Message-ID: <435E4373.7060607@brandywine.com>
Date: Tue, 25 Oct 2005 10:38:43 -0400
From: Daryl Richter <daryl@brandywine.com>
Reply-To: daryl@brandywine.com
Organization: Brandywine Asset Management
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Cc: pgsql-sql@postgresql.org
Subject: Re: automatic update or insert
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tobbe wrote:
> Hi.
> 
> I have a little problem.
> 
> In a system of mine i need to insert records into table [tbStat], and
> if the records exist i need to update them instead and increase a
> column [cQuantity] for every update.
> 
> I.e. the first insert sets cQuantity to 1, and for every other run
> cQuantity is increased.
> 

Regardless of how you implemented it, this seems unwise.  You can never 
know, nor validate, that this quantity is definitely correct.  Why can't 
you just insert another row and then count them?

If this is a transient value you might be ok, but I generally wouldn't 
put it in a DB in that case anyway...

> Currently i have implemented this as a stored procedure in the plpgsql
> language. This means that in my stored procedure i first do a select to
> find out if the row exists or not, then i do a insert or update
> depending if the row existed.
> 
> Unfortunately, stored procedures seems awfully slow. And i need the
> application to go faster.
> 
> One solution could be to implement the stored procedure in my program
> instead. I think that this will be atleast 50% faster than my stored
> procedure, so that would be ok.
> 
> However, this has made me thinking. Couldn't this be done directly in
> SQL?
> 
> 
> Brgds Robert
> 
> 
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-- 
Daryl Richter
Platform Author & Director of Technology

((         Brandywine Asset Management          )
  ( "Expanding the Science of Global Investing"  )
  (          http://www.brandywine.com           ))