Function FunctionNext_guts

src/backend/executor/nodeFunctionscan.c:70–312

---------------------------------------------------------------- * Scan Support * ---------------------------------------------------------------- */ ---------------------------------------------------------------- * FunctionNext * * This is a workhorse for ExecFunctionScan * ---------------------------------------------------------------- */

 * ----------------------------------------------------------------
 */
static TupleTableSlot *
FunctionNext_guts(FunctionScanState *node)
{
	EState	   *estate;
	ScanDirection direction;
	TupleTableSlot *scanslot;
	bool		alldone;
	int64		oldpos;
	int			funcno;
	int			att;

	/*
	 * get information from the estate and scan state
	 */
	estate = node->ss.ps.state;
	direction = estate->es_direction;
	scanslot = node->ss.ss_ScanTupleSlot;

	/*
	 * FunctionNext read tuple from tuplestore instead
	 * of executing the real function.
	 * Tuplestore is filled by the FunctionScan's initplan.
	 */
	if(node->resultInTupleStore)
	{
		bool gotOK = false;
		bool forward = true;

		/*
		 * Setup tuplestore reader on first call.
		 *
		 * The tuplestore should have been created by preprocess_initplans()
		 * already, we just read it here.
		 */
		if (!node->ts_state)
		{
			char rwfile_prefix[100];
			function_scan_create_bufname_prefix(rwfile_prefix, sizeof(rwfile_prefix), node->initplanId);

			node->ts_state = tuplestore_open_shared(get_shareinput_fileset(),
													rwfile_prefix);
		}

		gotOK = tuplestore_gettupleslot(node->ts_state, forward, false,
										scanslot);

		if(!gotOK)
		{
			return NULL;
		}
		return scanslot;
	}

	if (node->simple)
	{
		/*
		 * Fast path for the trivial case: the function return type and scan
		 * result type are the same, so we fetch the function result straight