Function ExecPartitionSelector

src/backend/executor/nodePartitionSelector.c:118–159

---------------------------------------------------------------- * ExecPartitionSelector(node) * * Pass-through rows, but for each row, compute which partitions * on other side of a join above can contain rows that match * the join quals. * ---------------------------------------------------------------- */

 * ----------------------------------------------------------------
 */
static TupleTableSlot *
ExecPartitionSelector(PlanState *pstate)
{
	PartitionSelectorState *node = (PartitionSelectorState *) pstate;
	PartitionSelector *ps = (PartitionSelector *) node->ps.plan;
	EState	   *estate = node->ps.state;
	ExprContext *econtext = node->ps.ps_ExprContext;
	PlanState *outerPlan = outerPlanState(node);
	TupleTableSlot *inputSlot;

	/* get tuple from child */
	Assert(outerPlan);
	inputSlot = ExecProcNode(outerPlan);

	if (TupIsNull(inputSlot))
	{
		/*
		 * No more tuples from outerPlan. The set of surviving partitions
		 * is now complete. Make the result available to the Append node
		 * by storing it in the special executor Param.
		 */
		ParamExecData *param;

		param = &(estate->es_param_exec_vals[ps->paramid]);
		Assert(param->execPlan == NULL);
		Assert(!param->isnull);
		param->value = PointerGetDatum(node);

		return NULL;
	}

	/*
	 * Run the partition pruning logic with this tuple, and accumulate
	 * the partitions matching this tuple to the result.
	 */
	ResetExprContext(econtext);
	econtext->ecxt_outertuple = inputSlot;
	node->part_prune_result = ExecAddMatchingSubPlans(node->prune_state,
													  node->part_prune_result);

	return inputSlot;
}

/* ----------------------------------------------------------------
 *		ExecReScanPartitionSelector(node)