Michael Hadjivassiliou <sporegnosis@gmail.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