Add some basic support for window frame clauses to the window-functions

patch.  This includes the ability to force the frame to cover the whole
partition, and the ability to make the frame end exactly on the current row
rather than its last ORDER BY peer.  Supporting any more of the full SQL
frame-clause syntax will require nontrivial hacking on the window aggregate
code, so it'll have to wait for 8.5 or beyond.

doc/src/sgml/advanced.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/advanced.sgml,v 1.55 2008/12/28 18:53:53 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/advanced.sgml,v 1.56 2008/12/31 00:08:32 tgl Exp $ -->
 
  <chapter id="tutorial-advanced">
   <title>Advanced Features</title>
@@ -429,27 +429,27 @@ SELECT depname, empno, salary, rank() OVER (PARTITION BY depname ORDER BY salary
    <para>
     We already saw that <literal>ORDER BY</> can be omitted if the ordering
     of rows is not important.  It is also possible to omit <literal>PARTITION
-    BY</>, in which case the window function is computed over all rows of the
-    virtual table; that is, there is one partition containing all the rows.
+    BY</>, in which case there is just one partition containing all the rows.
    </para>
 
    <para>
     There is another important concept associated with window functions:
     for each row, there is a set of rows within its partition called its
-    <firstterm>window frame</>.  When <literal>ORDER BY</> is omitted the
-    frame is always the same as the partition.  If <literal>ORDER BY</> is
-    supplied, the frame consists of all rows from the start of the partition
-    up to the current row, plus any following rows that are equal to the
-    current row according to the <literal>ORDER BY</> clause.
+    <firstterm>window frame</>.  Many (but not all) window functions act only
+    on the rows of the window frame, rather than of the whole partition.
+    By default, if <literal>ORDER BY</> is supplied then the frame consists of
+    all rows from the start of the partition up through the current row, plus
+    any following rows that are equal to the current row according to the
+    <literal>ORDER BY</> clause.  When <literal>ORDER BY</> is omitted the
+    default frame consists of all rows in the partition.
      <footnote>
       <para>
-       The SQL standard includes options to define the window frame in
-       other ways, but this definition is the only one currently supported
-       by <productname>PostgreSQL</productname>.
+       There are options to define the window frame in other ways, but
+       this tutorial does not cover them.  See
+       <xref linkend="syntax-window-functions"> for details.
       </para>
      </footnote>
-    Many window functions act only on the rows of the window frame, rather
-    than of the whole partition.  Here is an example using <function>sum</>:
+    Here is an example using <function>sum</>:
    </para>
 
 <programlisting>
@@ -550,6 +550,13 @@ SELECT sum(salary) OVER w, avg(salary) OVER w
   WINDOW w AS (PARTITION BY depname ORDER BY salary DESC);
 </programlisting>
    </para>
+
+   <para>
+    More details about window functions can be found in
+    <xref linkend="syntax-window-functions">,
+    <xref linkend="queries-window">, and the
+    <xref linkend="sql-select" endterm="sql-select-title"> reference page.
+   </para>
   </sect1>
 
 

doc/src/sgml/func.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.464 2008/12/28 18:53:53 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.465 2008/12/31 00:08:33 tgl Exp $ -->
 
  <chapter id="functions">
   <title>Functions and Operators</title>
@@ -10160,9 +10160,8 @@ SELECT xmlagg(x) FROM (SELECT x FROM test ORDER BY y DESC) AS tab;
   <para>
    <firstterm>Window functions</firstterm> provide the ability to perform
    calculations across sets of rows that are related to the current query
-   row.  For information about this feature see
-   <xref linkend="tutorial-window"> and
-   <xref linkend="syntax-window-functions">.
+   row.  See <xref linkend="tutorial-window"> for an introduction to this
+   feature.
   </para>
 
   <para>
@@ -10392,18 +10391,23 @@ SELECT xmlagg(x) FROM (SELECT x FROM test ORDER BY y DESC) AS tab;
   <para>
    Note that <function>first_value</>, <function>last_value</>, and
    <function>nth_value</> consider only the rows within the <quote>window
-   frame</>, that is the rows from the start of the partition through the
-   last peer of the current row.  This is particularly likely to give
-   unintuitive results for <function>last_value</>.
+   frame</>, which by default contains the rows from the start of the
+   partition through the last peer of the current row.  This is
+   likely to give unhelpful results for <function>nth_value</> and
+   particularly <function>last_value</>.  You can redefine the frame as
+   being the whole partition by adding <literal>ROWS BETWEEN UNBOUNDED
+   PRECEDING AND UNBOUNDED FOLLOWING</> to the <literal>OVER</> clause.
+   See <xref linkend="syntax-window-functions"> for more information.
   </para>
 
   <para>
    When an aggregate function is used as a window function, it aggregates
    over the rows within the current row's window frame.  To obtain
-   aggregation over the whole partition, be sure to omit <literal>ORDER BY</>
-   from the window definition.  An aggregate used with <literal>ORDER BY</>
-   produces a <quote>running sum</> type of behavior, which may or may not
-   be what's wanted.
+   aggregation over the whole partition, omit <literal>ORDER BY</> or use
+   <literal>ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING</>.
+   An aggregate used with <literal>ORDER BY</> and the default window frame
+   definition produces a <quote>running sum</> type of behavior, which may or
+   may not be what's wanted.
   </para>
 
   <note>
@@ -10416,7 +10420,9 @@ SELECT xmlagg(x) FROM (SELECT x FROM test ORDER BY y DESC) AS tab;
     same as the standard's default, namely <literal>RESPECT NULLS</>.
     Likewise, the standard's <literal>FROM FIRST</> or <literal>FROM LAST</>
     option for <function>nth_value</> is not implemented: only the
-    default <literal>FROM FIRST</> behavior is supported.
+    default <literal>FROM FIRST</> behavior is supported.  (You can achieve
+    the result of <literal>FROM LAST</> by reversing the <literal>ORDER BY</>
+    ordering.)
    </para>
   </note>
 

doc/src/sgml/queries.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/queries.sgml,v 1.51 2008/12/28 18:53:54 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/queries.sgml,v 1.52 2008/12/31 00:08:35 tgl Exp $ -->
 
 <chapter id="queries">
  <title>Queries</title>
@@ -993,7 +993,7 @@ SELECT product_id, p.name, (sum(s.units) * (p.price - p.cost)) AS profit
    </para>
 
    <para>
-    Currently, use of window functions always forces sorting, and so the
+    Currently, window functions always require presorted data, and so the
     query output will be ordered according to one or another of the window
     functions' <literal>PARTITION BY</>/<literal>ORDER BY</> clauses.
     It is not recommendable to rely on this, however.  Use an explicit

doc/src/sgml/ref/select.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/select.sgml,v 1.114 2008/12/29 18:23:53 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/select.sgml,v 1.115 2008/12/31 00:08:35 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -583,7 +583,21 @@ WINDOW <replaceable class="parameter">window_name</replaceable> AS ( <replaceabl
 [ <replaceable class="parameter">existing_window_name</replaceable> ]
 [ PARTITION BY <replaceable class="parameter">expression</replaceable> [, ...] ]
 [ ORDER BY <replaceable class="parameter">expression</replaceable> [ ASC | DESC | USING <replaceable class="parameter">operator</replaceable> ] [ NULLS { FIRST | LAST } ] [, ...] ]
+[ <replaceable class="parameter">framing_clause</replaceable> ]
 </synopsis>
+   </para>
+
+   <para>
+    If an <replaceable class="parameter">existing_window_name</replaceable>
+    is specified it must refer to an earlier entry in the <literal>WINDOW</>
+    list; the new window copies its partitioning clause from that entry,
+    as well as its ordering clause if any.  In this case the new window cannot
+    specify its own <literal>PARTITION BY</> clause, and it can specify
+    <literal>ORDER BY</> only if the copied window does not have one.
+    The framing clause is never copied from the existing window.
+   </para>
+
+   <para>
     The elements of the <literal>PARTITION BY</> list are interpreted in
     the same fashion as elements of a
     <xref linkend="sql-groupby" endterm="sql-groupby-title">, and
@@ -597,12 +611,29 @@ WINDOW <replaceable class="parameter">window_name</replaceable> AS ( <replaceabl
    </para>
 
    <para>
-    If an <replaceable class="parameter">existing_window_name</replaceable>
-    is specified it must refer to an earlier entry in the <literal>WINDOW</>
-    list; the new window copies its partitioning clause from that entry,
-    as well as its ordering clause if any.  In this case the new window cannot
-    specify its own <literal>PARTITION BY</> clause, and it can specify
-    <literal>ORDER BY</> only if the copied window does not have one.
+    The optional <replaceable class="parameter">framing_clause</> defines
+    the <firstterm>window frame</> for window functions that depend on the
+    frame (not all do).  It can be one of
+<synopsis>
+RANGE UNBOUNDED PRECEDING
+RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
+RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
+ROWS UNBOUNDED PRECEDING
+ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
+ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
+</synopsis>
+    The first two are equivalent and are also the default: they set the
+    frame to be all rows from the partition start up through the current row's
+    last peer in the <literal>ORDER BY</> ordering (which means all rows if
+    there is no <literal>ORDER BY</>).  The options
+    <literal>RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING</> and
+    <literal>ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING</>
+    are also equivalent: they always select all rows in the partition.
+    Lastly, <literal>ROWS UNBOUNDED PRECEDING</> or its verbose equivalent
+    <literal>ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW</> select
+    all rows up through the current row (regardless of duplicates).
+    Beware that this option can produce implementation-dependent results
+    if the <literal>ORDER BY</> ordering does not order the rows uniquely.
    </para>
 
    <para>
@@ -623,8 +654,9 @@ WINDOW <replaceable class="parameter">window_name</replaceable> AS ( <replaceabl
 
    <para>
     Window functions are described in detail in
-    <xref linkend="tutorial-window"> and
-    <xref linkend="syntax-window-functions">.
+    <xref linkend="tutorial-window">,
+    <xref linkend="syntax-window-functions">, and
+    <xref linkend="queries-window">.
    </para>
   </refsect2>
 
@@ -1453,12 +1485,10 @@ SELECT distributors.* WHERE distributors.name = 'Westward';
    <title><literal>WINDOW</literal> Clause Restrictions</title>
 
    <para>
-    The SQL standard provides for an optional <quote>framing clause</>,
-    introduced by the key word <literal>RANGE</> or <literal>ROWS</>,
-    in window definitions.  <productname>PostgreSQL</productname> does
-    not yet implement framing clauses, and always follows the
-    default framing behavior, which is equivalent to the framing clause
-    <literal>RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW</>.
+    The SQL standard provides additional options for the window
+    <replaceable class="parameter">framing_clause</>.
+    <productname>PostgreSQL</productname> currently supports only the
+    options listed above.
    </para>
   </refsect2>
 

doc/src/sgml/syntax.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/syntax.sgml,v 1.127 2008/12/28 18:53:54 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/syntax.sgml,v 1.128 2008/12/31 00:08:35 tgl Exp $ -->
 
 <chapter id="sql-syntax">
  <title>SQL Syntax</title>
@@ -1591,6 +1591,17 @@ sqrt(2)
 [ <replaceable class="parameter">window_name</replaceable> ]
 [ PARTITION BY <replaceable class="parameter">expression</replaceable> [, ...] ]
 [ ORDER BY <replaceable class="parameter">expression</replaceable> [ ASC | DESC | USING <replaceable class="parameter">operator</replaceable> ] [ NULLS { FIRST | LAST } ] [, ...] ]
+[ <replaceable class="parameter">framing_clause</replaceable> ]
+</synopsis>
+    and the optional <replaceable class="parameter">framing_clause</replaceable>
+    can be one of
+<synopsis>
+RANGE UNBOUNDED PRECEDING
+RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
+RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
+ROWS UNBOUNDED PRECEDING
+ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
+ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
 </synopsis>
 
     Here, <replaceable>expression</replaceable> represents any value
@@ -1603,19 +1614,33 @@ sqrt(2)
     Named window specifications are usually referenced with just
     <literal>OVER</> <replaceable>window_name</replaceable>, but it is
     also possible to write a window name inside the parentheses and then
-    optionally override its ordering clause with <literal>ORDER BY</>.
+    optionally override its ordering clause and/or framing clause.
     This latter syntax follows the same rules as modifying an existing
     window name within the <literal>WINDOW</literal> clause; see the
     <xref linkend="sql-select" endterm="sql-select-title"> reference
     page for details.
    </para>
 
+   <para>
+    The default framing option is <literal>RANGE UNBOUNDED PRECEDING</>,
+    which is the same as <literal>RANGE BETWEEN UNBOUNDED PRECEDING AND
+    CURRENT ROW</>; it selects rows up through the current row's last
+    peer in the <literal>ORDER BY</> ordering (which means all rows if
+    there is no <literal>ORDER BY</>).  The options
+    <literal>RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING</> and
+    <literal>ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING</>
+    are also equivalent: they always select all rows in the partition.
+    Lastly, <literal>ROWS UNBOUNDED PRECEDING</> or its verbose equivalent
+    <literal>ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW</> select
+    all rows up through the current row (regardless of duplicates).
+    Beware that this option can produce implementation-dependent results
+    if the <literal>ORDER BY</> ordering does not order the rows uniquely.
+   </para>
+
    <para>
     The built-in window functions are described in <xref
     linkend="functions-window-table">.  Also, any built-in or
     user-defined aggregate function can be used as a window function.
-    Currently, there is no provision for user-defined window functions
-    other than aggregates.
    </para>
 
    <para>

src/backend/executor/nodeWindowAgg.c

@@ -27,7 +27,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/nodeWindowAgg.c,v 1.1 2008/12/28 18:53:55 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/nodeWindowAgg.c,v 1.2 2008/12/31 00:08:35 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -118,11 +118,10 @@ typedef struct WindowStatePerAggData
 	bool		initValueIsNull;
 
 	/*
-	 * cached value for non-moving frame
+	 * cached value for current frame boundaries
 	 */
 	Datum		resultValue;
 	bool		resultValueIsNull;
-	bool		hasResult;
 
 	/*
 	 * We need the len and byval info for the agg's input, result, and
@@ -164,6 +163,10 @@ static void begin_partition(WindowAggState *winstate);
 static void spool_tuples(WindowAggState *winstate, int64 pos);
 static void release_partition(WindowAggState *winstate);
 
+static bool row_is_in_frame(WindowAggState *winstate, int64 pos,
+							TupleTableSlot *slot);
+static void update_frametailpos(WindowObject winobj, TupleTableSlot *slot);
+
 static WindowStatePerAggData *initialize_peragg(WindowAggState *winstate,
 												WindowFunc *wfunc,
 												WindowStatePerAgg peraggstate);
@@ -198,6 +201,7 @@ initialize_windowaggregate(WindowAggState *winstate,
 	}
 	peraggstate->transValueIsNull = peraggstate->initValueIsNull;
 	peraggstate->noTransValue = peraggstate->initValueIsNull;
+	peraggstate->resultValueIsNull = true;
 }
 
 /*
@@ -385,9 +389,7 @@ eval_windowaggregates(WindowAggState *winstate)
 	int					i;
 	MemoryContext		oldContext;
 	ExprContext		   *econtext;
-	TupleTableSlot	   *first_peer_slot = winstate->first_peer_slot;
-	TupleTableSlot	   *slot;
-	bool				first;
+	TupleTableSlot	   *agg_row_slot;
 
 	numaggs = winstate->numaggs;
 	if (numaggs == 0)
@@ -397,35 +399,45 @@ eval_windowaggregates(WindowAggState *winstate)
 	econtext = winstate->ss.ps.ps_ExprContext;
 
 	/*
-	 * We don't currently support explicitly-specified window frames.  That
-	 * means that the window frame always includes all the rows in the
-	 * partition preceding and including the current row, and all its
-	 * peers. As a special case, if there's no ORDER BY, all rows are peers,
-	 * so the window frame includes all rows in the partition.
+	 * Currently, we support only a subset of the SQL-standard window framing
+	 * rules.  In all the supported cases, the window frame always consists
+	 * of a contiguous group of rows extending forward from the start of the
+	 * partition, and rows only enter the frame, never exit it, as the
+	 * current row advances forward.  This makes it possible to use an
+	 * incremental strategy for evaluating aggregates: we run the transition
+	 * function for each row added to the frame, and run the final function
+	 * whenever we need the current aggregate value.  This is considerably
+	 * more efficient than the naive approach of re-running the entire
+	 * aggregate calculation for each current row.  It does assume that the
+	 * final function doesn't damage the running transition value.  (Some
+	 * C-coded aggregates do that for efficiency's sake --- but they are
+	 * supposed to do so only when their fcinfo->context is an AggState, not
+	 * a WindowAggState.)
 	 *
-	 * When there's peer rows, all rows in a peer group will have the same
-	 * aggregate values.  The values will be calculated when current position
-	 * reaches the first peer row, and on all the following peer rows we will
-	 * just return the saved results.
+	 * In many common cases, multiple rows share the same frame and hence
+	 * the same aggregate value. (In particular, if there's no ORDER BY in
+	 * a RANGE window, then all rows are peers and so they all have window
+	 * frame equal to the whole partition.)  We optimize such cases by
+	 * calculating the aggregate value once when we reach the first row of a
+	 * peer group, and then returning the saved value for all subsequent rows.
 	 *
-	 * 'aggregatedupto' keeps track of the last row that has already been
-	 * accumulated for the aggregates. When the current row has no peers,
-	 * aggregatedupto will be the same as the current row after this
-	 * function. If there are peer rows, all peers will be accumulated in one
-	 * call of this function, and aggregatedupto will be ahead of the current
-	 * position. If there's no ORDER BY, and thus all rows are peers, the
-	 * first call will aggregate all rows in the partition.
+	 * 'aggregatedupto' keeps track of the first row that has not yet been
+	 * accumulated into the aggregate transition values.  Whenever we start a
+	 * new peer group, we accumulate forward to the end of the peer group.
 	 *
-	 * TODO: In the future, we could implement sliding frames by recalculating
-	 * the aggregate whenever a row exits the frame. That would be pretty
-	 * slow, though. For aggregates like SUM and COUNT we could implement a
-	 * "negative transition function" that would be called for all the rows
-	 * that exit the frame.
+	 * TODO: In the future, we should implement the full SQL-standard set
+	 * of framing rules.  We could implement the other cases by recalculating
+	 * the aggregates whenever a row exits the frame.  That would be pretty
+	 * slow, though.  For aggregates like SUM and COUNT we could implement a
+	 * "negative transition function" that would be called for each row as it
+	 * exits the frame.  We'd have to think about avoiding recalculation of
+	 * volatile arguments of aggregate functions, too.
 	 */
 
 	/*
 	 * If we've already aggregated up through current row, reuse the
-	 * saved result values
+	 * saved result values.  NOTE: this test works for the currently
+	 * supported framing rules, but will need fixing when more are added.
 	 */
 	if (winstate->aggregatedupto > winstate->currentpos)
 	{
@@ -440,76 +452,61 @@ eval_windowaggregates(WindowAggState *winstate)
 	}
 
 	/* Initialize aggregates on first call for partition */
-	for (i = 0; i < numaggs; i++)
+	if (winstate->currentpos == 0)
 	{
-		peraggstate = &winstate->peragg[i];
-		wfuncno = peraggstate->wfuncno;
-		if (!peraggstate->hasResult)
+		for (i = 0; i < numaggs; i++)
+		{
+			peraggstate = &winstate->peragg[i];
+			wfuncno = peraggstate->wfuncno;
 			initialize_windowaggregate(winstate,
 									   &winstate->perfunc[wfuncno],
-									   &winstate->peragg[i]);
-	}
-
-	/*
-	 * If this is the first call for this partition, fetch the first row
-	 * for comparing peer rows. On subsequent calls, we'll always read
-	 * ahead until we reach the first non-peer row, and store that row in
-	 * first_peer_slot, for use in the next call.
-	 */
-	if (TupIsNull(first_peer_slot))
-	{
-		spool_tuples(winstate, winstate->aggregatedupto);
-		tuplestore_select_read_pointer(winstate->buffer, winstate->agg_ptr);
-		if (!tuplestore_gettupleslot(winstate->buffer, true, first_peer_slot))
-			elog(ERROR, "unexpected end of tuplestore");
+									   peraggstate);
+		}
 	}
 
 	/*
-	 * Advance until we reach the next non-peer row
+	 * Advance until we reach a row not in frame (or end of partition).
+	 *
+	 * Note the loop invariant: agg_row_slot is either empty or holds the
+	 * row at position aggregatedupto.  The agg_ptr read pointer must always
+	 * point to the next row to read into agg_row_slot.
 	 */
-	first = true;
+	agg_row_slot = winstate->agg_row_slot;
 	for (;;)
 	{
-		if (!first)
+		/* Fetch next row if we didn't already */
+		if (TupIsNull(agg_row_slot))
 		{
-			/* Fetch the next row, and see if it's a peer */
 			spool_tuples(winstate, winstate->aggregatedupto);
 			tuplestore_select_read_pointer(winstate->buffer,
 										   winstate->agg_ptr);
-			slot = winstate->temp_slot_1;
-			if (!tuplestore_gettupleslot(winstate->buffer, true, slot))
-				break;
-			if (!are_peers(winstate, first_peer_slot, slot))
-			{
-				ExecCopySlot(first_peer_slot, slot);
-				break;
-			}
-		}
-		else
-		{
-			/*
-			 * On first iteration, just accumulate the tuple saved from
-			 * last call
-			 */
-			slot = first_peer_slot;
-			first = false;
+			if (!tuplestore_gettupleslot(winstate->buffer, true, agg_row_slot))
+				break;			/* must be end of partition */
 		}
 
-		/* set tuple context for evaluation of aggregate arguments */
-		winstate->tmpcontext->ecxt_outertuple = slot;
+		/* Exit loop (for now) if not in frame */
+		if (!row_is_in_frame(winstate, winstate->aggregatedupto, agg_row_slot))
+			break;
 
+		/* Set tuple context for evaluation of aggregate arguments */
+		winstate->tmpcontext->ecxt_outertuple = agg_row_slot;
+
+		/* Accumulate row into the aggregates */
 		for (i = 0; i < numaggs; i++)
 		{
-			wfuncno = winstate->peragg[i].wfuncno;
-
+			peraggstate = &winstate->peragg[i];
+			wfuncno = peraggstate->wfuncno;
 			advance_windowaggregate(winstate,
 									&winstate->perfunc[wfuncno],
-									&winstate->peragg[i]);
-
+									peraggstate);
 		}
+
 		/* Reset per-input-tuple context after each tuple */
 		ResetExprContext(winstate->tmpcontext);
+
+		/* And advance the aggregated-row state */
 		winstate->aggregatedupto++;
+		ExecClearTuple(agg_row_slot);
 	}
 
 	/*
@@ -526,37 +523,44 @@ eval_windowaggregates(WindowAggState *winstate)
 		isnull = &econtext->ecxt_aggnulls[wfuncno];
 		finalize_windowaggregate(winstate,
 								 &winstate->perfunc[wfuncno],
-								 peraggstate, result, isnull);
+								 peraggstate,
+								 result, isnull);
 
 		/*
-		 * save the result for the next (non-shrinking frame) call.
+		 * save the result in case next row shares the same frame.
+		 *
+		 * XXX in some framing modes, eg ROWS/END_CURRENT_ROW, we can know
+		 * in advance that the next row can't possibly share the same frame.
+		 * Is it worth detecting that and skipping this code?
 		 */
-		if (!peraggstate->resulttypeByVal && !*isnull)
+		if (!peraggstate->resulttypeByVal)
 		{
 			/*
-			 * clear old resultValue in order not to leak memory.
+			 * clear old resultValue in order not to leak memory.  (Note:
+			 * the new result can't possibly be the same datum as old
+			 * resultValue, because we never passed it to the trans function.)
 			 */
-			if (peraggstate->hasResult &&
-				(DatumGetPointer(peraggstate->resultValue) !=
-					DatumGetPointer(*result)) &&
-				!peraggstate->resultValueIsNull)
+			if (!peraggstate->resultValueIsNull)
 				pfree(DatumGetPointer(peraggstate->resultValue));
 
 			/*
 			 * If pass-by-ref, copy it into our global context.
 			 */
-			oldContext = MemoryContextSwitchTo(winstate->wincontext);
-			peraggstate->resultValue = datumCopy(*result,
-												 peraggstate->resulttypeByVal,
-												 peraggstate->resulttypeLen);
-			MemoryContextSwitchTo(oldContext);
+			if (!*isnull)
+			{
+				oldContext = MemoryContextSwitchTo(winstate->wincontext);
+				peraggstate->resultValue =
+					datumCopy(*result,
+							  peraggstate->resulttypeByVal,
+							  peraggstate->resulttypeLen);
+				MemoryContextSwitchTo(oldContext);
+			}
 		}
 		else
 		{
 			peraggstate->resultValue = *result;
 		}
 		peraggstate->resultValueIsNull = *isnull;
-		peraggstate->hasResult = true;
 	}
 }
 
@@ -620,14 +624,16 @@ begin_partition(WindowAggState *winstate)
 	int				i;
 
 	winstate->partition_spooled = false;
+	winstate->frametail_valid = false;
 	winstate->spooled_rows = 0;
 	winstate->currentpos = 0;
 	winstate->frametailpos = -1;
 	winstate->aggregatedupto = 0;
+	ExecClearTuple(winstate->agg_row_slot);
 
 	/*
 	 * If this is the very first partition, we need to fetch the first
-	 * input row to store in it.
+	 * input row to store in first_part_slot.
 	 */
 	if (TupIsNull(winstate->first_part_slot))
 	{
@@ -775,35 +781,138 @@ release_partition(WindowAggState *winstate)
 		/* Release any partition-local state of this window function */
 		if (perfuncstate->winobj)
 			perfuncstate->winobj->localmem = NULL;
-
-		/* Reset agg result cache */
-		if (perfuncstate->plain_agg)
-		{
-			int		aggno = perfuncstate->aggno;
-			WindowStatePerAggData *peraggstate = &winstate->peragg[aggno];
-
-			peraggstate->resultValueIsNull = true;
-			peraggstate->hasResult = false;
-		}
 	}
 
 	/*
 	 * Release all partition-local memory (in particular, any partition-local
-	 * state or aggregate temp data that we might have trashed our pointers
-	 * to in the above loop).  We don't rely on retail pfree because some
+	 * state that we might have trashed our pointers to in the above loop, and
+	 * any aggregate temp data).  We don't rely on retail pfree because some
 	 * aggregates might have allocated data we don't have direct pointers to.
 	 */
 	MemoryContextResetAndDeleteChildren(winstate->wincontext);
 
-	/* Ensure eval_windowaggregates will see next call as partition start */
-	ExecClearTuple(winstate->first_peer_slot);
-
 	if (winstate->buffer)
 		tuplestore_end(winstate->buffer);
 	winstate->buffer = NULL;
 	winstate->partition_spooled = false;
 }
 
+/*
+ * row_is_in_frame
+ * Determine whether a row is in the current row's window frame according
+ * to our window framing rule
+ *
+ * The caller must have already determined that the row is in the partition
+ * and fetched it into a slot.  This function just encapsulates the framing
+ * rules.
+ */
+static bool
+row_is_in_frame(WindowAggState *winstate, int64 pos, TupleTableSlot *slot)
+{
+	WindowAgg  *node = (WindowAgg *) winstate->ss.ps.plan;
+	int			frameOptions = node->frameOptions;
+
+	Assert(pos >= 0);			/* else caller error */
+
+	/* We only support frame start mode UNBOUNDED PRECEDING for now */
+	Assert(frameOptions & FRAMEOPTION_START_UNBOUNDED_PRECEDING);
+
+	/* In UNBOUNDED FOLLOWING mode, all partition rows are in frame */
+	if (frameOptions & FRAMEOPTION_END_UNBOUNDED_FOLLOWING)
+		return true;
+
+	/* Else frame tail mode must be CURRENT ROW */
+	Assert(frameOptions & FRAMEOPTION_END_CURRENT_ROW);
+
+	/* if row is current row or a predecessor, it must be in frame */
+	if (pos <= winstate->currentpos)
+		return true;
+
+	/* In ROWS mode, *only* such rows are in frame */
+	if (frameOptions & FRAMEOPTION_ROWS)
+		return false;
+
+	/* Else must be RANGE mode */
+	Assert(frameOptions & FRAMEOPTION_RANGE);
+
+	/* In frame iff it's a peer of current row */
+	return are_peers(winstate, slot, winstate->ss.ss_ScanTupleSlot);
+}
+
+/*
+ * update_frametailpos
+ * make frametailpos valid for the current row
+ *
+ * Uses the winobj's read pointer for any required fetches; the winobj's
+ * mark must not be past the currently known frame tail.  Also uses the
+ * specified slot for any required fetches.
+ */
+static void
+update_frametailpos(WindowObject winobj, TupleTableSlot *slot)
+{
+	WindowAggState *winstate = winobj->winstate;
+	WindowAgg  *node = (WindowAgg *) winstate->ss.ps.plan;
+	int			frameOptions = node->frameOptions;
+	int64		ftnext;
+
+	if (winstate->frametail_valid)
+		return;					/* already known for current row */
+
+	/* We only support frame start mode UNBOUNDED PRECEDING for now */
+	Assert(frameOptions & FRAMEOPTION_START_UNBOUNDED_PRECEDING);
+
+	/* In UNBOUNDED FOLLOWING mode, all partition rows are in frame */
+	if (frameOptions & FRAMEOPTION_END_UNBOUNDED_FOLLOWING)
+	{
+		spool_tuples(winstate, -1);
+		winstate->frametailpos = winstate->spooled_rows - 1;
+		winstate->frametail_valid = true;
+		return;
+	}
+
+	/* Else frame tail mode must be CURRENT ROW */
+	Assert(frameOptions & FRAMEOPTION_END_CURRENT_ROW);
+
+	/* In ROWS mode, exactly the rows up to current are in frame */
+	if (frameOptions & FRAMEOPTION_ROWS)
+	{
+		winstate->frametailpos = winstate->currentpos;
+		winstate->frametail_valid = true;
+		return;
+	}
+
+	/* Else must be RANGE mode */
+	Assert(frameOptions & FRAMEOPTION_RANGE);
+
+	/* If no ORDER BY, all rows are peers with each other */
+	if (node->ordNumCols == 0)
+	{
+		spool_tuples(winstate, -1);
+		winstate->frametailpos = winstate->spooled_rows - 1;
+		winstate->frametail_valid = true;
+		return;
+	}
+
+	/*
+	 * Else we have to search for the first non-peer of the current row.
+	 * We assume the current value of frametailpos is a lower bound on the
+	 * possible frame tail location, ie, frame tail never goes backward, and
+	 * that currentpos is also a lower bound, ie, current row is always in
+	 * frame.
+	 */
+	ftnext = Max(winstate->frametailpos, winstate->currentpos) + 1;
+	for (;;)
+	{
+		if (!window_gettupleslot(winobj, ftnext, slot))
+			break;				/* end of partition */
+		if (!are_peers(winstate, slot, winstate->ss.ss_ScanTupleSlot))
+			break;				/* not peer of current row */
+		ftnext++;
+	}
+	winstate->frametailpos = ftnext - 1;
+	winstate->frametail_valid = true;
+}
+
 
 /* -----------------
  * ExecWindowAgg
@@ -849,11 +958,14 @@ restart:
 	{
 		/* Initialize for first partition and set current row = 0 */
 		begin_partition(winstate);
+		/* If there are no input rows, we'll detect that and exit below */
 	}
 	else
 	{
 		/* Advance current row within partition */
 		winstate->currentpos++;
+		/* This might mean that the frame tail moves, too */
+		winstate->frametail_valid = false;
 	}
 
 	/*
@@ -887,8 +999,7 @@ restart:
 	ResetExprContext(econtext);
 
 	/*
-	 * Read the current row from the tuplestore, and save in ScanTupleSlot
-	 * for possible use by WinGetFuncArgCurrent or the final projection step.
+	 * Read the current row from the tuplestore, and save in ScanTupleSlot.
 	 * (We can't rely on the outerplan's output slot because we may have to
 	 * read beyond the current row.)
 	 *
@@ -1002,7 +1113,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 	ExecInitScanTupleSlot(estate, &winstate->ss);
 	ExecInitResultTupleSlot(estate, &winstate->ss.ps);
 	winstate->first_part_slot = ExecInitExtraTupleSlot(estate);
-	winstate->first_peer_slot = ExecInitExtraTupleSlot(estate);
+	winstate->agg_row_slot = ExecInitExtraTupleSlot(estate);
 	winstate->temp_slot_1 = ExecInitExtraTupleSlot(estate);
 	winstate->temp_slot_2 = ExecInitExtraTupleSlot(estate);
 
@@ -1031,7 +1142,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 
 	ExecSetSlotDescriptor(winstate->first_part_slot,
 						  winstate->ss.ss_ScanTupleSlot->tts_tupleDescriptor);
-	ExecSetSlotDescriptor(winstate->first_peer_slot,
+	ExecSetSlotDescriptor(winstate->agg_row_slot,
 						  winstate->ss.ss_ScanTupleSlot->tts_tupleDescriptor);
 	ExecSetSlotDescriptor(winstate->temp_slot_1,
 						  winstate->ss.ss_ScanTupleSlot->tts_tupleDescriptor);
@@ -1081,6 +1192,10 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 		AclResult	aclresult;
 		int			i;
 
+		if (wfunc->winref != node->winref)			/* planner screwed up? */
+			elog(ERROR, "WindowFunc with winref %u assigned to WindowAgg with winref %u",
+				 wfunc->winref, node->winref);
+
 		/* Look for a previous duplicate window function */
 		for (i = 0; i <= wfuncno; i++)
 		{
@@ -1183,7 +1298,7 @@ ExecEndWindowAgg(WindowAggState *node)
 
 	ExecClearTuple(node->ss.ss_ScanTupleSlot);
 	ExecClearTuple(node->first_part_slot);
-	ExecClearTuple(node->first_peer_slot);
+	ExecClearTuple(node->agg_row_slot);
 	ExecClearTuple(node->temp_slot_1);
 	ExecClearTuple(node->temp_slot_2);
 
@@ -1219,7 +1334,7 @@ ExecReScanWindowAgg(WindowAggState *node, ExprContext *exprCtxt)
 	/* release all temp tuples, but especially first_part_slot */
 	ExecClearTuple(node->ss.ss_ScanTupleSlot);
 	ExecClearTuple(node->first_part_slot);
-	ExecClearTuple(node->first_peer_slot);
+	ExecClearTuple(node->agg_row_slot);
 	ExecClearTuple(node->temp_slot_1);
 	ExecClearTuple(node->temp_slot_2);
 
@@ -1411,6 +1526,8 @@ GetAggInitVal(Datum textInitVal, Oid transtype)
 /*
  * are_peers
  * compare two rows to see if they are equal according to the ORDER BY clause
+ *
+ * NB: this does not consider the window frame mode.
  */
 static bool
 are_peers(WindowAggState *winstate, TupleTableSlot *slot1,
@@ -1430,7 +1547,8 @@ are_peers(WindowAggState *winstate, TupleTableSlot *slot1,
 
 /*
  * window_gettupleslot
- *	Fetch the pos'th tuple of the current partition into the slot
+ *	Fetch the pos'th tuple of the current partition into the slot,
+ *	using the winobj's read pointer
  *
  * Returns true if successful, false if no such row
  */
@@ -1582,6 +1700,8 @@ WinSetMarkPosition(WindowObject winobj, int64 markpos)
  * WinRowsArePeers
  *		Compare two rows (specified by absolute position in window) to see
  *		if they are equal according to the ORDER BY clause.
+ *
+ * NB: this does not consider the window frame mode.
  */
 bool
 WinRowsArePeers(WindowObject winobj, int64 pos1, int64 pos2)
@@ -1593,7 +1713,6 @@ WinRowsArePeers(WindowObject winobj, int64 pos1, int64 pos2)
 	bool			res;
 
 	Assert(WindowObjectIsValid(winobj));
-
 	winstate = winobj->winstate;
 	node = (WindowAgg *) winstate->ss.ps.plan;
 
@@ -1642,27 +1761,28 @@ WinGetFuncArgInPartition(WindowObject winobj, int argno,
 						 int relpos, int seektype, bool set_mark,
 						 bool *isnull, bool *isout)
 {
+	WindowAggState *winstate;
 	ExprContext *econtext;
 	TupleTableSlot *slot;
 	bool		gottuple;
 	int64		abs_pos;
 
 	Assert(WindowObjectIsValid(winobj));
-
-	econtext = winobj->winstate->ss.ps.ps_ExprContext;
-	slot = winobj->winstate->temp_slot_1;
+	winstate = winobj->winstate;
+	econtext = winstate->ss.ps.ps_ExprContext;
+	slot = winstate->temp_slot_1;
 
 	switch (seektype)
 	{
 		case WINDOW_SEEK_CURRENT:
-			abs_pos = winobj->winstate->currentpos + relpos;
+			abs_pos = winstate->currentpos + relpos;
 			break;
 		case WINDOW_SEEK_HEAD:
 			abs_pos = relpos;
 			break;
 		case WINDOW_SEEK_TAIL:
-			spool_tuples(winobj->winstate, -1);
-			abs_pos = winobj->winstate->spooled_rows - 1 + relpos;
+			spool_tuples(winstate, -1);
+			abs_pos = winstate->spooled_rows - 1 + relpos;
 			break;
 		default:
 			elog(ERROR, "unrecognized window seek type: %d", seektype);
@@ -1670,10 +1790,7 @@ WinGetFuncArgInPartition(WindowObject winobj, int argno,
 			break;
 	}
 
-	if (abs_pos >= 0)
-		gottuple = window_gettupleslot(winobj, abs_pos, slot);
-	else
-		gottuple = false;
+	gottuple = window_gettupleslot(winobj, abs_pos, slot);
 
 	if (!gottuple)
 	{
@@ -1717,34 +1834,28 @@ WinGetFuncArgInFrame(WindowObject winobj, int argno,
 					 int relpos, int seektype, bool set_mark,
 					 bool *isnull, bool *isout)
 {
+	WindowAggState *winstate;
 	ExprContext *econtext;
 	TupleTableSlot *slot;
 	bool		gottuple;
 	int64		abs_pos;
-	int64		frametailpos;
 
 	Assert(WindowObjectIsValid(winobj));
-
-	/* if no ordering columns, partition and frame are the same thing */
-	if (((WindowAgg *) winobj->winstate->ss.ps.plan)->ordNumCols == 0)
-		return WinGetFuncArgInPartition(winobj, argno, relpos, seektype,
-										set_mark, isnull, isout);
-
-	econtext = winobj->winstate->ss.ps.ps_ExprContext;
-	slot = winobj->winstate->temp_slot_1;
-	frametailpos = winobj->winstate->frametailpos;
+	winstate = winobj->winstate;
+	econtext = winstate->ss.ps.ps_ExprContext;
+	slot = winstate->temp_slot_1;
 
 	switch (seektype)
 	{
 		case WINDOW_SEEK_CURRENT:
-			abs_pos = winobj->winstate->currentpos + relpos;
+			abs_pos = winstate->currentpos + relpos;
 			break;
 		case WINDOW_SEEK_HEAD:
 			abs_pos = relpos;
 			break;
 		case WINDOW_SEEK_TAIL:
-			/* abs_pos is calculated later */
-			abs_pos = 0; /* keep compiler quiet */
+			update_frametailpos(winobj, slot);
+			abs_pos = winstate->frametailpos + relpos;
 			break;
 		default:
 			elog(ERROR, "unrecognized window seek type: %d", seektype);
@@ -1752,58 +1863,9 @@ WinGetFuncArgInFrame(WindowObject winobj, int argno,
 			break;
 	}
 
-	/*
-	 * Seek for frame tail. If the tail position is before current,
-	 * always check if the tail is after the current or not.
-	 */
-	if (frametailpos <= winobj->winstate->currentpos)
-	{
-		int64 add = 1;
-
-		for (;;)
-		{
-			spool_tuples(winobj->winstate, winobj->winstate->currentpos + add);
-			if (winobj->winstate->spooled_rows > winobj->winstate->currentpos + add)
-			{
-				/*
-				 * When seektype is not TAIL, we may optimize not to
-				 * spool unnecessary tuples. In TAIL mode, we need to search
-				 * until we find a row that's definitely not a peer.
-				 */
-				if (!WinRowsArePeers(winobj, winobj->winstate->currentpos,
-									 winobj->winstate->currentpos + add) ||
-					(seektype != WINDOW_SEEK_TAIL &&
-					 winobj->winstate->currentpos + add < abs_pos))
-					break;
-				add++;
-			}
-			else
-			{
-				/*
-				 * If hit the partition end, the last row is the frame tail.
-				 */
-				break;
-			}
-		}
-		frametailpos = winobj->winstate->currentpos + add - 1;
-		winobj->winstate->frametailpos = frametailpos;
-	}
-
-	if (seektype == WINDOW_SEEK_TAIL)
-	{
-		abs_pos = frametailpos + relpos;
-	}
-
-	/*
-	 * If there is an ORDER BY (we don't support other window frame
-	 * specifications yet), the frame runs from first row of the partition
-	 * to the last peer of the current row. Otherwise the frame is the
-	 * whole partition.
-	 */
-	if (abs_pos < 0 || abs_pos > frametailpos)
-		gottuple = false;
-	else
-		gottuple = window_gettupleslot(winobj, abs_pos, slot);
+	gottuple = window_gettupleslot(winobj, abs_pos, slot);
+	if (gottuple)
+		gottuple = row_is_in_frame(winstate, abs_pos, slot);
 
 	if (!gottuple)
 	{

src/backend/nodes/copyfuncs.c

@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.417 2008/12/28 18:53:55 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.418 2008/12/31 00:08:35 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -678,6 +678,7 @@ _copyWindowAgg(WindowAgg *from)
 
 	CopyPlanFields((Plan *) from, (Plan *) newnode);
 
+	COPY_SCALAR_FIELD(winref);
 	COPY_SCALAR_FIELD(partNumCols);
 	if (from->partNumCols > 0)
 	{
@@ -690,6 +691,7 @@ _copyWindowAgg(WindowAgg *from)
 		COPY_POINTER_FIELD(ordColIdx, from->ordNumCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(ordOperators, from->ordNumCols * sizeof(Oid));
 	}
+	COPY_SCALAR_FIELD(frameOptions);
 
 	return newnode;
 }
@@ -1783,6 +1785,7 @@ _copyWindowClause(WindowClause *from)
 	COPY_STRING_FIELD(refname);
 	COPY_NODE_FIELD(partitionClause);
 	COPY_NODE_FIELD(orderClause);
+	COPY_SCALAR_FIELD(frameOptions);
 	COPY_SCALAR_FIELD(winref);
 	COPY_SCALAR_FIELD(copiedOrder);
 
@@ -2010,6 +2013,7 @@ _copyWindowDef(WindowDef *from)
 	COPY_STRING_FIELD(refname);
 	COPY_NODE_FIELD(partitionClause);
 	COPY_NODE_FIELD(orderClause);
+	COPY_SCALAR_FIELD(frameOptions);
 	COPY_LOCATION_FIELD(location);
 
 	return newnode;

src/backend/nodes/equalfuncs.c

@@ -22,7 +22,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.342 2008/12/28 18:53:56 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.343 2008/12/31 00:08:35 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2005,6 +2005,7 @@ _equalWindowDef(WindowDef *a, WindowDef *b)
 	COMPARE_STRING_FIELD(refname);
 	COMPARE_NODE_FIELD(partitionClause);
 	COMPARE_NODE_FIELD(orderClause);
+	COMPARE_SCALAR_FIELD(frameOptions);
 	COMPARE_LOCATION_FIELD(location);
 
 	return true;
@@ -2143,6 +2144,7 @@ _equalWindowClause(WindowClause *a, WindowClause *b)
 	COMPARE_STRING_FIELD(refname);
 	COMPARE_NODE_FIELD(partitionClause);
 	COMPARE_NODE_FIELD(orderClause);
+	COMPARE_SCALAR_FIELD(frameOptions);
 	COMPARE_SCALAR_FIELD(winref);
 	COMPARE_SCALAR_FIELD(copiedOrder);
 

src/backend/nodes/outfuncs.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.347 2008/12/28 18:53:56 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.348 2008/12/31 00:08:36 tgl Exp $
  *
  * NOTES
  *	  Every node type that can appear in stored rules' parsetrees *must*
@@ -575,6 +575,7 @@ _outWindowAgg(StringInfo str, WindowAgg *node)
 
 	_outPlanInfo(str, (Plan *) node);
 
+	WRITE_UINT_FIELD(winref);
 	WRITE_INT_FIELD(partNumCols);
 
 	appendStringInfo(str, " :partColIdx");
@@ -594,6 +595,8 @@ _outWindowAgg(StringInfo str, WindowAgg *node)
 	appendStringInfo(str, " :ordOperations");
 	for (i = 0; i < node->ordNumCols; i++)
 		appendStringInfo(str, " %u", node->ordOperators[i]);
+
+	WRITE_INT_FIELD(frameOptions);
 }
 
 static void
@@ -1953,6 +1956,7 @@ _outWindowClause(StringInfo str, WindowClause *node)
 	WRITE_STRING_FIELD(refname);
 	WRITE_NODE_FIELD(partitionClause);
 	WRITE_NODE_FIELD(orderClause);
+	WRITE_INT_FIELD(frameOptions);
 	WRITE_UINT_FIELD(winref);
 	WRITE_BOOL_FIELD(copiedOrder);
 }
@@ -2242,6 +2246,7 @@ _outWindowDef(StringInfo str, WindowDef *node)
 	WRITE_STRING_FIELD(refname);
 	WRITE_NODE_FIELD(partitionClause);
 	WRITE_NODE_FIELD(orderClause);
+	WRITE_INT_FIELD(frameOptions);
 	WRITE_LOCATION_FIELD(location);
 }
 

src/backend/nodes/readfuncs.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.218 2008/12/28 18:53:56 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.219 2008/12/31 00:08:36 tgl Exp $
  *
  * NOTES
  *	  Path and Plan nodes do not have any readfuncs support, because we
@@ -231,6 +231,7 @@ _readWindowClause(void)
 	READ_STRING_FIELD(refname);
 	READ_NODE_FIELD(partitionClause);
 	READ_NODE_FIELD(orderClause);
+	READ_INT_FIELD(frameOptions);
 	READ_UINT_FIELD(winref);
 	READ_BOOL_FIELD(copiedOrder);
 

src/backend/optimizer/plan/createplan.c

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.253 2008/12/28 18:53:56 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.254 2008/12/31 00:08:36 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3261,22 +3261,25 @@ make_agg(PlannerInfo *root, List *tlist, List *qual,
 }
 
 WindowAgg *
-make_windowagg(PlannerInfo *root, List *tlist, int numWindowFuncs,
+make_windowagg(PlannerInfo *root, List *tlist,
+			   int numWindowFuncs, Index winref,
 			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
 			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
-			   Plan *lefttree)
+			   int frameOptions, Plan *lefttree)
 {
 	WindowAgg  *node = makeNode(WindowAgg);
 	Plan	   *plan = &node->plan;
 	Path		windowagg_path;		/* dummy for result of cost_windowagg */
 	QualCost	qual_cost;
 
+	node->winref = winref;
 	node->partNumCols = partNumCols;
 	node->partColIdx = partColIdx;
 	node->partOperators = partOperators;
 	node->ordNumCols = ordNumCols;
 	node->ordColIdx = ordColIdx;
 	node->ordOperators = ordOperators;
+	node->frameOptions = frameOptions;
 
 	copy_plan_costsize(plan, lefttree);	/* only care about copying size */
 	cost_windowagg(&windowagg_path, root,

src/backend/optimizer/plan/planner.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.248 2008/12/28 18:53:56 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.249 2008/12/31 00:08:36 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1398,12 +1398,14 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 					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);
 			}
 		}
@@ -2412,6 +2414,7 @@ select_active_windows(PlannerInfo *root, WindowFuncLists *wflists)
 			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))
 			{

src/backend/parser/gram.y

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.648 2008/12/28 18:53:58 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.649 2008/12/31 00:08:36 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -406,6 +406,7 @@ static TypeName *TableFuncTypeName(List *columns);
 %type <list>	window_clause window_definition_list opt_partition_clause
 %type <windef>	window_definition over_clause window_specification
 %type <str>		opt_existing_window_name
+%type <ival>	opt_frame_clause frame_extent frame_bound
 
 
 /*
@@ -439,7 +440,7 @@ static TypeName *TableFuncTypeName(List *columns);
 	EACH ELSE ENABLE_P ENCODING ENCRYPTED END_P ENUM_P ESCAPE EXCEPT
 	EXCLUDING EXCLUSIVE EXECUTE EXISTS EXPLAIN EXTERNAL EXTRACT
 
-	FALSE_P FAMILY FETCH FIRST_P FLOAT_P FOR FORCE FOREIGN FORWARD
+	FALSE_P FAMILY FETCH FIRST_P FLOAT_P FOLLOWING FOR FORCE FOREIGN FORWARD
 	FREEZE FROM FULL FUNCTION
 
 	GLOBAL GRANT GRANTED GREATEST GROUP_P
@@ -469,14 +470,14 @@ static TypeName *TableFuncTypeName(List *columns);
 	ORDER OUT_P OUTER_P OVER OVERLAPS OVERLAY OWNED OWNER
 
 	PARSER PARTIAL PARTITION PASSWORD PLACING PLANS POSITION
-	PRECISION PRESERVE PREPARE PREPARED PRIMARY
+	PRECEDING PRECISION PRESERVE PREPARE PREPARED PRIMARY
 	PRIOR PRIVILEGES PROCEDURAL PROCEDURE
 
 	QUOTE
 
-	READ REAL REASSIGN RECHECK RECURSIVE REFERENCES REINDEX RELATIVE_P RELEASE
-	RENAME REPEATABLE REPLACE REPLICA RESET RESTART RESTRICT RETURNING RETURNS
-	REVOKE RIGHT ROLE ROLLBACK ROW ROWS RULE
+	RANGE READ REAL REASSIGN RECHECK RECURSIVE REFERENCES REINDEX
+	RELATIVE_P RELEASE RENAME REPEATABLE REPLACE REPLICA RESET RESTART
+	RESTRICT RETURNING RETURNS REVOKE RIGHT ROLE ROLLBACK ROW ROWS RULE
 
 	SAVEPOINT SCHEMA SCROLL SEARCH SECOND_P SECURITY SELECT SEQUENCE
 	SERIALIZABLE SERVER SESSION SESSION_USER SET SETOF SHARE
@@ -488,7 +489,7 @@ static TypeName *TableFuncTypeName(List *columns);
 	TO TRAILING TRANSACTION TREAT TRIGGER TRIM TRUE_P
 	TRUNCATE TRUSTED TYPE_P
 
-	UNCOMMITTED UNENCRYPTED UNION UNIQUE UNKNOWN UNLISTEN UNTIL
+	UNBOUNDED UNCOMMITTED UNENCRYPTED UNION UNIQUE UNKNOWN UNLISTEN UNTIL
 	UPDATE USER USING
 
 	VACUUM VALID VALIDATOR VALUE_P VALUES VARCHAR VARIADIC VARYING
@@ -533,10 +534,12 @@ static TypeName *TableFuncTypeName(List *columns);
  * between POSTFIXOP and Op.  We can safely assign the same priority to
  * various unreserved keywords as needed to resolve ambiguities (this can't
  * have any bad effects since obviously the keywords will still behave the
- * same as if they weren't keywords).  We need to do this for PARTITION
- * to support opt_existing_window_name.
+ * same as if they weren't keywords).  We need to do this for PARTITION,
+ * RANGE, ROWS to support opt_existing_window_name; and for RANGE, ROWS
+ * so that they can follow a_expr without creating
+ * postfix-operator problems.
  */
-%nonassoc	IDENT PARTITION
+%nonassoc	IDENT PARTITION RANGE ROWS
 %left		Op OPERATOR		/* multi-character ops and user-defined operators */
 %nonassoc	NOTNULL
 %nonassoc	ISNULL
@@ -9235,10 +9238,11 @@ over_clause: OVER window_specification
 			| OVER ColId
 				{
 					WindowDef *n = makeNode(WindowDef);
-					n->name = NULL;
-					n->refname = $2;
+					n->name = $2;
+					n->refname = NULL;
 					n->partitionClause = NIL;
 					n->orderClause = NIL;
+					n->frameOptions = FRAMEOPTION_DEFAULTS;
 					n->location = @2;
 					$$ = n;
 				}
@@ -9247,13 +9251,14 @@ over_clause: OVER window_specification
 		;
 
 window_specification: '(' opt_existing_window_name opt_partition_clause
-						opt_sort_clause ')'
+						opt_sort_clause opt_frame_clause ')'
 				{
 					WindowDef *n = makeNode(WindowDef);
 					n->name = NULL;
 					n->refname = $2;
 					n->partitionClause = $3;
 					n->orderClause = $4;
+					n->frameOptions = $5;
 					n->location = @1;
 					$$ = n;
 				}
@@ -9268,7 +9273,6 @@ window_specification: '(' opt_existing_window_name opt_partition_clause
  * that the shift/reduce conflict is resolved in favor of reducing the rule.
  * These keywords are thus precluded from being an existing_window_name but
  * are not reserved for any other purpose.
- * (RANGE/ROWS are not an issue as of 8.4 for lack of frame_clause support.)
  */
 opt_existing_window_name: ColId						{ $$ = $1; }
 			| /*EMPTY*/				%prec Op		{ $$ = NULL; }
@@ -9278,6 +9282,83 @@ opt_partition_clause: PARTITION BY expr_list		{ $$ = $3; }
 			| /*EMPTY*/								{ $$ = NIL; }
 		;
 
+/*
+ * This is only a subset of the full SQL:2008 frame_clause grammar.
+ * We don't support <expression> PRECEDING, <expression> FOLLOWING,
+ * nor <window frame exclusion> yet.
+ */
+opt_frame_clause:
+			RANGE frame_extent
+				{
+					$$ = FRAMEOPTION_NONDEFAULT | FRAMEOPTION_RANGE | $2;
+				}
+			| ROWS frame_extent
+				{
+					$$ = FRAMEOPTION_NONDEFAULT | FRAMEOPTION_ROWS | $2;
+				}
+			| /*EMPTY*/
+				{ $$ = FRAMEOPTION_DEFAULTS; }
+		;
+
+frame_extent: frame_bound
+				{
+					/* reject invalid cases */
+					if ($1 & FRAMEOPTION_START_UNBOUNDED_FOLLOWING)
+						ereport(ERROR,
+								(errcode(ERRCODE_WINDOWING_ERROR),
+								 errmsg("frame start cannot be UNBOUNDED FOLLOWING"),
+								 scanner_errposition(@1)));
+					if ($1 & FRAMEOPTION_START_CURRENT_ROW)
+						ereport(ERROR,
+								(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+								 errmsg("frame start at CURRENT ROW is not implemented"),
+								 scanner_errposition(@1)));
+					$$ = $1 | FRAMEOPTION_END_CURRENT_ROW;
+				}
+			| BETWEEN frame_bound AND frame_bound
+				{
+					/* reject invalid cases */
+					if ($2 & FRAMEOPTION_START_UNBOUNDED_FOLLOWING)
+						ereport(ERROR,
+								(errcode(ERRCODE_WINDOWING_ERROR),
+								 errmsg("frame start cannot be UNBOUNDED FOLLOWING"),
+								 scanner_errposition(@2)));
+					if ($2 & FRAMEOPTION_START_CURRENT_ROW)
+						ereport(ERROR,
+								(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+								 errmsg("frame start at CURRENT ROW is not implemented"),
+								 scanner_errposition(@2)));
+					if ($4 & FRAMEOPTION_START_UNBOUNDED_PRECEDING)
+						ereport(ERROR,
+								(errcode(ERRCODE_WINDOWING_ERROR),
+								 errmsg("frame end cannot be UNBOUNDED PRECEDING"),
+								 scanner_errposition(@4)));
+					/* shift converts START_ options to END_ options */
+					$$ = FRAMEOPTION_BETWEEN | $2 | ($4 << 1);
+				}
+		;
+
+/*
+ * This is used for both frame start and frame end, with output set up on
+ * the assumption it's frame start; the frame_extent productions must reject
+ * invalid cases.
+ */
+frame_bound:
+			UNBOUNDED PRECEDING
+				{
+					$$ = FRAMEOPTION_START_UNBOUNDED_PRECEDING;
+				}
+			| UNBOUNDED FOLLOWING
+				{
+					$$ = FRAMEOPTION_START_UNBOUNDED_FOLLOWING;
+				}
+			| CURRENT_P ROW
+				{
+					$$ = FRAMEOPTION_START_CURRENT_ROW;
+				}
+		;
+
+
 /*
  * Supporting nonterminals for expressions.
  */
@@ -10012,6 +10093,7 @@ unreserved_keyword:
 			| EXTERNAL
 			| FAMILY
 			| FIRST_P
+			| FOLLOWING
 			| FORCE
 			| FORWARD
 			| FUNCTION
@@ -10086,6 +10168,7 @@ unreserved_keyword:
 			| PARTITION
 			| PASSWORD
 			| PLANS
+			| PRECEDING
 			| PREPARE
 			| PREPARED
 			| PRESERVE
@@ -10094,6 +10177,7 @@ unreserved_keyword:
 			| PROCEDURAL
 			| PROCEDURE
 			| QUOTE
+			| RANGE
 			| READ
 			| REASSIGN
 			| RECHECK
@@ -10151,6 +10235,7 @@ unreserved_keyword:
 			| TRUNCATE
 			| TRUSTED
 			| TYPE_P
+			| UNBOUNDED
 			| UNCOMMITTED
 			| UNENCRYPTED
 			| UNKNOWN

src/backend/parser/keywords.c

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/keywords.c,v 1.207 2008/12/28 18:53:58 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/keywords.c,v 1.208 2008/12/31 00:08:37 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -172,6 +172,7 @@ const ScanKeyword ScanKeywords[] = {
 	{"fetch", FETCH, RESERVED_KEYWORD},
 	{"first", FIRST_P, UNRESERVED_KEYWORD},
 	{"float", FLOAT_P, COL_NAME_KEYWORD},
+	{"following", FOLLOWING, UNRESERVED_KEYWORD},
 	{"for", FOR, RESERVED_KEYWORD},
 	{"force", FORCE, UNRESERVED_KEYWORD},
 	{"foreign", FOREIGN, RESERVED_KEYWORD},
@@ -299,6 +300,7 @@ const ScanKeyword ScanKeywords[] = {
 	{"placing", PLACING, RESERVED_KEYWORD},
 	{"plans", PLANS, UNRESERVED_KEYWORD},
 	{"position", POSITION, COL_NAME_KEYWORD},
+	{"preceding", PRECEDING, UNRESERVED_KEYWORD},
 	{"precision", PRECISION, COL_NAME_KEYWORD},
 	{"prepare", PREPARE, UNRESERVED_KEYWORD},
 	{"prepared", PREPARED, UNRESERVED_KEYWORD},
@@ -309,6 +311,7 @@ const ScanKeyword ScanKeywords[] = {
 	{"procedural", PROCEDURAL, UNRESERVED_KEYWORD},
 	{"procedure", PROCEDURE, UNRESERVED_KEYWORD},
 	{"quote", QUOTE, UNRESERVED_KEYWORD},
+	{"range", RANGE, UNRESERVED_KEYWORD},
 	{"read", READ, UNRESERVED_KEYWORD},
 	{"real", REAL, COL_NAME_KEYWORD},
 	{"reassign", REASSIGN, UNRESERVED_KEYWORD},
@@ -388,6 +391,7 @@ const ScanKeyword ScanKeywords[] = {
 	{"truncate", TRUNCATE, UNRESERVED_KEYWORD},
 	{"trusted", TRUSTED, UNRESERVED_KEYWORD},
 	{"type", TYPE_P, UNRESERVED_KEYWORD},
+	{"unbounded", UNBOUNDED, UNRESERVED_KEYWORD},
 	{"uncommitted", UNCOMMITTED, UNRESERVED_KEYWORD},
 	{"unencrypted", UNENCRYPTED, UNRESERVED_KEYWORD},
 	{"union", UNION, RESERVED_KEYWORD},

src/backend/parser/parse_agg.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_agg.c,v 1.85 2008/12/28 18:53:58 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_agg.c,v 1.86 2008/12/31 00:08:37 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -123,25 +123,27 @@ transformWindowFuncCall(ParseState *pstate, WindowFunc *wfunc,
 									locate_windowfunc((Node *) wfunc->args))));
 
 	/*
-	 * If the OVER clause just specifies a reference name, find that
+	 * If the OVER clause just specifies a window name, find that
 	 * WINDOW clause (which had better be present).  Otherwise, try to
 	 * match all the properties of the OVER clause, and make a new entry
 	 * in the p_windowdefs list if no luck.
 	 */
-	Assert(!windef->name);
-	if (windef->refname &&
-		windef->partitionClause == NIL &&
-		windef->orderClause == NIL)
+	if (windef->name)
 	{
 		Index		winref = 0;
 		ListCell   *lc;
 
+		Assert(windef->refname == NULL &&
+			   windef->partitionClause == NIL &&
+			   windef->orderClause == NIL &&
+			   windef->frameOptions == FRAMEOPTION_DEFAULTS);
+
 		foreach(lc, pstate->p_windowdefs)
 		{
 			WindowDef *refwin = (WindowDef *) lfirst(lc);
 
 			winref++;
-			if (refwin->name && strcmp(refwin->name, windef->refname) == 0)
+			if (refwin->name && strcmp(refwin->name, windef->name) == 0)
 			{
 				wfunc->winref = winref;
 				break;
@@ -150,7 +152,7 @@ transformWindowFuncCall(ParseState *pstate, WindowFunc *wfunc,
 		if (lc == NULL)			/* didn't find it? */
 			ereport(ERROR,
 					(errcode(ERRCODE_UNDEFINED_OBJECT),
-					 errmsg("window \"%s\" does not exist", windef->refname),
+					 errmsg("window \"%s\" does not exist", windef->name),
 					 parser_errposition(pstate, windef->location)));
 	}
 	else
@@ -164,14 +166,15 @@ transformWindowFuncCall(ParseState *pstate, WindowFunc *wfunc,
 
 			winref++;
 			if (refwin->refname && windef->refname &&
-				strcmp(refwin->name, windef->refname) == 0)
+				strcmp(refwin->refname, windef->refname) == 0)
 				/* matched on refname */ ;
 			else if (!refwin->refname && !windef->refname)
 				/* matched, no refname */ ;
 			else
 				continue;
 			if (equal(refwin->partitionClause, windef->partitionClause) &&
-				equal(refwin->orderClause, windef->orderClause))
+				equal(refwin->orderClause, windef->orderClause) &&
+				refwin->frameOptions == windef->frameOptions)
 			{
 				/* found a duplicate window specification */
 				wfunc->winref = winref;

src/backend/parser/parse_clause.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_clause.c,v 1.182 2008/12/28 18:53:58 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_clause.c,v 1.183 2008/12/31 00:08:37 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1554,7 +1554,7 @@ transformWindowDefinitions(ParseState *pstate,
 		 * Per spec, a windowdef that references a previous one copies the
 		 * previous partition clause (and mustn't specify its own).  It can
 		 * specify its own ordering clause. but only if the previous one
-		 * had none.
+		 * had none.  It always specifies its own framing clause.
 		 */
 		if (refwc)
 		{
@@ -1592,6 +1592,7 @@ transformWindowDefinitions(ParseState *pstate,
 			wc->orderClause = orderClause;
 			wc->copiedOrder = false;
 		}
+		wc->frameOptions = windef->frameOptions;
 		wc->winref = winref;
 
 		result = lappend(result, wc);

src/backend/utils/adt/ruleutils.c

@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.291 2008/12/28 18:53:59 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.292 2008/12/31 00:08:37 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2903,7 +2903,7 @@ get_rule_windowspec(WindowClause *wc, List *targetList,
 		appendStringInfoString(buf, quote_identifier(wc->refname));
 		needspace = true;
 	}
-	/* partitions are always inherited, so only print if no refname */
+	/* partition clauses are always inherited, so only print if no refname */
 	if (wc->partitionClause && !wc->refname)
 	{
 		if (needspace)
@@ -2921,6 +2921,7 @@ get_rule_windowspec(WindowClause *wc, List *targetList,
 		}
 		needspace = true;
 	}
+	/* print ordering clause only if not inherited */
 	if (wc->orderClause && !wc->copiedOrder)
 	{
 		if (needspace)
@@ -2929,6 +2930,38 @@ get_rule_windowspec(WindowClause *wc, List *targetList,
 		get_rule_orderby(wc->orderClause, targetList, false, context);
 		needspace = true;
 	}
+	/* framing clause is never inherited, so print unless it's default */
+	if (wc->frameOptions & FRAMEOPTION_NONDEFAULT)
+	{
+		if (needspace)
+			appendStringInfoChar(buf, ' ');
+		if (wc->frameOptions & FRAMEOPTION_RANGE)
+			appendStringInfoString(buf, "RANGE ");
+		else if (wc->frameOptions & FRAMEOPTION_ROWS)
+			appendStringInfoString(buf, "ROWS ");
+		else
+			Assert(false);
+		if (wc->frameOptions & FRAMEOPTION_BETWEEN)
+			appendStringInfoString(buf, "BETWEEN ");
+		if (wc->frameOptions & FRAMEOPTION_START_UNBOUNDED_PRECEDING)
+			appendStringInfoString(buf, "UNBOUNDED PRECEDING ");
+		else if (wc->frameOptions & FRAMEOPTION_START_CURRENT_ROW)
+			appendStringInfoString(buf, "CURRENT ROW ");
+		else
+			Assert(false);
+		if (wc->frameOptions & FRAMEOPTION_BETWEEN)
+		{
+			appendStringInfoString(buf, "AND ");
+			if (wc->frameOptions & FRAMEOPTION_END_UNBOUNDED_FOLLOWING)
+				appendStringInfoString(buf, "UNBOUNDED FOLLOWING ");
+			else if (wc->frameOptions & FRAMEOPTION_END_CURRENT_ROW)
+				appendStringInfoString(buf, "CURRENT ROW ");
+			else
+				Assert(false);
+		}
+		/* we will now have a trailing space; remove it */
+		buf->len--;
+	}
 	appendStringInfoChar(buf, ')');
 }
 

src/include/catalog/catversion.h

@@ -37,7 +37,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.514 2008/12/28 18:53:59 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.515 2008/12/31 00:08:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	200812281
+#define CATALOG_VERSION_NO	200812301
 
 #endif

src/include/nodes/execnodes.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.197 2008/12/28 18:54:00 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.198 2008/12/31 00:08:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1533,12 +1533,14 @@ typedef struct WindowAggState
 									 * have been spooled into tuplestore */
 	bool		more_partitions;	/* true if there's more partitions after
 									 * this one */
+	bool		frametail_valid;	/* true if frametailpos is known up to date
+									 * for current row */
 
 	TupleTableSlot *first_part_slot;	/* first tuple of current or next
 										 * partition */
 
 	/* temporary slots for tuples fetched back from tuplestore */
-	TupleTableSlot *first_peer_slot;
+	TupleTableSlot *agg_row_slot;
 	TupleTableSlot *temp_slot_1;
 	TupleTableSlot *temp_slot_2;
 } WindowAggState;

src/include/nodes/parsenodes.h

@@ -13,7 +13,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.385 2008/12/28 18:54:00 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.386 2008/12/31 00:08:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -382,17 +382,46 @@ typedef struct SortBy
 
 /*
  * WindowDef - raw representation of WINDOW and OVER clauses
+ *
+ * For entries in a WINDOW list, "name" is the window name being defined.
+ * For OVER clauses, we use "name" for the "OVER window" syntax, or "refname"
+ * for the "OVER (window)" syntax, which is subtly different --- the latter
+ * implies overriding the window frame clause.
  */
 typedef struct WindowDef
 {
 	NodeTag		type;
-	char	   *name;				/* window name (NULL in an OVER clause) */
+	char	   *name;				/* window's own name */
 	char	   *refname;			/* referenced window name, if any */
 	List	   *partitionClause;	/* PARTITION BY expression list */
 	List	   *orderClause;		/* ORDER BY (list of SortBy) */
+	int			frameOptions;		/* frame_clause options, see below */
 	int			location;			/* parse location, or -1 if none/unknown */
 } WindowDef;
 
+/*
+ * frameOptions is an OR of these bits.  The NONDEFAULT and BETWEEN bits are
+ * used so that ruleutils.c can tell which properties were specified and
+ * which were defaulted; the correct behavioral bits must be set either way.
+ * The START_foo and END_foo options must come in pairs of adjacent bits for
+ * the convenience of gram.y, even though some of them are useless/invalid.
+ * We will need more bits (and fields) to cover the full SQL:2008 option set.
+ */
+#define FRAMEOPTION_NONDEFAULT					0x00001	/* any specified? */
+#define FRAMEOPTION_RANGE						0x00002	/* RANGE behavior */
+#define FRAMEOPTION_ROWS						0x00004	/* ROWS behavior */
+#define FRAMEOPTION_BETWEEN						0x00008	/* BETWEEN given? */
+#define FRAMEOPTION_START_UNBOUNDED_PRECEDING	0x00010	/* start is U. P. */
+#define FRAMEOPTION_END_UNBOUNDED_PRECEDING		0x00020	/* (disallowed) */
+#define FRAMEOPTION_START_UNBOUNDED_FOLLOWING	0x00040	/* (disallowed) */
+#define FRAMEOPTION_END_UNBOUNDED_FOLLOWING		0x00080	/* end is U. F. */
+#define FRAMEOPTION_START_CURRENT_ROW			0x00100	/* start is C. R. */
+#define FRAMEOPTION_END_CURRENT_ROW				0x00200	/* end is C. R. */
+
+#define FRAMEOPTION_DEFAULTS \
+	(FRAMEOPTION_RANGE | FRAMEOPTION_START_UNBOUNDED_PRECEDING | \
+	 FRAMEOPTION_END_CURRENT_ROW)
+
 /*
  * RangeSubselect - subquery appearing in a FROM clause
  */
@@ -744,8 +773,8 @@ typedef struct SortGroupClause
  * winref is an ID number referenced by WindowFunc nodes; it must be unique
  * among the members of a Query's windowClause list.
  * When refname isn't null, the partitionClause is always copied from there;
- * the orderClause might or might not be copied.  (We don't implement
- * framing clauses yet, but if we did, they are never copied, per spec.)
+ * the orderClause might or might not be copied (see copiedOrder); the framing
+ * options are never copied, per spec.
  */
 typedef struct WindowClause
 {
@@ -754,6 +783,7 @@ typedef struct WindowClause
 	char	   *refname;			/* referenced window name, if any */
 	List	   *partitionClause;	/* PARTITION BY list */
 	List	   *orderClause;		/* ORDER BY list */
+	int			frameOptions;		/* frame_clause options, see WindowDef */
 	Index		winref;				/* ID referenced by window functions */
 	bool		copiedOrder;		/* did we copy orderClause from refname? */
 } WindowClause;

src/include/nodes/plannodes.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/plannodes.h,v 1.106 2008/12/28 18:54:00 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/plannodes.h,v 1.107 2008/12/31 00:08:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -543,12 +543,14 @@ typedef struct Agg
 typedef struct WindowAgg
 {
 	Plan		plan;
+	Index		winref;			/* ID referenced by window functions */
 	int			partNumCols;	/* number of columns in partition clause */
 	AttrNumber *partColIdx;		/* their indexes in the target list */
 	Oid		   *partOperators;	/* equality operators for partition columns */
 	int			ordNumCols;		/* number of columns in ordering clause */
 	AttrNumber *ordColIdx;		/* their indexes in the target list */
 	Oid		   *ordOperators;	/* equality operators for ordering columns */
+	int			frameOptions;	/* frame_clause options, see WindowDef */
 } WindowAgg;
 
 /* ----------------

src/include/optimizer/planmain.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/planmain.h,v 1.115 2008/12/28 18:54:01 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/planmain.h,v 1.116 2008/12/31 00:08:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -57,10 +57,10 @@ extern Agg *make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 long numGroups, int numAggs,
 		 Plan *lefttree);
 extern WindowAgg *make_windowagg(PlannerInfo *root, List *tlist,
-			   int numWindowFuncs,
+			   int numWindowFuncs, Index winref,
 			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
 			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
-			   Plan *lefttree);
+			   int frameOptions, Plan *lefttree);
 extern Group *make_group(PlannerInfo *root, List *tlist, List *qual,
 		   int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
 		   double numGroups,

src/test/regress/expected/window.out

@@ -587,30 +587,153 @@ SELECT empno, depname, salary, bonus, depadj, MIN(bonus) OVER (ORDER BY empno),
     11 | develop   |   5200 |   500 |    200 |  500 | 200
 (10 rows)
 
+-- test non-default frame specifications
+SELECT four, ten,
+	sum(ten) over (partition by four order by ten),
+	last_value(ten) over (partition by four order by ten)
+FROM (select distinct ten, four from tenk1) ss;
+ four | ten | sum | last_value 
+------+-----+-----+------------
+    0 |   0 |   0 |          0
+    0 |   2 |   2 |          2
+    0 |   4 |   6 |          4
+    0 |   6 |  12 |          6
+    0 |   8 |  20 |          8
+    1 |   1 |   1 |          1
+    1 |   3 |   4 |          3
+    1 |   5 |   9 |          5
+    1 |   7 |  16 |          7
+    1 |   9 |  25 |          9
+    2 |   0 |   0 |          0
+    2 |   2 |   2 |          2
+    2 |   4 |   6 |          4
+    2 |   6 |  12 |          6
+    2 |   8 |  20 |          8
+    3 |   1 |   1 |          1
+    3 |   3 |   4 |          3
+    3 |   5 |   9 |          5
+    3 |   7 |  16 |          7
+    3 |   9 |  25 |          9
+(20 rows)
+
+SELECT four, ten,
+	sum(ten) over (partition by four order by ten range between unbounded preceding and current row),
+	last_value(ten) over (partition by four order by ten range between unbounded preceding and current row)
+FROM (select distinct ten, four from tenk1) ss;
+ four | ten | sum | last_value 
+------+-----+-----+------------
+    0 |   0 |   0 |          0
+    0 |   2 |   2 |          2
+    0 |   4 |   6 |          4
+    0 |   6 |  12 |          6
+    0 |   8 |  20 |          8
+    1 |   1 |   1 |          1
+    1 |   3 |   4 |          3
+    1 |   5 |   9 |          5
+    1 |   7 |  16 |          7
+    1 |   9 |  25 |          9
+    2 |   0 |   0 |          0
+    2 |   2 |   2 |          2
+    2 |   4 |   6 |          4
+    2 |   6 |  12 |          6
+    2 |   8 |  20 |          8
+    3 |   1 |   1 |          1
+    3 |   3 |   4 |          3
+    3 |   5 |   9 |          5
+    3 |   7 |  16 |          7
+    3 |   9 |  25 |          9
+(20 rows)
+
+SELECT four, ten,
+	sum(ten) over (partition by four order by ten range between unbounded preceding and unbounded following),
+	last_value(ten) over (partition by four order by ten range between unbounded preceding and unbounded following)
+FROM (select distinct ten, four from tenk1) ss;
+ four | ten | sum | last_value 
+------+-----+-----+------------
+    0 |   0 |  20 |          8
+    0 |   2 |  20 |          8
+    0 |   4 |  20 |          8
+    0 |   6 |  20 |          8
+    0 |   8 |  20 |          8
+    1 |   1 |  25 |          9
+    1 |   3 |  25 |          9
+    1 |   5 |  25 |          9
+    1 |   7 |  25 |          9
+    1 |   9 |  25 |          9
+    2 |   0 |  20 |          8
+    2 |   2 |  20 |          8
+    2 |   4 |  20 |          8
+    2 |   6 |  20 |          8
+    2 |   8 |  20 |          8
+    3 |   1 |  25 |          9
+    3 |   3 |  25 |          9
+    3 |   5 |  25 |          9
+    3 |   7 |  25 |          9
+    3 |   9 |  25 |          9
+(20 rows)
+
+SELECT four, ten/4 as two,
+	sum(ten/4) over (partition by four order by ten/4 range between unbounded preceding and current row),
+	last_value(ten/4) over (partition by four order by ten/4 range between unbounded preceding and current row)
+FROM (select distinct ten, four from tenk1) ss;
+ four | two | sum | last_value 
+------+-----+-----+------------
+    0 |   0 |   0 |          0
+    0 |   0 |   0 |          0
+    0 |   1 |   2 |          1
+    0 |   1 |   2 |          1
+    0 |   2 |   4 |          2
+    1 |   0 |   0 |          0
+    1 |   0 |   0 |          0
+    1 |   1 |   2 |          1
+    1 |   1 |   2 |          1
+    1 |   2 |   4 |          2
+    2 |   0 |   0 |          0
+    2 |   0 |   0 |          0
+    2 |   1 |   2 |          1
+    2 |   1 |   2 |          1
+    2 |   2 |   4 |          2
+    3 |   0 |   0 |          0
+    3 |   0 |   0 |          0
+    3 |   1 |   2 |          1
+    3 |   1 |   2 |          1
+    3 |   2 |   4 |          2
+(20 rows)
+
+SELECT four, ten/4 as two,
+	sum(ten/4) over (partition by four order by ten/4 rows between unbounded preceding and current row),
+	last_value(ten/4) over (partition by four order by ten/4 rows between unbounded preceding and current row)
+FROM (select distinct ten, four from tenk1) ss;
+ four | two | sum | last_value 
+------+-----+-----+------------
+    0 |   0 |   0 |          0
+    0 |   0 |   0 |          0
+    0 |   1 |   1 |          1
+    0 |   1 |   2 |          1
+    0 |   2 |   4 |          2
+    1 |   0 |   0 |          0
+    1 |   0 |   0 |          0
+    1 |   1 |   1 |          1
+    1 |   1 |   2 |          1
+    1 |   2 |   4 |          2
+    2 |   0 |   0 |          0
+    2 |   0 |   0 |          0
+    2 |   1 |   1 |          1
+    2 |   1 |   2 |          1
+    2 |   2 |   4 |          2
+    3 |   0 |   0 |          0
+    3 |   0 |   0 |          0
+    3 |   1 |   1 |          1
+    3 |   1 |   2 |          1
+    3 |   2 |   4 |          2
+(20 rows)
+
 -- with UNION
 SELECT count(*) OVER (PARTITION BY four) FROM (SELECT * FROM tenk1 UNION ALL SELECT * FROM tenk2)s LIMIT 0;
  count 
 -------
 (0 rows)
 
--- via a VIEW
-CREATE TEMPORARY VIEW vsumsalary AS
-SELECT SUM(salary) OVER (PARTITION BY depname) FROM empsalary;
-SELECT * FROM vsumsalary;
-  sum  
--------
- 25100
- 25100
- 25100
- 25100
- 25100
-  7400
-  7400
- 14600
- 14600
- 14600
-(10 rows)
-
 -- ordering by a non-integer constant is allowed
 SELECT rank() OVER (ORDER BY length('abc'));
  rank 
@@ -669,5 +792,4 @@ ERROR:  argument of ntile must be greater than zero
 SELECT nth_value(four, 0) OVER (ORDER BY ten), ten, four FROM tenk1;
 ERROR:  argument of nth_value must be greater than zero
 -- cleanup
-DROP VIEW vsumsalary;
 DROP TABLE empsalary;

src/test/regress/sql/window.sql

@@ -135,14 +135,35 @@ SELECT empno, depname, salary, bonus, depadj, MIN(bonus) OVER (ORDER BY empno),
 		THEN 200 END AS depadj FROM empsalary
 )s;
 
+-- test non-default frame specifications
+SELECT four, ten,
+	sum(ten) over (partition by four order by ten),
+	last_value(ten) over (partition by four order by ten)
+FROM (select distinct ten, four from tenk1) ss;
+
+SELECT four, ten,
+	sum(ten) over (partition by four order by ten range between unbounded preceding and current row),
+	last_value(ten) over (partition by four order by ten range between unbounded preceding and current row)
+FROM (select distinct ten, four from tenk1) ss;
+
+SELECT four, ten,
+	sum(ten) over (partition by four order by ten range between unbounded preceding and unbounded following),
+	last_value(ten) over (partition by four order by ten range between unbounded preceding and unbounded following)
+FROM (select distinct ten, four from tenk1) ss;
+
+SELECT four, ten/4 as two,
+	sum(ten/4) over (partition by four order by ten/4 range between unbounded preceding and current row),
+	last_value(ten/4) over (partition by four order by ten/4 range between unbounded preceding and current row)
+FROM (select distinct ten, four from tenk1) ss;
+
+SELECT four, ten/4 as two,
+	sum(ten/4) over (partition by four order by ten/4 rows between unbounded preceding and current row),
+	last_value(ten/4) over (partition by four order by ten/4 rows between unbounded preceding and current row)
+FROM (select distinct ten, four from tenk1) ss;
+
 -- with UNION
 SELECT count(*) OVER (PARTITION BY four) FROM (SELECT * FROM tenk1 UNION ALL SELECT * FROM tenk2)s LIMIT 0;
 
--- via a VIEW
-CREATE TEMPORARY VIEW vsumsalary AS
-SELECT SUM(salary) OVER (PARTITION BY depname) FROM empsalary;
-SELECT * FROM vsumsalary;
-
 -- ordering by a non-integer constant is allowed
 SELECT rank() OVER (ORDER BY length('abc'));
 
@@ -175,5 +196,4 @@ SELECT ntile(0) OVER (ORDER BY ten), ten, four FROM tenk1;
 SELECT nth_value(four, 0) OVER (ORDER BY ten), ten, four FROM tenk1;
 
 -- cleanup
-DROP VIEW vsumsalary;
 DROP TABLE empsalary;