Thread: PG_FREE_IF_COPY()

Given the following snippet:
HeapTupleHeader     tuple;Datum               temp;bool              isnull;tuple = PG_GETARG_HEAPTUPLEHEADER(0);temp
=GetAttributeByName(tuple, "data", &isnull); 


When using this for a btree operator functions, you need to
PG_FREE_IF_COPY(?,?);

Which of the above parameters need I free?

tuple, or temp,.... Or both?

... John

"John Hansen" <john@geeknet.com.au> writes:
> Given the following snippet:
>     HeapTupleHeader     tuple;
>     Datum               temp;
>     bool              isnull;
>     tuple = PG_GETARG_HEAPTUPLEHEADER(0);
>     temp  = GetAttributeByName(tuple, "data", &isnull);

> When using this for a btree operator functions, you need to
> PG_FREE_IF_COPY(?,?);

> Which of the above parameters need I free?

It'd probably be wise to do a FREE_IF_COPY on the tuple.

GetAttributeByName, however, hasn't copied anything (if it's
a pass-by-ref type you'll just get a pointer into the tuple).
If you do a copy further down that might be a reason to free
something, but this code alone isn't making a copy.
        regards, tom lane

Tom Lane [mailto:tgl@sss.pgh.pa.us] wrote:
> "John Hansen" <john@geeknet.com.au> writes:
> > Given the following snippet:
> >     HeapTupleHeader     tuple;
> >     Datum               temp;
> >     bool              isnull;
>
> >     tuple = PG_GETARG_HEAPTUPLEHEADER(0);
> >     temp  = GetAttributeByName(tuple, "data", &isnull);
>
> > When using this for a btree operator functions, you need to
> > PG_FREE_IF_COPY(?,?);
>
> > Which of the above parameters need I free?
>
> It'd probably be wise to do a FREE_IF_COPY on the tuple.
>
> GetAttributeByName, however, hasn't copied anything (if it's
> a pass-by-ref type you'll just get a pointer into the tuple).
> If you do a copy further down that might be a reason to free
> something, but this code alone isn't making a copy.

Cool, thanks...

>
>             regards, tom lane
>
>

... John