On May 6, 2007, at 8:07 PM, Tom Lane wrote:
Jim Nasby <[EMAIL PROTECTED]> writes:
Also, what would be the appropriate way to put this into initdb?
You seem to have missed a step here, which is to convince people that
these belong in core at all. So far I've not even seen an argument that
would justify putting them in contrib.


These are all examples of using generate series plus additional math to generate a series of dates/timestamps:
http://archives.postgresql.org/pgsql-general/2007-01/msg01292.php
http://archives.postgresql.org/pgsql-sql/2006-02/msg00249.php
http://archives.postgresql.org/pgsql-general/2005-06/msg01254.php
http://archives.postgresql.org/pgsql-sql/2007-03/msg00093.php
http://archives.postgresql.org/pgsql-novice/2007-01/msg00002.php
http://archives.postgresql.org/pgsql-sql/2006-03/msg00391.php
http://archives.postgresql.org/pgsql-hackers/2006-09/msg00330.php

That's from the first page of search results for 'generate_series timestamp'.

FWIW, I could also make use of this in some of my code.

If they *were* of sufficiently
wide use to justify putting them into core, a more efficient
implementation would probably be expected.

Ok, I'll look into a C version, but why do SQL functions have such a high overhead? I'm seeing an SQL function taking ~2.6x longer than the equivalent code run directly in a query. With 100 days, the difference drops a bit to ~2.4x. (this is on HEAD from a few months ago)

This is on my MacBook Pro with the Jean-Pierre's version of generate_series:

decibel=# select count(*) from generate_series(now(),now()+'10 days'::interval,'1'::interval);
Time: 1851.407 ms
decibel=# select count(*) from generate_series(1,86400*10);
Time: 657.894 ms
decibel=# select count(*) from (select now() + (generate_series (1,86400*10) * '1 second'::interval)) a;
Time: 733.592 ms
decibel=# select count(*) from (select 'epoch'::timestamptz + s.i * '1 second'::interval AS "generate_series" from generate_series(extract ('epoch' from now())::bigint, extract('epoch' from now()+'10 days'::interval)::bigint, extract('epoch' from '1'::interval)::bigint) s(i)) a;
Time: 699.606 ms
--
Jim Nasby                                            [EMAIL PROTECTED]
EnterpriseDB      http://enterprisedb.com      512.569.9461 (cell)



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