From: Richard Huxton <dev@archonet.com>
To: Werner Scholtes <Werner.Scholtes@heuboe.de>
Cc: Divakar Singh <dpsmails@yahoo.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: performance libpq vs JDBC
Date: Thu, 16 Dec 2010 12:37:50 +0000
Message-ID: <4D0A081E.9010103@archonet.com> (raw)
In-Reply-To: <128DB53227227D43B4AAEED73E89A81901E2C4B590@vm-exchg-2k8.heuboe.hbintern>
References: <128DB53227227D43B4AAEED73E89A81901E2C4B584@vm-exchg-2k8.heuboe.hbintern>
<209185.49892.qm@web65409.mail.ac4.yahoo.com>
<128DB53227227D43B4AAEED73E89A81901E2C4B58B@vm-exchg-2k8.heuboe.hbintern>
<4D0A02A8.5050206@archonet.com>
<128DB53227227D43B4AAEED73E89A81901E2C4B590@vm-exchg-2k8.heuboe.hbintern>
On 16/12/10 12:28, Werner Scholtes wrote:
> Thanks a lot for your advice. I found the difference: My Java program
> sends one huge SQL string containing 1000 INSERT statements separated
> by ';' (without using prepared statements at all!), whereas my C++
> program sends one INSERT statement with parameters to be prepared and
> after that 1000 times parameters. Now I refactured my C++ program to
> send also 1000 INSERT statements in one call to PQexec and reached
> the same performance as my Java program.
So - it was the network round-trip overhead. Like Divakar suggested,
COPY or VALUES (),(),() would work too.
You mention multiple updates/deletes too. Perhaps the cleanest and
fastest method would be to build a TEMP table containing IDs/values
required and join against that for your updates/deletes.
> I just wonder why anyone should use prepared statements at all?
Not everything is a simple INSERT. Preparing saves planning-time on
repeated SELECTs. It also provides some SQL injection safety since you
provide parameters rather than building a SQL string.
--
Richard Huxton
Archonet Ltd
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Cc: dev@archonet.com, Werner.Scholtes@heuboe.de, dpsmails@yahoo.com
Subject: Re: performance libpq vs JDBC
In-Reply-To: <4D0A081E.9010103@archonet.com>
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