Thread: Must a C state transition function use palloc on the returned value?

Hi,

I'm defining a new aggregate using a C transition function. It is of
type TEXT, so the C function gets pointers (*text) to the internal-state1 and
next-data-item parameters. 

Question is if the returning value of type *text must be palloc'ed or
can be just taken from the input parameters. In the latter case I get
error messages like 

NOTICE:  PortalHeapMemoryFree: 0x0x40b22ce8 not in alloc set!

Dirk

Dirk Lutzebaeck <lutzeb@aeccom.com> writes:
> I'm defining a new aggregate using a C transition function. It is of
> type TEXT, so the C function gets pointers (*text) to the internal-state1 and
> next-data-item parameters. 

> Question is if the returning value of type *text must be palloc'ed or
> can be just taken from the input parameters.

The result must be a fresh palloc, since both inputs will be pfreed the
moment you return.  7.1 will copy the result for you if you are so
incautious as to try to return an input, but 7.0.* just falls over :-(
        regards, tom lane

Tom Lane writes:> Dirk Lutzebaeck <lutzeb@aeccom.com> writes:> > I'm defining a new aggregate using a C transition
function.It is of> > type TEXT, so the C function gets pointers (*text) to the internal-state1 and> > next-data-item
parameters.> > > Question is if the returning value of type *text must be palloc'ed or> > can be just taken from the
inputparameters.> > The result must be a fresh palloc, since both inputs will be pfreed the> moment you return.  7.1
willcopy the result for you if you are so> incautious as to try to return an input, but 7.0.* just falls over :-(
 

Thanks! It works now...

Dirk