mailte Laurent Manchon folgendes: > Hi, > > I have a slow response of my PostgreSQL database 7.4 using this query below > on a table with 80 rows: > > select count(*)from tbl; PLEASE READ THE ANSWERS FOR YOUR OTHER MAILS. Andreas -- Andreas Krets

[PERFORM] slow result

2007-01-23 Thread Laurent Manchon
Hi, I have a slow response of my PostgreSQL database 7.4 using this query below on a table with 80 rows: select count(*)from tbl; PostgreSQL return result in 28 sec every time. although MS-SQL return result in 0.02 sec every time. My server is a DELL PowerEdge 2600 with bi-processor Xeon a

Re: [PERFORM] slow result

2007-01-23 Thread Steinar H. Gunderson
On Tue, Jan 23, 2007 at 11:55:41AM +0100, Steinar H. Gunderson wrote: > you'll find them to be much master. s/master/faster/ /* Steinar */ -- Homepage: http://www.sesse.net/ ---(end of broadcast)--- TIP 9: In versions below 8.0, the planner will i

Re: [PERFORM] slow result

2007-01-23 Thread Steinar H. Gunderson
On Tue, Jan 23, 2007 at 11:34:52AM +0100, Laurent Manchon wrote: > I have a slow response of my PostgreSQL database 7.4 using this query below > on a table with 80 rows: > > select count(*)from tbl; Contrary to your expectations, this is _not_ a query you'd expect to be fast in Postgres. Try

Re: [PERFORM] slow result

2007-01-23 Thread A. Kretschmer
am Tue, dem 23.01.2007, um 11:34:52 +0100 mailte Laurent Manchon folgendes: > Hi, > > I have a slow response of my PostgreSQL database 7.4 using this query below > on a table with 80 rows: > > select count(*)from tbl; If i remember correctly, i saw this question yesterday on an other list..

Re: [PERFORM] slow result

2007-01-23 Thread Heiko W.Rupp
Am 23.01.2007 um 11:34 schrieb Laurent Manchon: Hi, I have a slow response of my PostgreSQL database 7.4 using this query below on a table with 80 rows: select count(*)from tbl; count(*) is doing a full tablescan over all your 80 rows. This is a well known "feature" of postgre

[PERFORM] slow result

2007-01-23 Thread Laurent Manchon
Hi, I have a slow response of my PostgreSQL database 7.4 using this query below on a table with 80 rows: select count(*)from tbl; PostgreSQL return result in 28 sec every time. although MS-SQL return result in 0.02 sec every time. My server is a DELL PowerEdge 2600 with bi-processor Xeon a