Re: extending by using procedurallanguage C : problems

Peter Eisentraut wrote:

>Feite Brekeveld writes:
>
>
>
>>I'm having some trouble extending postgresql with some C-functions.
>>
>>
>
>It seems to me that you should actually read the documentation on writing
>C extension functions, found in the Programmer's Guide, because the
>interface you are using is completely wrong.
>
>
>
Hi,

that seems like an 'ouch' for me!

I've read chapter 12.5.3 !

using the examples for the 'old-style' the only remark I can make myself on the email sent is the misuse of the word
'procedural'.

An example from an earlier version of postgres works fine:
--------------------------------------------------------------
#include "/usr/include/pgsql/server/postgres.h"

double *ctof(double *deg)
{
  double *ret = palloc(sizeof(double));

  *ret = (*deg * 9.0 / 5.0) + 32.0;
  return ret;
}

create or replace function ctof(float8) RETURNS float8
  AS '/users/home/feite/proj/postgres.d/pgsql/pg_osiris' LANGUAGE C
  WITH (isStrict);
-----------------------------------------------------------------
Also thisone is working fine:
-----------------------------------------------------------------
#include "/usr/include/pgsql/server/postgres.h"
#include "examp.h"

double *mav(double *a, double *b)
{
  double *ret = palloc(sizeof(double));

  *ret = ti_mav(a , b);
  return ret;
}

#include "examp.h"

double ti_mav(double *a, double *b)
{
  double ret;

  ret = (*a + *b) / 2.0;
  return ret;
}

[feite@osiris-1 pgsql]$ psql -U postgres tst
Welcome to psql, the PostgreSQL interactive terminal.

Type:  \copyright for distribution terms
       \h for help with SQL commands
       \? for help on internal slash commands
       \g or terminate with semicolon to execute query
       \q to quit

tst=# select mav(8,22);
 mav
-----
  15
(1 row)


---------------------------------------------------------------
The code I sent before is a minor change to get data from shared memory instead. The exception occurs ONLY when the
'shmat'statement is there. 

(Same kind of function written in pl/perlu works fine !)

It seems that you know a lot about it. Please give me some tips on this issue. I would appreciate is very much !

Thanks,

Feite Brekeveld