Re: Transaction manipulation commands in user defined c functions?

Unfortunately part of the code must be in c. I could follow a hybrid
approach
by coding the stuff surrounded by the transaction blocks in c functions and
the rest in pl/pgsql,
however that approach is not elegant imho.

I can understand that the c api for managing transactions might change in
the future. r there plans for it to become "standardized" at some point?

>Well, sure. Look at the way that plpgsql implements a BEGIN/EXCEPTION
>block, for example. You need to establish a subtransaction and have
>a TRY/CATCH block to catch the error and clean up.

can you suggest some .c files or links to have a look?

Thanks.

On Wed, Jun 9, 2010 at 7:14 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Michael Hadjivassiliou <sporegnosis(at)gmail(dot)com> writes:
> > I've been searching for a way to do transaction blocks and savepoints
> within
> > a user defined c function. Apparently the docs state that if an SPI
> function
> > throws an error, control goes out of the function and the current
> > transaction is rolled back, yet it hints that you can do subtransactions
> > within a c function.
>
> Well, sure. Look at the way that plpgsql implements a BEGIN/EXCEPTION
> block, for example. You need to establish a subtransaction and have
> a TRY/CATCH block to catch the error and clean up.
>
> But having said that ... it's pretty messy and I wonder why you are
> wanting to do this in a C function. Your code would be a lot more
> future-proof in plpgsql, say. And if you're invoking operations as
> heavyweight as a subtransaction, you're certainly not going to get any
> noticeable performance win from using C.
>
> regards, tom lane
>