Function ExecInitInsertProjection

src/backend/executor/nodeModifyTable.c:451–502

* ExecInitInsertProjection * Do one-time initialization of projection data for INSERT tuples. * * INSERT queries may need a projection to filter out junk attrs in the tlist. * * This is also a convenient place to verify that the * output of an INSERT matches the target table. */

 * output of an INSERT matches the target table.
 */
static void
ExecInitInsertProjection(ModifyTableState *mtstate,
						 ResultRelInfo *resultRelInfo)
{
	ModifyTable *node = (ModifyTable *) mtstate->ps.plan;
	Plan	   *subplan = outerPlan(node);
	EState	   *estate = mtstate->ps.state;
	List	   *insertTargetList = NIL;
	bool		need_projection = false;
	ListCell   *l;

	/* Extract non-junk columns of the subplan's result tlist. */
	foreach(l, subplan->targetlist)
	{
		TargetEntry *tle = (TargetEntry *) lfirst(l);

		if (!tle->resjunk)
			insertTargetList = lappend(insertTargetList, tle);
		else
			need_projection = true;
	}

	/*
	 * The junk-free list must produce a tuple suitable for the result
	 * relation.
	 */
	ExecCheckPlanOutput(resultRelInfo->ri_RelationDesc, insertTargetList);

	/* We'll need a slot matching the table's format. */
	resultRelInfo->ri_newTupleSlot =
		table_slot_create(resultRelInfo->ri_RelationDesc,
						  &estate->es_tupleTable);

	/* Build ProjectionInfo if needed (it probably isn't). */
	if (need_projection)
	{
		TupleDesc	relDesc = RelationGetDescr(resultRelInfo->ri_RelationDesc);

		/* need an expression context to do the projection */
		if (mtstate->ps.ps_ExprContext == NULL)
			ExecAssignExprContext(estate, &mtstate->ps);

		resultRelInfo->ri_projectNew =
			ExecBuildProjectionInfo(insertTargetList,
									mtstate->ps.ps_ExprContext,
									resultRelInfo->ri_newTupleSlot,
									&mtstate->ps,
									relDesc);
	}

	resultRelInfo->ri_projectNewInfoValid = true;
}

/*
 * ExecInitUpdateProjection