From: | Richard Huxton <dev(at)archonet(dot)com> |
---|---|
To: | Kate F <kate(at)cats(dot)meow(dot)at> |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Function proposal to find the type of a datum |
Date: | 2007-02-02 10:09:24 |
Message-ID: | 45C30DD4.1050105@archonet.com |
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Thread: | |
Lists: | pgsql-hackers |
Kate F wrote:
> I see my misunderstanding: '2' IS OF (INTEGER) yields false: fine.
> However I was expecting that pg_type_of('2') would return 'INTEGER': it
> wouldn't, of course. So, I understand you here: there would be no
> difference between this and IS OF in the way I had imagined.
It's not even possible to have a function that determines the type of a
value given that we have overlapping types. How do you know that "2"
isn't an int8 rather than int4, or numeric, or just text. What about
'now'? That's a valid timestamp as well as text.
Now, if we had an can_be_cast_to(TEXT-VAL,TYPE) that would at least let
you check against a pre-determined list of types. The only way I know of
at present is to trap an exception if it fails.
I think you're going to have to store your arguments with their types.
--
Richard Huxton
Archonet Ltd
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