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From: Josh Berkus <josh@agliodbs.com>
Reply-To: josh@agliodbs.com
Organization: Aglio Database Solutions
To: pgsql-sql@postgresql.org
Subject: Suggestion:  Need conversion-testing functions.
Date: Fri, 18 Apr 2003 14:07:33 -0700
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Message-Id: <200304181407.33083.josh@agliodbs.com>

Folks,

A current issue that I am struggling with is that there is no way to test=
=20
whether a data type can be cast within a PL/pgSQL function.   If, for=20
example, I want to test whether a string can be cast into a timestamp, I=20
cannot do it without raising  an exception, which will then abort my=20
function.

One would think that isfinite() would allow testing of dates in this way, b=
ut=20
isfinite() returns an exception instead of False if the value passed is an=
=20
invalid date.   This makes isfinite(), IMHO, completely useless as a functi=
on=20
-- it doesn't do anything CAST( AS DATE) wouldn't do.

We need "testing functions" for, at a minimum:
text --> date
text --> timestamp
text --> ip address
text --> interval
text --> integer

While I am happy to pay someone to do the necessary coding, I feel strongly=
=20
that once these functions are built they should be included in the main set=
=20
of builtins.

Comments?  Volunteers?

--=20
-Josh Berkus
 Aglio Database Solutions
 San Francisco