Re: Selecting a constant question - Mailing list pgsql-hackers

From Hannu Krosing
Subject Re: Selecting a constant question
Date
Msg-id 1181619715.6242.3.camel@hannu-laptop
Whole thread Raw
In response to Re: Selecting a constant question  ("Dann Corbit" <DCorbit@connx.com>)
Responses Re: Selecting a constant question
List pgsql-hackers
Ühel kenal päeval, E, 2007-06-11 kell 13:38, kirjutas Dann Corbit:
> > -----Original Message-----
> > From: Tom Lane [mailto:tgl@sss.pgh.pa.us]
> > Sent: Monday, June 11, 2007 1:32 PM
> > To: Dann Corbit
> > Cc: Gregory Stark; pgsql-hackers@postgresql.org
> > Subject: Re: [HACKERS] Selecting a constant question
...
> > You should be treating typlen as signed not unsigned, and not assuming
> a
> > fixed width for any negative value.
> > 
> > Since the width refers to the server internal representation, and not
> to
> > what comes down the wire, I find it pretty strange for an application
> to
> > be using typlen for anything at all actually.
> 
> Thanks for the response.
> 
> Since libpq function PQfsize returns -2 for all constant character
> strings in SQL statements ... What is the proper procedure to determine
> the length of a constant character column after query execution but
> before fetching the first row of data?

Why not just get the first row and determine the width from it before
you actually use any of tha data ?

----------
Hannu




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