Re: Best way to construct PostgreSQL ArrayType (_int4) from C int array

On Wed, Apr 27, 2011 at 6:02 AM, Adrian Schreyer <ams214@cam.ac.uk> wrote:
> At the moment I am using the following code to construct a PostgreSQL
> array from a C array in my C extension but I am not so sure if this is
> really the best solution:
>
> const int *data = array.data(); // C array
> Datum *d = (Datum *) palloc(sizeof(Datum) * size);
>
> for (int i = 0; i < size; i++) d[i] = Int32GetDatum(data[i]);
>
> ArrayType *a = construct_array(d, size, INT4OID, sizeof(int4), true, 'i');
>
> Is this okay or is there a better solution (existing function in the
> PostgreSQL source for example)?

That's pretty much the best way AFAIK. Int32GetDatum doesn't do
anything fancy -- it's just a 32 bit mask/assignment.  constructing
the array at once is going to be a lot better than incrementally
creating it.  Do you expect the arrays to be large, say bigger than
10k elements?

merlin