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Re: Performance issue with Insert

From: Jenish <jenishvyas(at)gmail(dot)com>
To: tv(at)fuzzy(dot)cz
Cc: Kevin Grittner <kevin(dot)grittner(at)wicourts(dot)gov>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Performance issue with Insert
Date: 2011-06-27 15:58:26
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance

I have already checked all the statements present in the trigger, no one is
taking more then 20 ms.

I am using 8-Processor, Quad-Core Server ,CPU utilization is more then 90-95
% for all. (htop result)

DB has 960 concurrent users.

io : writing 3-4 MB per second or less (iotop result).

Scenario :  All insert are waiting for previous insert to complete. Cant
we avoid this situation ?
What is the "max_connections" postgresql support?

Plz help....

Thanks & regards,

On Mon, Jun 27, 2011 at 6:32 PM, <tv(at)fuzzy(dot)cz> wrote:

> > Hi,
> >
> > DB : POSTGRES 8.4.8
> > OS  : Debian
> > HD : SAS 10k rpm
> >
> > Shared_buffer is 4096 25 % of RAM , effective_cache is 8GB 75% of RAM
> >
> > After insert trigger is again calling 2 more trigger and insert record in
> > another table depends on condition.
> >
> > with all trigger enable there are 8 insert and 32 updates(approx. update
> > is
> > depends on hierarchy)
> Hi,
> it's very difficult to give you reliable recommendations with this little
> info, but the triggers are obviously the bottleneck. We have no idea what
> queries are executed in them, but I guess there are some slow queries.
> Find out what queries are executed in the triggers, benchmark each of them
> and make them faster. Just don't forget that those SQL queries are
> executed as prepared statements, so they may behave a bit differently than
> plain queries. So use 'PREPARE' and 'EXPLAIN EXECUTE' to tune them.
> > Plz explain multiple connections. Current scenario application server is
> > sending all requests.
> PostgreSQL does not support parallel queries (i.e. a query distributed on
> multiple CPUs) so each query may use just a single CPU. If you're CPU
> bound (one CPU is 100% utilized but the other CPUs are idle), you can
> usually parallelize the workload on your own - just use multiple
> connections.
> But if you're using an application server and there are multiple
> connections used, this is not going to help you. How many connections are
> active at the same time? Are the CPUs idle or utilized?
> Tomas

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