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Subject: Re: Insert performance
From: =?ISO-8859-1?Q?jo=EBl?= Winteregg <joel.winteregg@gmail.com>
To: Richard Huxton <dev@archonet.com>
Cc: pgsql-performance@postgresql.org
In-Reply-To: <45ED1996.7050008@archonet.com>
References: <1172596221.393824.41130@j27g2000cwj.googlegroups.com>
	<45ED1996.7050008@archonet.com>
Content-Type: text/plain; charset=ISO-8859-1
Date: Tue, 06 Mar 2007 08:53:27 +0100
Message-Id: <1173167607.4917.8.camel@hatman>
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Hi Richard,

> > 
> > Here is my problem. With some heavy insert into a simple BD (one
> > table, no indexes) i can't get better perf than 8000 inserts/sec. I'm
> > testing it using a simple C software which use libpq and which use:
> > - Insert prepared statement (to avoid too many request parsing on the
> > server)
> > - transaction of 100000 inserts
> 
> Are each of the INSERTs in their own transaction?
> 

No, as said above transactions are made of 100000 inserts...

> If so, you'll be limited by the speed of the disk the WAL is running on.
> 
> That means you have two main options:
> 1. Have multiple connections inserting simultaneously.

Yes, you're right. That what i have been testing and what provide the
best performance ! I saw that postgresql frontend was using a lot of CPU
and not both of them (i'm using a pentium D, dual core). To the opposit,
the postmaster process use not much resources. Using several client,
both CPU are used and i saw an increase of performance (about 18000
inserts/sec).

So i think my bottle neck is more the CPU speed than the disk speed,
what do you think ?

I use 2 disks (raid 0) for the data and a single disk for pg_xlog.

> 2. Batch your inserts together, from 10 to 10,000 per transaction.
> 

Yes, that's what i'm doing.


Thanks a lot for the advices !


regards,


Joël