Re: Procedure for feature requests? - Mailing list pgsql-general

is there a way to create a cast with assignment e.g.?

CREATE CAST ((date,date) AS int4) WITH FUNCTION generate_series(date,date) AS ASSIGNMENT;

http://www.postgresql.org/docs/8.4/static/sql-createcast.html
?
Martin Gainty
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> Date: Sat, 3 Oct 2009 16:23:36 +0100
> From: sam@samason.me.uk
> To: pgsql-general@postgresql.org
> Subject: Re: [GENERAL] Procedure for feature requests?
>
> On Fri, Oct 02, 2009 at 09:48:14PM +0000, Tim Landscheidt wrote:
> > Sam Mason <sam@samason.me.uk> wrote:
> > > 8.4 has a generate_series(timestamp,timestamp,interval) which would seem
> > > to be a bit more flexible than you want.
> >
> > Yes, I know :-). But as "generate_series(A, B, C)" can also
> > be written as "A + generate_series(0, (C - B) / C) * C" (or
> > something "flexible" like that :-)), a
>
> For things as complicated as timestamps I'm not sure if this is such a
> trivial transform. If you can figure out the limit then it seems easy,
> though I'm not sure how you'd do that.
>
> > "generate_series(DATE, DATE)" would inter alia get rid off
> > the need to cast the result from TIMESTAMP to DATE and to
> > explicitly specify "'1 day'". Just a small, trivial enhance-
> > ment for a popular use case :-).
>
> Interesting, I tend to aim for maximum expressiveness not ease of
> expressiveness. It would be somewhat easy to add the above if you want
> though:
>
> CREATE FUNCTION generate_series(date,date)
> RETURNS SETOF date
> IMMUTABLE LANGUAGE sql AS $$
> SELECT generate_series($1::timestamp,$2::timestamp,interval '1 day')::date;
> $$;
>
> or I suppose you could use the integer series generation:
>
> SELECT $1 + generate_series(0,$2 - $1);
>
> Hum, now I'll have to see which is "better".
>
> That second version seems to be slightly quicker (20 to 30%, for ranges
> from a year up to a century respectively) so you may prefer it, but the
> difference is going to be in the noise for any query I've ever used
> generate_series for.
>
> --
> Sam http://samason.me.uk/
>
> --
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