Re: C function to return tuple

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От Marios Vodas
Тема Re: C function to return tuple
Дата
Msg-id AANLkTin8ungEFJM7=Rj9hUkNcV8hrk8Ah3PV7tL4yEMg@mail.gmail.com
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Ответ на Re: C function to return tuple  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: C function to return tuple  (Tom Lane <tgl@sss.pgh.pa.us>)
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I see what you mean and I changed the code BUT still my main problem is that I want to know how to fill values array. I remind you that d_type contains attributes of another composite type p_type.
I need a solution to that because I need to use it in other parts of the code.

Datum d_swap(PG_FUNCTION_ARGS) {
    HeapTupleHeader t = PG_GETARG_HEAPTUPLEHEADER(0);
    HeapTupleHeader i;
    HeapTupleHeader e;
    bool isnull;

    TupleDesc tupdesc;
    Datum values[3];
    HeapTuple tuple;

    i = DatumGetHeapTupleHeader(GetAttributeByName(t, "i", &isnull));
    e = DatumGetHeapTupleHeader(GetAttributeByName(t, "e", &isnull));

    if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE) {
        ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("function returning record called in context that cannot accept type record")));
    }

    BlessTupleDesc(tupdesc);

//I need to get this working
    values[0] = e;
    values[1] = i;
    values[2] = GetAttributeByName(t, "id", &isnull);

    tuple = heap_form_tuple(tupdesc, values, &isnull);

    PG_RETURN_DATUM(HeapTupleGetDatum(tuple));
}

On Sun, Sep 26, 2010 at 7:16 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Marios Vodas <mvodas@gmail.com> writes:
> My problem is that I don't know how to construct the d_type tuple in the c
> function.

Seems like the main problem with that function is that you're passing
an uninitialized "nulls" array to heap_form_tuple.

I kinda wonder why you are using a fixed-length values array together
with a variable-length, dynamically allocated nulls array, but that'
just odd style not wrong in itself.

                       regards, tom lane

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