X-Original-To: pgsql-interfaces-postgresql.org@localhost.postgresql.org Received: from localhost (unknown [64.117.224.193]) by svr1.postgresql.org (Postfix) with ESMTP id AC9C430FE72 for ; Thu, 26 Jun 2003 22:19:17 +0000 (GMT) Received: from svr1.postgresql.org ([64.117.224.193]) by localhost (svr1.postgresql.org [64.117.224.193]) (amavisd-new, port 10024) with ESMTP id 30943-02 for ; Thu, 26 Jun 2003 19:19:06 -0300 (ADT) Received: from rtp-core-1.cisco.com (rtp-core-1.cisco.com [64.102.124.12]) by svr1.postgresql.org (Postfix) with ESMTP id 620C430FAE6 for ; Thu, 26 Jun 2003 19:19:06 -0300 (ADT) Received: from unity.cisco.com (evvbu-exchange-100tx.cisco.com [64.101.140.74]) by rtp-core-1.cisco.com (8.12.9/8.12.6) with SMTP id h5QMI2ai004101; Thu, 26 Jun 2003 18:18:03 -0400 (EDT) Subject: Re: Dissecting Tuples in C From: Clay Luther To: "Nigel J. Andrews" Cc: pgsql-interfaces@postgresql.org In-Reply-To: References: Content-Type: multipart/alternative; boundary="=-sapnR1TTwMhBla8qK8ZR" Organization: Cisco System, Inc. Message-Id: <1056665701.22881.41.camel@gkar> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.2 (1.2.2-5) Date: 26 Jun 2003 17:15:01 -0500 X-Archive-Number: 200306/85 X-Sequence-Number: 4296 --=-sapnR1TTwMhBla8qK8ZR Content-Type: text/plain Content-Transfer-Encoding: 7bit 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 > --=-sapnR1TTwMhBla8qK8ZR Content-Type: text/html; charset=utf-8 Re: [INTERFACES] Dissecting Tuples in C 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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