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Re: performance libpq vs JDBC

From: Richard Huxton <dev(at)archonet(dot)com>
To: Werner Scholtes <Werner(dot)Scholtes(at)heuboe(dot)de>
Cc: Divakar Singh <dpsmails(at)yahoo(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: performance libpq vs JDBC
Date: 2010-12-16 12:37:50
Message-ID: 4D0A081E.9010103@archonet.com (view raw or flat)
Thread:
Lists: pgsql-performance
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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