Thread: Re: [GENERAL] How to know which queries are to be optimised?

Re: [GENERAL] How to know which queries are to be optimised?

From
Bruno Wolff III
Date:
On Wed, Aug 04, 2004 at 14:00:39 +0200,
  Ulrich Wisser <ulrich.wisser@relevanttraffic.se> wrote:

This topic really belongs on the performance list. I have copied that
list and set followups to go there and copy you.

>
> my web application grows slower and slower over time. After some
> profiling I came to the conclusion that my SQL queries are the biggest
> time spenders (25 seconds). Obviously I need to optimise my queries and
> maybe introduce some new indexes.

This sounds like you aren't doing proper maintainance. You need to be
vacuuming with a large enough FSM setting.

> The problem is, that my application uses dynamic queries. I therefor can
> not determine what are the most common queries.
>
> I have used the postgresql logging ption before. Is there a tool to
> analyze the logfile for the most common and/or most time consuming queries?

You can log queries that run for at least a specified amount of time.
This will be useful in finding what the long running queries are.
You can then use explain analyse to see why they are long running.

Re: [GENERAL] How to know which queries are to be optimised?

From
Ulrich Wisser
Date:
Hi Bruno,

>>my web application grows slower and slower over time. After some
>>profiling I came to the conclusion that my SQL queries are the biggest
>>time spenders (25 seconds). Obviously I need to optimise my queries and
>>maybe introduce some new indexes.
>
> This sounds like you aren't doing proper maintainance. You need to be
> vacuuming with a large enough FSM setting.

I do a vacuum full analyze every night.
How can I see if my FSM setting is appropriate?

>>The problem is, that my application uses dynamic queries. I therefor can
>>not determine what are the most common queries.
>>
>>I have used the postgresql logging ption before. Is there a tool to
>>analyze the logfile for the most common and/or most time consuming queries?
>
>
> You can log queries that run for at least a specified amount of time.
> This will be useful in finding what the long running queries are.
> You can then use explain analyse to see why they are long running.

But is there a tool that could compile a summary out of the log? The log
grows awefully big after a short time.

Thanks

/Ulrich






Re: [GENERAL] How to know which queries are to be optimised?

From
Richard Huxton
Date:
Ulrich Wisser wrote:
>> You can log queries that run for at least a specified amount of time.
>> This will be useful in finding what the long running queries are.
>> You can then use explain analyse to see why they are long running.
>
> But is there a tool that could compile a summary out of the log? The log
> grows awefully big after a short time.

You might want to look at the "Practical Query Analyser" - haven't used
it myself yet, but it seems a sensible idea.

http://pqa.projects.postgresql.org/

--
   Richard Huxton
   Archonet Ltd

Re: [GENERAL] How to know which queries are to be optimised?

From
Christopher Kings-Lynne
Date:
> I do a vacuum full analyze every night.
> How can I see if my FSM setting is appropriate?

On a busy website, run vacuum analyze once an hour, or even better, use
contrib/pg_autovacuum

Chris



Re: [GENERAL] How to know which queries are to be optimised?

From
Christopher Kings-Lynne
Date:
> But is there a tool that could compile a summary out of the log? The log
> grows awefully big after a short time.

Actually, yes there is.  Check out www.pgfoundry.org.  I think it's called
pqa or postgres query analyzer or somethign.

Chris


Re: [GENERAL] How to know which queries are to be optimised?

From
Rudi Starcevic
Date:
Hi,

>> But is there a tool that could compile a summary out of the log? The
>> log grows awefully big after a short time.

There's also pg_analyzer to check out.

http://www.samse.fr/GPL/pg_analyzer/

Some of it's features are: written in Perl and produces HTML output.

> You might want to look at the "Practical Query Analyser" - haven't used
> it myself yet, but it seems a sensible idea.
>
> http://pqa.projects.postgresql.org/


Cheers,
Rudi.