Message-ID: <469D1E4F.5090805@tweakers.net>
Date: Tue, 17 Jul 2007 21:53:51 +0200
From: Arjen van der Meijden <acmmailing@tweakers.net>
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To: Thomas Finneid <tfinneid@student.matnat.uio.no>
CC: pgsql-performance@postgresql.org
Subject: Re: insert vs select into performance
References: <469D1AD3.9030004@ifi.uio.no>
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Have you also tried the COPY-statement? Afaik select into is similar to 
what happens in there.

Best regards,

Arjen

On 17-7-2007 21:38 Thomas Finneid wrote:
> Hi
> 
> I was doing some testing on "insert" compared to "select into". I 
> inserted 100 000 rows (with 8 column values) into a table, which took 14 
> seconds, compared to a select into, which took 0.8 seconds.
> (fyi, the inserts where batched, autocommit was turned off and it all 
> happend on the local machine)
> 
> Now I am wondering why the select into is that much faster?
> Does the select into translate into a specially optimised function in c 
> that can cut corners which a insert can not do (e.g. lazy copying), or 
> is it some other reason?
> 
> The reason I am asking is that select into shows that a number of rows 
> can be inserted into a table quite a lot faster than one would think was 
> possible with ordinary sql. If that is the case, it means that if I 
> write an pl-pgsql insert function in C instead of sql, then I can have 
> my db perform order of magnitude faster.
> 
> Any comments?
> 
> regards
> 
> thomas
> 
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