Thread: calling a C function from pgsql function

On 08/29/2012 09:18 PM, tamanna madaan wrote:

> 1. what are the ways to get  the value returned by this library function .

You need to wrap the C library function with a PostgreSQL C extension
that uses the fmgr.h APIs, so it's callable from SQL and can return a
result to SQL. See:

     http://www.postgresql.org/docs/current/static/xfunc-c.html

> 2. when test1 is called, will it wait for "test1" to return before
> continuing with the next statement in "test" or it will continue with
> the next statement parallely while "test1" is being executed.

The call will return when the C wrapper function returns, so they'll be
executed in series not in parallel.

> 3. Moreover, will test1  be called sequentially in order for all the
> three arguments i.e arg1 first and arg3 in last. Or there can be a
> different order.

The calls will be executed in the order they appear in the PL/PgSQL
function.

--
Craig Ringer

Hello

see http://www.postgresql.org/docs/9.1/static/xfunc-c.html

plpgsql can call any sql function, so you have to register your C
function as custom postgresql sql function

Regards

Pavel Stehule

2012/8/29 tamanna madaan <tamanna.madaan@globallogic.com>:
> Hi All
>
> I have created a function in C language . This is to be called from a pgsql
> function .
> Let say the C language function name is "test1" and pgsql function name is
> "test" .
>
> test1 is called from test three times with different arguments .  For
> example :
>
> test ()
> begin
>
> test1(arg1);    --test1 is a C library function  returning an int
> test1(arg2);
> test1(arg3);
>
> end;
>
> Now, my questions are :
>
> 1. what are the ways to get  the value returned by this library function .
> 2. when test1 is called, will it wait for "test1" to return before
> continuing with the next statement in "test" or it will continue with the
> next statement parallely while "test1" is being executed.
> 3. Moreover, will test1  be called sequentially in order for all the three
> arguments i.e arg1 first and arg3 in last. Or there can be a different
> order.
>
> Thanks..
> Tamanna
>
>
>
>
>
>
>
>
> --
>
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