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Date: Thu, 14 Jan 2010 22:27:19 +0100
From: "fkater@googlemail.com" <fkater@googlemail.com>
To: Florian Weimer <fweimer@bfk.de>
Cc: pgsql-performance@postgresql.org
Subject: Re: Inserting 8MB bytea: just 25% of disk perf used?
Message-ID: <20100114212719.GE2384@comppasch2>
References: <20100114142903.GB2973@comppasch2>
 <82aawgoh09.fsf@mid.bfk.de>
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Florian Weimer:

> > Do you have any further idea why 16MB/s seems to be the limit here?
> 
> BYTEA deserialization is very slow, and this could be a factor here.
> Have you checked that you are in fact I/O bound?

Could you elaborate that a bit? It sounds interesting but I
do not get what you mean by:

"bytea deserialization": Do you mean from an escaped string
back to real binary data? Does that apply to my case (I use
PGexecParam and have the Format arg set to 1, binary) ?

"I/O bound": What do you mean by that?


> You can speed things up by sending the data in binary, by passing
> approriate parameters to PQexecParams().

Do you mean the Format arg =1 ? If not, what is appropriate
here?

 Felix