unused-targets-2.patch

*** a/src/backend/optimizer/plan/planner.c
--- b/src/backend/optimizer/plan/planner.c
***************
*** 104,109 **** static void get_column_info_for_window(PlannerInfo *root, WindowClause *wc,
--- 104,110 ----
  						   int *ordNumCols,
  						   AttrNumber **ordColIdx,
  						   Oid **ordOperators);
+ static List *adjust_targetlist(PlannerInfo *root, List *tlist);
  
  
  /*****************************************************************************
***************
*** 1008,1013 **** grouping_planner(PlannerInfo *root, double tuple_fraction)
--- 1009,1015 ----
  	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)
***************
*** 1680,1685 **** grouping_planner(PlannerInfo *root, double tuple_fraction)
--- 1682,1690 ----
  		}
  	}							/* 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).
  	 */
***************
*** 1779,1784 **** grouping_planner(PlannerInfo *root, double tuple_fraction)
--- 1784,1792 ----
  															   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,
***************
*** 1802,1807 **** grouping_planner(PlannerInfo *root, double tuple_fraction)
--- 1810,1821 ----
  														   limit_tuples);
  			current_pathkeys = root->sort_pathkeys;
  		}
+ 		else
+ 		{
+ 			if (tlist_is_adjustable)
+ 				result_plan->targetlist = adjust_targetlist(root,
+ 													result_plan->targetlist);
+ 		}
  	}
  
  	/*
***************
*** 3372,3377 **** get_column_info_for_window(PlannerInfo *root, WindowClause *wc, List *tlist,
--- 3386,3484 ----
  	}
  }
  
+ /*
+  * adjust_targetlist
+  *	  Remove resjunk sort entries used only for ORDER BY clause 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 used only for ORDER BY clause 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)
+ 	{
+ 		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