Re: Union Query Improvement - Mailing list pgsql-general

From Chris
Subject Re: Union Query Improvement
Date
Msg-id 45D2B975.5020501@gmail.com
Whole thread Raw
In response to Union Query Improvement  (Ray Bannon <bannonr@comcast.net>)
List pgsql-general
Ray Bannon wrote:
> I have a query which is running a bit slowly, and I'm wondering if anyone
> has a design improvement. Basically it's a series of unions as follows:
>
> Select ID, plan_name from table/view
> Where plan_name = 'A'
> And rownum = 1
> UNION
> Select ID, plan_name from table/view
> Where plan_name = 'B'
> And rownum = 1
> UNION
> Select ID, plan_name from table/view
> Where plan_name = 'C'
> And rownum = 1
> UNION
>
> Ad infinitum for about 100 iterations.

I'm sure I'm missing something but wouldn't this give the same results:

select id, plan_name from table where rownum=1 and plan_name in ('A',
'B', 'C');

?

Or do the rownum's change later on?

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