c function - undefined symbols

Steffn wrote:

Undefined symbols:
"_Float8GetDatum", referenced from:
_add_one_float8 in foo.o
ld: symbol(s) not found
collect2: ld returned 1 exit status

Following the documentation I only added
"/Library/PostgreSQL/8.3/include/**" to my header search path. What else
do I need to configure?

I'm not a "C" hacker, but that's failing at the linking stage, not the
compiling stage. Are you missing the right lib to go with your headers?

--
Richard Huxton
Archonet Ltd

Hi!

Thanks for your reply. Yes, thats also my suspicion. But what library to
include?
I added /Library/PostgreSQL/8.3/lib/** to my library search path, but it
won't help. If I knew which library I have to add, I think I can figure
out how to properly configure my build settings. Couldn't find any hints
in the docu nor in the mailing list.

Thanks,
steffn

Richard Huxton wrote, On 12/10/08 11:21 AM:

I added /Library/PostgreSQL/8.3/lib/** to my library search path,

Try to add "-L/PostgreSQL/8.3/lib -lpg" options to linker's command line.
You can get details with "ld --help".

Good luck.

-----------------------------------------------
Quan Zongliang
quanzongliang@gmail.com
CIT Japan: http://www.cit.co.jp
CIT China: http://www.citbj.com.cn

Steffn wrote:

I am currently trying my first steps in writing my own functions in C. I
read through the documentation and tried the most simple examples as shown in
<http://www.postgresql.org/docs/8.3/static/xfunc-c.html&gt;. Sadly
this was already the point where I stumbled. I luckily compiled and
tested the add_one integer variant. But as soon as I added the
add_one_float8 I couldn't link no more. My linker dies with.

Undefined symbols:
"_Float8GetDatum", referenced from:
_add_one_float8 in foo.o
ld: symbol(s) not found
collect2: ld returned 1 exit status

Following the documentation I only added
"/Library/PostgreSQL/8.3/include/**" to my header search path. What else
do I need to configure?

I guess that the include path you need is /Library/PostgreSQL/8.3/include/server.

Where in the documentation did you find the path?
I read the following in
http://www.postgresql.org/docs/8.3/static/xfunc-c.html#AEN40954

"Use pg_config --includedir-server to find out where the
PostgreSQL server header files are installed on your system"

What is the result of "pg_config --includedir-server" for you?

Yours,
Laurenz Albe

Steffn <steffn@gmx.at> writes:

Thanks for your reply. Yes, thats also my suspicion. But what library to
include?

There is no library to include --- you need to be building *your* code
as a library that can be loaded into the Postgres backend, which will
supply the missing function. This is somewhat platform-specific and
frankly I'd suggest using pgxs rather than puzzling it out for yourself.
See
http://www.postgresql.org/docs/8.3/static/xfunc-c.html#XFUNC-C-PGXS

regards, tom lane