Re: pg_generate_sequence and info_schema patch (Was: SELECT Question)

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Joe Conway <mail(at)joeconway(dot)com>
Cc: Kris Jurka <books(at)ejurka(dot)com>, Alex <alex(at)meerkatsoft(dot)com>, "Lada 'Ray' Lostak" <ray(at)unreal64(dot)net>, pgsql-patches(at)postgresql(dot)org
Subject: Re: pg_generate_sequence and info_schema patch (Was: SELECT Question)
Date: 2004-02-04 06:21:44
Message-ID: 6838.1075875704@sss.pgh.pa.us
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Joe Conway <mail(at)joeconway(dot)com> writes:
> A first shot at documentation for generate_series() is available here in
> html form:
> http://www.joeconway.com/functions-srf.html
> Feedback welcome.

This bit seems unnecessarily vague:

Depending on the requested combination of start, stop, and step, it is
possible to return zero rows.

I think you can provide a precise specification without losing
simplicity of explanation. Maybe something like

When step is positive, zero rows are returned if start > stop.
Conversely, when step is negative, zero rows are returned if
start < stop. It is an error for step to be zero.

... and then carry on with the examples, which seem fine (although
the one showing the error for step=0 might be thought redundant
with the text).

regards, tom lane

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