Improve EXPLAIN's display of window functions.

Up to now we just punted on showing the window definitions used
in a plan, with window function calls represented as "OVER (?)".
To improve that, show the window definition implemented by each
WindowAgg plan node, and reference their window names in OVER.
For nameless window clauses generated by "OVER (...)", assign
unique names w1, w2, etc.

In passing, re-order the properties shown for a WindowAgg node
so that the Run Condition (if any) appears after the Window
property and before the Filter (if any).  This seems more
sensible since the Run Condition is associated with the Window
and acts before the Filter.

Thanks to David G. Johnston and Álvaro Herrera for design
suggestions.

Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: David Rowley <dgrowleyml@gmail.com>
Discussion: https://postgr.es/m/144530.1741469955@sss.pgh.pa.us

contrib/postgres_fdw/expected/postgres_fdw.out

@@ -3968,10 +3968,11 @@ select c2, sum(c2), count(c2) over (partition by c2%2) from ft2 where c2 < 10 gr
                                                  QUERY PLAN                                                 
 ------------------------------------------------------------------------------------------------------------
  Sort
-   Output: c2, (sum(c2)), (count(c2) OVER (?)), ((c2 % 2))
+   Output: c2, (sum(c2)), (count(c2) OVER w1), ((c2 % 2))
    Sort Key: ft2.c2
    ->  WindowAgg
-         Output: c2, (sum(c2)), count(c2) OVER (?), ((c2 % 2))
+         Output: c2, (sum(c2)), count(c2) OVER w1, ((c2 % 2))
+         Window: w1 AS (PARTITION BY ((ft2.c2 % 2)))
          ->  Sort
                Output: c2, ((c2 % 2)), (sum(c2))
                Sort Key: ((ft2.c2 % 2))
@@ -3979,7 +3980,7 @@ select c2, sum(c2), count(c2) over (partition by c2%2) from ft2 where c2 < 10 gr
                      Output: c2, ((c2 % 2)), (sum(c2))
                      Relations: Aggregate on (public.ft2)
                      Remote SQL: SELECT c2, (c2 % 2), sum(c2) FROM "S 1"."T 1" WHERE ((c2 < 10)) GROUP BY 1
-(12 rows)
+(13 rows)
 
 select c2, sum(c2), count(c2) over (partition by c2%2) from ft2 where c2 < 10 group by c2 order by 1;
  c2 | sum | count 
@@ -4001,10 +4002,11 @@ select c2, array_agg(c2) over (partition by c2%2 order by c2 desc) from ft1 wher
                                             QUERY PLAN                                             
 ---------------------------------------------------------------------------------------------------
  Sort
-   Output: c2, (array_agg(c2) OVER (?)), ((c2 % 2))
+   Output: c2, (array_agg(c2) OVER w1), ((c2 % 2))
    Sort Key: ft1.c2
    ->  WindowAgg
-         Output: c2, array_agg(c2) OVER (?), ((c2 % 2))
+         Output: c2, array_agg(c2) OVER w1, ((c2 % 2))
+         Window: w1 AS (PARTITION BY ((ft1.c2 % 2)) ORDER BY ft1.c2)
          ->  Sort
                Output: c2, ((c2 % 2))
                Sort Key: ((ft1.c2 % 2)), ft1.c2 DESC
@@ -4012,7 +4014,7 @@ select c2, array_agg(c2) over (partition by c2%2 order by c2 desc) from ft1 wher
                      Output: c2, ((c2 % 2))
                      Relations: Aggregate on (public.ft1)
                      Remote SQL: SELECT c2, (c2 % 2) FROM "S 1"."T 1" WHERE ((c2 < 10)) GROUP BY 1
-(12 rows)
+(13 rows)
 
 select c2, array_agg(c2) over (partition by c2%2 order by c2 desc) from ft1 where c2 < 10 group by c2 order by 1;
  c2 |  array_agg  
@@ -4032,12 +4034,13 @@ select c2, array_agg(c2) over (partition by c2%2 order by c2 desc) from ft1 wher
 explain (verbose, costs off)
 select c2, array_agg(c2) over (partition by c2%2 order by c2 range between current row and unbounded following) from ft1 where c2 < 10 group by c2 order by 1;
                                                       QUERY PLAN                                                       
----------------------------------------------------------------------------------------------------
+-----------------------------------------------------------------------------------------------------------------------
  Sort
-   Output: c2, (array_agg(c2) OVER (?)), ((c2 % 2))
+   Output: c2, (array_agg(c2) OVER w1), ((c2 % 2))
    Sort Key: ft1.c2
    ->  WindowAgg
-         Output: c2, array_agg(c2) OVER (?), ((c2 % 2))
+         Output: c2, array_agg(c2) OVER w1, ((c2 % 2))
+         Window: w1 AS (PARTITION BY ((ft1.c2 % 2)) ORDER BY ft1.c2 RANGE BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING)
          ->  Sort
                Output: c2, ((c2 % 2))
                Sort Key: ((ft1.c2 % 2)), ft1.c2
@@ -4045,7 +4048,7 @@ select c2, array_agg(c2) over (partition by c2%2 order by c2 range between curre
                      Output: c2, ((c2 % 2))
                      Relations: Aggregate on (public.ft1)
                      Remote SQL: SELECT c2, (c2 % 2) FROM "S 1"."T 1" WHERE ((c2 < 10)) GROUP BY 1
-(12 rows)
+(13 rows)
 
 select c2, array_agg(c2) over (partition by c2%2 order by c2 range between current row and unbounded following) from ft1 where c2 < 10 group by c2 order by 1;
  c2 |  array_agg  

src/backend/commands/explain.c

@@ -107,6 +107,11 @@ static void show_sort_group_keys(PlanState *planstate, const char *qlabel,
 								 List *ancestors, ExplainState *es);
 static void show_sortorder_options(StringInfo buf, Node *sortexpr,
 								   Oid sortOperator, Oid collation, bool nullsFirst);
+static void show_window_def(WindowAggState *planstate,
+							List *ancestors, ExplainState *es);
+static void show_window_keys(StringInfo buf, PlanState *planstate,
+							 int nkeys, AttrNumber *keycols,
+							 List *ancestors, ExplainState *es);
 static void show_storage_info(char *maxStorageType, int64 maxSpaceUsed,
 							  ExplainState *es);
 static void show_tablesample(TableSampleClause *tsc, PlanState *planstate,
@@ -2333,12 +2338,13 @@ ExplainNode(PlanState *planstate, List *ancestors,
 										   planstate, es);
 			break;
 		case T_WindowAgg:
+			show_window_def(castNode(WindowAggState, planstate), ancestors, es);
+			show_upper_qual(((WindowAgg *) plan)->runConditionOrig,
+							"Run Condition", planstate, ancestors, es);
 			show_upper_qual(plan->qual, "Filter", planstate, ancestors, es);
 			if (plan->qual)
 				show_instrumentation_count("Rows Removed by Filter", 1,
 										   planstate, es);
-			show_upper_qual(((WindowAgg *) plan)->runConditionOrig,
-							"Run Condition", planstate, ancestors, es);
 			show_windowagg_info(castNode(WindowAggState, planstate), es);
 			break;
 		case T_Group:
@@ -3007,6 +3013,113 @@ show_sortorder_options(StringInfo buf, Node *sortexpr,
 	}
 }
 
+/*
+ * Show the window definition for a WindowAgg node.
+ */
+static void
+show_window_def(WindowAggState *planstate, List *ancestors, ExplainState *es)
+{
+	WindowAgg  *wagg = (WindowAgg *) planstate->ss.ps.plan;
+	StringInfoData wbuf;
+	bool		needspace = false;
+
+	initStringInfo(&wbuf);
+	appendStringInfo(&wbuf, "%s AS (", quote_identifier(wagg->winname));
+
+	/* The key columns refer to the tlist of the child plan */
+	ancestors = lcons(wagg, ancestors);
+	if (wagg->partNumCols > 0)
+	{
+		appendStringInfoString(&wbuf, "PARTITION BY ");
+		show_window_keys(&wbuf, outerPlanState(planstate),
+						 wagg->partNumCols, wagg->partColIdx,
+						 ancestors, es);
+		needspace = true;
+	}
+	if (wagg->ordNumCols > 0)
+	{
+		if (needspace)
+			appendStringInfoChar(&wbuf, ' ');
+		appendStringInfoString(&wbuf, "ORDER BY ");
+		show_window_keys(&wbuf, outerPlanState(planstate),
+						 wagg->ordNumCols, wagg->ordColIdx,
+						 ancestors, es);
+		needspace = true;
+	}
+	ancestors = list_delete_first(ancestors);
+	if (wagg->frameOptions & FRAMEOPTION_NONDEFAULT)
+	{
+		List	   *context;
+		bool		useprefix;
+		char	   *framestr;
+
+		/* Set up deparsing context for possible frame expressions */
+		context = set_deparse_context_plan(es->deparse_cxt,
+										   (Plan *) wagg,
+										   ancestors);
+		useprefix = (es->rtable_size > 1 || es->verbose);
+		framestr = get_window_frame_options_for_explain(wagg->frameOptions,
+														wagg->startOffset,
+														wagg->endOffset,
+														context,
+														useprefix);
+		if (needspace)
+			appendStringInfoChar(&wbuf, ' ');
+		appendStringInfoString(&wbuf, framestr);
+		pfree(framestr);
+	}
+	appendStringInfoChar(&wbuf, ')');
+	ExplainPropertyText("Window", wbuf.data, es);
+	pfree(wbuf.data);
+}
+
+/*
+ * Append the keys of a window's PARTITION BY or ORDER BY clause to buf.
+ * We can't use show_sort_group_keys for this because that's too opinionated
+ * about how the result will be displayed.
+ * Note that the "planstate" node should be the WindowAgg's child.
+ */
+static void
+show_window_keys(StringInfo buf, PlanState *planstate,
+				 int nkeys, AttrNumber *keycols,
+				 List *ancestors, ExplainState *es)
+{
+	Plan	   *plan = planstate->plan;
+	List	   *context;
+	bool		useprefix;
+
+	/* Set up deparsing context */
+	context = set_deparse_context_plan(es->deparse_cxt,
+									   plan,
+									   ancestors);
+	useprefix = (es->rtable_size > 1 || es->verbose);
+
+	for (int keyno = 0; keyno < nkeys; keyno++)
+	{
+		/* find key expression in tlist */
+		AttrNumber	keyresno = keycols[keyno];
+		TargetEntry *target = get_tle_by_resno(plan->targetlist,
+											   keyresno);
+		char	   *exprstr;
+
+		if (!target)
+			elog(ERROR, "no tlist entry for key %d", keyresno);
+		/* Deparse the expression, showing any top-level cast */
+		exprstr = deparse_expression((Node *) target->expr, context,
+									 useprefix, true);
+		if (keyno > 0)
+			appendStringInfoString(buf, ", ");
+		appendStringInfoString(buf, exprstr);
+		pfree(exprstr);
+
+		/*
+		 * We don't attempt to provide sort order information because
+		 * WindowAgg carries equality operators not comparison operators;
+		 * compare show_agg_keys.
+		 */
+	}
+}
+
 /*
  * Show information on storage method and maximum memory/disk space used.
  */

src/backend/optimizer/plan/createplan.c

@@ -285,12 +285,9 @@ static Memoize *make_memoize(Plan *lefttree, Oid *hashoperators,
 							 Oid *collations, List *param_exprs,
 							 bool singlerow, bool binary_mode,
 							 uint32 est_entries, Bitmapset *keyparamids);
-static WindowAgg *make_windowagg(List *tlist, Index winref,
+static WindowAgg *make_windowagg(List *tlist, WindowClause *wc,
 								 int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
 								 int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
-								 int frameOptions, Node *startOffset, Node *endOffset,
-								 Oid startInRangeFunc, Oid endInRangeFunc,
-								 Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
 								 List *runCondition, List *qual, bool topWindow,
 								 Plan *lefttree);
 static Group *make_group(List *tlist, List *qual, int numGroupCols,
@@ -2683,7 +2680,7 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 
 	/* And finally we can make the WindowAgg node */
 	plan = make_windowagg(tlist,
-						  wc->winref,
+						  wc,
 						  partNumCols,
 						  partColIdx,
 						  partOperators,
@@ -2692,14 +2689,6 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 						  ordColIdx,
 						  ordOperators,
 						  ordCollations,
-						  wc->frameOptions,
-						  wc->startOffset,
-						  wc->endOffset,
-						  wc->startInRangeFunc,
-						  wc->endInRangeFunc,
-						  wc->inRangeColl,
-						  wc->inRangeAsc,
-						  wc->inRangeNullsFirst,
 						  best_path->runCondition,
 						  best_path->qual,
 						  best_path->topwindow,
@@ -6704,18 +6693,16 @@ make_agg(List *tlist, List *qual,
 }
 
 static WindowAgg *
-make_windowagg(List *tlist, Index winref,
+make_windowagg(List *tlist, WindowClause *wc,
 			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
 			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
-			   int frameOptions, Node *startOffset, Node *endOffset,
-			   Oid startInRangeFunc, Oid endInRangeFunc,
-			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
 			   List *runCondition, List *qual, bool topWindow, Plan *lefttree)
 {
 	WindowAgg  *node = makeNode(WindowAgg);
 	Plan	   *plan = &node->plan;
 
-	node->winref = winref;
+	node->winname = wc->name;
+	node->winref = wc->winref;
 	node->partNumCols = partNumCols;
 	node->partColIdx = partColIdx;
 	node->partOperators = partOperators;
@@ -6724,17 +6711,17 @@ make_windowagg(List *tlist, Index winref,
 	node->ordColIdx = ordColIdx;
 	node->ordOperators = ordOperators;
 	node->ordCollations = ordCollations;
-	node->frameOptions = frameOptions;
-	node->startOffset = startOffset;
-	node->endOffset = endOffset;
+	node->frameOptions = wc->frameOptions;
+	node->startOffset = wc->startOffset;
+	node->endOffset = wc->endOffset;
 	node->runCondition = runCondition;
 	/* a duplicate of the above for EXPLAIN */
 	node->runConditionOrig = runCondition;
-	node->startInRangeFunc = startInRangeFunc;
-	node->endInRangeFunc = endInRangeFunc;
-	node->inRangeColl = inRangeColl;
-	node->inRangeAsc = inRangeAsc;
-	node->inRangeNullsFirst = inRangeNullsFirst;
+	node->startInRangeFunc = wc->startInRangeFunc;
+	node->endInRangeFunc = wc->endInRangeFunc;
+	node->inRangeColl = wc->inRangeColl;
+	node->inRangeAsc = wc->inRangeAsc;
+	node->inRangeNullsFirst = wc->inRangeNullsFirst;
 	node->topWindow = topWindow;
 
 	plan->targetlist = tlist;

src/backend/optimizer/plan/planner.c

@@ -214,6 +214,7 @@ static List *postprocess_setop_tlist(List *new_tlist, List *orig_tlist);
 static void optimize_window_clauses(PlannerInfo *root,
 									WindowFuncLists *wflists);
 static List *select_active_windows(PlannerInfo *root, WindowFuncLists *wflists);
+static void name_active_windows(List *activeWindows);
 static PathTarget *make_window_input_target(PlannerInfo *root,
 											PathTarget *final_target,
 											List *activeWindows);
@@ -1539,7 +1540,11 @@ grouping_planner(PlannerInfo *root, double tuple_fraction,
 				 */
 				optimize_window_clauses(root, wflists);
 
+				/* Extract the list of windows actually in use. */
 				activeWindows = select_active_windows(root, wflists);
+
+				/* Make sure they all have names, for EXPLAIN's use. */
+				name_active_windows(activeWindows);
 			}
 			else
 				parse->hasWindowFuncs = false;
@@ -5914,6 +5919,52 @@ select_active_windows(PlannerInfo *root, WindowFuncLists *wflists)
 	return result;
 }
 
+/*
+ * name_active_windows
+ *	  Ensure all active windows have unique names.
+ *
+ * The parser will have checked that user-assigned window names are unique
+ * within the Query.  Here we assign made-up names to any unnamed
+ * WindowClauses for the benefit of EXPLAIN.  (We don't want to do this
+ * at parse time, because it'd mess up decompilation of views.)
+ *
+ * activeWindows: result of select_active_windows
+ */
+static void
+name_active_windows(List *activeWindows)
+{
+	int			next_n = 1;
+	char		newname[16];
+	ListCell   *lc;
+
+	foreach(lc, activeWindows)
+	{
+		WindowClause *wc = lfirst_node(WindowClause, lc);
+
+		/* Nothing to do if it has a name already. */
+		if (wc->name)
+			continue;
+
+		/* Select a name not currently present in the list. */
+		for (;;)
+		{
+			ListCell   *lc2;
+
+			snprintf(newname, sizeof(newname), "w%d", next_n++);
+			foreach(lc2, activeWindows)
+			{
+				WindowClause *wc2 = lfirst_node(WindowClause, lc2);
+
+				if (wc2->name && strcmp(wc2->name, newname) == 0)
+					break;		/* matched */
+			}
+			if (lc2 == NULL)
+				break;			/* reached the end with no match */
+		}
+		wc->name = pstrdup(newname);
+	}
+}
+
 /*
  * common_prefix_cmp
  *	  QSort comparison function for WindowClauseSortData

src/backend/utils/adt/ruleutils.c

@@ -441,6 +441,9 @@ static void get_rule_orderby(List *orderList, List *targetList,
 static void get_rule_windowclause(Query *query, deparse_context *context);
 static void get_rule_windowspec(WindowClause *wc, List *targetList,
 								deparse_context *context);
+static void get_window_frame_options(int frameOptions,
+									 Node *startOffset, Node *endOffset,
+									 deparse_context *context);
 static char *get_variable(Var *var, int levelsup, bool istoplevel,
 						  deparse_context *context);
 static void get_special_variable(Node *node, deparse_context *context,
@@ -6811,45 +6814,64 @@ get_rule_windowspec(WindowClause *wc, List *targetList,
 	{
 		if (needspace)
 			appendStringInfoChar(buf, ' ');
-		if (wc->frameOptions & FRAMEOPTION_RANGE)
+		get_window_frame_options(wc->frameOptions,
+								 wc->startOffset, wc->endOffset,
+								 context);
+	}
+	appendStringInfoChar(buf, ')');
+}
+
+/*
+ * Append the description of a window's framing options to context->buf
+ */
+static void
+get_window_frame_options(int frameOptions,
+						 Node *startOffset, Node *endOffset,
+						 deparse_context *context)
+{
+	StringInfo	buf = context->buf;
+
+	if (frameOptions & FRAMEOPTION_NONDEFAULT)
+	{
+		if (frameOptions & FRAMEOPTION_RANGE)
 			appendStringInfoString(buf, "RANGE ");
-		else if (wc->frameOptions & FRAMEOPTION_ROWS)
+		else if (frameOptions & FRAMEOPTION_ROWS)
 			appendStringInfoString(buf, "ROWS ");
-		else if (wc->frameOptions & FRAMEOPTION_GROUPS)
+		else if (frameOptions & FRAMEOPTION_GROUPS)
 			appendStringInfoString(buf, "GROUPS ");
 		else
 			Assert(false);
-		if (wc->frameOptions & FRAMEOPTION_BETWEEN)
+		if (frameOptions & FRAMEOPTION_BETWEEN)
 			appendStringInfoString(buf, "BETWEEN ");
-		if (wc->frameOptions & FRAMEOPTION_START_UNBOUNDED_PRECEDING)
+		if (frameOptions & FRAMEOPTION_START_UNBOUNDED_PRECEDING)
 			appendStringInfoString(buf, "UNBOUNDED PRECEDING ");
-		else if (wc->frameOptions & FRAMEOPTION_START_CURRENT_ROW)
+		else if (frameOptions & FRAMEOPTION_START_CURRENT_ROW)
 			appendStringInfoString(buf, "CURRENT ROW ");
-		else if (wc->frameOptions & FRAMEOPTION_START_OFFSET)
+		else if (frameOptions & FRAMEOPTION_START_OFFSET)
 		{
-			get_rule_expr(wc->startOffset, context, false);
-			if (wc->frameOptions & FRAMEOPTION_START_OFFSET_PRECEDING)
+			get_rule_expr(startOffset, context, false);
+			if (frameOptions & FRAMEOPTION_START_OFFSET_PRECEDING)
 				appendStringInfoString(buf, " PRECEDING ");
-			else if (wc->frameOptions & FRAMEOPTION_START_OFFSET_FOLLOWING)
+			else if (frameOptions & FRAMEOPTION_START_OFFSET_FOLLOWING)
 				appendStringInfoString(buf, " FOLLOWING ");
 			else
 				Assert(false);
 		}
 		else
 			Assert(false);
-		if (wc->frameOptions & FRAMEOPTION_BETWEEN)
+		if (frameOptions & FRAMEOPTION_BETWEEN)
 		{
 			appendStringInfoString(buf, "AND ");
-			if (wc->frameOptions & FRAMEOPTION_END_UNBOUNDED_FOLLOWING)
+			if (frameOptions & FRAMEOPTION_END_UNBOUNDED_FOLLOWING)
 				appendStringInfoString(buf, "UNBOUNDED FOLLOWING ");
-			else if (wc->frameOptions & FRAMEOPTION_END_CURRENT_ROW)
+			else if (frameOptions & FRAMEOPTION_END_CURRENT_ROW)
 				appendStringInfoString(buf, "CURRENT ROW ");
-			else if (wc->frameOptions & FRAMEOPTION_END_OFFSET)
+			else if (frameOptions & FRAMEOPTION_END_OFFSET)
 			{
-				get_rule_expr(wc->endOffset, context, false);
-				if (wc->frameOptions & FRAMEOPTION_END_OFFSET_PRECEDING)
+				get_rule_expr(endOffset, context, false);
+				if (frameOptions & FRAMEOPTION_END_OFFSET_PRECEDING)
 					appendStringInfoString(buf, " PRECEDING ");
-				else if (wc->frameOptions & FRAMEOPTION_END_OFFSET_FOLLOWING)
+				else if (frameOptions & FRAMEOPTION_END_OFFSET_FOLLOWING)
 					appendStringInfoString(buf, " FOLLOWING ");
 				else
 					Assert(false);
@@ -6857,16 +6879,46 @@ get_rule_windowspec(WindowClause *wc, List *targetList,
 			else
 				Assert(false);
 		}
-		if (wc->frameOptions & FRAMEOPTION_EXCLUDE_CURRENT_ROW)
+		if (frameOptions & FRAMEOPTION_EXCLUDE_CURRENT_ROW)
 			appendStringInfoString(buf, "EXCLUDE CURRENT ROW ");
-		else if (wc->frameOptions & FRAMEOPTION_EXCLUDE_GROUP)
+		else if (frameOptions & FRAMEOPTION_EXCLUDE_GROUP)
 			appendStringInfoString(buf, "EXCLUDE GROUP ");
-		else if (wc->frameOptions & FRAMEOPTION_EXCLUDE_TIES)
+		else if (frameOptions & FRAMEOPTION_EXCLUDE_TIES)
 			appendStringInfoString(buf, "EXCLUDE TIES ");
 		/* we will now have a trailing space; remove it */
-		buf->len--;
+		buf->data[--(buf->len)] = '\0';
 	}
-	appendStringInfoChar(buf, ')');
+}
+
+/*
+ * Return the description of a window's framing options as a palloc'd string
+ */
+char *
+get_window_frame_options_for_explain(int frameOptions,
+									 Node *startOffset, Node *endOffset,
+									 List *dpcontext, bool forceprefix)
+{
+	StringInfoData buf;
+	deparse_context context;
+
+	initStringInfo(&buf);
+	context.buf = &buf;
+	context.namespaces = dpcontext;
+	context.resultDesc = NULL;
+	context.targetList = NIL;
+	context.windowClause = NIL;
+	context.varprefix = forceprefix;
+	context.prettyFlags = 0;
+	context.wrapColumn = WRAP_COLUMN_DEFAULT;
+	context.indentLevel = 0;
+	context.colNamesVisible = true;
+	context.inGroupBy = false;
+	context.varInOrderBy = false;
+	context.appendparents = NULL;
+
+	get_window_frame_options(frameOptions, startOffset, endOffset, &context);
+
+	return buf.data;
 }
 
 /* ----------
@@ -11030,6 +11082,9 @@ get_windowfunc_expr_helper(WindowFunc *wfunc, deparse_context *context,
 
 	appendStringInfoString(buf, ") OVER ");
 
+	if (context->windowClause)
+	{
+		/* Query-decompilation case: search the windowClause list */
 		foreach(l, context->windowClause)
 		{
 			WindowClause *wc = (WindowClause *) lfirst(l);
@@ -11044,16 +11099,33 @@ get_windowfunc_expr_helper(WindowFunc *wfunc, deparse_context *context,
 			}
 		}
 		if (l == NULL)
-	{
-		if (context->windowClause)
 			elog(ERROR, "could not find window clause for winref %u",
 				 wfunc->winref);
-
+	}
+	else
+	{
 		/*
-		 * In EXPLAIN, we don't have window context information available, so
-		 * we have to settle for this:
+		 * In EXPLAIN, search the namespace stack for a matching WindowAgg
+		 * node (probably it's always the first entry), and print winname.
 		 */
-		appendStringInfoString(buf, "(?)");
+		foreach(l, context->namespaces)
+		{
+			deparse_namespace *dpns = (deparse_namespace *) lfirst(l);
+
+			if (dpns->plan && IsA(dpns->plan, WindowAgg))
+			{
+				WindowAgg  *wagg = (WindowAgg *) dpns->plan;
+
+				if (wagg->winref == wfunc->winref)
+				{
+					appendStringInfoString(buf, quote_identifier(wagg->winname));
+					break;
+				}
+			}
+		}
+		if (l == NULL)
+			elog(ERROR, "could not find window clause for winref %u",
+				 wfunc->winref);
 	}
 }
 

src/include/nodes/plannodes.h

@@ -1171,6 +1171,9 @@ typedef struct WindowAgg
 {
 	Plan		plan;
 
+	/* name of WindowClause implemented by this node */
+	char	   *winname;
+
 	/* ID referenced by window functions */
 	Index		winref;
 

src/include/utils/ruleutils.h

@@ -43,6 +43,11 @@ extern List *set_deparse_context_plan(List *dpcontext,
 									  struct Plan *plan, List *ancestors);
 extern List *select_rtable_names_for_explain(List *rtable,
 											 Bitmapset *rels_used);
+extern char *get_window_frame_options_for_explain(int frameOptions,
+												  Node *startOffset,
+												  Node *endOffset,
+												  List *dpcontext,
+												  bool forceprefix);
 extern char *generate_collation_name(Oid collid);
 extern char *generate_opclass_name(Oid opclass);
 extern char *get_range_partbound_string(List *bound_datums);

src/test/regress/expected/box.out

@@ -595,11 +595,12 @@ EXPLAIN (COSTS OFF)
 SELECT rank() OVER (ORDER BY b <-> point '123,456') n, b <-> point '123,456' dist, id
 FROM quad_box_tbl;
                                    QUERY PLAN                                   
----------------------------------------------------------
+--------------------------------------------------------------------------------
  WindowAgg
+   Window: w1 AS (ORDER BY (b <-> '(123,456)'::point) ROWS UNBOUNDED PRECEDING)
    ->  Index Scan using quad_box_tbl_idx on quad_box_tbl
          Order By: (b <-> '(123,456)'::point)
-(3 rows)
+(4 rows)
 
 CREATE TEMP TABLE quad_box_tbl_ord_idx1 AS
 SELECT rank() OVER (ORDER BY b <-> point '123,456') n, b <-> point '123,456' dist, id
@@ -617,12 +618,13 @@ EXPLAIN (COSTS OFF)
 SELECT rank() OVER (ORDER BY b <-> point '123,456') n, b <-> point '123,456' dist, id
 FROM quad_box_tbl WHERE b <@ box '((200,300),(500,600))';
                                    QUERY PLAN                                   
----------------------------------------------------------
+--------------------------------------------------------------------------------
  WindowAgg
+   Window: w1 AS (ORDER BY (b <-> '(123,456)'::point) ROWS UNBOUNDED PRECEDING)
    ->  Index Scan using quad_box_tbl_idx on quad_box_tbl
          Index Cond: (b <@ '(500,600),(200,300)'::box)
          Order By: (b <-> '(123,456)'::point)
-(4 rows)
+(5 rows)
 
 CREATE TEMP TABLE quad_box_tbl_ord_idx2 AS
 SELECT rank() OVER (ORDER BY b <-> point '123,456') n, b <-> point '123,456' dist, id

src/test/regress/expected/create_index_spgist.out

@@ -330,11 +330,12 @@ EXPLAIN (COSTS OFF)
 SELECT row_number() OVER (ORDER BY p <-> '0,0') n, p <-> '0,0' dist, p
 FROM quad_point_tbl;
                                  QUERY PLAN                                 
------------------------------------------------------------
+----------------------------------------------------------------------------
  WindowAgg
+   Window: w1 AS (ORDER BY (p <-> '(0,0)'::point) ROWS UNBOUNDED PRECEDING)
    ->  Index Only Scan using sp_quad_ind on quad_point_tbl
          Order By: (p <-> '(0,0)'::point)
-(3 rows)
+(4 rows)
 
 CREATE TEMP TABLE quad_point_tbl_ord_idx1 AS
 SELECT row_number() OVER (ORDER BY p <-> '0,0') n, p <-> '0,0' dist, p
@@ -350,12 +351,13 @@ EXPLAIN (COSTS OFF)
 SELECT row_number() OVER (ORDER BY p <-> '0,0') n, p <-> '0,0' dist, p
 FROM quad_point_tbl WHERE p <@ box '(200,200,1000,1000)';
                                  QUERY PLAN                                 
------------------------------------------------------------
+----------------------------------------------------------------------------
  WindowAgg
+   Window: w1 AS (ORDER BY (p <-> '(0,0)'::point) ROWS UNBOUNDED PRECEDING)
    ->  Index Only Scan using sp_quad_ind on quad_point_tbl
          Index Cond: (p <@ '(1000,1000),(200,200)'::box)
          Order By: (p <-> '(0,0)'::point)
-(4 rows)
+(5 rows)
 
 CREATE TEMP TABLE quad_point_tbl_ord_idx2 AS
 SELECT row_number() OVER (ORDER BY p <-> '0,0') n, p <-> '0,0' dist, p
@@ -371,12 +373,13 @@ EXPLAIN (COSTS OFF)
 SELECT row_number() OVER (ORDER BY p <-> '333,400') n, p <-> '333,400' dist, p
 FROM quad_point_tbl WHERE p IS NOT NULL;
                                    QUERY PLAN                                   
------------------------------------------------------------
+--------------------------------------------------------------------------------
  WindowAgg
+   Window: w1 AS (ORDER BY (p <-> '(333,400)'::point) ROWS UNBOUNDED PRECEDING)
    ->  Index Only Scan using sp_quad_ind on quad_point_tbl
          Index Cond: (p IS NOT NULL)
          Order By: (p <-> '(333,400)'::point)
-(4 rows)
+(5 rows)
 
 CREATE TEMP TABLE quad_point_tbl_ord_idx3 AS
 SELECT row_number() OVER (ORDER BY p <-> '333,400') n, p <-> '333,400' dist, p
@@ -497,11 +500,12 @@ EXPLAIN (COSTS OFF)
 SELECT row_number() OVER (ORDER BY p <-> '0,0') n, p <-> '0,0' dist, p
 FROM kd_point_tbl;
                                  QUERY PLAN                                 
--------------------------------------------------------
+----------------------------------------------------------------------------
  WindowAgg
+   Window: w1 AS (ORDER BY (p <-> '(0,0)'::point) ROWS UNBOUNDED PRECEDING)
    ->  Index Only Scan using sp_kd_ind on kd_point_tbl
          Order By: (p <-> '(0,0)'::point)
-(3 rows)
+(4 rows)
 
 CREATE TEMP TABLE kd_point_tbl_ord_idx1 AS
 SELECT row_number() OVER (ORDER BY p <-> '0,0') n, p <-> '0,0' dist, p
@@ -517,12 +521,13 @@ EXPLAIN (COSTS OFF)
 SELECT row_number() OVER (ORDER BY p <-> '0,0') n, p <-> '0,0' dist, p
 FROM kd_point_tbl WHERE p <@ box '(200,200,1000,1000)';
                                  QUERY PLAN                                 
----------------------------------------------------------
+----------------------------------------------------------------------------
  WindowAgg
+   Window: w1 AS (ORDER BY (p <-> '(0,0)'::point) ROWS UNBOUNDED PRECEDING)
    ->  Index Only Scan using sp_kd_ind on kd_point_tbl
          Index Cond: (p <@ '(1000,1000),(200,200)'::box)
          Order By: (p <-> '(0,0)'::point)
-(4 rows)
+(5 rows)
 
 CREATE TEMP TABLE kd_point_tbl_ord_idx2 AS
 SELECT row_number() OVER (ORDER BY p <-> '0,0') n, p <-> '0,0' dist, p
@@ -538,12 +543,13 @@ EXPLAIN (COSTS OFF)
 SELECT row_number() OVER (ORDER BY p <-> '333,400') n, p <-> '333,400' dist, p
 FROM kd_point_tbl WHERE p IS NOT NULL;
                                    QUERY PLAN                                   
--------------------------------------------------------
+--------------------------------------------------------------------------------
  WindowAgg
+   Window: w1 AS (ORDER BY (p <-> '(333,400)'::point) ROWS UNBOUNDED PRECEDING)
    ->  Index Only Scan using sp_kd_ind on kd_point_tbl
          Index Cond: (p IS NOT NULL)
          Order By: (p <-> '(333,400)'::point)
-(4 rows)
+(5 rows)
 
 CREATE TEMP TABLE kd_point_tbl_ord_idx3 AS
 SELECT row_number() OVER (ORDER BY p <-> '333,400') n, p <-> '333,400' dist, p

src/test/regress/expected/explain.out

@@ -243,6 +243,42 @@ select explain_filter('explain (buffers, format json) select * from int8_tbl i8'
  ]
 (1 row)
 
+-- Check expansion of window definitions
+select explain_filter('explain verbose select sum(unique1) over w, sum(unique2) over (w order by hundred), sum(tenthous) over (w order by hundred) from tenk1 window w as (partition by ten)');
+                                            explain_filter                                             
+-------------------------------------------------------------------------------------------------------
+ WindowAgg  (cost=N.N..N.N rows=N width=N)
+   Output: sum(unique1) OVER w, (sum(unique2) OVER w1), (sum(tenthous) OVER w1), ten, hundred
+   Window: w AS (PARTITION BY tenk1.ten)
+   ->  WindowAgg  (cost=N.N..N.N rows=N width=N)
+         Output: ten, hundred, unique1, unique2, tenthous, sum(unique2) OVER w1, sum(tenthous) OVER w1
+         Window: w1 AS (PARTITION BY tenk1.ten ORDER BY tenk1.hundred)
+         ->  Sort  (cost=N.N..N.N rows=N width=N)
+               Output: ten, hundred, unique1, unique2, tenthous
+               Sort Key: tenk1.ten, tenk1.hundred
+               ->  Seq Scan on public.tenk1  (cost=N.N..N.N rows=N width=N)
+                     Output: ten, hundred, unique1, unique2, tenthous
+(11 rows)
+
+select explain_filter('explain verbose select sum(unique1) over w1, sum(unique2) over (w1 order by hundred), sum(tenthous) over (w1 order by hundred rows 10 preceding) from tenk1 window w1 as (partition by ten)');
+                                             explain_filter                                              
+---------------------------------------------------------------------------------------------------------
+ WindowAgg  (cost=N.N..N.N rows=N width=N)
+   Output: sum(unique1) OVER w1, (sum(unique2) OVER w2), (sum(tenthous) OVER w3), ten, hundred
+   Window: w1 AS (PARTITION BY tenk1.ten)
+   ->  WindowAgg  (cost=N.N..N.N rows=N width=N)
+         Output: ten, hundred, unique1, unique2, tenthous, (sum(unique2) OVER w2), sum(tenthous) OVER w3
+         Window: w3 AS (PARTITION BY tenk1.ten ORDER BY tenk1.hundred ROWS 'N'::bigint PRECEDING)
+         ->  WindowAgg  (cost=N.N..N.N rows=N width=N)
+               Output: ten, hundred, unique1, unique2, tenthous, sum(unique2) OVER w2
+               Window: w2 AS (PARTITION BY tenk1.ten ORDER BY tenk1.hundred)
+               ->  Sort  (cost=N.N..N.N rows=N width=N)
+                     Output: ten, hundred, unique1, unique2, tenthous
+                     Sort Key: tenk1.ten, tenk1.hundred
+                     ->  Seq Scan on public.tenk1  (cost=N.N..N.N rows=N width=N)
+                           Output: ten, hundred, unique1, unique2, tenthous
+(14 rows)
+
 -- Check output including I/O timings.  These fields are conditional
 -- but always set in JSON format, so check them only in this case.
 set track_io_timing = on;
@@ -742,11 +778,12 @@ select explain_filter('explain (analyze,buffers off,costs off) select sum(n) ove
                                   explain_filter                                  
 ----------------------------------------------------------------------------------
  WindowAgg (actual time=N.N..N.N rows=N.N loops=N)
+   Window: w1 AS ()
    Storage: Memory  Maximum Storage: NkB
    ->  Function Scan on generate_series a (actual time=N.N..N.N rows=N.N loops=N)
  Planning Time: N.N ms
  Execution Time: N.N ms
-(5 rows)
+(6 rows)
 
 -- Test tuplestore storage usage in Window aggregate (disk case)
 set work_mem to 64;
@@ -754,17 +791,19 @@ select explain_filter('explain (analyze,buffers off,costs off) select sum(n) ove
                                   explain_filter                                  
 ----------------------------------------------------------------------------------
  WindowAgg (actual time=N.N..N.N rows=N.N loops=N)
+   Window: w1 AS ()
    Storage: Disk  Maximum Storage: NkB
    ->  Function Scan on generate_series a (actual time=N.N..N.N rows=N.N loops=N)
  Planning Time: N.N ms
  Execution Time: N.N ms
-(5 rows)
+(6 rows)
 
 -- Test tuplestore storage usage in Window aggregate (memory and disk case, final result is disk)
 select explain_filter('explain (analyze,buffers off,costs off) select sum(n) over(partition by m) from (SELECT n < 3 as m, n from generate_series(1,2000) a(n))');
                                      explain_filter                                     
 ----------------------------------------------------------------------------------------
  WindowAgg (actual time=N.N..N.N rows=N.N loops=N)
+   Window: w1 AS (PARTITION BY ((a.n < N)))
    Storage: Disk  Maximum Storage: NkB
    ->  Sort (actual time=N.N..N.N rows=N.N loops=N)
          Sort Key: ((a.n < N))
@@ -772,6 +811,6 @@ select explain_filter('explain (analyze,buffers off,costs off) select sum(n) ove
          ->  Function Scan on generate_series a (actual time=N.N..N.N rows=N.N loops=N)
  Planning Time: N.N ms
  Execution Time: N.N ms
-(8 rows)
+(9 rows)
 
 reset work_mem;

src/test/regress/expected/generated_virtual.out

@@ -1427,6 +1427,7 @@ order by t1.a;
  Sort
    Sort Key: t1.a
    ->  WindowAgg
+         Window: w1 AS (PARTITION BY t2.a)
          ->  Sort
                Sort Key: t2.a
                ->  Nested Loop Left Join
@@ -1434,7 +1435,7 @@ order by t1.a;
                      ->  Seq Scan on gtest32 t1
                      ->  Materialize
                            ->  Seq Scan on gtest32 t2
-(10 rows)
+(11 rows)
 
 select sum(t2.b) over (partition by t2.a),
        sum(t2.c) over (partition by t2.a),

src/test/regress/expected/groupingsets.out

@@ -1436,8 +1436,9 @@ explain (costs off)
                  QUERY PLAN                  
 ---------------------------------------------
  Sort
-   Sort Key: (sum((sum(c))) OVER (?)), a, b
+   Sort Key: (sum((sum(c))) OVER w1), a, b
    ->  WindowAgg
+         Window: w1 AS (ORDER BY a, b)
          ->  Sort
                Sort Key: a, b
                ->  MixedAggregate
@@ -1446,7 +1447,7 @@ explain (costs off)
                      Hash Key: b
                      Group Key: ()
                      ->  Seq Scan on gstest2
-(11 rows)
+(12 rows)
 
 select a, b, sum(v.x)
   from (values (1),(2)) v(x), gstest_data(v.x)
@@ -2428,8 +2429,9 @@ select a, b, row_number() over (order by a, b nulls first)
 from (values (1, 1), (2, 2)) as t (a, b) where a = b
 group by grouping sets((a, b), (a));
                                          QUERY PLAN                                         
-----------------------------------------------------------------------
+--------------------------------------------------------------------------------------------
  WindowAgg
+   Window: w1 AS (ORDER BY "*VALUES*".column1, "*VALUES*".column2 ROWS UNBOUNDED PRECEDING)
    ->  Sort
          Sort Key: "*VALUES*".column1, "*VALUES*".column2 NULLS FIRST
          ->  HashAggregate
@@ -2437,7 +2439,7 @@ group by grouping sets((a, b), (a));
                Hash Key: "*VALUES*".column1
                ->  Values Scan on "*VALUES*"
                      Filter: (column1 = column2)
-(8 rows)
+(9 rows)
 
 select a, b, row_number() over (order by a, b nulls first)
 from (values (1, 1), (2, 2)) as t (a, b) where a = b

src/test/regress/expected/partition_prune.out

@@ -4678,6 +4678,7 @@ select min(a) over (partition by a order by a) from part_abc where a >= stable_o
  Append
    ->  Subquery Scan on "*SELECT* 1_1"
          ->  WindowAgg
+               Window: w1 AS (PARTITION BY part_abc.a ORDER BY part_abc.a)
                ->  Append
                      Subplans Removed: 1
                      ->  Index Scan using part_abc_2_a_idx on part_abc_2 part_abc_1
@@ -4694,6 +4695,7 @@ select min(a) over (partition by a order by a) from part_abc where a >= stable_o
                                  Filter: (d <= stable_one())
    ->  Subquery Scan on "*SELECT* 2"
          ->  WindowAgg
+               Window: w1 AS (PARTITION BY part_abc_5.a ORDER BY part_abc_5.a)
                ->  Append
                      Subplans Removed: 1
                      ->  Index Scan using part_abc_2_a_idx on part_abc_2 part_abc_6
@@ -4708,7 +4710,7 @@ select min(a) over (partition by a order by a) from part_abc where a >= stable_o
                            ->  Index Scan using part_abc_3_3_a_idx on part_abc_3_3 part_abc_9
                                  Index Cond: (a >= (stable_one() + 1))
                                  Filter: (d >= stable_one())
-(33 rows)
+(35 rows)
 
 drop view part_abc_view;
 drop table part_abc;

src/test/regress/expected/polygon.out

@@ -286,10 +286,11 @@ FROM quad_poly_tbl WHERE p <@ polygon '((300,300),(400,600),(600,500),(700,200))
                                    QUERY PLAN                                    
 ---------------------------------------------------------------------------------
  WindowAgg
+   Window: w1 AS (ORDER BY (p <-> '(123,456)'::point) ROWS UNBOUNDED PRECEDING)
    ->  Index Scan using quad_poly_tbl_idx on quad_poly_tbl
          Index Cond: (p <@ '((300,300),(400,600),(600,500),(700,200))'::polygon)
          Order By: (p <-> '(123,456)'::point)
-(4 rows)
+(5 rows)
 
 CREATE TEMP TABLE quad_poly_tbl_ord_idx2 AS
 SELECT rank() OVER (ORDER BY p <-> point '123,456') n, p <-> point '123,456' dist, id

src/test/regress/expected/select_parallel.out

@@ -1130,9 +1130,10 @@ explain (costs off, verbose)
  Aggregate
    Output: count(*)
    ->  Hash Right Semi Join
-         Hash Cond: ((b.unique1 = a.unique1) AND ((row_number() OVER (?)) = a.two))
+         Hash Cond: ((b.unique1 = a.unique1) AND ((row_number() OVER w1) = a.two))
          ->  WindowAgg
-               Output: b.unique1, row_number() OVER (?)
+               Output: b.unique1, row_number() OVER w1
+               Window: w1 AS (ROWS UNBOUNDED PRECEDING)
                ->  Gather
                      Output: b.unique1
                      Workers Planned: 4
@@ -1145,7 +1146,7 @@ explain (costs off, verbose)
                      Workers Planned: 4
                      ->  Parallel Seq Scan on public.tenk1 a
                            Output: a.unique1, a.two
-(18 rows)
+(19 rows)
 
 -- LIMIT/OFFSET within sub-selects can't be pushed to workers.
 explain (costs off)

src/test/regress/expected/sqljson.out

@@ -1012,16 +1012,17 @@ EXPLAIN (VERBOSE, COSTS OFF)
 SELECT JSON_OBJECTAGG(i: ('111' || i)::bytea FORMAT JSON WITH UNIQUE RETURNING text) OVER (PARTITION BY i % 2)
 FROM generate_series(1,5) i;
                                                             QUERY PLAN                                                            
------------------------------------------------------------------------------------------------------------------------------------
+----------------------------------------------------------------------------------------------------------------------------------
  WindowAgg
-   Output: JSON_OBJECTAGG(i : (('111'::text || (i)::text))::bytea FORMAT JSON WITH UNIQUE KEYS RETURNING text) OVER (?), ((i % 2))
+   Output: JSON_OBJECTAGG(i : (('111'::text || (i)::text))::bytea FORMAT JSON WITH UNIQUE KEYS RETURNING text) OVER w1, ((i % 2))
+   Window: w1 AS (PARTITION BY ((i.i % 2)))
    ->  Sort
          Output: ((i % 2)), i
          Sort Key: ((i.i % 2))
          ->  Function Scan on pg_catalog.generate_series i
                Output: (i % 2), i
                Function Call: generate_series(1, 5)
-(8 rows)
+(9 rows)
 
 CREATE VIEW json_objectagg_view AS
 SELECT JSON_OBJECTAGG(i: ('111' || i)::bytea FORMAT JSON WITH UNIQUE RETURNING text) FILTER (WHERE i > 3)
@@ -1048,16 +1049,17 @@ EXPLAIN (VERBOSE, COSTS OFF)
 SELECT JSON_ARRAYAGG(('111' || i)::bytea FORMAT JSON NULL ON NULL RETURNING text) OVER (PARTITION BY i % 2)
 FROM generate_series(1,5) i;
                                                        QUERY PLAN                                                        
---------------------------------------------------------------------------------------------------------------------------
+-------------------------------------------------------------------------------------------------------------------------
  WindowAgg
-   Output: JSON_ARRAYAGG((('111'::text || (i)::text))::bytea FORMAT JSON NULL ON NULL RETURNING text) OVER (?), ((i % 2))
+   Output: JSON_ARRAYAGG((('111'::text || (i)::text))::bytea FORMAT JSON NULL ON NULL RETURNING text) OVER w1, ((i % 2))
+   Window: w1 AS (PARTITION BY ((i.i % 2)))
    ->  Sort
          Output: ((i % 2)), i
          Sort Key: ((i.i % 2))
          ->  Function Scan on pg_catalog.generate_series i
                Output: (i % 2), i
                Function Call: generate_series(1, 5)
-(8 rows)
+(9 rows)
 
 CREATE VIEW json_arrayagg_view AS
 SELECT JSON_ARRAYAGG(('111' || i)::bytea FORMAT JSON NULL ON NULL RETURNING text) FILTER (WHERE i > 3)

src/test/regress/expected/window.out

@@ -652,10 +652,11 @@ select first_value(max(x)) over (), y
                  QUERY PLAN                  
 ---------------------------------------------
  WindowAgg
+   Window: w1 AS ()
    ->  HashAggregate
          Group Key: (tenk1.ten + tenk1.four)
          ->  Seq Scan on tenk1
-(4 rows)
+(5 rows)
 
 -- window functions returning pass-by-ref values from different rows
 select x, lag(x, 1) over (order by x), lead(x, 3) over (order by x)
@@ -3538,13 +3539,14 @@ select f1, sum(f1) over (partition by f1 order by f2
                          range between 1 preceding and 1 following)
 from t1 where f1 = f2;
                                                  QUERY PLAN                                                  
----------------------------------
+-------------------------------------------------------------------------------------------------------------
  WindowAgg
+   Window: w1 AS (PARTITION BY f1 ORDER BY f2 RANGE BETWEEN '1'::bigint PRECEDING AND '1'::bigint FOLLOWING)
    ->  Sort
          Sort Key: f1
          ->  Seq Scan on t1
                Filter: (f1 = f2)
-(5 rows)
+(6 rows)
 
 select f1, sum(f1) over (partition by f1 order by f2
                          range between 1 preceding and 1 following)
@@ -3584,13 +3586,14 @@ select f1, sum(f1) over (partition by f1 order by f2
                          groups between 1 preceding and 1 following)
 from t1 where f1 = f2;
                                                   QUERY PLAN                                                  
----------------------------------
+--------------------------------------------------------------------------------------------------------------
  WindowAgg
+   Window: w1 AS (PARTITION BY f1 ORDER BY f2 GROUPS BETWEEN '1'::bigint PRECEDING AND '1'::bigint FOLLOWING)
    ->  Sort
          Sort Key: f1
          ->  Seq Scan on t1
                Filter: (f1 = f2)
-(5 rows)
+(6 rows)
 
 select f1, sum(f1) over (partition by f1 order by f2
                          groups between 1 preceding and 1 following)
@@ -3712,12 +3715,13 @@ SELECT
                       CURRENT ROW AND UNBOUNDED FOLLOWING) cd
 FROM empsalary;
                                       QUERY PLAN                                      
-----------------------------------------
+--------------------------------------------------------------------------------------
  WindowAgg
+   Window: w1 AS (PARTITION BY depname ORDER BY enroll_date ROWS UNBOUNDED PRECEDING)
    ->  Sort
          Sort Key: depname, enroll_date
          ->  Seq Scan on empsalary
-(4 rows)
+(5 rows)
 
 -- Ensure WindowFuncs which cannot support their WindowClause's frameOptions
 -- being changed are untouched
@@ -3732,17 +3736,19 @@ SELECT
                    CURRENT ROW AND CURRENT ROW) cnt
 FROM empsalary;
                                                         QUERY PLAN                                                         
-------------------------------------------------------------------------------------------------------
+---------------------------------------------------------------------------------------------------------------------------
  WindowAgg
-   Output: empno, depname, (row_number() OVER (?)), (rank() OVER (?)), count(*) OVER (?), enroll_date
+   Output: empno, depname, (row_number() OVER w1), (rank() OVER w1), count(*) OVER w2, enroll_date
+   Window: w2 AS (PARTITION BY empsalary.depname ORDER BY empsalary.enroll_date RANGE BETWEEN CURRENT ROW AND CURRENT ROW)
    ->  WindowAgg
-         Output: depname, enroll_date, empno, row_number() OVER (?), rank() OVER (?)
+         Output: depname, enroll_date, empno, row_number() OVER w1, rank() OVER w1
+         Window: w1 AS (PARTITION BY empsalary.depname ORDER BY empsalary.enroll_date ROWS UNBOUNDED PRECEDING)
          ->  Sort
                Output: depname, enroll_date, empno
                Sort Key: empsalary.depname, empsalary.enroll_date
                ->  Seq Scan on pg_temp.empsalary
                      Output: depname, enroll_date, empno
-(9 rows)
+(11 rows)
 
 -- Ensure the above query gives us the expected results
 SELECT
@@ -3778,15 +3784,17 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE depname = 'sales';
                                       QUERY PLAN                                       
---------------------------------------------------------------------------
+---------------------------------------------------------------------------------------
  Subquery Scan on emp
    ->  WindowAgg
+         Window: w2 AS ()
          ->  WindowAgg
+               Window: w1 AS (PARTITION BY (((empsalary.depname)::text || 'A'::text)))
                ->  Sort
                      Sort Key: (((empsalary.depname)::text || 'A'::text))
                      ->  Seq Scan on empsalary
                            Filter: ((depname)::text = 'sales'::text)
-(7 rows)
+(9 rows)
 
 -- pushdown is unsafe because there's a PARTITION BY clause without depname:
 EXPLAIN (COSTS OFF)
@@ -3797,17 +3805,19 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE depname = 'sales';
                              QUERY PLAN                             
--------------------------------------------------------
+--------------------------------------------------------------------
  Subquery Scan on emp
    Filter: ((emp.depname)::text = 'sales'::text)
    ->  WindowAgg
+         Window: w2 AS (PARTITION BY empsalary.enroll_date)
          ->  Sort
                Sort Key: empsalary.enroll_date
                ->  WindowAgg
+                     Window: w1 AS (PARTITION BY empsalary.depname)
                      ->  Sort
                            Sort Key: empsalary.depname
                            ->  Seq Scan on empsalary
-(9 rows)
+(11 rows)
 
 -- Test window function run conditions are properly pushed down into the
 -- WindowAgg
@@ -3818,13 +3828,14 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE rn < 3;
                              QUERY PLAN                              
-----------------------------------------------
+---------------------------------------------------------------------
  WindowAgg
-   Run Condition: (row_number() OVER (?) < 3)
+   Window: w1 AS (ORDER BY empsalary.empno ROWS UNBOUNDED PRECEDING)
+   Run Condition: (row_number() OVER w1 < 3)
    ->  Sort
          Sort Key: empsalary.empno
          ->  Seq Scan on empsalary
-(5 rows)
+(6 rows)
 
 -- The following 3 statements should result the same result.
 SELECT * FROM
@@ -3869,13 +3880,14 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE r <= 3;
                               QUERY PLAN                              
------------------------------------------
+----------------------------------------------------------------------
  WindowAgg
-   Run Condition: (rank() OVER (?) <= 3)
+   Window: w1 AS (ORDER BY empsalary.salary ROWS UNBOUNDED PRECEDING)
+   Run Condition: (rank() OVER w1 <= 3)
    ->  Sort
          Sort Key: empsalary.salary DESC
          ->  Seq Scan on empsalary
-(5 rows)
+(6 rows)
 
 SELECT * FROM
   (SELECT empno,
@@ -3899,15 +3911,16 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE dr = 1;
                                  QUERY PLAN                                 
------------------------------------------------------
+----------------------------------------------------------------------------
  Subquery Scan on emp
    Filter: (emp.dr = 1)
    ->  WindowAgg
-         Run Condition: (dense_rank() OVER (?) <= 1)
+         Window: w1 AS (ORDER BY empsalary.salary ROWS UNBOUNDED PRECEDING)
+         Run Condition: (dense_rank() OVER w1 <= 1)
          ->  Sort
                Sort Key: empsalary.salary DESC
                ->  Seq Scan on empsalary
-(7 rows)
+(8 rows)
 
 SELECT * FROM
   (SELECT empno,
@@ -3929,13 +3942,14 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE c <= 3;
                  QUERY PLAN                  
--------------------------------------------
+---------------------------------------------
  WindowAgg
-   Run Condition: (count(*) OVER (?) <= 3)
+   Window: w1 AS (ORDER BY empsalary.salary)
+   Run Condition: (count(*) OVER w1 <= 3)
    ->  Sort
          Sort Key: empsalary.salary DESC
          ->  Seq Scan on empsalary
-(5 rows)
+(6 rows)
 
 SELECT * FROM
   (SELECT empno,
@@ -3958,13 +3972,14 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE c <= 3;
                        QUERY PLAN                       
----------------------------------------------------------
+--------------------------------------------------------
  WindowAgg
-   Run Condition: (count(empsalary.empno) OVER (?) <= 3)
+   Window: w1 AS (ORDER BY empsalary.salary)
+   Run Condition: (count(empsalary.empno) OVER w1 <= 3)
    ->  Sort
          Sort Key: empsalary.salary DESC
          ->  Seq Scan on empsalary
-(5 rows)
+(6 rows)
 
 SELECT * FROM
   (SELECT empno,
@@ -3987,13 +4002,14 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE c >= 3;
                                           QUERY PLAN                                          
--------------------------------------------
+----------------------------------------------------------------------------------------------
  WindowAgg
-   Run Condition: (count(*) OVER (?) >= 3)
+   Window: w1 AS (ORDER BY empsalary.salary ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING)
+   Run Condition: (count(*) OVER w1 >= 3)
    ->  Sort
          Sort Key: empsalary.salary DESC
          ->  Seq Scan on empsalary
-(5 rows)
+(6 rows)
 
 EXPLAIN (COSTS OFF)
 SELECT * FROM
@@ -4003,11 +4019,12 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE 11 <= c;
                 QUERY PLAN                 
---------------------------------------------
+-------------------------------------------
  WindowAgg
-   Run Condition: (11 <= count(*) OVER (?))
+   Window: w1 AS ()
+   Run Condition: (11 <= count(*) OVER w1)
    ->  Seq Scan on empsalary
-(3 rows)
+(4 rows)
 
 EXPLAIN (COSTS OFF)
 SELECT * FROM
@@ -4018,15 +4035,16 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE dr = 1;
                      QUERY PLAN                     
------------------------------------------------------
+----------------------------------------------------
  Subquery Scan on emp
    Filter: (emp.dr = 1)
    ->  WindowAgg
-         Run Condition: (dense_rank() OVER (?) <= 1)
+         Window: w1 AS (ORDER BY empsalary.salary)
+         Run Condition: (dense_rank() OVER w1 <= 1)
          ->  Sort
                Sort Key: empsalary.salary DESC
                ->  Seq Scan on empsalary
-(7 rows)
+(8 rows)
 
 -- Ensure we get a run condition when there's a PARTITION BY clause
 EXPLAIN (COSTS OFF)
@@ -4037,13 +4055,14 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE rn < 3;
                                              QUERY PLAN                                             
-------------------------------------------------------
+----------------------------------------------------------------------------------------------------
  WindowAgg
-   Run Condition: (row_number() OVER (?) < 3)
+   Window: w1 AS (PARTITION BY empsalary.depname ORDER BY empsalary.empno ROWS UNBOUNDED PRECEDING)
+   Run Condition: (row_number() OVER w1 < 3)
    ->  Sort
          Sort Key: empsalary.depname, empsalary.empno
          ->  Seq Scan on empsalary
-(5 rows)
+(6 rows)
 
 -- and ensure we get the correct results from the above plan
 SELECT * FROM
@@ -4072,14 +4091,15 @@ SELECT empno, depname FROM
    FROM empsalary) emp
 WHERE rn < 3;
                                                 QUERY PLAN                                                
-------------------------------------------------------------
+----------------------------------------------------------------------------------------------------------
  Subquery Scan on emp
    ->  WindowAgg
-         Run Condition: (row_number() OVER (?) < 3)
+         Window: w1 AS (PARTITION BY empsalary.depname ORDER BY empsalary.empno ROWS UNBOUNDED PRECEDING)
+         Run Condition: (row_number() OVER w1 < 3)
          ->  Sort
                Sort Key: empsalary.depname, empsalary.empno
                ->  Seq Scan on empsalary
-(6 rows)
+(7 rows)
 
 -- likewise with count(empno) instead of row_number()
 EXPLAIN (COSTS OFF)
@@ -4091,13 +4111,14 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE c <= 3;
                                  QUERY PLAN                                 
-------------------------------------------------------------
+----------------------------------------------------------------------------
  WindowAgg
-   Run Condition: (count(empsalary.empno) OVER (?) <= 3)
+   Window: w1 AS (PARTITION BY empsalary.depname ORDER BY empsalary.salary)
+   Run Condition: (count(empsalary.empno) OVER w1 <= 3)
    ->  Sort
          Sort Key: empsalary.depname, empsalary.salary DESC
          ->  Seq Scan on empsalary
-(5 rows)
+(6 rows)
 
 -- and again, check the results are what we expect.
 SELECT * FROM
@@ -4130,11 +4151,12 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE c = 1;
                       QUERY PLAN                       
---------------------------------------------------------
+-------------------------------------------------------
  WindowAgg
-   Run Condition: (count(empsalary.empno) OVER (?) = 1)
+   Window: w1 AS ()
+   Run Condition: (count(empsalary.empno) OVER w1 = 1)
    ->  Seq Scan on empsalary
-(3 rows)
+(4 rows)
 
 -- Try another case with a WindowFunc with a byref return type
 SELECT * FROM
@@ -4158,22 +4180,25 @@ SELECT * FROM
    FROM empsalary
 ) e WHERE rn <= 1 AND c1 <= 3 AND nt < 2;
                                                QUERY PLAN                                               
------------------------------------------------------------------------------------------------
+--------------------------------------------------------------------------------------------------------
  Subquery Scan on e
    ->  WindowAgg
-         Filter: (((row_number() OVER (?)) <= 1) AND ((ntile(2) OVER (?)) < 2))
-         Run Condition: (count(empsalary.salary) OVER (?) <= 3)
+         Window: w3 AS (PARTITION BY (((empsalary.depname)::text || ''::text)))
+         Run Condition: (count(empsalary.salary) OVER w3 <= 3)
+         Filter: (((row_number() OVER w2) <= 1) AND ((ntile(2) OVER w2) < 2))
          ->  Sort
                Sort Key: (((empsalary.depname)::text || ''::text))
                ->  WindowAgg
-                     Run Condition: ((row_number() OVER (?) <= 1) AND (ntile(2) OVER (?) < 2))
+                     Window: w2 AS (PARTITION BY empsalary.depname)
+                     Run Condition: ((row_number() OVER w2 <= 1) AND (ntile(2) OVER w2 < 2))
                      ->  Sort
                            Sort Key: empsalary.depname
                            ->  WindowAgg
+                                 Window: w1 AS (PARTITION BY ((''::text || (empsalary.depname)::text)))
                                  ->  Sort
                                        Sort Key: ((''::text || (empsalary.depname)::text))
                                        ->  Seq Scan on empsalary
-(14 rows)
+(17 rows)
 
 -- Ensure we correctly filter out all of the run conditions from each window
 SELECT * FROM
@@ -4200,11 +4225,12 @@ SELECT 1 FROM
    WHERE e1.empno = e2.empno) s
 WHERE s.c = 1;
                                 QUERY PLAN                                
----------------------------------------------------------
+--------------------------------------------------------------------------
  Subquery Scan on s
    Filter: (s.c = 1)
    ->  WindowAgg
-         Run Condition: (ntile(e2.salary) OVER (?) <= 1)
+         Window: w1 AS (PARTITION BY e1.depname ROWS UNBOUNDED PRECEDING)
+         Run Condition: (ntile(e2.salary) OVER w1 <= 1)
          ->  Sort
                Sort Key: e1.depname
                ->  Merge Join
@@ -4215,7 +4241,7 @@ WHERE s.c = 1;
                      ->  Sort
                            Sort Key: e2.empno
                            ->  Seq Scan on empsalary e2
-(14 rows)
+(15 rows)
 
 -- Ensure the run condition optimization is used in cases where the WindowFunc
 -- has a Var from another query level
@@ -4225,15 +4251,16 @@ SELECT 1 FROM
    FROM (SELECT (SELECT 1) AS x) AS s1) s
 WHERE s.c = 1;
                            QUERY PLAN                           
------------------------------------------------------------------
+----------------------------------------------------------------
  Subquery Scan on s
    Filter: (s.c = 1)
    ->  WindowAgg
-         Run Condition: (ntile((InitPlan 1).col1) OVER (?) <= 1)
+         Window: w1 AS (ROWS UNBOUNDED PRECEDING)
+         Run Condition: (ntile((InitPlan 1).col1) OVER w1 <= 1)
          InitPlan 1
            ->  Result
          ->  Result
-(7 rows)
+(8 rows)
 
 -- Tests to ensure we don't push down the run condition when it's not valid to
 -- do so.
@@ -4247,14 +4274,15 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE c <= 3;
                                              QUERY PLAN                                             
------------------------------------------------
+----------------------------------------------------------------------------------------------------
  Subquery Scan on emp
    Filter: (emp.c <= 3)
    ->  WindowAgg
+         Window: w1 AS (ORDER BY empsalary.salary ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING)
          ->  Sort
                Sort Key: empsalary.salary DESC
                ->  Seq Scan on empsalary
-(6 rows)
+(7 rows)
 
 -- Ensure we don't push down when the window function's monotonic properties
 -- don't match that of the clauses.
@@ -4266,14 +4294,15 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE 3 <= c;
                     QUERY PLAN                     
-------------------------------------------
+---------------------------------------------------
  Subquery Scan on emp
    Filter: (3 <= emp.c)
    ->  WindowAgg
+         Window: w1 AS (ORDER BY empsalary.salary)
          ->  Sort
                Sort Key: empsalary.salary
                ->  Seq Scan on empsalary
-(6 rows)
+(7 rows)
 
 -- Ensure we don't use a run condition when there's a volatile function in the
 -- WindowFunc
@@ -4285,14 +4314,15 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE c = 1;
                     QUERY PLAN                    
-----------------------------------------------
+--------------------------------------------------
  Subquery Scan on emp
    Filter: (emp.c = 1)
    ->  WindowAgg
+         Window: w1 AS (ORDER BY empsalary.empno)
          ->  Sort
                Sort Key: empsalary.empno DESC
                ->  Seq Scan on empsalary
-(6 rows)
+(7 rows)
 
 -- Ensure we don't use a run condition when the WindowFunc contains subplans
 EXPLAIN (COSTS OFF)
@@ -4303,16 +4333,17 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE c = 1;
                     QUERY PLAN                    
-----------------------------------------------
+--------------------------------------------------
  Subquery Scan on emp
    Filter: (emp.c = 1)
    ->  WindowAgg
+         Window: w1 AS (ORDER BY empsalary.empno)
          InitPlan 1
            ->  Result
          ->  Sort
                Sort Key: empsalary.empno DESC
                ->  Seq Scan on empsalary
-(8 rows)
+(9 rows)
 
 -- Test Sort node collapsing
 EXPLAIN (COSTS OFF)
@@ -4323,15 +4354,17 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE depname = 'sales';
                                         QUERY PLAN                                         
-----------------------------------------------------------------------
+-------------------------------------------------------------------------------------------
  Subquery Scan on emp
    ->  WindowAgg
+         Window: w2 AS (ORDER BY empsalary.empno)
          ->  WindowAgg
+               Window: w1 AS (PARTITION BY empsalary.empno ORDER BY empsalary.enroll_date)
                ->  Sort
                      Sort Key: empsalary.empno, empsalary.enroll_date
                      ->  Seq Scan on empsalary
                            Filter: ((depname)::text = 'sales'::text)
-(7 rows)
+(9 rows)
 
 -- Ensure that the evaluation order of the WindowAggs results in the WindowAgg
 -- with the same sort order that's required by the ORDER BY is evaluated last.
@@ -4344,16 +4377,18 @@ SELECT empno,
 FROM empsalary
 ORDER BY depname, empno;
                                QUERY PLAN                                
-----------------------------------------------------
+-------------------------------------------------------------------------
  WindowAgg
+   Window: w2 AS (PARTITION BY depname ORDER BY empno)
    ->  Incremental Sort
          Sort Key: depname, empno
          Presorted Key: depname
          ->  WindowAgg
+               Window: w1 AS (PARTITION BY depname ORDER BY enroll_date)
                ->  Sort
                      Sort Key: depname, enroll_date
                      ->  Seq Scan on empsalary
-(8 rows)
+(10 rows)
 
 -- As above, but with an adjusted ORDER BY to ensure the above plan didn't
 -- perform only 2 sorts by accident.
@@ -4366,16 +4401,18 @@ SELECT empno,
 FROM empsalary
 ORDER BY depname, enroll_date;
                             QUERY PLAN                             
------------------------------------------------
+-------------------------------------------------------------------
  WindowAgg
+   Window: w2 AS (PARTITION BY depname ORDER BY enroll_date)
    ->  Incremental Sort
          Sort Key: depname, enroll_date
          Presorted Key: depname
          ->  WindowAgg
+               Window: w1 AS (PARTITION BY depname ORDER BY empno)
                ->  Sort
                      Sort Key: depname, empno
                      ->  Seq Scan on empsalary
-(8 rows)
+(10 rows)
 
 SET enable_hashagg TO off;
 -- Ensure we don't get a sort for both DISTINCT and ORDER BY.  We expect the
@@ -4390,20 +4427,22 @@ SELECT DISTINCT
 FROM empsalary
 ORDER BY depname, enroll_date;
                                          QUERY PLAN                                          
------------------------------------------------------------------------------------------------
+---------------------------------------------------------------------------------------------
  Unique
    ->  Incremental Sort
-         Sort Key: depname, enroll_date, empno, (sum(salary) OVER (?)), (min(salary) OVER (?))
+         Sort Key: depname, enroll_date, empno, (sum(salary) OVER w1), (min(salary) OVER w2)
          Presorted Key: depname, enroll_date
          ->  WindowAgg
+               Window: w2 AS (PARTITION BY depname ORDER BY enroll_date)
                ->  Incremental Sort
                      Sort Key: depname, enroll_date
                      Presorted Key: depname
                      ->  WindowAgg
+                           Window: w1 AS (PARTITION BY depname ORDER BY empno)
                            ->  Sort
                                  Sort Key: depname, empno
                                  ->  Seq Scan on empsalary
-(12 rows)
+(14 rows)
 
 -- As above but adjust the ORDER BY clause to help ensure the plan with the
 -- minimum amount of sorting wasn't a fluke.
@@ -4417,20 +4456,22 @@ SELECT DISTINCT
 FROM empsalary
 ORDER BY depname, empno;
                                          QUERY PLAN                                          
------------------------------------------------------------------------------------------------
+---------------------------------------------------------------------------------------------
  Unique
    ->  Incremental Sort
-         Sort Key: depname, empno, enroll_date, (sum(salary) OVER (?)), (min(salary) OVER (?))
+         Sort Key: depname, empno, enroll_date, (sum(salary) OVER w2), (min(salary) OVER w1)
          Presorted Key: depname, empno
          ->  WindowAgg
+               Window: w2 AS (PARTITION BY depname ORDER BY empno)
                ->  Incremental Sort
                      Sort Key: depname, empno
                      Presorted Key: depname
                      ->  WindowAgg
+                           Window: w1 AS (PARTITION BY depname ORDER BY enroll_date)
                            ->  Sort
                                  Sort Key: depname, enroll_date
                                  ->  Seq Scan on empsalary
-(12 rows)
+(14 rows)
 
 RESET enable_hashagg;
 -- Test Sort node reordering
@@ -4440,13 +4481,15 @@ SELECT
   lag(1) OVER (PARTITION BY depname ORDER BY salary,enroll_date,empno)
 FROM empsalary;
                                     QUERY PLAN                                    
--------------------------------------------------------------
+----------------------------------------------------------------------------------
  WindowAgg
+   Window: w2 AS (PARTITION BY depname ORDER BY salary, enroll_date)
    ->  WindowAgg
+         Window: w1 AS (PARTITION BY depname ORDER BY salary, enroll_date, empno)
          ->  Sort
                Sort Key: depname, salary, enroll_date, empno
                ->  Seq Scan on empsalary
-(5 rows)
+(7 rows)
 
 -- Test incremental sorting
 EXPLAIN (COSTS OFF)
@@ -4460,18 +4503,20 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE first_emp = 1 OR last_emp = 1;
                                                          QUERY PLAN                                                         
------------------------------------------------------------------------------------
+----------------------------------------------------------------------------------------------------------------------------
  Subquery Scan on emp
    Filter: ((emp.first_emp = 1) OR (emp.last_emp = 1))
    ->  WindowAgg
+         Window: w2 AS (PARTITION BY empsalary.depname ORDER BY empsalary.enroll_date ROWS UNBOUNDED PRECEDING)
          ->  Incremental Sort
                Sort Key: empsalary.depname, empsalary.enroll_date
                Presorted Key: empsalary.depname
                ->  WindowAgg
+                     Window: w1 AS (PARTITION BY empsalary.depname ORDER BY empsalary.enroll_date ROWS UNBOUNDED PRECEDING)
                      ->  Sort
                            Sort Key: empsalary.depname, empsalary.enroll_date DESC
                            ->  Seq Scan on empsalary
-(10 rows)
+(12 rows)
 
 SELECT * FROM
   (SELECT depname,
@@ -5299,11 +5344,12 @@ LIMIT 1;
 --------------------------------------------------------------------------
  Limit
    ->  WindowAgg
+         Window: w1 AS (ORDER BY t1.unique1)
          ->  Nested Loop
                ->  Index Only Scan using tenk1_unique1 on tenk1 t1
                ->  Index Only Scan using tenk1_thous_tenthous on tenk1 t2
                      Index Cond: (tenthous = t1.unique1)
-(6 rows)
+(7 rows)
 
 -- Ensure we get a cheap total plan.  Lack of ORDER BY in the WindowClause
 -- means that all rows must be read from the join, so a cheap startup plan
@@ -5317,13 +5363,14 @@ LIMIT 1;
 -------------------------------------------------------------------
  Limit
    ->  WindowAgg
+         Window: w1 AS ()
          ->  Hash Join
                Hash Cond: (t1.unique1 = t2.tenthous)
                ->  Index Only Scan using tenk1_unique1 on tenk1 t1
                ->  Hash
                      ->  Seq Scan on tenk1 t2
                            Filter: (two = 1)
-(8 rows)
+(9 rows)
 
 -- Ensure we get a cheap total plan.  This time use UNBOUNDED FOLLOWING, which
 -- needs to read all join rows to output the first WindowAgg row.
@@ -5332,16 +5379,17 @@ SELECT COUNT(*) OVER (ORDER BY t1.unique1 ROWS BETWEEN UNBOUNDED PRECEDING AND U
 FROM tenk1 t1 INNER JOIN tenk1 t2 ON t1.unique1 = t2.tenthous
 LIMIT 1;
                                               QUERY PLAN                                              
---------------------------------------------------------------------------------
+------------------------------------------------------------------------------------------------------
  Limit
    ->  WindowAgg
+         Window: w1 AS (ORDER BY t1.unique1 ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING)
          ->  Merge Join
                Merge Cond: (t1.unique1 = t2.tenthous)
                ->  Index Only Scan using tenk1_unique1 on tenk1 t1
                ->  Sort
                      Sort Key: t2.tenthous
                      ->  Index Only Scan using tenk1_thous_tenthous on tenk1 t2
-(8 rows)
+(9 rows)
 
 -- Ensure we get a cheap total plan.  This time use 10000 FOLLOWING so we need
 -- to read all join rows.
@@ -5350,16 +5398,17 @@ SELECT COUNT(*) OVER (ORDER BY t1.unique1 ROWS BETWEEN UNBOUNDED PRECEDING AND 1
 FROM tenk1 t1 INNER JOIN tenk1 t2 ON t1.unique1 = t2.tenthous
 LIMIT 1;
                                                  QUERY PLAN                                                 
---------------------------------------------------------------------------------
+------------------------------------------------------------------------------------------------------------
  Limit
    ->  WindowAgg
+         Window: w1 AS (ORDER BY t1.unique1 ROWS BETWEEN UNBOUNDED PRECEDING AND '10000'::bigint FOLLOWING)
          ->  Merge Join
                Merge Cond: (t1.unique1 = t2.tenthous)
                ->  Index Only Scan using tenk1_unique1 on tenk1 t1
                ->  Sort
                      Sort Key: t2.tenthous
                      ->  Index Only Scan using tenk1_thous_tenthous on tenk1 t2
-(8 rows)
+(9 rows)
 
 -- Tests for problems with failure to walk or mutate expressions
 -- within window frame clauses.
@@ -5385,13 +5434,14 @@ AS $$
 $$ LANGUAGE SQL STABLE;
 EXPLAIN (costs off) SELECT * FROM pg_temp.f(2);
                                        QUERY PLAN                                       
-------------------------------------------------------
+----------------------------------------------------------------------------------------
  Subquery Scan on f
    ->  WindowAgg
+         Window: w AS (ORDER BY s.s ROWS BETWEEN CURRENT ROW AND '2'::bigint FOLLOWING)
          ->  Sort
                Sort Key: s.s
                ->  Function Scan on generate_series s
-(5 rows)
+(6 rows)
 
 SELECT * FROM pg_temp.f(2);
     f    

src/test/regress/sql/explain.sql

@@ -70,6 +70,11 @@ select explain_filter('explain (analyze, serialize, buffers, format yaml) select
 select explain_filter('explain (buffers, format text) select * from int8_tbl i8');
 select explain_filter('explain (buffers, format json) select * from int8_tbl i8');
 
+-- Check expansion of window definitions
+
+select explain_filter('explain verbose select sum(unique1) over w, sum(unique2) over (w order by hundred), sum(tenthous) over (w order by hundred) from tenk1 window w as (partition by ten)');
+select explain_filter('explain verbose select sum(unique1) over w1, sum(unique2) over (w1 order by hundred), sum(tenthous) over (w1 order by hundred rows 10 preceding) from tenk1 window w1 as (partition by ten)');
+
 -- Check output including I/O timings.  These fields are conditional
 -- but always set in JSON format, so check them only in this case.
 set track_io_timing = on;