Re: temporal variants of generate_series()

On Apr 28, 2007, at 8:00 PM, David Fetter wrote:
> Here's an SQL version without much in the way of bounds checking :)
>
> CREATE OR REPLACE FUNCTION generate_series (
>     start_ts timestamptz,
>     end_ts timestamptz,
>     step interval
> ) RETURNS SETOF timestamptz
> LANGUAGE sql
> AS $$
> SELECT
>     CASE
>         WHEN $1 < $2 THEN
>             $1
>         WHEN $1 > $2 THEN
>             $2
>         END + s.i * $3 AS "generate_series"
> FROM generate_series(
>     0,
>     floor(
>         CASE
>             WHEN $1 < $2 AND $3 > INTERVAL '0 seconds' THEN
>                 extract('epoch' FROM $2) -
>                 extract('epoch' FROM $1)
>             WHEN $1 > $2 AND $3 < INTERVAL '0 seconds' THEN
>                 extract('epoch' FROM $1) -
>                 extract('epoch' FROM $2)
>         END/extract('epoch' FROM $3)
>     )::int8
> ) AS s(i);
> $$;
>
> It should be straight-forward to make similar ones to those below.

Are you sure the case statements are needed? It seems it would be  
better to just punt to the behavior of generate_series (esp. if  
generate_series eventually learns how to count backwards).
--
Jim Nasby                                            jim@nasby.net
EnterpriseDB      http://enterprisedb.com      512.569.9461 (cell)