[brbrbr]

Hello

I'm working with PostgreSQL under Windows operationg system, and now I need to write some external C-language functionf for PostgreSQL. As I read in documentation it is possible to compile .so shared library with function and export it from .so. But as I also read it is possible only in linux/unix system using gcc, not in windows.

Is it possible to export C-language function to PostgreSQL in Windows? Would be nice if it also possible using Visual Studio

I'm sorry if such questions were already asked, but I didn't find them.

[brbrbr]

I read on some forum that it's possible in Windows to compile .dll that contains needed c-language function.

I tested it on a function that returns 1. Here is mydll.c listing:

#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif

#include "postgres.h"
#include "commands/trigger.h"   /* ... and triggers */

PG_FUNCTION_INFO_V1(trigf);

Datum trigf(PG_FUNCTION_ARGS)
{
	PG_RETURN_INT32(1);
}

I also created .def file

EXPORTS trigf

then I'm trying to import the functions from .dll

CREATE FUNCTION func_name() RETURNS integer
AS 'c:/path/mydll.dll'
LANGUAGE 'C';

an error appears

ERROR: incompatible library "c:/path/mydll.dll": missing magic block
SQL state: XX000
Hint: Extension libraries are required to use the PG_MODULE_MAGIC macro.

as I read somewhere it is neccessary to include

#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif

code to source file to prevent the error, but it didn't helps.

Could someone help me with this problem? Or, may be, somebody already faced and solved it?

[brbrbr]

The problem is solved.

It occurs that Visual Studio were using PostgreSQL 8.1.4 libraries instead of 8.2.4, although function was testing in PostgreSQL 8.2.4.

[prduque]

I'm having the same problem in creating an external C function compiled with Visual Studio C++.

I'm using PostgreSQL 8.3.3, and when i compile in the IDE it makes the dll, but i receive missing PG_MODULE_MAGIC error.

If I try to compile in command-line with
CL -Ipath_to_pg_serve_include myfunc.cpp
it says missing "libintl.h", as well as some type redefinition errors:

C:\Documents and Settings\pduque.WOLVERINE\My Documents\MyFuncpg>cl /I"C:\Program Files\PostgreSQL\8.3\include\server" myfunc.cpp

Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 14.00.50727.42 for 80x86
Copyright (C) Microsoft Corporation. All rights reserved.

myfunc.cpp
c:\program files\postgresql\8.3\include\server\pg_config_os.h (188) : error C2011
: 'timezone' : 'struct' type redefinition
c:\program files\postgresql\8.3\include\server\pg_config_os.h (188) : see
declaration of 'timezone'
c:\program files\postgresql\8.3\include\server\pg_config_os.h (197) : error C2011
: 'itimerval' : 'struct' type redefinition
c:\program files\postgresql\8.3\include\server\pg_config_os.h (197) : see
declaration of 'itimerval'
c:\program files\postgresql\8.3\include\server\c.h(97) : fatal error C1083: Cann
ot open include file: 'libintl.h': No such file or directory

[prduque]

It was a bug with PGDLLIMPORT.
corrected it, and now I can build the dll ok.
But it still says missing Magic number