From: Clay Luther <claycle@cisco.com>
To: Nigel J. Andrews <nandrews@investsystems.co.uk>
Cc: pgsql-interfaces@postgresql.org
Subject: Re: Dissecting Tuples in C
Date: 26 Jun 2003 17:15:01 -0500
Message-ID: <1056665701.22881.41.camel@gkar> (raw)
In-Reply-To: <Pine.LNX.4.21.0306262152010.15389-100000@ponder.fairway2k.co.uk>
References: <Pine.LNX.4.21.0306262152010.15389-100000@ponder.fairway2k.co.uk>
Hrmmmm....let me be more clear.
How do I get the TupleDesc for a HeapTuple, for example? The Trigger
structure has HeapTuples, but I need the TupleDesc as well to be able to
use functions like SPI_getvalue().
Clay
On Thu, 2003-06-26 at 15:58, Nigel J. Andrews wrote:
> On 26 Jun 2003, Clay Luther wrote:
>
> > I am trying to get up to speed writing C triggers and I have a
> question
> > about the relation between HeapTuples and other tuple-related types,
> > like TupleTableSlots, and the routines and macros used to manipulate
> > them. I am reading and re-reading the online docs, but still have
> some
> > broad questions.
> >
> > For example, suppose I just wanted a trigger to iterate through the
> > HeapTuple pointed at by the tirgger data tg_trigtuple, printing out
> the
> > column names, types, and values (lets say, only ints and strings for
> > simplicity). How would I do this?
> >
> > A pointer to a good document would be just as good as a detailed
> answer.
>
> Take a browse around the things in contrib. However, I'd say the
> easiest way to
> do the specific thing you ask about is to look up the SPI utility
> functions in
> the docs and then write something like the psuedo code:
>
> i = 1;
> while (i < tupdesc->natts)
> {
> char *colname = SPI_fname(tg_trigtuple, i);
> char *coltype = SPI_gettype(tg_trigtuple, i);
> char *colvalue = SPI_getvalue(tg_trigtuple, i);
>
> i++;
> }
>
> That's very much psuedo code. It's bad that I can't remember the exact
> names
> and parameters considering I was doing such things only a week ago
> but, that's
> what being busy does to my memory.
>
> But really, you can't go wrong looking in chapter 9 (server side
> programming) at the spi functions. Well you can just watch out that
> the column
> numbering starts at 1 for spi.
>
>
> --
> Nigel J. Andrews
>
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To: pgsql-interfaces@postgresql.org
Cc: claycle@cisco.com, nandrews@investsystems.co.uk
Subject: Re: Dissecting Tuples in C
In-Reply-To: <1056665701.22881.41.camel@gkar>
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