unused-targets-20130618.patch

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index d80c264..239fd40 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -112,6 +112,7 @@ static void get_column_info_for_window(PlannerInfo *root, WindowClause *wc,
 						   int *ordNumCols,
 						   AttrNumber **ordColIdx,
 						   Oid **ordOperators);
+static List *adjust_targetlist(PlannerInfo *root, List *tlist);
 
 
 /*****************************************************************************
@@ -1016,6 +1017,7 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 	double		dNumGroups = 0;
 	bool		use_hashed_distinct = false;
 	bool		tested_hashed_distinct = false;
+	bool		tlist_is_adjustable;
 
 	/* Tweak caller-supplied tuple_fraction if have LIMIT/OFFSET */
 	if (parse->limitCount || parse->limitOffset)
@@ -1616,6 +1618,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 		}
 	}							/* end of if (setOperations) */
 
+	/* Check whether we can remove rejunk sort entries safely */
+	tlist_is_adjustable = is_projection_capable_plan(result_plan);
+
 	/*
 	 * If there is a DISTINCT clause, add the necessary node(s).
 	 */
@@ -1715,6 +1720,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 															   result_plan,
 															current_pathkeys,
 															   -1.0);
+
+				/* We can't remove rejunk sort entries safely */
+				tlist_is_adjustable = false;
 			}
 
 			result_plan = (Plan *) make_unique(result_plan,
@@ -1738,6 +1746,12 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 														   limit_tuples);
 			current_pathkeys = root->sort_pathkeys;
 		}
+		else
+		{
+			if (tlist_is_adjustable)
+				result_plan->targetlist = adjust_targetlist(root,
+													result_plan->targetlist);
+		}
 	}
 
 	/*
@@ -3388,6 +3402,103 @@ get_column_info_for_window(PlannerInfo *root, WindowClause *wc, List *tlist,
 	}
 }
 
+/*
+ * adjust_targetlist
+ *	  Remove resjunk sort entries if any.
+ */
+static List *
+adjust_targetlist(PlannerInfo *root, List *tlist)
+{
+	List	   *new_tlist;
+	Query	   *parse = root->parse;
+	Bitmapset  *srefs;
+	Bitmapset  *grefs;
+	ListCell   *lc;
+	bool		found;
+	ListCell   *curr;
+	ListCell   *prev;
+	ListCell   *next;
+
+	/* Collect the sortgroupref numbers of ORDER BY clause. */
+	srefs = NULL;
+	foreach(lc, parse->sortClause)
+	{
+		SortGroupClause *scl = (SortGroupClause *) lfirst(lc);
+
+		srefs = bms_add_member(srefs, scl->tleSortGroupRef);
+	}
+
+	/* Collect the sortgroupref numbers of GROUP BY/DISTINCT ON clause. */
+	grefs = NULL;
+	if (parse->groupClause)
+	{
+		foreach(lc, parse->groupClause)
+		{
+			SortGroupClause *gcl = (SortGroupClause *) lfirst(lc);
+
+			grefs = bms_add_member(grefs, gcl->tleSortGroupRef);
+		}
+	}
+	if (parse->hasDistinctOn)
+	{
+		foreach(lc, parse->distinctClause)
+		{
+			SortGroupClause *gcl = (SortGroupClause *) lfirst(lc);
+
+			grefs = bms_add_member(grefs, gcl->tleSortGroupRef);
+		}
+	}
+
+	/* Find the sortgroupref numbers used only for ORDER BY clause. */
+	srefs = bms_difference(srefs, grefs);
+	if(bms_is_empty(srefs))
+		return tlist;
+
+	/* Remove resjunk sort entries if any. */
+	curr = list_head(tlist);
+	prev = NULL;
+	found = false;
+	while(curr)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(curr);
+
+		next = lnext(curr);
+
+		if (tle->resjunk && tle->ressortgroupref != 0 &&
+			bms_is_member(tle->ressortgroupref, srefs))
+		{
+			tlist = list_delete_cell(tlist, curr, prev);
+			found = true;
+		}
+		else
+			prev = curr;
+
+		curr = next;
+	}
+	if (!found)
+		return tlist;
+
+	/* Get the resno right. */
+	if (found)
+	{
+		int			resno = 1;
+
+		foreach(lc, tlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(lc);
+
+			if (tle->resno != resno)
+			{
+				tle = flatCopyTargetEntry(tle);
+				tle->resno = resno;
+			}
+			resno++;
+		}
+	}
+
+	return tlist;
+}
+
 
 /*
  * expression_planner