Function postgresIterateForeignScan

contrib/postgres_fdw/postgres_fdw.c:1598–1637

* postgresIterateForeignScan * Retrieve next row from the result set, or clear tuple slot to indicate * EOF. */

 *		EOF.
 */
static TupleTableSlot *
postgresIterateForeignScan(ForeignScanState *node)
{
	PgFdwScanState *fsstate = (PgFdwScanState *) node->fdw_state;
	TupleTableSlot *slot = node->ss.ss_ScanTupleSlot;

	/*
	 * In sync mode, if this is the first call after Begin or ReScan, we need
	 * to create the cursor on the remote side.  In async mode, we would have
	 * already created the cursor before we get here, even if this is the
	 * first call after Begin or ReScan.
	 */
	if (!fsstate->cursor_exists)
		create_cursor(node);

	/*
	 * Get some more tuples, if we've run out.
	 */
	if (fsstate->next_tuple >= fsstate->num_tuples)
	{
		/* In async mode, just clear tuple slot. */
		if (fsstate->async_capable)
			return ExecClearTuple(slot);
		/* No point in another fetch if we already detected EOF, though. */
		if (!fsstate->eof_reached)
			fetch_more_data(node);
		/* If we didn't get any tuples, must be end of data. */
		if (fsstate->next_tuple >= fsstate->num_tuples)
			return ExecClearTuple(slot);
	}

	/*
	 * Return the next tuple.
	 */
	ExecStoreHeapTuple(fsstate->tuples[fsstate->next_tuple++],
					   slot,
					   false);

	return slot;
}

/*
 * postgresReScanForeignScan