| From: | John Taylor <postgres(at)jtresponse(dot)co(dot)uk> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | pgsql-novice(at)postgresql(dot)org |
| Subject: | Re: performance problems with subselects |
| Date: | 2002-04-23 14:34:18 |
| Message-ID: | 02042315341809.01601@splash.hq.jtresponse.co.uk |
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| Lists: | pgsql-novice |
On Tuesday 23 April 2002 15:04, Tom Lane wrote:
> John Taylor <postgres(at)jtresponse(dot)co(dot)uk> writes:
> > I am aware that I am using almost the same select from orderheader 3
> > times, but I'm not sure how I can improve on this.
>
> Can you do this?
>
> INSERT INTO target SELECT foo, bar, baz FROM source WHERE condition
>
> To the extent that you are computing multiple fields from the same
> row in the source table, this will help.
Where would I do that ?
Do you mean to select the order number (theorder) into a temporary table ?
The problem is that I need to use the order number in 3 seperate subselects.
>
> Also, avoid that IN construct.
OK. Thats done.
Thanks
JohnT
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