Re: [HACKERS] Re: [INTERFACES] retrieving varchar size

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От Bruce Momjian
Тема Re: [HACKERS] Re: [INTERFACES] retrieving varchar size
Дата
Msg-id 199804232109.RAA08650@candle.pha.pa.us
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Ответ на Re: [HACKERS] Re: [INTERFACES] retrieving varchar size  (David Hartwig <daveh@insightdist.com>)
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> > The information you want is in pg_attribute.atttypmod.  It is normally
> > -1, but is set for char() and varchar() fields, and includes the 4-byte
> > length.  See bin/psql/psql.c for a sample of its use.
>
> I see everyone writing in terms of length.   You do mean precision, don't
> you?    For our purposes, this precision should  arrive in the result
> header.   (redundancy in each tuple could be over looked)   The goal is to be
> able to put realistic bounds on memory allocation before the entire result is
> read in.   For this to work, functions must also be able to propagate the
> their precision.
>
> Did I spell doom to this idea?

Hmm.  The problem is that many of us use the old 'text' type, which
doesn't have a defined length.  Not sure how to handle this in a
portable libpq way?


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