Re: Planner features, discussion

On 15 Jul 2010, at 3:05, Craig Ringer wrote:

> It was an example of how it'd be nice to avoid the need for a join when
> dealing with scalar values. I'd love to be able to write:
>
> WITH aconstant AS (1)
> SELECT x.*, aconstant FROM generate_series(1,10) AS x;
>
> ... but can't presently do so because the WITH terms are only visible as
> potential from-list items.

But why is that a problem? The below seems to work just fine:

dalroi=> WITH constants AS (SELECT 1 AS aconstant)
SELECT 'x' AS column, aconstant FROM constants WHERE aconstant = 1;
column | aconstant
--------+-----------
x | 1
(1 row)

Sure, you'll have to join with the with-query to get any meaningful results, but if there are any complicated calculations in that query, won't they be calculated just once - like you intended?

If not, I think we're all failing to see the point you're trying to make.

Alban Hertroys

--
If you can't see the forest for the trees,
cut the trees and you'll see there is no forest.

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