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Connecting to Postgres Database from C Program

Posted on 2007-03-28
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Last Modified: 2010-04-01
Hi Experts,

I need to connect to the Postgres database from a C.  I was able to connect to the database.  Then I tried to execute the following command

create function sendevent() returns trigger as '/usr/lib/pgsql/libevent.so' language 'C';

When I do that I am getting the error message " permission denied for language c"

What am I doing wrong?  Also,  would it be possible to connect from a C++ program?

This is how I am building my program.
gcc -I/usr/include -I/usr/include/libxml2 -I/usr/include/pgsql/server -g -c ConnectDB.c
gcc  -I/usr/include -I/usr/include/libxml2 -I/usr/include/pgsql/server -g -o conn -L/usr/lib -lpq ConnectDB.o
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Question by:ambuli
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6 Comments
 

Author Comment

by:ambuli
ID: 18813203
Hmm.  some web reference points out that I need to have super user privileges when I do this.  Is it correct?
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Expert Comment

by:ShineOn
ID: 18813409
That would likely be it.
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Expert Comment

by:ShineOn
ID: 18813443
If what you found did the trick, post your solution and post a free question in Community Support asking to have this closed with points refunded.  Be sure to include a link to this question.
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Expert Comment

by:ivanovn
ID: 18816385
You need to have USAGE privilege enabled for the user that's attempting to connect using the C language.
You can do this by granting the USAGE privilege as follows:

GRANT USAGE ON LANGUAGE langname TO username
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Author Comment

by:ambuli
ID: 18816528
Thanks ivanovn.  But when I do that, I am getting an error message saying

ERROR:  language "c" is not trusted

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Accepted Solution

by:
ivanovn earned 500 total points
ID: 18817291
Yes, C language is not trusted in PostgreSQL because of possible security issues (such as the ability of any user to execute C functions on your database).

However, I believe you can fix this if you execute the following:
UPDATE pg_language
SET lanpltrusted = true
WHERE lanname = 'c';
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