]> granicus.if.org Git - postgresql/blobdiff - src/backend/optimizer/plan/planner.c
Update copyright for 2009.
[postgresql] / src / backend / optimizer / plan / planner.c
index 40a659391c6fddf25b58d95c5e4a48cec39b74aa..841d85f7397da28f478290fdaae80de563a89c53 100644 (file)
@@ -3,12 +3,12 @@
  * planner.c
  *       The query optimizer external interface.
  *
- * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.242 2008/08/17 01:19:59 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.250 2009/01/01 17:23:44 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -82,6 +82,18 @@ static void locate_grouping_columns(PlannerInfo *root,
                                                List *sub_tlist,
                                                AttrNumber *groupColIdx);
 static List *postprocess_setop_tlist(List *new_tlist, List *orig_tlist);
+static List *select_active_windows(PlannerInfo *root, WindowFuncLists *wflists);
+static List *make_pathkeys_for_window(PlannerInfo *root, WindowClause *wc,
+                                                                         List *tlist, bool canonicalize);
+static void get_column_info_for_window(PlannerInfo *root, WindowClause *wc,
+                                                                          List *tlist,
+                                                                          int numSortCols, AttrNumber *sortColIdx,
+                                                                          int *partNumCols,
+                                                                          AttrNumber **partColIdx,
+                                                                          Oid **partOperators,
+                                                                          int *ordNumCols,
+                                                                          AttrNumber **ordColIdx,
+                                                                          Oid **ordOperators);
 
 
 /*****************************************************************************
@@ -140,6 +152,8 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
        glob->rewindPlanIDs = NULL;
        glob->finalrtable = NIL;
        glob->relationOids = NIL;
+       glob->invalItems = NIL;
+       glob->lastPHId = 0;
        glob->transientPlan = false;
 
        /* Determine what fraction of the plan is likely to be scanned */
@@ -172,7 +186,8 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
        }
 
        /* primary planning entry point (may recurse for subqueries) */
-       top_plan = subquery_planner(glob, parse, 1, tuple_fraction, &root);
+       top_plan = subquery_planner(glob, parse, NULL,
+                                                               false, tuple_fraction, &root);
 
        /*
         * If creating a plan for a scrollable cursor, make sure it can run
@@ -213,6 +228,7 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
        result->returningLists = root->returningLists;
        result->rowMarks = parse->rowMarks;
        result->relationOids = glob->relationOids;
+       result->invalItems = glob->invalItems;
        result->nParamExec = list_length(glob->paramlist);
 
        return result;
@@ -226,7 +242,8 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
  *
  * glob is the global state for the current planner run.
  * parse is the querytree produced by the parser & rewriter.
- * level is the current recursion depth (1 at the top-level Query).
+ * parent_root is the immediate parent Query's info (NULL at the top level).
+ * hasRecursion is true if this is a recursive WITH query.
  * tuple_fraction is the fraction of tuples we expect will be retrieved.
  * tuple_fraction is interpreted as explained for grouping_planner, below.
  *
@@ -247,7 +264,8 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
  */
 Plan *
 subquery_planner(PlannerGlobal *glob, Query *parse,
-                                Index level, double tuple_fraction,
+                                PlannerInfo *parent_root,
+                                bool hasRecursion, double tuple_fraction,
                                 PlannerInfo **subroot)
 {
        int                     num_old_subplans = list_length(glob->subplans);
@@ -261,12 +279,28 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
        root = makeNode(PlannerInfo);
        root->parse = parse;
        root->glob = glob;
-       root->query_level = level;
+       root->query_level = parent_root ? parent_root->query_level + 1 : 1;
+       root->parent_root = parent_root;
        root->planner_cxt = CurrentMemoryContext;
        root->init_plans = NIL;
+       root->cte_plan_ids = NIL;
        root->eq_classes = NIL;
        root->append_rel_list = NIL;
 
+       root->hasRecursion = hasRecursion;
+       if (hasRecursion)
+               root->wt_param_id = SS_assign_worktable_param(root);
+       else
+               root->wt_param_id = -1;
+       root->non_recursive_plan = NULL;
+
+       /*
+        * If there is a WITH list, process each WITH query and build an
+        * initplan SubPlan structure for it.
+        */
+       if (parse->cteList)
+               SS_process_ctes(root);
+
        /*
         * Look for ANY and EXISTS SubLinks in WHERE and JOIN/ON clauses, and try
         * to transform them into joins.  Note that this step does not descend
@@ -491,27 +525,18 @@ preprocess_expression(PlannerInfo *root, Node *expr, int kind)
        /*
         * Simplify constant expressions.
         *
+        * Note: one essential effect here is to insert the current actual values
+        * of any default arguments for functions.  To ensure that happens, we
+        * *must* process all expressions here.  Previous PG versions sometimes
+        * skipped const-simplification if it didn't seem worth the trouble, but
+        * we can't do that anymore.
+        *
         * Note: this also flattens nested AND and OR expressions into N-argument
         * form.  All processing of a qual expression after this point must be
         * careful to maintain AND/OR flatness --- that is, do not generate a tree
         * with AND directly under AND, nor OR directly under OR.
-        *
-        * Because this is a relatively expensive process, we skip it when the
-        * query is trivial, such as "SELECT 2+2;" or "INSERT ... VALUES()". The
-        * expression will only be evaluated once anyway, so no point in
-        * pre-simplifying; we can't execute it any faster than the executor can,
-        * and we will waste cycles copying the tree.  Notice however that we
-        * still must do it for quals (to get AND/OR flatness); and if we are in a
-        * subquery we should not assume it will be done only once.
-        *
-        * For VALUES lists we never do this at all, again on the grounds that we
-        * should optimize for one-time evaluation.
         */
-       if (kind != EXPRKIND_VALUES &&
-               (root->parse->jointree->fromlist != NIL ||
-                kind == EXPRKIND_QUAL ||
-                root->query_level > 1))
-               expr = eval_const_expressions(root, expr);
+       expr = eval_const_expressions(root, expr);
 
        /*
         * If it's a qual or havingQual, canonicalize it.
@@ -635,9 +660,13 @@ inheritance_planner(PlannerInfo *root)
                subroot.parse = (Query *)
                        adjust_appendrel_attrs((Node *) parse,
                                                                   appinfo);
+               subroot.returningLists = NIL;
                subroot.init_plans = NIL;
+               /* We needn't modify the child's append_rel_list */
                /* There shouldn't be any OJ info to translate, as yet */
                Assert(subroot.join_info_list == NIL);
+               /* and we haven't created PlaceHolderInfos, either */
+               Assert(subroot.placeholder_list == NIL);
 
                /* Generate plan */
                subplan = grouping_planner(&subroot, 0.0 /* retrieve all tuples */ );
@@ -774,7 +803,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 
                /*
                 * Construct the plan for set operations.  The result will not need
-                * any work except perhaps a top-level sort and/or LIMIT.
+                * any work except perhaps a top-level sort and/or LIMIT.  Note that
+                * any special work for recursive unions is the responsibility of
+                * plan_set_operations.
                 */
                result_plan = plan_set_operations(root, tuple_fraction,
                                                                                  &set_sortclauses);
@@ -833,9 +864,14 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
                AggClauseCounts agg_counts;
                int                     numGroupCols;
                bool            use_hashed_grouping = false;
+               WindowFuncLists *wflists = NULL;
+               List       *activeWindows = NIL;
 
                MemSet(&agg_counts, 0, sizeof(AggClauseCounts));
 
+               /* A recursive query should always have setOperations */
+               Assert(!root->hasRecursion);
+
                /* Preprocess GROUP BY clause, if any */
                if (parse->groupClause)
                        preprocess_groupclause(root);
@@ -844,6 +880,22 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
                /* Preprocess targetlist */
                tlist = preprocess_targetlist(root, tlist);
 
+               /*
+                * Locate any window functions in the tlist.  (We don't need to look
+                * anywhere else, since expressions used in ORDER BY will be in there
+                * too.)  Note that they could all have been eliminated by constant
+                * folding, in which case we don't need to do any more work.
+                */
+               if (parse->hasWindowFuncs)
+               {
+                       wflists = find_window_functions((Node *) tlist,
+                                                                                       list_length(parse->windowClause));
+                       if (wflists->numWindowFuncs > 0)
+                               activeWindows = select_active_windows(root, wflists);
+                       else
+                               parse->hasWindowFuncs = false;
+               }
+
                /*
                 * Generate appropriate target list for subplan; may be different from
                 * tlist if grouping or aggregation is needed.
@@ -868,6 +920,19 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
                else
                        root->group_pathkeys = NIL;
 
+               /* We consider only the first (bottom) window in pathkeys logic */
+               if (activeWindows != NIL)
+               {
+                       WindowClause *wc = (WindowClause *) linitial(activeWindows);
+
+                       root->window_pathkeys = make_pathkeys_for_window(root,
+                                                                                                                        wc,
+                                                                                                                        tlist,
+                                                                                                                        false);
+               }
+               else
+                       root->window_pathkeys = NIL;
+
                if (parse->distinctClause &&
                        grouping_is_sortable(parse->distinctClause))
                        root->distinct_pathkeys =
@@ -905,11 +970,12 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
                 * Figure out whether we want a sorted result from query_planner.
                 *
                 * If we have a sortable GROUP BY clause, then we want a result sorted
-                * properly for grouping.  Otherwise, if there's a sortable DISTINCT
-                * clause that's more rigorous than the ORDER BY clause, we try to
-                * produce output that's sufficiently well sorted for the DISTINCT.
-                * Otherwise, if there is an ORDER BY clause, we want to sort by the
-                * ORDER BY clause.
+                * properly for grouping.  Otherwise, if we have window functions to
+                * evaluate, we try to sort for the first window.  Otherwise, if
+                * there's a sortable DISTINCT clause that's more rigorous than the
+                * ORDER BY clause, we try to produce output that's sufficiently well
+                * sorted for the DISTINCT.  Otherwise, if there is an ORDER BY
+                * clause, we want to sort by the ORDER BY clause.
                 *
                 * Note: if we have both ORDER BY and GROUP BY, and ORDER BY is a
                 * superset of GROUP BY, it would be tempting to request sort by ORDER
@@ -920,6 +986,8 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
                 */
                if (root->group_pathkeys)
                        root->query_pathkeys = root->group_pathkeys;
+               else if (root->window_pathkeys)
+                       root->query_pathkeys = root->window_pathkeys;
                else if (list_length(root->distinct_pathkeys) >
                                 list_length(root->sort_pathkeys))
                        root->query_pathkeys = root->distinct_pathkeys;
@@ -1070,10 +1138,10 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
                                 *
                                 * Below this point, any tlist eval cost for added-on nodes
                                 * should be accounted for as we create those nodes.
-                                * Presently, of the node types we can add on, only Agg and
-                                * Group project new tlists (the rest just copy their input
-                                * tuples) --- so make_agg() and make_group() are responsible
-                                * for computing the added cost.
+                                * Presently, of the node types we can add on, only Agg,
+                                * WindowAgg, and Group project new tlists (the rest just copy
+                                * their input tuples) --- so make_agg(), make_windowagg() and
+                                * make_group() are responsible for computing the added cost.
                                 */
                                cost_qual_eval(&tlist_cost, sub_tlist, root);
                                result_plan->startup_cost += tlist_cost.startup;
@@ -1203,6 +1271,144 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
                                                                                                   NULL);
                        }
                }                                               /* end of non-minmax-aggregate case */
+
+               /*
+                * Since each window function could require a different sort order,
+                * we stack up a WindowAgg node for each window, with sort steps
+                * between them as needed.
+                */
+               if (activeWindows)
+               {
+                       List       *window_tlist;
+                       ListCell   *l;
+
+                       /*
+                        * If the top-level plan node is one that cannot do expression
+                        * evaluation, we must insert a Result node to project the
+                        * desired tlist.  (In some cases this might not really be
+                        * required, but it's not worth trying to avoid it.)  Note that
+                        * on second and subsequent passes through the following loop,
+                        * the top-level node will be a WindowAgg which we know can
+                        * project; so we only need to check once.
+                        */
+                       if (!is_projection_capable_plan(result_plan))
+                       {
+                               result_plan = (Plan *) make_result(root,
+                                                                                                  NIL,
+                                                                                                  NULL,
+                                                                                                  result_plan);
+                       }
+
+                       /*
+                        * The "base" targetlist for all steps of the windowing process
+                        * is a flat tlist of all Vars and Aggs needed in the result.
+                        * (In some cases we wouldn't need to propagate all of these
+                        * all the way to the top, since they might only be needed as
+                        * inputs to WindowFuncs.  It's probably not worth trying to
+                        * optimize that though.)  As we climb up the stack, we add
+                        * outputs for the WindowFuncs computed at each level.  Also,
+                        * each input tlist has to present all the columns needed to
+                        * sort the data for the next WindowAgg step.  That's handled
+                        * internally by make_sort_from_pathkeys, but we need the
+                        * copyObject steps here to ensure that each plan node has
+                        * a separately modifiable tlist.
+                        */
+                       window_tlist = flatten_tlist(tlist);
+                       if (parse->hasAggs)
+                               window_tlist = add_to_flat_tlist(window_tlist,
+                                                                                       pull_agg_clause((Node *) tlist));
+                       result_plan->targetlist = (List *) copyObject(window_tlist);
+
+                       foreach(l, activeWindows)
+                       {
+                               WindowClause *wc = (WindowClause *) lfirst(l);
+                               List       *window_pathkeys;
+                               int                     partNumCols;
+                               AttrNumber *partColIdx;
+                               Oid                *partOperators;
+                               int                     ordNumCols;
+                               AttrNumber *ordColIdx;
+                               Oid                *ordOperators;
+
+                               window_pathkeys = make_pathkeys_for_window(root,
+                                                                                                                  wc,
+                                                                                                                  tlist,
+                                                                                                                  true);
+
+                               /*
+                                * This is a bit tricky: we build a sort node even if we don't
+                                * really have to sort.  Even when no explicit sort is needed,
+                                * we need to have suitable resjunk items added to the input
+                                * plan's tlist for any partitioning or ordering columns that
+                                * aren't plain Vars.  Furthermore, this way we can use
+                                * existing infrastructure to identify which input columns are
+                                * the interesting ones.
+                                */
+                               if (window_pathkeys)
+                               {
+                                       Sort       *sort_plan;
+
+                                       sort_plan = make_sort_from_pathkeys(root,
+                                                                                                               result_plan,
+                                                                                                               window_pathkeys,
+                                                                                                               -1.0);
+                                       if (!pathkeys_contained_in(window_pathkeys,
+                                                                                          current_pathkeys))
+                                       {
+                                               /* we do indeed need to sort */
+                                               result_plan = (Plan *) sort_plan;
+                                               current_pathkeys = window_pathkeys;
+                                       }
+                                       /* In either case, extract the per-column information */
+                                       get_column_info_for_window(root, wc, tlist,
+                                                                                          sort_plan->numCols,
+                                                                                          sort_plan->sortColIdx,
+                                                                                          &partNumCols,
+                                                                                          &partColIdx,
+                                                                                          &partOperators,
+                                                                                          &ordNumCols,
+                                                                                          &ordColIdx,
+                                                                                          &ordOperators);
+                               }
+                               else
+                               {
+                                       /* empty window specification, nothing to sort */
+                                       partNumCols = 0;
+                                       partColIdx = NULL;
+                                       partOperators = NULL;
+                                       ordNumCols = 0;
+                                       ordColIdx = NULL;
+                                       ordOperators = NULL;
+                               }
+
+                               if (lnext(l))
+                               {
+                                       /* Add the current WindowFuncs to the running tlist */
+                                       window_tlist = add_to_flat_tlist(window_tlist,
+                                                                                       wflists->windowFuncs[wc->winref]);
+                               }
+                               else
+                               {
+                                       /* Install the original tlist in the topmost WindowAgg */
+                                       window_tlist = tlist;
+                               }
+
+                               /* ... and make the WindowAgg plan node */
+                               result_plan = (Plan *)
+                                       make_windowagg(root,
+                                                                  (List *) copyObject(window_tlist),
+                                                                  list_length(wflists->windowFuncs[wc->winref]),
+                                                                  wc->winref,
+                                                                  partNumCols,
+                                                                  partColIdx,
+                                                                  partOperators,
+                                                                  ordNumCols,
+                                                                  ordColIdx,
+                                                                  ordOperators,
+                                                                  wc->frameOptions,
+                                                                  result_plan);
+                       }
+               }
        }                                                       /* end of if (setOperations) */
 
        /*
@@ -2008,7 +2214,8 @@ make_subplanTargetList(PlannerInfo *root,
         * If we're not grouping or aggregating, there's nothing to do here;
         * query_planner should receive the unmodified target list.
         */
-       if (!parse->hasAggs && !parse->groupClause && !root->hasHavingQual)
+       if (!parse->hasAggs && !parse->groupClause && !root->hasHavingQual &&
+               !parse->hasWindowFuncs)
        {
                *need_tlist_eval = true;
                return tlist;
@@ -2017,10 +2224,12 @@ make_subplanTargetList(PlannerInfo *root,
        /*
         * Otherwise, start with a "flattened" tlist (having just the vars
         * mentioned in the targetlist and HAVING qual --- but not upper-level
-        * Vars; they will be replaced by Params later on).
+        * Vars; they will be replaced by Params later on).  Note this includes
+        * vars used in resjunk items, so we are covering the needs of ORDER BY
+        * and window specifications.
         */
        sub_tlist = flatten_tlist(tlist);
-       extravars = pull_var_clause(parse->havingQual, false);
+       extravars = pull_var_clause(parse->havingQual, true);
        sub_tlist = add_to_flat_tlist(sub_tlist, extravars);
        list_free(extravars);
        *need_tlist_eval = false;       /* only eval if not flat tlist */
@@ -2044,7 +2253,7 @@ make_subplanTargetList(PlannerInfo *root,
                {
                        SortGroupClause *grpcl = (SortGroupClause *) lfirst(gl);
                        Node       *groupexpr = get_sortgroupclause_expr(grpcl, tlist);
-                       TargetEntry *te = NULL;
+                       TargetEntry *te;
 
                        /*
                         * Find or make a matching sub_tlist entry.  If the groupexpr
@@ -2052,20 +2261,10 @@ make_subplanTargetList(PlannerInfo *root,
                         * won't make multiple groupClause entries for the same TLE.)
                         */
                        if (groupexpr && IsA(groupexpr, Var))
-                       {
-                               ListCell   *sl;
-
-                               foreach(sl, sub_tlist)
-                               {
-                                       TargetEntry *lte = (TargetEntry *) lfirst(sl);
+                               te = tlist_member(groupexpr, sub_tlist);
+                       else
+                               te = NULL;
 
-                                       if (equal(groupexpr, lte->expr))
-                                       {
-                                               te = lte;
-                                               break;
-                                       }
-                               }
-                       }
                        if (!te)
                        {
                                te = makeTargetEntry((Expr *) groupexpr,
@@ -2090,7 +2289,7 @@ make_subplanTargetList(PlannerInfo *root,
  *
  * This is only needed if we don't use the sub_tlist chosen by
  * make_subplanTargetList.     We have to forget the column indexes found
- * by that routine and re-locate the grouping vars in the real sub_tlist.
+ * by that routine and re-locate the grouping exprs in the real sub_tlist.
  */
 static void
 locate_grouping_columns(PlannerInfo *root,
@@ -2115,18 +2314,10 @@ locate_grouping_columns(PlannerInfo *root,
        {
                SortGroupClause *grpcl = (SortGroupClause *) lfirst(gl);
                Node       *groupexpr = get_sortgroupclause_expr(grpcl, tlist);
-               TargetEntry *te = NULL;
-               ListCell   *sl;
+               TargetEntry *te = tlist_member(groupexpr, sub_tlist);
 
-               foreach(sl, sub_tlist)
-               {
-                       te = (TargetEntry *) lfirst(sl);
-                       if (equal(groupexpr, te->expr))
-                               break;
-               }
-               if (!sl)
+               if (!te)
                        elog(ERROR, "failed to locate grouping columns");
-
                groupColIdx[keyno++] = te->resno;
        }
 }
@@ -2168,3 +2359,220 @@ postprocess_setop_tlist(List *new_tlist, List *orig_tlist)
                elog(ERROR, "resjunk output columns are not implemented");
        return new_tlist;
 }
+
+/*
+ * select_active_windows
+ *             Create a list of the "active" window clauses (ie, those referenced
+ *             by non-deleted WindowFuncs) in the order they are to be executed.
+ */
+static List *
+select_active_windows(PlannerInfo *root, WindowFuncLists *wflists)
+{
+       List       *result;
+       List       *actives;
+       ListCell   *lc;
+
+       /* First, make a list of the active windows */
+       actives = NIL;
+       foreach(lc, root->parse->windowClause)
+       {
+               WindowClause *wc = (WindowClause *) lfirst(lc);
+
+               /* It's only active if wflists shows some related WindowFuncs */
+               Assert(wc->winref <= wflists->maxWinRef);
+               if (wflists->windowFuncs[wc->winref] != NIL)
+                       actives = lappend(actives, wc);
+       }
+
+       /*
+        * Now, ensure that windows with identical partitioning/ordering clauses
+        * are adjacent in the list.  This is required by the SQL standard, which
+        * says that only one sort is to be used for such windows, even if they
+        * are otherwise distinct (eg, different names or framing clauses).
+        *
+        * There is room to be much smarter here, for example detecting whether
+        * one window's sort keys are a prefix of another's (so that sorting
+        * for the latter would do for the former), or putting windows first
+        * that match a sort order available for the underlying query.  For the
+        * moment we are content with meeting the spec.
+        */
+       result = NIL;
+       while (actives != NIL)
+       {
+               WindowClause *wc = (WindowClause *) linitial(actives);
+               ListCell   *prev;
+               ListCell   *next;
+
+               /* Move wc from actives to result */
+               actives = list_delete_first(actives);
+               result = lappend(result, wc);
+
+               /* Now move any matching windows from actives to result */
+               prev = NULL;
+               for (lc = list_head(actives); lc; lc = next)
+               {
+                       WindowClause *wc2 = (WindowClause *) lfirst(lc);
+
+                       next = lnext(lc);
+                       /* framing options are NOT to be compared here! */
+                       if (equal(wc->partitionClause, wc2->partitionClause) &&
+                               equal(wc->orderClause, wc2->orderClause))
+                       {
+                               actives = list_delete_cell(actives, lc, prev);
+                               result = lappend(result, wc2);
+                       }
+                       else
+                               prev = lc;
+               }
+       }
+
+       return result;
+}
+
+/*
+ * make_pathkeys_for_window
+ *             Create a pathkeys list describing the required input ordering
+ *             for the given WindowClause.
+ *
+ * The required ordering is first the PARTITION keys, then the ORDER keys.
+ * In the future we might try to implement windowing using hashing, in which
+ * case the ordering could be relaxed, but for now we always sort.
+ */
+static List *
+make_pathkeys_for_window(PlannerInfo *root, WindowClause *wc,
+                                                List *tlist, bool canonicalize)
+{
+       List       *window_pathkeys;
+       List       *window_sortclauses;
+
+       /* Throw error if can't sort */
+       if (!grouping_is_sortable(wc->partitionClause))
+               ereport(ERROR,
+                               (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+                                errmsg("could not implement window PARTITION BY"),
+                                errdetail("Window partitioning columns must be of sortable datatypes.")));
+       if (!grouping_is_sortable(wc->orderClause))
+               ereport(ERROR,
+                               (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+                                errmsg("could not implement window ORDER BY"),
+                                errdetail("Window ordering columns must be of sortable datatypes.")));
+
+       /* Okay, make the combined pathkeys */
+       window_sortclauses = list_concat(list_copy(wc->partitionClause),
+                                                                        list_copy(wc->orderClause));
+       window_pathkeys = make_pathkeys_for_sortclauses(root,
+                                                                                                       window_sortclauses,
+                                                                                                       tlist,
+                                                                                                       canonicalize);
+       list_free(window_sortclauses);
+       return window_pathkeys;
+}
+
+/*----------
+ * get_column_info_for_window
+ *             Get the partitioning/ordering column numbers and equality operators
+ *             for a WindowAgg node.
+ *
+ * This depends on the behavior of make_pathkeys_for_window()!
+ *
+ * We are given the target WindowClause and an array of the input column
+ * numbers associated with the resulting pathkeys.  In the easy case, there
+ * are the same number of pathkey columns as partitioning + ordering columns
+ * and we just have to copy some data around.  However, it's possible that
+ * some of the original partitioning + ordering columns were eliminated as
+ * redundant during the transformation to pathkeys.  (This can happen even
+ * though the parser gets rid of obvious duplicates.  A typical scenario is a
+ * window specification "PARTITION BY x ORDER BY y" coupled with a clause
+ * "WHERE x = y" that causes the two sort columns to be recognized as
+ * redundant.)  In that unusual case, we have to work a lot harder to
+ * determine which keys are significant.
+ *
+ * The method used here is a bit brute-force: add the sort columns to a list
+ * one at a time and note when the resulting pathkey list gets longer.  But
+ * it's a sufficiently uncommon case that a faster way doesn't seem worth
+ * the amount of code refactoring that'd be needed.
+ *----------
+ */
+static void
+get_column_info_for_window(PlannerInfo *root, WindowClause *wc, List *tlist,
+                                                  int numSortCols, AttrNumber *sortColIdx,
+                                                  int *partNumCols,
+                                                  AttrNumber **partColIdx,
+                                                  Oid **partOperators,
+                                                  int *ordNumCols,
+                                                  AttrNumber **ordColIdx,
+                                                  Oid **ordOperators)
+{
+       int                     numPart = list_length(wc->partitionClause);
+       int                     numOrder = list_length(wc->orderClause);
+
+       if (numSortCols == numPart + numOrder)
+       {
+               /* easy case */
+               *partNumCols = numPart;
+               *partColIdx = sortColIdx;
+               *partOperators = extract_grouping_ops(wc->partitionClause);
+               *ordNumCols = numOrder;
+               *ordColIdx = sortColIdx + numPart;
+               *ordOperators = extract_grouping_ops(wc->orderClause);
+       }
+       else
+       {
+               List       *sortclauses;
+               List       *pathkeys;
+               int                     scidx;
+               ListCell   *lc;
+
+               /* first, allocate what's certainly enough space for the arrays */
+               *partNumCols = 0;
+               *partColIdx = (AttrNumber *) palloc(numPart * sizeof(AttrNumber));
+               *partOperators = (Oid *) palloc(numPart * sizeof(Oid));
+               *ordNumCols = 0;
+               *ordColIdx = (AttrNumber *) palloc(numOrder * sizeof(AttrNumber));
+               *ordOperators = (Oid *) palloc(numOrder * sizeof(Oid));
+               sortclauses = NIL;
+               pathkeys = NIL;
+               scidx = 0;
+               foreach(lc, wc->partitionClause)
+               {
+                       SortGroupClause *sgc = (SortGroupClause *) lfirst(lc);
+                       List       *new_pathkeys;
+
+                       sortclauses = lappend(sortclauses, sgc);
+                       new_pathkeys = make_pathkeys_for_sortclauses(root,
+                                                                                                                sortclauses,
+                                                                                                                tlist,
+                                                                                                                true);
+                       if (list_length(new_pathkeys) > list_length(pathkeys))
+                       {
+                               /* this sort clause is actually significant */
+                               *partColIdx[*partNumCols] = sortColIdx[scidx++];
+                               *partOperators[*partNumCols] = sgc->eqop;
+                               (*partNumCols)++;
+                               pathkeys = new_pathkeys;
+                       }
+               }
+               foreach(lc, wc->orderClause)
+               {
+                       SortGroupClause *sgc = (SortGroupClause *) lfirst(lc);
+                       List       *new_pathkeys;
+
+                       sortclauses = lappend(sortclauses, sgc);
+                       new_pathkeys = make_pathkeys_for_sortclauses(root,
+                                                                                                                sortclauses,
+                                                                                                                tlist,
+                                                                                                                true);
+                       if (list_length(new_pathkeys) > list_length(pathkeys))
+                       {
+                               /* this sort clause is actually significant */
+                               *ordColIdx[*ordNumCols] = sortColIdx[scidx++];
+                               *ordOperators[*ordNumCols] = sgc->eqop;
+                               (*ordNumCols)++;
+                               pathkeys = new_pathkeys;
+                       }
+               }
+               /* complain if we didn't eat exactly the right number of sort cols */
+               if (scidx != numSortCols)
+                       elog(ERROR, "failed to deconstruct sort operators into partitioning/ordering operators");
+       }
+}