From: Tomasz Myrta <jasiek@klaster.net>
To: Lista dyskusyjna pgsql-sql <pgsql-sql@postgresql.org>
Subject: pl/pgsql, cursors and C function
Date: Tue, 23 Sep 2003 13:41:00 +0200
Message-ID: <3F70314C.30507@klaster.net> (raw)
Hi
I'm making my first steps in C functions. I want to avoid doing all the
SQL job in them, pl/pgsql looks a better choice. I tried to do this by
passing opened cursor from pl/pgsql function to C function.
Here is simple C function:
#include <server/postgres.h>
#include <server/executor/spi.h>
PG_FUNCTION_INFO_V1(test2);
Datum test2(PG_FUNCTION_ARGS)
{
Portal p;
int n;
p=SPI_cursor_find("xxx");
if(!p)
elog(ERROR,"Cursor error");
SPI_cursor_fetch(p,true,1);
n=SPI_processed;
PG_RETURN_INT32(n);
}
And pl/pgsql one:
CREATE OR REPLACE FUNCTION test() returns integer AS '
DECLARE
_m CURSOR FOR select id from some_table limit 1;
n integer;
BEGIN
_m=''xxx'';
open _m;
n=test2();
close _m;
return n;
END;
' language 'plpgsql';
select test();
I don't understand ERROR message at all:
ERROR: SPI_prepare() failed on "SELECT $1 "
This error is raised when trying to execute SPI_cursor_fetch. What does
it mean? What does the SPI_prepare have to already opened cursor?
Where can I find better SPI documentation than "Postgresql Server
Programming" ?
Regards,
Tomasz Myrta
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Cc: jasiek@klaster.net
Subject: Re: pl/pgsql, cursors and C function
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