From: | M Simms <grim(at)argh(dot)demon(dot)co(dot)uk> |
---|---|
To: | michael(dot)j(dot)davis(at)tvguide(dot)com (Michael J Davis) |
Cc: | pgsql-sql(at)postgreSQL(dot)org |
Subject: | Re: [SQL] Update problem I cannot work out |
Date: | 1999-05-02 12:24:16 |
Message-ID: | 199905021224.NAA15135@argh.demon.co.uk |
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Thread: | |
Lists: | pgsql-sql |
>
> Try something like:
>
> Create function new_function(value_data_type)
> 'Select sum(t1.var1) from t1 where t1.var2 = $1' LANGUAGE
> 'sql';
>
> update t2 set var1=t2.var1+new_function(t2.var2);
>
*snip*
Hi, thanks for replying.
My reply to this is the question, that as each function contains a
select, is this technically a single pass.
I get the feeling there will be tremendous overhead on this theory with a
large dataset, in comparison to a single query that does the
update. Can anyone comment on how much slower this could be (although
obviously if there is no way to do it in a single query then there is
no choice)?
Thanks
M Simms
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