in src/theta_sketch_pg_functions.c [440:463]
Datum pg_theta_sketch_union(PG_FUNCTION_ARGS) {
const bytea* bytes_in1;
const bytea* bytes_in2;
void* unionptr;
void* sketchptr;
struct ptr_with_size bytes_out;
unsigned lg_k;
lg_k = PG_NARGS() > 2 ? PG_GETARG_INT32(2) : 0;
unionptr = lg_k ? theta_union_new(lg_k) : theta_union_new_default();
if (!PG_ARGISNULL(0)) {
bytes_in1 = PG_GETARG_BYTEA_P(0);
theta_union_update_with_bytes(unionptr, VARDATA(bytes_in1), VARSIZE(bytes_in1) - VARHDRSZ);
}
if (!PG_ARGISNULL(1)) {
bytes_in2 = PG_GETARG_BYTEA_P(1);
theta_union_update_with_bytes(unionptr, VARDATA(bytes_in2), VARSIZE(bytes_in2) - VARHDRSZ);
}
sketchptr = theta_union_get_result(unionptr);
bytes_out = theta_sketch_serialize(sketchptr, VARHDRSZ);
theta_sketch_delete(sketchptr);
SET_VARSIZE(bytes_out.ptr, bytes_out.size);
PG_RETURN_BYTEA_P(bytes_out.ptr);
}