Function ExecDynamicForeignScan

src/backend/executor/nodeDynamicForeignscan.c:191–253

TupleTableSlot *
ExecDynamicForeignScan(PlanState *pstate)
{
	DynamicForeignScanState *node = castNode(DynamicForeignScanState, pstate);
	TupleTableSlot *slot = NULL;

	DynamicForeignScan	   *plan = (DynamicForeignScan *) node->ss.ps.plan;
	node->as_valid_subplans = NULL;
	if (NULL != plan->join_prune_paramids && !node->did_pruning)
	{
		node->did_pruning = true;
		node->as_valid_subplans =
			ExecFindMatchingSubPlans(node->as_prune_state,
									 node->ss.ps.state,
									 list_length(plan->partOids),
									 plan->join_prune_paramids);

		int	i = 0;
		int	partOidIdx = -1;
		node->nOids = bms_num_members(node->as_valid_subplans);
		List	*newPartOids = NIL;
		void	**new_fdw_private_array; /* array of fdw_private*/
		ListCell	*lc;
		/* Need to re-populate fdw_private_array based on dynamically eliminated partitions */
		new_fdw_private_array = (void **) palloc(node->nOids * sizeof(void *));
		for(i = 0; i < node->nOids; i++)
		{
			partOidIdx = bms_next_member(node->as_valid_subplans, partOidIdx);
			newPartOids = lappend_oid(newPartOids, node->partOids[partOidIdx]);
			new_fdw_private_array[i] = node->fdw_private_array[partOidIdx];
		}
		pfree(node->partOids);
		pfree(node->fdw_private_array);
		node->partOids = palloc(sizeof(Oid) * node->nOids);
		foreach_with_count(lc, newPartOids, i)
			node->partOids[i] = lfirst_oid(lc);
		node->fdw_private_array = new_fdw_private_array;
	}

	/*
	 * Scan the table to find next tuple to return. If the current table
	 * is finished, close it and open the next table for scan.
	 */
	for (;;)
	{
		if (!node->foreignScanState)
		{
			/* No partition open. Open the next one, if any. */
			if (!initNextTableToScan(node))
				break;
		}

		slot = ExecProcNode(&node->foreignScanState->ss.ps);

		if (!TupIsNull(slot))
			break;

		/* No more tuples from this partition. Move to next one. */