Combining Aggregates

diff --git a/doc/src/sgml/ref/create_aggregate.sgml b/doc/src/sgml/ref/create_aggregate.sgml
index eaa410b..6cbdf58 100644
--- a/doc/src/sgml/ref/create_aggregate.sgml
+++ b/doc/src/sgml/ref/create_aggregate.sgml
@@ -27,6 +27,8 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ <replacea
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , CFUNC = <replaceable class="PARAMETER">cfunc</replaceable> ]
+    [ , CFUNC_EXTRA ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -45,6 +47,8 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ [ <replac
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , CFUNC = <replaceable class="PARAMETER">cfunc</replaceable> ]
+    [ , CFUNC_EXTRA ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , HYPOTHETICAL ]
 )
@@ -58,6 +62,8 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , CFUNC = <replaceable class="PARAMETER">cfunc</replaceable> ]
+    [ , CFUNC_EXTRA ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -105,12 +111,15 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
    functions:
    a state transition function
    <replaceable class="PARAMETER">sfunc</replaceable>,
-   and an optional final calculation function
-   <replaceable class="PARAMETER">ffunc</replaceable>.
+   an optional final calculation function
+   <replaceable class="PARAMETER">ffunc</replaceable>,
+   and an optional combine function
+   <replaceable class="PARAMETER">cfunc</replaceable>.
    These are used as follows:
 <programlisting>
 <replaceable class="PARAMETER">sfunc</replaceable>( internal-state, next-data-values ) ---> next-internal-state
 <replaceable class="PARAMETER">ffunc</replaceable>( internal-state ) ---> aggregate-value
+<replaceable class="PARAMETER">cfunc</replaceable>( internal-state, internal-state ) ---> next-internal-state
 </programlisting>
   </para>
 
@@ -128,6 +137,13 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
   </para>
 
   <para>
+   An aggregate function may also supply a combining function, which allows
+   the aggregation process to be broken down into multiple steps.  This
+   facilitates query optimization techniques such as parallel query,
+   pre-join aggregation and aggregation while sorting.
+  </para>
+
+  <para>
    An aggregate function can provide an initial condition,
    that is, an initial value for the internal state value.
    This is specified and stored in the database as a value of type
diff --git a/src/backend/catalog/pg_aggregate.c b/src/backend/catalog/pg_aggregate.c
index 1ad923c..f1f8805 100644
--- a/src/backend/catalog/pg_aggregate.c
+++ b/src/backend/catalog/pg_aggregate.c
@@ -57,10 +57,12 @@ AggregateCreate(const char *aggName,
 				Oid variadicArgType,
 				List *aggtransfnName,
 				List *aggfinalfnName,
+				List *aggcombinefnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
 				bool finalfnExtraArgs,
+				bool combinefnExtraArgs,
 				bool mfinalfnExtraArgs,
 				List *aggsortopName,
 				Oid aggTransType,
@@ -77,6 +79,7 @@ AggregateCreate(const char *aggName,
 	Form_pg_proc proc;
 	Oid			transfn;
 	Oid			finalfn = InvalidOid;	/* can be omitted */
+	Oid			combinefn = InvalidOid;	/* can be omitted */
 	Oid			mtransfn = InvalidOid;	/* can be omitted */
 	Oid			minvtransfn = InvalidOid;		/* can be omitted */
 	Oid			mfinalfn = InvalidOid;	/* can be omitted */
@@ -90,6 +93,7 @@ AggregateCreate(const char *aggName,
 	Oid			fnArgs[FUNC_MAX_ARGS];
 	int			nargs_transfn;
 	int			nargs_finalfn;
+	int			nargs_combinefn;
 	Oid			procOid;
 	TupleDesc	tupDesc;
 	int			i;
@@ -396,6 +400,50 @@ AggregateCreate(const char *aggName,
 	}
 	Assert(OidIsValid(finaltype));
 
+	/* handle the combinefn, if supplied */
+	if (aggcombinefnName)
+	{
+		/*
+		 * If combinefnExtraArgs is specified, the transfn takes the transtype
+		 * plus all args; otherwise, it just takes the transtype plus any
+		 * direct args.  (Non-direct args are useless at runtime, and are
+		 * actually passed as NULLs, but we may need them in the function
+		 * signature to allow resolution of a polymorphic agg's result type.)
+		 */
+		Oid			cfnVariadicArgType = variadicArgType;
+
+		/* the 1st and 2nd args must be the trans type */
+		fnArgs[0] = aggTransType;
+		fnArgs[1] = aggTransType;
+		memcpy(fnArgs + 2, aggArgTypes, numArgs * sizeof(Oid));
+		if (combinefnExtraArgs)
+			nargs_combinefn = numArgs + 2;
+		else
+		{
+			nargs_combinefn = numDirectArgs + 2;
+			if (numDirectArgs < numArgs)
+			{
+				/* variadic argument doesn't affect finalfn */
+				cfnVariadicArgType = InvalidOid;
+			}
+		}
+
+		combinefn = lookup_agg_function(aggcombinefnName, nargs_combinefn,
+									  fnArgs, cfnVariadicArgType,
+									  &finaltype);
+
+		/*
+		 * When combinefnExtraArgs is specified, the combinefn will certainly
+		 * be passed at least one null argument, so complain if it's strict.
+		 * Nothing bad would happen at runtime (you'd just get a null result),
+		 * but it's surely not what the user wants, so let's complain now.
+		 */
+		if (combinefnExtraArgs && func_strict(combinefn))
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("combine function with extra arguments must not be declared STRICT")));
+	}
+
 	/*
 	 * If finaltype (i.e. aggregate return type) is polymorphic, inputs must
 	 * be polymorphic also, else parser will fail to deduce result type.
diff --git a/src/backend/commands/aggregatecmds.c b/src/backend/commands/aggregatecmds.c
index fcf86dd..32b704f 100644
--- a/src/backend/commands/aggregatecmds.c
+++ b/src/backend/commands/aggregatecmds.c
@@ -61,10 +61,12 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	char		aggKind = AGGKIND_NORMAL;
 	List	   *transfuncName = NIL;
 	List	   *finalfuncName = NIL;
+	List	   *combinefuncName = NIL;
 	List	   *mtransfuncName = NIL;
 	List	   *minvtransfuncName = NIL;
 	List	   *mfinalfuncName = NIL;
 	bool		finalfuncExtraArgs = false;
+	bool		combinefuncExtraArgs = false;
 	bool		mfinalfuncExtraArgs = false;
 	List	   *sortoperatorName = NIL;
 	TypeName   *baseType = NULL;
@@ -124,6 +126,8 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 			transfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "finalfunc") == 0)
 			finalfuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "cfunc") == 0)
+			combinefuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "msfunc") == 0)
 			mtransfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "minvfunc") == 0)
@@ -132,6 +136,8 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 			mfinalfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "finalfunc_extra") == 0)
 			finalfuncExtraArgs = defGetBoolean(defel);
+		else if (pg_strcasecmp(defel->defname, "cfunc_extra") == 0)
+			combinefuncExtraArgs = defGetBoolean(defel);
 		else if (pg_strcasecmp(defel->defname, "mfinalfunc_extra") == 0)
 			mfinalfuncExtraArgs = defGetBoolean(defel);
 		else if (pg_strcasecmp(defel->defname, "sortop") == 0)
@@ -383,10 +389,12 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 						   variadicArgType,
 						   transfuncName,		/* step function name */
 						   finalfuncName,		/* final function name */
+						   combinefuncName,		/* combine function name */
 						   mtransfuncName,		/* fwd trans function name */
 						   minvtransfuncName,	/* inv trans function name */
 						   mfinalfuncName,		/* final function name */
 						   finalfuncExtraArgs,
+						   combinefuncExtraArgs,
 						   mfinalfuncExtraArgs,
 						   sortoperatorName,	/* sort operator name */
 						   transTypeId, /* transition data type */
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 4175ddc..e4b8d9b 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -11898,10 +11898,12 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	PGresult   *res;
 	int			i_aggtransfn;
 	int			i_aggfinalfn;
+	int			i_aggcombinefn;
 	int			i_aggmtransfn;
 	int			i_aggminvtransfn;
 	int			i_aggmfinalfn;
 	int			i_aggfinalextra;
+	int			i_aggcombineextra;
 	int			i_aggmfinalextra;
 	int			i_aggsortop;
 	int			i_hypothetical;
@@ -11914,10 +11916,12 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	int			i_convertok;
 	const char *aggtransfn;
 	const char *aggfinalfn;
+	const char *aggcombinefn;
 	const char *aggmtransfn;
 	const char *aggminvtransfn;
 	const char *aggmfinalfn;
 	bool		aggfinalextra;
+	bool		aggcombineextra;
 	bool		aggmfinalextra;
 	const char *aggsortop;
 	char	   *aggsortconvop;
@@ -11944,7 +11948,26 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	selectSourceSchema(fout, agginfo->aggfn.dobj.namespace->dobj.name);
 
 	/* Get aggregate-specific details */
-	if (fout->remoteVersion >= 90400)
+	if (fout->remoteVersion >= 90500)
+	{
+		appendPQExpBuffer(query, "SELECT aggtransfn, "
+			"aggfinalfn, aggtranstype::pg_catalog.regtype, "
+			"aggcombinefn, aggmtransfn, aggminvtransfn, "
+			"aggmfinalfn, aggmtranstype::pg_catalog.regtype, "
+			"aggfinalextra, aggcombineextra, aggmfinalextra, "
+			"aggsortop::pg_catalog.regoperator, "
+			"(aggkind = 'h') AS hypothetical, "
+			"aggtransspace, agginitval, "
+			"aggmtransspace, aggminitval, "
+			"true AS convertok, "
+			"pg_catalog.pg_get_function_arguments(p.oid) AS funcargs, "
+			"pg_catalog.pg_get_function_identity_arguments(p.oid) AS funciargs "
+			"FROM pg_catalog.pg_aggregate a, pg_catalog.pg_proc p "
+			"WHERE a.aggfnoid = p.oid "
+			"AND p.oid = '%u'::pg_catalog.oid",
+			agginfo->aggfn.dobj.catId.oid);
+	}
+	else if (fout->remoteVersion >= 90400)
 	{
 		appendPQExpBuffer(query, "SELECT aggtransfn, "
 						  "aggfinalfn, aggtranstype::pg_catalog.regtype, "
@@ -12054,10 +12077,12 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 
 	i_aggtransfn = PQfnumber(res, "aggtransfn");
 	i_aggfinalfn = PQfnumber(res, "aggfinalfn");
+	i_aggcombinefn = PQfnumber(res, "aggcombinefn");
 	i_aggmtransfn = PQfnumber(res, "aggmtransfn");
 	i_aggminvtransfn = PQfnumber(res, "aggminvtransfn");
 	i_aggmfinalfn = PQfnumber(res, "aggmfinalfn");
 	i_aggfinalextra = PQfnumber(res, "aggfinalextra");
+	i_aggcombineextra = PQfnumber(res, "aggcombineextra");
 	i_aggmfinalextra = PQfnumber(res, "aggmfinalextra");
 	i_aggsortop = PQfnumber(res, "aggsortop");
 	i_hypothetical = PQfnumber(res, "hypothetical");
@@ -12071,10 +12096,12 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 
 	aggtransfn = PQgetvalue(res, 0, i_aggtransfn);
 	aggfinalfn = PQgetvalue(res, 0, i_aggfinalfn);
+	aggcombinefn = PQgetvalue(res, 0, i_aggcombinefn);
 	aggmtransfn = PQgetvalue(res, 0, i_aggmtransfn);
 	aggminvtransfn = PQgetvalue(res, 0, i_aggminvtransfn);
 	aggmfinalfn = PQgetvalue(res, 0, i_aggmfinalfn);
 	aggfinalextra = (PQgetvalue(res, 0, i_aggfinalextra)[0] == 't');
+	aggcombineextra = (PQgetvalue(res, 0, i_aggcombineextra)[0] == 't');
 	aggmfinalextra = (PQgetvalue(res, 0, i_aggmfinalextra)[0] == 't');
 	aggsortop = PQgetvalue(res, 0, i_aggsortop);
 	hypothetical = (PQgetvalue(res, 0, i_hypothetical)[0] == 't');
@@ -12159,6 +12186,13 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 			appendPQExpBufferStr(details, ",\n    FINALFUNC_EXTRA");
 	}
 
+	if (strcmp(aggcombinefn, "-") != 0)
+	{
+		appendPQExpBuffer(details, ",\n    CFUNC = %s",	aggcombinefn);
+		if (aggcombineextra)
+			appendPQExpBufferStr(details, ",\n    CFUNC_EXTRA");
+	}
+
 	if (strcmp(aggmtransfn, "-") != 0)
 	{
 		appendPQExpBuffer(details, ",\n    MSFUNC = %s,\n    MINVFUNC = %s,\n    MSTYPE = %s",
diff --git a/src/include/catalog/pg_aggregate.h b/src/include/catalog/pg_aggregate.h
index 10cdea1..a7c9cf0 100644
--- a/src/include/catalog/pg_aggregate.h
+++ b/src/include/catalog/pg_aggregate.h
@@ -32,10 +32,12 @@
  *	aggnumdirectargs	number of arguments that are "direct" arguments
  *	aggtransfn			transition function
  *	aggfinalfn			final function (0 if none)
+ *	aggcombinefn		combine function (0 if none)
  *	aggmtransfn			forward function for moving-aggregate mode (0 if none)
  *	aggminvtransfn		inverse function for moving-aggregate mode (0 if none)
  *	aggmfinalfn			final function for moving-aggregate mode (0 if none)
  *	aggfinalextra		true to pass extra dummy arguments to aggfinalfn
+ *	aggcombineextra		true to pass extra dummy arguments to aggcombinefn
  *	aggmfinalextra		true to pass extra dummy arguments to aggmfinalfn
  *	aggsortop			associated sort operator (0 if none)
  *	aggtranstype		type of aggregate's transition (state) data
@@ -55,10 +57,12 @@ CATALOG(pg_aggregate,2600) BKI_WITHOUT_OIDS
 	int16		aggnumdirectargs;
 	regproc		aggtransfn;
 	regproc		aggfinalfn;
+	regproc		aggcombinefn;
 	regproc		aggmtransfn;
 	regproc		aggminvtransfn;
 	regproc		aggmfinalfn;
 	bool		aggfinalextra;
+	bool		aggcombineextra;
 	bool		aggmfinalextra;
 	Oid			aggsortop;
 	Oid			aggtranstype;
@@ -84,24 +88,26 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  * ----------------
  */
 
-#define Natts_pg_aggregate					17
+#define Natts_pg_aggregate					19
 #define Anum_pg_aggregate_aggfnoid			1
 #define Anum_pg_aggregate_aggkind			2
 #define Anum_pg_aggregate_aggnumdirectargs	3
 #define Anum_pg_aggregate_aggtransfn		4
 #define Anum_pg_aggregate_aggfinalfn		5
-#define Anum_pg_aggregate_aggmtransfn		6
-#define Anum_pg_aggregate_aggminvtransfn	7
-#define Anum_pg_aggregate_aggmfinalfn		8
-#define Anum_pg_aggregate_aggfinalextra		9
-#define Anum_pg_aggregate_aggmfinalextra	10
-#define Anum_pg_aggregate_aggsortop			11
-#define Anum_pg_aggregate_aggtranstype		12
-#define Anum_pg_aggregate_aggtransspace		13
-#define Anum_pg_aggregate_aggmtranstype		14
-#define Anum_pg_aggregate_aggmtransspace	15
-#define Anum_pg_aggregate_agginitval		16
-#define Anum_pg_aggregate_aggminitval		17
+#define Anum_pg_aggregate_aggcombinefn		6
+#define Anum_pg_aggregate_aggmtransfn		7
+#define Anum_pg_aggregate_aggminvtransfn	8
+#define Anum_pg_aggregate_aggmfinalfn		9
+#define Anum_pg_aggregate_aggfinalextra		10
+#define Anum_pg_aggregate_aggcombineextra	11
+#define Anum_pg_aggregate_aggmfinalextra	12
+#define Anum_pg_aggregate_aggsortop			13
+#define Anum_pg_aggregate_aggtranstype		14
+#define Anum_pg_aggregate_aggtransspace		15
+#define Anum_pg_aggregate_aggmtranstype		16
+#define Anum_pg_aggregate_aggmtransspace	17
+#define Anum_pg_aggregate_agginitval		18
+#define Anum_pg_aggregate_aggminitval		19
 
 /*
  * Symbolic values for aggkind column.  We distinguish normal aggregates
@@ -125,184 +131,184 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  */
 
 /* avg */
-DATA(insert ( 2100	n 0 int8_avg_accum	numeric_avg		int8_avg_accum	int8_accum_inv	numeric_avg		f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg		int4_avg_accum	int4_avg_accum_inv	int8_avg	f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg		int2_avg_accum	int2_avg_accum_inv	int8_avg	f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg	numeric_avg_accum numeric_accum_inv numeric_avg f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2104	n 0 float4_accum	float8_avg		-				-				-				f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2105	n 0 float8_accum	float8_avg		-				-				-				f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2106	n 0 interval_accum	interval_avg	interval_accum	interval_accum_inv interval_avg f f 0	1187	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
+DATA(insert ( 2100	n 0 int8_avg_accum	numeric_avg		-	int8_avg_accum	int8_accum_inv	numeric_avg		f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg		-	int4_avg_accum	int4_avg_accum_inv	int8_avg	f f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg		-	int2_avg_accum	int2_avg_accum_inv	int8_avg	f f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg	-	numeric_avg_accum numeric_accum_inv numeric_avg f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2104	n 0 float4_accum	float8_avg		-	-				-				-				f f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2105	n 0 float8_accum	float8_avg		-	-				-				-				f f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2106	n 0 interval_accum	interval_avg	-	interval_accum	interval_accum_inv interval_avg f f f 0	1187	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
 
 /* sum */
-DATA(insert ( 2107	n 0 int8_avg_accum	numeric_sum		int8_avg_accum	int8_accum_inv	numeric_sum		f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2108	n 0 int4_sum		-				int4_avg_accum	int4_avg_accum_inv int2int4_sum f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2109	n 0 int2_sum		-				int2_avg_accum	int2_avg_accum_inv int2int4_sum f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2110	n 0 float4pl		-				-				-				-				f f 0	700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2111	n 0 float8pl		-				-				-				-				f f 0	701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2112	n 0 cash_pl			-				cash_pl			cash_mi			-				f f 0	790		0	790		0	_null_ _null_ ));
-DATA(insert ( 2113	n 0 interval_pl		-				interval_pl		interval_mi		-				f f 0	1186	0	1186	0	_null_ _null_ ));
-DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum numeric_avg_accum numeric_accum_inv numeric_sum f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2107	n 0 int8_avg_accum	numeric_sum		-			int8_avg_accum	int8_accum_inv	numeric_sum		f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2108	n 0 int4_sum		-				-			int4_avg_accum	int4_avg_accum_inv int2int4_sum f f f 0	20		0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2109	n 0 int2_sum		-				-			int2_avg_accum	int2_avg_accum_inv int2int4_sum f f f 0	20		0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2110	n 0 float4pl		-				float4pl	-				-				-				f f f 0	700		0	0		0	_null_ _null_ ));
+DATA(insert ( 2111	n 0 float8pl		-				float8pl	-				-				-				f f f 0	701		0	0		0	_null_ _null_ ));
+DATA(insert ( 2112	n 0 cash_pl			-				cash_pl		cash_pl			cash_mi			-				f f f 0	790		0	790		0	_null_ _null_ ));
+DATA(insert ( 2113	n 0 interval_pl		-				interval_pl	interval_pl		interval_mi		-				f f f 0	1186	0	1186	0	_null_ _null_ ));
+DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum -			numeric_avg_accum numeric_accum_inv numeric_sum f f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* max */
-DATA(insert ( 2115	n 0 int8larger		-				-				-				-				f f 413		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2116	n 0 int4larger		-				-				-				-				f f 521		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2117	n 0 int2larger		-				-				-				-				f f 520		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2118	n 0 oidlarger		-				-				-				-				f f 610		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2119	n 0 float4larger	-				-				-				-				f f 623		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2120	n 0 float8larger	-				-				-				-				f f 674		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2121	n 0 int4larger		-				-				-				-				f f 563		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2122	n 0 date_larger		-				-				-				-				f f 1097	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2123	n 0 time_larger		-				-				-				-				f f 1112	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2124	n 0 timetz_larger	-				-				-				-				f f 1554	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2125	n 0 cashlarger		-				-				-				-				f f 903		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2126	n 0 timestamp_larger	-			-				-				-				f f 2064	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2127	n 0 timestamptz_larger	-			-				-				-				f f 1324	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2128	n 0 interval_larger -				-				-				-				f f 1334	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2129	n 0 text_larger		-				-				-				-				f f 666		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2130	n 0 numeric_larger	-				-				-				-				f f 1756	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2050	n 0 array_larger	-				-				-				-				f f 1073	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2244	n 0 bpchar_larger	-				-				-				-				f f 1060	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2797	n 0 tidlarger		-				-				-				-				f f 2800	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3526	n 0 enum_larger		-				-				-				-				f f 3519	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3564	n 0 network_larger	-				-				-				-				f f 1205	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2115	n 0 int8larger		-				int8larger			-				-				-				f f f 413		20		0	0		0	_null_ _null_ ));
+DATA(insert ( 2116	n 0 int4larger		-				int4larger			-				-				-				f f f 521		23		0	0		0	_null_ _null_ ));
+DATA(insert ( 2117	n 0 int2larger		-				int2larger			-				-				-				f f f 520		21		0	0		0	_null_ _null_ ));
+DATA(insert ( 2118	n 0 oidlarger		-				oidlarger			-				-				-				f f f 610		26		0	0		0	_null_ _null_ ));
+DATA(insert ( 2119	n 0 float4larger	-				float4larger		-				-				-				f f f 623		700		0	0		0	_null_ _null_ ));
+DATA(insert ( 2120	n 0 float8larger	-				float8larger		-				-				-				f f f 674		701		0	0		0	_null_ _null_ ));
+DATA(insert ( 2121	n 0 int4larger		-				int4larger			-				-				-				f f f 563		702		0	0		0	_null_ _null_ ));
+DATA(insert ( 2122	n 0 date_larger		-				date_larger			-				-				-				f f f 1097	1082	0	0		0	_null_ _null_ ));
+DATA(insert ( 2123	n 0 time_larger		-				time_larger			-				-				-				f f f 1112	1083	0	0		0	_null_ _null_ ));
+DATA(insert ( 2124	n 0 timetz_larger	-				timetz_larger		-				-				-				f f f 1554	1266	0	0		0	_null_ _null_ ));
+DATA(insert ( 2125	n 0 cashlarger		-				cashlarger			-				-				-				f f f 903		790		0	0		0	_null_ _null_ ));
+DATA(insert ( 2126	n 0 timestamp_larger	-			timestamp_larger	-				-				-				f f f 2064	1114	0	0		0	_null_ _null_ ));
+DATA(insert ( 2127	n 0 timestamptz_larger	-			timestamptz_larger	-				-				-				f f f 1324	1184	0	0		0	_null_ _null_ ));
+DATA(insert ( 2128	n 0 interval_larger -				interval_larger		-				-				-				f f f 1334	1186	0	0		0	_null_ _null_ ));
+DATA(insert ( 2129	n 0 text_larger		-				text_larger			-				-				-				f f f 666		25		0	0		0	_null_ _null_ ));
+DATA(insert ( 2130	n 0 numeric_larger	-				numeric_larger		-				-				-				f f f 1756	1700	0	0		0	_null_ _null_ ));
+DATA(insert ( 2050	n 0 array_larger	-				array_larger		-				-				-				f f f 1073	2277	0	0		0	_null_ _null_ ));
+DATA(insert ( 2244	n 0 bpchar_larger	-				bpchar_larger		-				-				-				f f f 1060	1042	0	0		0	_null_ _null_ ));
+DATA(insert ( 2797	n 0 tidlarger		-				tidlarger			-				-				-				f f f 2800	27		0	0		0	_null_ _null_ ));
+DATA(insert ( 3526	n 0 enum_larger		-				enum_larger			-				-				-				f f f 3519	3500	0	0		0	_null_ _null_ ));
+DATA(insert ( 3564	n 0 network_larger	-				network_larger		-				-				-				f f f 1205	869		0	0		0	_null_ _null_ ));
 
 /* min */
-DATA(insert ( 2131	n 0 int8smaller		-				-				-				-				f f 412		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2132	n 0 int4smaller		-				-				-				-				f f 97		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2133	n 0 int2smaller		-				-				-				-				f f 95		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2134	n 0 oidsmaller		-				-				-				-				f f 609		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2135	n 0 float4smaller	-				-				-				-				f f 622		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2136	n 0 float8smaller	-				-				-				-				f f 672		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2137	n 0 int4smaller		-				-				-				-				f f 562		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2138	n 0 date_smaller	-				-				-				-				f f 1095	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2139	n 0 time_smaller	-				-				-				-				f f 1110	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2140	n 0 timetz_smaller	-				-				-				-				f f 1552	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2141	n 0 cashsmaller		-				-				-				-				f f 902		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2142	n 0 timestamp_smaller	-			-				-				-				f f 2062	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2143	n 0 timestamptz_smaller -			-				-				-				f f 1322	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2144	n 0 interval_smaller	-			-				-				-				f f 1332	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2145	n 0 text_smaller	-				-				-				-				f f 664		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2146	n 0 numeric_smaller -				-				-				-				f f 1754	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2051	n 0 array_smaller	-				-				-				-				f f 1072	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2245	n 0 bpchar_smaller	-				-				-				-				f f 1058	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2798	n 0 tidsmaller		-				-				-				-				f f 2799	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3527	n 0 enum_smaller	-				-				-				-				f f 3518	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3565	n 0 network_smaller -				-				-				-				f f 1203	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2131	n 0 int8smaller		-				int8smaller			-				-				-				f f f 412		20		0	0		0	_null_ _null_ ));
+DATA(insert ( 2132	n 0 int4smaller		-				int4smaller			-				-				-				f f f 97		23		0	0		0	_null_ _null_ ));
+DATA(insert ( 2133	n 0 int2smaller		-				int2smaller			-				-				-				f f f 95		21		0	0		0	_null_ _null_ ));
+DATA(insert ( 2134	n 0 oidsmaller		-				oidsmaller			-				-				-				f f f 609		26		0	0		0	_null_ _null_ ));
+DATA(insert ( 2135	n 0 float4smaller	-				float4smaller		-				-				-				f f f 622		700		0	0		0	_null_ _null_ ));
+DATA(insert ( 2136	n 0 float8smaller	-				float8smaller		-				-				-				f f f 672		701		0	0		0	_null_ _null_ ));
+DATA(insert ( 2137	n 0 int4smaller		-				int4smaller			-				-				-				f f f 562		702		0	0		0	_null_ _null_ ));
+DATA(insert ( 2138	n 0 date_smaller	-				date_smaller		-				-				-				f f f 1095	1082	0	0		0	_null_ _null_ ));
+DATA(insert ( 2139	n 0 time_smaller	-				time_smaller		-				-				-				f f f 1110	1083	0	0		0	_null_ _null_ ));
+DATA(insert ( 2140	n 0 timetz_smaller	-				timetz_smaller		-				-				-				f f f 1552	1266	0	0		0	_null_ _null_ ));
+DATA(insert ( 2141	n 0 cashsmaller		-				cashsmaller			-				-				-				f f f 902		790		0	0		0	_null_ _null_ ));
+DATA(insert ( 2142	n 0 timestamp_smaller	-			timestamp_smaller	-				-				-				f f f 2062	1114	0	0		0	_null_ _null_ ));
+DATA(insert ( 2143	n 0 timestamptz_smaller -			timestamptz_smaller	-				-				-				f f f 1322	1184	0	0		0	_null_ _null_ ));
+DATA(insert ( 2144	n 0 interval_smaller	-			interval_smaller	-				-				-				f f f 1332	1186	0	0		0	_null_ _null_ ));
+DATA(insert ( 2145	n 0 text_smaller	-				text_smaller		-				-				-				f f f 664		25		0	0		0	_null_ _null_ ));
+DATA(insert ( 2146	n 0 numeric_smaller -				numeric_smaller		-				-				-				f f f 1754	1700	0	0		0	_null_ _null_ ));
+DATA(insert ( 2051	n 0 array_smaller	-				array_smaller		-				-				-				f f f 1072	2277	0	0		0	_null_ _null_ ));
+DATA(insert ( 2245	n 0 bpchar_smaller	-				bpchar_smaller		-				-				-				f f f 1058	1042	0	0		0	_null_ _null_ ));
+DATA(insert ( 2798	n 0 tidsmaller		-				tidsmaller			-				-				-				f f f 2799	27		0	0		0	_null_ _null_ ));
+DATA(insert ( 3527	n 0 enum_smaller	-				enum_smaller		-				-				-				f f f 3518	3500	0	0		0	_null_ _null_ ));
+DATA(insert ( 3565	n 0 network_smaller -				network_smaller		-				-				-				f f f 1203	869		0	0		0	_null_ _null_ ));
 
 /* count */
-DATA(insert ( 2147	n 0 int8inc_any		-				int8inc_any		int8dec_any		-				f f 0		20		0	20		0	"0" "0" ));
-DATA(insert ( 2803	n 0 int8inc			-				int8inc			int8dec			-				f f 0		20		0	20		0	"0" "0" ));
+DATA(insert ( 2147	n 0 int8inc_any		-				int8pl	int8inc_any		int8dec_any		-				f f f 0		20		0	20		0	"0" "0" ));
+DATA(insert ( 2803	n 0 int8inc			-				int8pl	int8inc			int8dec			-				f f f 0		20		0	20		0	"0" "0" ));
 
 /* var_pop */
-DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop		int8_accum		int8_accum_inv	numeric_var_pop f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2719	n 0 int4_accum	numeric_var_pop		int4_accum		int4_accum_inv	numeric_var_pop f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2720	n 0 int2_accum	numeric_var_pop		int2_accum		int2_accum_inv	numeric_var_pop f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2721	n 0 float4_accum	float8_var_pop	-				-				-				f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2722	n 0 float8_accum	float8_var_pop	-				-				-				f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop numeric_accum numeric_accum_inv numeric_var_pop f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop		-	int8_accum		int8_accum_inv	numeric_var_pop f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2719	n 0 int4_accum	numeric_var_pop		-	int4_accum		int4_accum_inv	numeric_var_pop f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2720	n 0 int2_accum	numeric_var_pop		-	int2_accum		int2_accum_inv	numeric_var_pop f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2721	n 0 float4_accum	float8_var_pop	-	-				-				-				f f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2722	n 0 float8_accum	float8_var_pop	-	-				-				-				f f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop -	numeric_accum numeric_accum_inv numeric_var_pop f f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* var_samp */
-DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp	int8_accum		int8_accum_inv	numeric_var_samp f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2642	n 0 int4_accum	numeric_var_samp	int4_accum		int4_accum_inv	numeric_var_samp f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2643	n 0 int2_accum	numeric_var_samp	int2_accum		int2_accum_inv	numeric_var_samp f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2644	n 0 float4_accum	float8_var_samp -				-				-				f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2645	n 0 float8_accum	float8_var_samp -				-				-				f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp numeric_accum numeric_accum_inv numeric_var_samp f f 0 2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp		-	int8_accum		int8_accum_inv	numeric_var_samp	f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2642	n 0 int4_accum	numeric_var_samp		-	int4_accum		int4_accum_inv	numeric_var_samp	f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2643	n 0 int2_accum	numeric_var_samp		-	int2_accum		int2_accum_inv	numeric_var_samp	f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2644	n 0 float4_accum	float8_var_samp		-	-				-				-					f f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2645	n 0 float8_accum	float8_var_samp		-	-				-				-					f f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp	- numeric_accum numeric_accum_inv numeric_var_samp		f f f 0 2281	128 2281	128 _null_ _null_ ));
 
 /* variance: historical Postgres syntax for var_samp */
-DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp	int8_accum		int8_accum_inv	numeric_var_samp f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2149	n 0 int4_accum	numeric_var_samp	int4_accum		int4_accum_inv	numeric_var_samp f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2150	n 0 int2_accum	numeric_var_samp	int2_accum		int2_accum_inv	numeric_var_samp f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2151	n 0 float4_accum	float8_var_samp -				-				-				f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2152	n 0 float8_accum	float8_var_samp -				-				-				f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp numeric_accum numeric_accum_inv numeric_var_samp f f 0 2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp		-	int8_accum		int8_accum_inv	numeric_var_samp	f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2149	n 0 int4_accum	numeric_var_samp		-	int4_accum		int4_accum_inv	numeric_var_samp	f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2150	n 0 int2_accum	numeric_var_samp		-	int2_accum		int2_accum_inv	numeric_var_samp	f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2151	n 0 float4_accum	float8_var_samp		-	-				-				-					f f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2152	n 0 float8_accum	float8_var_samp		-	-				-				-					f f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp	-	numeric_accum numeric_accum_inv numeric_var_samp	f f f 0 2281	128 2281	128 _null_ _null_ ));
 
 /* stddev_pop */
-DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop		int8_accum	int8_accum_inv	numeric_stddev_pop	f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2725	n 0 int4_accum	numeric_stddev_pop		int4_accum	int4_accum_inv	numeric_stddev_pop	f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2726	n 0 int2_accum	numeric_stddev_pop		int2_accum	int2_accum_inv	numeric_stddev_pop	f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-				-				-				f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-				-				-				f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop numeric_accum numeric_accum_inv numeric_stddev_pop f f 0 2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop		-	int8_accum	int8_accum_inv	numeric_stddev_pop		f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2725	n 0 int4_accum	numeric_stddev_pop		-	int4_accum	int4_accum_inv	numeric_stddev_pop		f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2726	n 0 int2_accum	numeric_stddev_pop		-	int2_accum	int2_accum_inv	numeric_stddev_pop		f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-	-			-				-						f f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-	-			-				-						f f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop	-	numeric_accum numeric_accum_inv numeric_stddev_pop	f f f 0 2281	128 2281	128 _null_ _null_ ));
 
 /* stddev_samp */
-DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp		int8_accum	int8_accum_inv	numeric_stddev_samp f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2713	n 0 int4_accum	numeric_stddev_samp		int4_accum	int4_accum_inv	numeric_stddev_samp f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2714	n 0 int2_accum	numeric_stddev_samp		int2_accum	int2_accum_inv	numeric_stddev_samp f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp	-				-				-				f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp	-				-				-				f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp numeric_accum numeric_accum_inv numeric_stddev_samp f f 0 2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp		-	int8_accum	int8_accum_inv	numeric_stddev_samp		f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2713	n 0 int4_accum	numeric_stddev_samp		-	int4_accum	int4_accum_inv	numeric_stddev_samp		f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2714	n 0 int2_accum	numeric_stddev_samp		-	int2_accum	int2_accum_inv	numeric_stddev_samp		f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp	-	-			-				-						f f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp	-	-			-				-						f f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp	-	numeric_accum numeric_accum_inv numeric_stddev_samp	f f f 0 2281	128 2281	128 _null_ _null_ ));
 
 /* stddev: historical Postgres syntax for stddev_samp */
-DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp		int8_accum	int8_accum_inv	numeric_stddev_samp f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2155	n 0 int4_accum	numeric_stddev_samp		int4_accum	int4_accum_inv	numeric_stddev_samp f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2156	n 0 int2_accum	numeric_stddev_samp		int2_accum	int2_accum_inv	numeric_stddev_samp f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp	-				-				-				f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp	-				-				-				f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp numeric_accum numeric_accum_inv numeric_stddev_samp f f 0 2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp		-	int8_accum	int8_accum_inv	numeric_stddev_samp		f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2155	n 0 int4_accum	numeric_stddev_samp		-	int4_accum	int4_accum_inv	numeric_stddev_samp		f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2156	n 0 int2_accum	numeric_stddev_samp		-	int2_accum	int2_accum_inv	numeric_stddev_samp		f f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp	-	-			-				-						f f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp	-	-			-				-						f f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp	-	numeric_accum numeric_accum_inv numeric_stddev_samp	f f f 0 2281	128 2281	128 _null_ _null_ ));
 
 /* SQL2003 binary regression aggregates */
-DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-				-				-				f f 0	20		0	0		0	"0" _null_ ));
-DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-	-				-				-			f f f 0	20		0	0		0	"0" _null_ ));
+DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-	-				-				-			f f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-	-				-				-			f f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-	-				-				-			f f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-	-				-				-			f f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-	-				-				-			f f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-	-				-				-			f f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-	-				-				-			f f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-	-				-				-			f f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-	-				-				-			f f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-	-				-				-			f f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-	-				-				-			f f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
 
 /* boolean-and and boolean-or */
-DATA(insert ( 2517	n 0 booland_statefunc	-			bool_accum		bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2518	n 0 boolor_statefunc	-			bool_accum		bool_accum_inv	bool_anytrue	f f 59	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2519	n 0 booland_statefunc	-			bool_accum		bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2517	n 0 booland_statefunc	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f f 58	16		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2518	n 0 boolor_statefunc	-	-	bool_accum	bool_accum_inv	bool_anytrue	f f f 59	16		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2519	n 0 booland_statefunc	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f f 58	16		0	2281	16	_null_ _null_ ));
 
 /* bitwise integer */
-DATA(insert ( 2236	n 0 int2and		-					-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2237	n 0 int2or		-					-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2238	n 0 int4and		-					-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2239	n 0 int4or		-					-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2240	n 0 int8and		-					-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2241	n 0 int8or		-					-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2242	n 0 bitand		-					-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
-DATA(insert ( 2243	n 0 bitor		-					-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
+DATA(insert ( 2236	n 0 int2and		-				int2and	-				-				-				f f f 0	21		0	0		0	_null_ _null_ ));
+DATA(insert ( 2237	n 0 int2or		-				int2or	-				-				-				f f f 0	21		0	0		0	_null_ _null_ ));
+DATA(insert ( 2238	n 0 int4and		-				int4and	-				-				-				f f f 0	23		0	0		0	_null_ _null_ ));
+DATA(insert ( 2239	n 0 int4or		-				int4or	-				-				-				f f f 0	23		0	0		0	_null_ _null_ ));
+DATA(insert ( 2240	n 0 int8and		-				int8and	-				-				-				f f f 0	20		0	0		0	_null_ _null_ ));
+DATA(insert ( 2241	n 0 int8or		-				int8or	-				-				-				f f f 0	20		0	0		0	_null_ _null_ ));
+DATA(insert ( 2242	n 0 bitand		-				bitand	-				-				-				f f f 0	1560	0	0		0	_null_ _null_ ));
+DATA(insert ( 2243	n 0 bitor		-				bitor	-				-				-				f f f 0	1560	0	0		0	_null_ _null_ ));
 
 /* xml */
-DATA(insert ( 2901	n 0 xmlconcat2	-					-				-				-				f f 0	142		0	0		0	_null_ _null_ ));
+DATA(insert ( 2901	n 0 xmlconcat2	-					-	-				-				-				f f f 0	142		0	0		0	_null_ _null_ ));
 
 /* array */
-DATA(insert ( 2335	n 0 array_agg_transfn	array_agg_finalfn	-				-				-				t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn -		-				-				t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 2335	n 0 array_agg_transfn		array_agg_finalfn		-	-		-				-				t f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn	-	-		-				-				t f f 0	2281	0	0		0	_null_ _null_ ));
 
 /* text */
-DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-	-				-				-				f f f 0	2281	0	0		0	_null_ _null_ ));
 
 /* bytea */
-DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-				-				-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-	-				-				-		f f f 0	2281	0	0		0	_null_ _null_ ));
 
 /* json */
-DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-	-				-				-				f f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -	-				-				-				f f f 0	2281	0	0		0	_null_ _null_ ));
 
 /* jsonb */
 DATA(insert ( 3267	n 0 jsonb_agg_transfn	jsonb_agg_finalfn			-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
 DATA(insert ( 3270	n 0 jsonb_object_agg_transfn jsonb_object_agg_finalfn -				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
 
 /* ordered-set and hypothetical-set aggregates */
-DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-	-		-		-		t f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-	-		-		-		f f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-	-		-		-		f f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-	-		-		-		t f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-	-		-		-		f f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-	-		-		-		f f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-	-		-		-		t f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-	-		-		-		t f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-	-		-		-		t f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-	-		-		-		t f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-	-		-		-		t f f 0	2281	0	0		0	_null_ _null_ ));
 
 
 /*
@@ -321,10 +327,12 @@ extern Oid AggregateCreate(const char *aggName,
 				Oid variadicArgType,
 				List *aggtransfnName,
 				List *aggfinalfnName,
+				List *aggcombinefnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
 				bool finalfnExtraArgs,
+				bool combinefnExtraArgs,
 				bool mfinalfnExtraArgs,
 				List *aggsortopName,
 				Oid aggTransType,
diff --git a/src/test/regress/expected/create_aggregate.out b/src/test/regress/expected/create_aggregate.out
index 82a34fb..906c2b5 100644
--- a/src/test/regress/expected/create_aggregate.out
+++ b/src/test/regress/expected/create_aggregate.out
@@ -101,6 +101,13 @@ CREATE AGGREGATE sumdouble (float8)
     msfunc = float8pl,
     minvfunc = float8mi
 );
+-- aggregate combine functions
+CREATE AGGREGATE mymax (int)
+(
+	stype = int4,
+	sfunc = int4larger,
+	cfunc = int4larger
+);
 -- invalid: nonstrict inverse with strict forward function
 CREATE FUNCTION float8mi_n(float8, float8) RETURNS float8 AS
 $$ SELECT $1 - $2; $$
diff --git a/src/test/regress/sql/create_aggregate.sql b/src/test/regress/sql/create_aggregate.sql
index 0ec1572..0ebd0d9 100644
--- a/src/test/regress/sql/create_aggregate.sql
+++ b/src/test/regress/sql/create_aggregate.sql
@@ -115,6 +115,14 @@ CREATE AGGREGATE sumdouble (float8)
     minvfunc = float8mi
 );
 
+-- aggregate combine functions
+CREATE AGGREGATE mymax (int)
+(
+	stype = int4,
+	sfunc = int4larger,
+	cfunc = int4larger
+);
+
 -- invalid: nonstrict inverse with strict forward function
 
 CREATE FUNCTION float8mi_n(float8, float8) RETURNS float8 AS

diff --git a/doc/src/sgml/ref/create_aggregate.sgml b/doc/src/sgml/ref/create_aggregate.sgml
index eaa410b..f0e4407 100644
--- a/doc/src/sgml/ref/create_aggregate.sgml
+++ b/doc/src/sgml/ref/create_aggregate.sgml
@@ -27,6 +27,7 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ <replacea
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , CFUNC = <replaceable class="PARAMETER">cfunc</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -45,6 +46,7 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ [ <replac
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , CFUNC = <replaceable class="PARAMETER">cfunc</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , HYPOTHETICAL ]
 )
@@ -58,6 +60,7 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , CFUNC = <replaceable class="PARAMETER">cfunc</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -105,12 +108,15 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
    functions:
    a state transition function
    <replaceable class="PARAMETER">sfunc</replaceable>,
-   and an optional final calculation function
-   <replaceable class="PARAMETER">ffunc</replaceable>.
+   an optional final calculation function
+   <replaceable class="PARAMETER">ffunc</replaceable>,
+   and an optional combine function
+   <replaceable class="PARAMETER">cfunc</replaceable>.
    These are used as follows:
 <programlisting>
 <replaceable class="PARAMETER">sfunc</replaceable>( internal-state, next-data-values ) ---> next-internal-state
 <replaceable class="PARAMETER">ffunc</replaceable>( internal-state ) ---> aggregate-value
+<replaceable class="PARAMETER">cfunc</replaceable>( internal-state, internal-state ) ---> next-internal-state
 </programlisting>
   </para>
 
@@ -128,6 +134,13 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
   </para>
 
   <para>
+   An aggregate function may also supply a combining function, which allows
+   the aggregation process to be broken down into multiple steps.  This
+   facilitates query optimization techniques such as parallel query,
+   pre-join aggregation and aggregation while sorting.
+  </para>
+
+  <para>
    An aggregate function can provide an initial condition,
    that is, an initial value for the internal state value.
    This is specified and stored in the database as a value of type
diff --git a/src/backend/catalog/pg_aggregate.c b/src/backend/catalog/pg_aggregate.c
index 121c27f..848a868 100644
--- a/src/backend/catalog/pg_aggregate.c
+++ b/src/backend/catalog/pg_aggregate.c
@@ -57,6 +57,7 @@ AggregateCreate(const char *aggName,
 				Oid variadicArgType,
 				List *aggtransfnName,
 				List *aggfinalfnName,
+				List *aggcombinefnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
@@ -77,6 +78,7 @@ AggregateCreate(const char *aggName,
 	Form_pg_proc proc;
 	Oid			transfn;
 	Oid			finalfn = InvalidOid;	/* can be omitted */
+	Oid			combinefn = InvalidOid;	/* can be omitted */
 	Oid			mtransfn = InvalidOid;	/* can be omitted */
 	Oid			minvtransfn = InvalidOid;		/* can be omitted */
 	Oid			mfinalfn = InvalidOid;	/* can be omitted */
@@ -396,6 +398,20 @@ AggregateCreate(const char *aggName,
 	}
 	Assert(OidIsValid(finaltype));
 
+	/* handle the combinefn, if supplied */
+	if (aggcombinefnName)
+	{
+		/*
+		 * Combine function must have 2 argument, each of which is the
+		 * trans type
+		 */
+		fnArgs[0] = aggTransType;
+		fnArgs[1] = aggTransType;
+
+		combinefn = lookup_agg_function(aggcombinefnName, 2, fnArgs,
+										variadicArgType, &finaltype);
+	}
+
 	/*
 	 * If finaltype (i.e. aggregate return type) is polymorphic, inputs must
 	 * be polymorphic also, else parser will fail to deduce result type.
@@ -567,6 +583,7 @@ AggregateCreate(const char *aggName,
 	values[Anum_pg_aggregate_aggnumdirectargs - 1] = Int16GetDatum(numDirectArgs);
 	values[Anum_pg_aggregate_aggtransfn - 1] = ObjectIdGetDatum(transfn);
 	values[Anum_pg_aggregate_aggfinalfn - 1] = ObjectIdGetDatum(finalfn);
+	values[Anum_pg_aggregate_aggcombinefn - 1] = ObjectIdGetDatum(combinefn);
 	values[Anum_pg_aggregate_aggmtransfn - 1] = ObjectIdGetDatum(mtransfn);
 	values[Anum_pg_aggregate_aggminvtransfn - 1] = ObjectIdGetDatum(minvtransfn);
 	values[Anum_pg_aggregate_aggmfinalfn - 1] = ObjectIdGetDatum(mfinalfn);
diff --git a/src/backend/commands/aggregatecmds.c b/src/backend/commands/aggregatecmds.c
index 894c89d..035882e 100644
--- a/src/backend/commands/aggregatecmds.c
+++ b/src/backend/commands/aggregatecmds.c
@@ -61,6 +61,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	char		aggKind = AGGKIND_NORMAL;
 	List	   *transfuncName = NIL;
 	List	   *finalfuncName = NIL;
+	List	   *combinefuncName = NIL;
 	List	   *mtransfuncName = NIL;
 	List	   *minvtransfuncName = NIL;
 	List	   *mfinalfuncName = NIL;
@@ -124,6 +125,8 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 			transfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "finalfunc") == 0)
 			finalfuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "cfunc") == 0)
+			combinefuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "msfunc") == 0)
 			mtransfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "minvfunc") == 0)
@@ -383,6 +386,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 						   variadicArgType,
 						   transfuncName,		/* step function name */
 						   finalfuncName,		/* final function name */
+						   combinefuncName,		/* combine function name */
 						   mtransfuncName,		/* fwd trans function name */
 						   minvtransfuncName,	/* inv trans function name */
 						   mfinalfuncName,		/* final function name */
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 183d3d9..5e041ab 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -907,25 +907,38 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			pname = sname = "Group";
 			break;
 		case T_Agg:
-			sname = "Aggregate";
-			switch (((Agg *) plan)->aggstrategy)
 			{
-				case AGG_PLAIN:
-					pname = "Aggregate";
-					strategy = "Plain";
-					break;
-				case AGG_SORTED:
-					pname = "GroupAggregate";
-					strategy = "Sorted";
-					break;
-				case AGG_HASHED:
-					pname = "HashAggregate";
-					strategy = "Hashed";
-					break;
-				default:
-					pname = "Aggregate ???";
-					strategy = "???";
-					break;
+				char	   *modifier;
+				Agg		   *agg = (Agg *) plan;
+
+				sname = "Aggregate";
+
+				if (agg->finalizeAggs == false)
+					modifier = "Partial ";
+				else if (agg->combineStates == true)
+					modifier = "Finalize ";
+				else
+					modifier = "";
+
+				switch (agg->aggstrategy)
+				{
+					case AGG_PLAIN:
+						pname = psprintf("%sAggregate", modifier);
+						strategy = "Plain";
+						break;
+					case AGG_SORTED:
+						pname = psprintf("%sGroupAggregate", modifier);
+						strategy = "Sorted";
+						break;
+					case AGG_HASHED:
+						pname = psprintf("%sHashAggregate", modifier);
+						strategy = "Hashed";
+						break;
+					default:
+						pname = "Aggregate ???";
+						strategy = "???";
+						break;
+				}
 			}
 			break;
 		case T_WindowAgg:
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index 2e36855..1639256 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -3,15 +3,24 @@
  * nodeAgg.c
  *	  Routines to handle aggregate nodes.
  *
- *	  ExecAgg evaluates each aggregate in the following steps:
+ *	  ExecAgg normally evaluates each aggregate in the following steps:
  *
  *		 transvalue = initcond
  *		 foreach input_tuple do
  *			transvalue = transfunc(transvalue, input_value(s))
  *		 result = finalfunc(transvalue, direct_argument(s))
  *
- *	  If a finalfunc is not supplied then the result is just the ending
- *	  value of transvalue.
+ *	  If a finalfunc is not supplied or finalizeAggs is false, then the result
+ *	  is just the ending value of transvalue.
+ *
+ *	  If combineStates is true then we assume that input values are other
+ *	  transition states. In this case we use the aggregate's combinefunc to
+ *	  'add' the passed in trans state to the trans state being operated on.
+ *	  This allows aggregation to happen in multiple stages. 'combineStates'
+ *	  will only be true if another nodeAgg is below this one in the plan tree.
+ *
+ *	  'finalizeAggs' should be false for all nodeAggs apart from the upper most
+ *	  one in the plan tree.
  *
  *	  If a normal aggregate call specifies DISTINCT or ORDER BY, we sort the
  *	  input tuples and eliminate duplicates (if required) before performing
@@ -197,7 +206,7 @@ typedef struct AggStatePerTransData
 	 */
 	int			numTransInputs;
 
-	/* Oid of the state transition function */
+	/* Oid of the state transition or combine function */
 	Oid			transfn_oid;
 
 	/* Oid of state value's datatype */
@@ -209,8 +218,8 @@ typedef struct AggStatePerTransData
 	List	   *aggdirectargs;	/* states of direct-argument expressions */
 
 	/*
-	 * fmgr lookup data for transition function.  Note in particular that the
-	 * fn_strict flag is kept here.
+	 * fmgr lookup data for transition function or combination function.  Note
+	 * in particular that the fn_strict flag is kept here.
 	 */
 	FmgrInfo	transfn;
 
@@ -421,6 +430,10 @@ static void advance_transition_function(AggState *aggstate,
 							AggStatePerTrans pertrans,
 							AggStatePerGroup pergroupstate);
 static void advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup);
+static void advance_combination_function(AggState *aggstate,
+							AggStatePerTrans pertrans,
+							AggStatePerGroup pergroupstate);
+static void combine_aggregates(AggState *aggstate, AggStatePerGroup pergroup);
 static void process_ordered_aggregate_single(AggState *aggstate,
 								 AggStatePerTrans pertrans,
 								 AggStatePerGroup pergroupstate);
@@ -796,6 +809,8 @@ advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
 	int			numGroupingSets = Max(aggstate->phase->numsets, 1);
 	int			numTrans = aggstate->numtrans;
 
+	Assert(!aggstate->combineStates);
+
 	for (transno = 0; transno < numTrans; transno++)
 	{
 		AggStatePerTrans pertrans = &aggstate->pertrans[transno];
@@ -879,6 +894,109 @@ advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
 	}
 }
 
+static void
+combine_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
+{
+	int			transno;
+	int			numTrans = aggstate->numtrans;
+
+	/* combine not supported with grouping sets */
+	Assert(aggstate->phase->numsets == 0);
+	Assert(aggstate->combineStates);
+
+	for (transno = 0; transno < numTrans; transno++)
+	{
+		AggStatePerTrans pertrans = &aggstate->pertrans[transno];
+		TupleTableSlot *slot;
+		FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
+		AggStatePerGroup pergroupstate = &pergroup[transno];
+
+		/* Evaluate the current input expressions for this aggregate */
+		slot = ExecProject(pertrans->evalproj, NULL);
+		Assert(slot->tts_nvalid >= 1);
+
+		fcinfo->arg[1] = slot->tts_values[0];
+		fcinfo->argnull[1] = slot->tts_isnull[0];
+
+		advance_combination_function(aggstate, pertrans, pergroupstate);
+	}
+}
+
+/*
+ * Perform combination of states between 2 aggregate states. Effectively this
+ * 'adds' two states together by whichever logic is defined in the aggregate
+ * function's combine function.
+ *
+ * Note that in this case transfn is set to the combination function. This
+ * perhaps should be changed to avoid confusion, but one field is ok for now
+ * as they'll never be needed at the same time.
+ */
+static void
+advance_combination_function(AggState *aggstate,
+							 AggStatePerTrans pertrans,
+							 AggStatePerGroup pergroupstate)
+{
+	FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
+	MemoryContext oldContext;
+	Datum		newVal;
+
+	if (pertrans->transfn.fn_strict)
+	{
+		/* if we're asked to merge to a NULL state, then do nothing */
+		if (fcinfo->argnull[1])
+			return;
+
+		if (pergroupstate->noTransValue)
+		{
+			pergroupstate->transValue = fcinfo->arg[1];
+			pergroupstate->transValueIsNull = false;
+			return;
+		}
+	}
+
+	/* We run the combine functions in per-input-tuple memory context */
+	oldContext = MemoryContextSwitchTo(aggstate->tmpcontext->ecxt_per_tuple_memory);
+
+	/* set up aggstate->curpertrans for AggGetAggref() */
+	aggstate->curpertrans = pertrans;
+
+	/*
+	 * OK to call the combine function
+	 */
+	fcinfo->arg[0] = pergroupstate->transValue;
+	fcinfo->argnull[0] = pergroupstate->transValueIsNull;
+	fcinfo->isnull = false;		/* just in case combine func doesn't set it */
+
+	newVal = FunctionCallInvoke(fcinfo);
+
+	aggstate->curpertrans = NULL;
+
+	/*
+	 * If pass-by-ref datatype, must copy the new value into aggcontext and
+	 * pfree the prior transValue.  But if the combine function returned a
+	 * pointer to its first input, we don't need to do anything.
+	 */
+	if (!pertrans->transtypeByVal &&
+		DatumGetPointer(newVal) != DatumGetPointer(pergroupstate->transValue))
+	{
+		if (!fcinfo->isnull)
+		{
+			MemoryContextSwitchTo(aggstate->aggcontexts[aggstate->current_set]->ecxt_per_tuple_memory);
+			newVal = datumCopy(newVal,
+							   pertrans->transtypeByVal,
+							   pertrans->transtypeLen);
+		}
+		if (!pergroupstate->transValueIsNull)
+			pfree(DatumGetPointer(pergroupstate->transValue));
+	}
+
+	pergroupstate->transValue = newVal;
+	pergroupstate->transValueIsNull = fcinfo->isnull;
+
+	MemoryContextSwitchTo(oldContext);
+
+}
+
 
 /*
  * Run the transition function for a DISTINCT or ORDER BY aggregate
@@ -1278,8 +1396,14 @@ finalize_aggregates(AggState *aggstate,
 												pergroupstate);
 		}
 
-		finalize_aggregate(aggstate, peragg, pergroupstate,
-						   &aggvalues[aggno], &aggnulls[aggno]);
+		if (aggstate->finalizeAggs)
+			finalize_aggregate(aggstate, peragg, pergroupstate,
+							   &aggvalues[aggno], &aggnulls[aggno]);
+		else
+		{
+			aggvalues[aggno] = pergroupstate->transValue;
+			aggnulls[aggno] = pergroupstate->transValueIsNull;
+		}
 	}
 }
 
@@ -1294,9 +1418,11 @@ project_aggregates(AggState *aggstate)
 	ExprContext *econtext = aggstate->ss.ps.ps_ExprContext;
 
 	/*
-	 * Check the qual (HAVING clause); if the group does not match, ignore it.
+	 * iif performing the final aggregate stage we'll check the qual (HAVING
+	 * clause); if the group does not match, ignore it.
 	 */
-	if (ExecQual(aggstate->ss.ps.qual, econtext, false))
+	if (aggstate->finalizeAggs == false ||
+		ExecQual(aggstate->ss.ps.qual, econtext, false))
 	{
 		/*
 		 * Form and return or store a projection tuple using the aggregate
@@ -1811,7 +1937,10 @@ agg_retrieve_direct(AggState *aggstate)
 				 */
 				for (;;)
 				{
-					advance_aggregates(aggstate, pergroup);
+					if (!aggstate->combineStates)
+						advance_aggregates(aggstate, pergroup);
+					else
+						combine_aggregates(aggstate, pergroup);
 
 					/* Reset per-input-tuple context after each tuple */
 					ResetExprContext(tmpcontext);
@@ -1919,7 +2048,10 @@ agg_fill_hash_table(AggState *aggstate)
 		entry = lookup_hash_entry(aggstate, outerslot);
 
 		/* Advance the aggregates */
-		advance_aggregates(aggstate, entry->pergroup);
+		if (!aggstate->combineStates)
+			advance_aggregates(aggstate, entry->pergroup);
+		else
+			combine_aggregates(aggstate, entry->pergroup);
 
 		/* Reset per-input-tuple context after each tuple */
 		ResetExprContext(tmpcontext);
@@ -2051,6 +2183,8 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 	aggstate->pertrans = NULL;
 	aggstate->curpertrans = NULL;
 	aggstate->agg_done = false;
+	aggstate->combineStates = node->combineStates;
+	aggstate->finalizeAggs = node->finalizeAggs;
 	aggstate->input_done = false;
 	aggstate->pergroup = NULL;
 	aggstate->grp_firstTuple = NULL;
@@ -2402,7 +2536,21 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 						   get_func_name(aggref->aggfnoid));
 		InvokeFunctionExecuteHook(aggref->aggfnoid);
 
-		transfn_oid = aggform->aggtransfn;
+		/*
+		 * if this aggregation is performing state combines, then instead of
+		 * using the transition function, we'll use the combine function
+		 */
+		if (aggstate->combineStates)
+		{
+			transfn_oid = aggform->aggcombinefn;
+
+			/* If not set then the planner messed up */
+			if (!OidIsValid(transfn_oid))
+				elog(ERROR, "combinefn not set during aggregate state combine phase");
+		}
+		else
+			transfn_oid = aggform->aggtransfn;
+
 		peragg->finalfn_oid = finalfn_oid = aggform->aggfinalfn;
 
 		/* Check that aggregate owner has permission to call component fns */
@@ -2583,44 +2731,69 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 		pertrans->numTransInputs = numArguments;
 
 	/*
-	 * Set up infrastructure for calling the transfn
+	 * When combining states, we have no use at all for the aggregate
+	 * function's transfn. Instead we use the combinefn. However we do
+	 * reuse the transfnexpr for the combinefn, perhaps this should change
 	 */
-	build_aggregate_transfn_expr(inputTypes,
-								 numArguments,
-								 numDirectArgs,
-								 aggref->aggvariadic,
-								 aggtranstype,
-								 aggref->inputcollid,
-								 aggtransfn,
-								 InvalidOid,	/* invtrans is not needed here */
-								 &transfnexpr,
-								 NULL);
-	fmgr_info(aggtransfn, &pertrans->transfn);
-	fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
-
-	InitFunctionCallInfoData(pertrans->transfn_fcinfo,
-							 &pertrans->transfn,
-							 pertrans->numTransInputs + 1,
-							 pertrans->aggCollation,
-							 (void *) aggstate, NULL);
+	if (aggstate->combineStates)
+	{
+		build_aggregate_combinefn_expr(aggref->aggvariadic,
+									   aggtranstype,
+									   aggref->inputcollid,
+									   aggtransfn,
+									   &transfnexpr);
+		fmgr_info(aggtransfn, &pertrans->transfn);
+		fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
+
+		InitFunctionCallInfoData(pertrans->transfn_fcinfo,
+								 &pertrans->transfn,
+								 2,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
 
-	/*
-	 * If the transfn is strict and the initval is NULL, make sure input type
-	 * and transtype are the same (or at least binary-compatible), so that
-	 * it's OK to use the first aggregated input value as the initial
-	 * transValue.  This should have been checked at agg definition time, but
-	 * we must check again in case the transfn's strictness property has been
-	 * changed.
-	 */
-	if (pertrans->transfn.fn_strict && pertrans->initValueIsNull)
+	}
+	else
 	{
-		if (numArguments <= numDirectArgs ||
-			!IsBinaryCoercible(inputTypes[numDirectArgs],
-							   aggtranstype))
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
-					 errmsg("aggregate %u needs to have compatible input type and transition type",
-							aggref->aggfnoid)));
+		/*
+		 * Set up infrastructure for calling the transfn
+		 */
+		build_aggregate_transfn_expr(inputTypes,
+									 numArguments,
+									 numDirectArgs,
+									 aggref->aggvariadic,
+									 aggtranstype,
+									 aggref->inputcollid,
+									 aggtransfn,
+									 InvalidOid,	/* invtrans is not needed here */
+									 &transfnexpr,
+									 NULL);
+		fmgr_info(aggtransfn, &pertrans->transfn);
+		fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
+
+		InitFunctionCallInfoData(pertrans->transfn_fcinfo,
+								 &pertrans->transfn,
+								 pertrans->numTransInputs + 1,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+
+		/*
+		 * If the transfn is strict and the initval is NULL, make sure input type
+		 * and transtype are the same (or at least binary-compatible), so that
+		 * it's OK to use the first aggregated input value as the initial
+		 * transValue.  This should have been checked at agg definition time, but
+		 * we must check again in case the transfn's strictness property has been
+		 * changed.
+		 */
+		if (pertrans->transfn.fn_strict && pertrans->initValueIsNull)
+		{
+			if (numArguments <= numDirectArgs ||
+				!IsBinaryCoercible(inputTypes[numDirectArgs],
+								   aggtranstype))
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						 errmsg("aggregate %u needs to have compatible input type and transition type",
+								aggref->aggfnoid)));
+		}
 	}
 
 	/* get info about the state value's datatype */
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 26264cb..0c78882 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -865,6 +865,8 @@ _copyAgg(const Agg *from)
 
 	COPY_SCALAR_FIELD(aggstrategy);
 	COPY_SCALAR_FIELD(numCols);
+	COPY_SCALAR_FIELD(combineStates);
+	COPY_SCALAR_FIELD(finalizeAggs);
 	if (from->numCols > 0)
 	{
 		COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 222e2ed..ec6790a 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1989,6 +1989,8 @@ _readAgg(void)
 	READ_ENUM_FIELD(aggstrategy, AggStrategy);
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
+	READ_BOOL_FIELD(combineStates);
+	READ_BOOL_FIELD(finalizeAggs);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 	READ_NODE_FIELD(groupingSets);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 411b36c..ee39552 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -1053,6 +1053,8 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path)
 								 groupOperators,
 								 NIL,
 								 numGroups,
+								 false,
+								 true,
 								 subplan);
 	}
 	else
@@ -4547,9 +4549,8 @@ Agg *
 make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
 		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
-		 List *groupingSets,
-		 long numGroups,
-		 Plan *lefttree)
+		 List *groupingSets, long numGroups, bool combineStates,
+		 bool finalizeAggs, Plan *lefttree)
 {
 	Agg		   *node = makeNode(Agg);
 	Plan	   *plan = &node->plan;
@@ -4558,6 +4559,8 @@ make_agg(PlannerInfo *root, List *tlist, List *qual,
 
 	node->aggstrategy = aggstrategy;
 	node->numCols = numGroupCols;
+	node->combineStates = combineStates;
+	node->finalizeAggs = finalizeAggs;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
 	node->numGroups = numGroups;
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index a9cccee..cb91ee5 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -1995,6 +1995,8 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 									extract_grouping_ops(parse->groupClause),
 												NIL,
 												numGroups,
+												false,
+												true,
 												result_plan);
 				/* Hashed aggregation produces randomly-ordered results */
 				current_pathkeys = NIL;
@@ -2306,6 +2308,8 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 								 extract_grouping_ops(parse->distinctClause),
 											NIL,
 											numDistinctRows,
+											false,
+											true,
 											result_plan);
 			/* Hashed aggregation produces randomly-ordered results */
 			current_pathkeys = NIL;
@@ -2539,6 +2543,8 @@ build_grouping_chain(PlannerInfo *root,
 									 extract_grouping_ops(groupClause),
 									 gsets,
 									 numGroups,
+									 false,
+									 true,
 									 sort_plan);
 
 		sort_plan->lefttree = NULL;
@@ -2575,6 +2581,8 @@ build_grouping_chain(PlannerInfo *root,
 										extract_grouping_ops(groupClause),
 										gsets,
 										numGroups,
+										false,
+										true,
 										result_plan);
 
 		((Agg *) result_plan)->chain = chain;
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 8884fb1..38c16eb 100644
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -775,6 +775,8 @@ make_union_unique(SetOperationStmt *op, Plan *plan,
 								 extract_grouping_ops(groupList),
 								 NIL,
 								 numGroups,
+								 false,
+								 true,
 								 plan);
 		/* Hashed aggregation produces randomly-ordered results */
 		*sortClauses = NIL;
diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c
index 2c45bd6..96a7386 100644
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -1929,6 +1929,43 @@ build_aggregate_transfn_expr(Oid *agg_input_types,
 
 /*
  * Like build_aggregate_transfn_expr, but creates an expression tree for the
+ * combine function of an aggregate, rather than the transition function.
+ */
+void
+build_aggregate_combinefn_expr(bool agg_variadic,
+							   Oid agg_state_type,
+							   Oid agg_input_collation,
+							   Oid combinefn_oid,
+							   Expr **combinefnexpr)
+{
+	Param	   *argp;
+	List	   *args;
+	FuncExpr   *fexpr;
+
+	/* Build arg list to use in the combinefn FuncExpr node. */
+	argp = makeNode(Param);
+	argp->paramkind = PARAM_EXEC;
+	argp->paramid = -1;
+	argp->paramtype = agg_state_type;
+	argp->paramtypmod = -1;
+	argp->paramcollid = agg_input_collation;
+	argp->location = -1;
+
+	/* trans state type is arg 1 and 2 */
+	args = list_make2(argp, argp);
+
+	fexpr = makeFuncExpr(combinefn_oid,
+						 agg_state_type,
+						 args,
+						 InvalidOid,
+						 agg_input_collation,
+						 COERCE_EXPLICIT_CALL);
+	fexpr->funcvariadic = agg_variadic;
+	*combinefnexpr = (Expr *) fexpr;
+}
+
+/*
+ * Like build_aggregate_transfn_expr, but creates an expression tree for the
  * final function of an aggregate, rather than the transition function.
  */
 void
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 36863df..cb39107 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -12279,6 +12279,7 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	PGresult   *res;
 	int			i_aggtransfn;
 	int			i_aggfinalfn;
+	int			i_aggcombinefn;
 	int			i_aggmtransfn;
 	int			i_aggminvtransfn;
 	int			i_aggmfinalfn;
@@ -12295,6 +12296,7 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	int			i_convertok;
 	const char *aggtransfn;
 	const char *aggfinalfn;
+	const char *aggcombinefn;
 	const char *aggmtransfn;
 	const char *aggminvtransfn;
 	const char *aggmfinalfn;
@@ -12325,7 +12327,26 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	selectSourceSchema(fout, agginfo->aggfn.dobj.namespace->dobj.name);
 
 	/* Get aggregate-specific details */
-	if (fout->remoteVersion >= 90400)
+	if (fout->remoteVersion >= 90600)
+	{
+		appendPQExpBuffer(query, "SELECT aggtransfn, "
+			"aggfinalfn, aggtranstype::pg_catalog.regtype, "
+			"aggcombinefn, aggmtransfn, aggminvtransfn, "
+			"aggmfinalfn, aggmtranstype::pg_catalog.regtype, "
+			"aggfinalextra, aggmfinalextra, "
+			"aggsortop::pg_catalog.regoperator, "
+			"(aggkind = 'h') AS hypothetical, "
+			"aggtransspace, agginitval, "
+			"aggmtransspace, aggminitval, "
+			"true AS convertok, "
+			"pg_catalog.pg_get_function_arguments(p.oid) AS funcargs, "
+			"pg_catalog.pg_get_function_identity_arguments(p.oid) AS funciargs "
+			"FROM pg_catalog.pg_aggregate a, pg_catalog.pg_proc p "
+			"WHERE a.aggfnoid = p.oid "
+			"AND p.oid = '%u'::pg_catalog.oid",
+			agginfo->aggfn.dobj.catId.oid);
+	}
+	else if (fout->remoteVersion >= 90400)
 	{
 		appendPQExpBuffer(query, "SELECT aggtransfn, "
 						  "aggfinalfn, aggtranstype::pg_catalog.regtype, "
@@ -12435,6 +12456,7 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 
 	i_aggtransfn = PQfnumber(res, "aggtransfn");
 	i_aggfinalfn = PQfnumber(res, "aggfinalfn");
+	i_aggcombinefn = PQfnumber(res, "aggcombinefn");
 	i_aggmtransfn = PQfnumber(res, "aggmtransfn");
 	i_aggminvtransfn = PQfnumber(res, "aggminvtransfn");
 	i_aggmfinalfn = PQfnumber(res, "aggmfinalfn");
@@ -12452,6 +12474,7 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 
 	aggtransfn = PQgetvalue(res, 0, i_aggtransfn);
 	aggfinalfn = PQgetvalue(res, 0, i_aggfinalfn);
+	aggcombinefn = PQgetvalue(res, 0, i_aggcombinefn);
 	aggmtransfn = PQgetvalue(res, 0, i_aggmtransfn);
 	aggminvtransfn = PQgetvalue(res, 0, i_aggminvtransfn);
 	aggmfinalfn = PQgetvalue(res, 0, i_aggmfinalfn);
@@ -12540,6 +12563,11 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 			appendPQExpBufferStr(details, ",\n    FINALFUNC_EXTRA");
 	}
 
+	if (strcmp(aggcombinefn, "-") != 0)
+	{
+		appendPQExpBuffer(details, ",\n    CFUNC = %s",	aggcombinefn);
+	}
+
 	if (strcmp(aggmtransfn, "-") != 0)
 	{
 		appendPQExpBuffer(details, ",\n    MSFUNC = %s,\n    MINVFUNC = %s,\n    MSTYPE = %s",
diff --git a/src/include/catalog/pg_aggregate.h b/src/include/catalog/pg_aggregate.h
index dd6079f..b306f9b 100644
--- a/src/include/catalog/pg_aggregate.h
+++ b/src/include/catalog/pg_aggregate.h
@@ -33,6 +33,7 @@
  *	aggnumdirectargs	number of arguments that are "direct" arguments
  *	aggtransfn			transition function
  *	aggfinalfn			final function (0 if none)
+ *	aggcombinefn		combine function (0 if none)
  *	aggmtransfn			forward function for moving-aggregate mode (0 if none)
  *	aggminvtransfn		inverse function for moving-aggregate mode (0 if none)
  *	aggmfinalfn			final function for moving-aggregate mode (0 if none)
@@ -56,6 +57,7 @@ CATALOG(pg_aggregate,2600) BKI_WITHOUT_OIDS
 	int16		aggnumdirectargs;
 	regproc		aggtransfn;
 	regproc		aggfinalfn;
+	regproc		aggcombinefn;
 	regproc		aggmtransfn;
 	regproc		aggminvtransfn;
 	regproc		aggmfinalfn;
@@ -85,24 +87,25 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  * ----------------
  */
 
-#define Natts_pg_aggregate					17
+#define Natts_pg_aggregate					18
 #define Anum_pg_aggregate_aggfnoid			1
 #define Anum_pg_aggregate_aggkind			2
 #define Anum_pg_aggregate_aggnumdirectargs	3
 #define Anum_pg_aggregate_aggtransfn		4
 #define Anum_pg_aggregate_aggfinalfn		5
-#define Anum_pg_aggregate_aggmtransfn		6
-#define Anum_pg_aggregate_aggminvtransfn	7
-#define Anum_pg_aggregate_aggmfinalfn		8
-#define Anum_pg_aggregate_aggfinalextra		9
-#define Anum_pg_aggregate_aggmfinalextra	10
-#define Anum_pg_aggregate_aggsortop			11
-#define Anum_pg_aggregate_aggtranstype		12
-#define Anum_pg_aggregate_aggtransspace		13
-#define Anum_pg_aggregate_aggmtranstype		14
-#define Anum_pg_aggregate_aggmtransspace	15
-#define Anum_pg_aggregate_agginitval		16
-#define Anum_pg_aggregate_aggminitval		17
+#define Anum_pg_aggregate_aggcombinefn		6
+#define Anum_pg_aggregate_aggmtransfn		7
+#define Anum_pg_aggregate_aggminvtransfn	8
+#define Anum_pg_aggregate_aggmfinalfn		9
+#define Anum_pg_aggregate_aggfinalextra		10
+#define Anum_pg_aggregate_aggmfinalextra	11
+#define Anum_pg_aggregate_aggsortop			12
+#define Anum_pg_aggregate_aggtranstype		13
+#define Anum_pg_aggregate_aggtransspace		14
+#define Anum_pg_aggregate_aggmtranstype		15
+#define Anum_pg_aggregate_aggmtransspace	16
+#define Anum_pg_aggregate_agginitval		17
+#define Anum_pg_aggregate_aggminitval		18
 
 /*
  * Symbolic values for aggkind column.  We distinguish normal aggregates
@@ -126,184 +129,184 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  */
 
 /* avg */
-DATA(insert ( 2100	n 0 int8_avg_accum	numeric_poly_avg		int8_avg_accum	int8_avg_accum_inv	numeric_poly_avg	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg		int4_avg_accum	int4_avg_accum_inv	int8_avg					f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg		int2_avg_accum	int2_avg_accum_inv	int8_avg					f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg	numeric_avg_accum numeric_accum_inv numeric_avg					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2104	n 0 float4_accum	float8_avg		-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2105	n 0 float8_accum	float8_avg		-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2106	n 0 interval_accum	interval_avg	interval_accum	interval_accum_inv interval_avg					f f 0	1187	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
+DATA(insert ( 2100	n 0 int8_avg_accum	numeric_poly_avg	-	int8_avg_accum	int8_avg_accum_inv	numeric_poly_avg	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg			-	int4_avg_accum	int4_avg_accum_inv	int8_avg			f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg			-	int2_avg_accum	int2_avg_accum_inv	int8_avg			f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg		-	numeric_avg_accum numeric_accum_inv numeric_avg			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2104	n 0 float4_accum	float8_avg			-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2105	n 0 float8_accum	float8_avg			-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2106	n 0 interval_accum	interval_avg		-	interval_accum	interval_accum_inv interval_avg			f f 0	1187	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
 
 /* sum */
-DATA(insert ( 2107	n 0 int8_avg_accum	numeric_poly_sum		int8_avg_accum	int8_avg_accum_inv numeric_poly_sum f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2108	n 0 int4_sum		-				int4_avg_accum	int4_avg_accum_inv int2int4_sum					f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2109	n 0 int2_sum		-				int2_avg_accum	int2_avg_accum_inv int2int4_sum					f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2110	n 0 float4pl		-				-				-				-								f f 0	700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2111	n 0 float8pl		-				-				-				-								f f 0	701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2112	n 0 cash_pl			-				cash_pl			cash_mi			-								f f 0	790		0	790		0	_null_ _null_ ));
-DATA(insert ( 2113	n 0 interval_pl		-				interval_pl		interval_mi		-								f f 0	1186	0	1186	0	_null_ _null_ ));
-DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum numeric_avg_accum numeric_accum_inv numeric_sum					f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2107	n 0 int8_avg_accum	numeric_poly_sum	-			int8_avg_accum	int8_avg_accum_inv	numeric_poly_sum	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2108	n 0 int4_sum		-					int8pl		int4_avg_accum	int4_avg_accum_inv	int2int4_sum		f f 0	20		0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2109	n 0 int2_sum		-					int8pl		int2_avg_accum	int2_avg_accum_inv	int2int4_sum		f f 0	20		0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2110	n 0 float4pl		-					float4pl	-				-					-					f f 0	700		0	0		0	_null_ _null_ ));
+DATA(insert ( 2111	n 0 float8pl		-					float8pl	-				-					-					f f 0	701		0	0		0	_null_ _null_ ));
+DATA(insert ( 2112	n 0 cash_pl			-					cash_pl		cash_pl			cash_mi				-					f f 0	790		0	790		0	_null_ _null_ ));
+DATA(insert ( 2113	n 0 interval_pl		-					interval_pl	interval_pl		interval_mi			-					f f 0	1186	0	1186	0	_null_ _null_ ));
+DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum		-		numeric_avg_accum	numeric_accum_inv	numeric_sum			f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* max */
-DATA(insert ( 2115	n 0 int8larger		-				-				-				-				f f 413		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2116	n 0 int4larger		-				-				-				-				f f 521		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2117	n 0 int2larger		-				-				-				-				f f 520		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2118	n 0 oidlarger		-				-				-				-				f f 610		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2119	n 0 float4larger	-				-				-				-				f f 623		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2120	n 0 float8larger	-				-				-				-				f f 674		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2121	n 0 int4larger		-				-				-				-				f f 563		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2122	n 0 date_larger		-				-				-				-				f f 1097	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2123	n 0 time_larger		-				-				-				-				f f 1112	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2124	n 0 timetz_larger	-				-				-				-				f f 1554	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2125	n 0 cashlarger		-				-				-				-				f f 903		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2126	n 0 timestamp_larger	-			-				-				-				f f 2064	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2127	n 0 timestamptz_larger	-			-				-				-				f f 1324	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2128	n 0 interval_larger -				-				-				-				f f 1334	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2129	n 0 text_larger		-				-				-				-				f f 666		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2130	n 0 numeric_larger	-				-				-				-				f f 1756	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2050	n 0 array_larger	-				-				-				-				f f 1073	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2244	n 0 bpchar_larger	-				-				-				-				f f 1060	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2797	n 0 tidlarger		-				-				-				-				f f 2800	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3526	n 0 enum_larger		-				-				-				-				f f 3519	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3564	n 0 network_larger	-				-				-				-				f f 1205	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2115	n 0 int8larger		-				int8larger			-				-				-				f f 413		20		0	0		0	_null_ _null_ ));
+DATA(insert ( 2116	n 0 int4larger		-				int4larger			-				-				-				f f 521		23		0	0		0	_null_ _null_ ));
+DATA(insert ( 2117	n 0 int2larger		-				int2larger			-				-				-				f f 520		21		0	0		0	_null_ _null_ ));
+DATA(insert ( 2118	n 0 oidlarger		-				oidlarger			-				-				-				f f 610		26		0	0		0	_null_ _null_ ));
+DATA(insert ( 2119	n 0 float4larger	-				float4larger		-				-				-				f f 623		700		0	0		0	_null_ _null_ ));
+DATA(insert ( 2120	n 0 float8larger	-				float8larger		-				-				-				f f 674		701		0	0		0	_null_ _null_ ));
+DATA(insert ( 2121	n 0 int4larger		-				int4larger			-				-				-				f f 563		702		0	0		0	_null_ _null_ ));
+DATA(insert ( 2122	n 0 date_larger		-				date_larger			-				-				-				f f 1097	1082	0	0		0	_null_ _null_ ));
+DATA(insert ( 2123	n 0 time_larger		-				time_larger			-				-				-				f f 1112	1083	0	0		0	_null_ _null_ ));
+DATA(insert ( 2124	n 0 timetz_larger	-				timetz_larger		-				-				-				f f 1554	1266	0	0		0	_null_ _null_ ));
+DATA(insert ( 2125	n 0 cashlarger		-				cashlarger			-				-				-				f f 903		790		0	0		0	_null_ _null_ ));
+DATA(insert ( 2126	n 0 timestamp_larger	-			timestamp_larger	-				-				-				f f 2064	1114	0	0		0	_null_ _null_ ));
+DATA(insert ( 2127	n 0 timestamptz_larger	-			timestamptz_larger	-				-				-				f f 1324	1184	0	0		0	_null_ _null_ ));
+DATA(insert ( 2128	n 0 interval_larger -				interval_larger		-				-				-				f f 1334	1186	0	0		0	_null_ _null_ ));
+DATA(insert ( 2129	n 0 text_larger		-				text_larger			-				-				-				f f 666		25		0	0		0	_null_ _null_ ));
+DATA(insert ( 2130	n 0 numeric_larger	-				numeric_larger		-				-				-				f f 1756	1700	0	0		0	_null_ _null_ ));
+DATA(insert ( 2050	n 0 array_larger	-				array_larger		-				-				-				f f 1073	2277	0	0		0	_null_ _null_ ));
+DATA(insert ( 2244	n 0 bpchar_larger	-				bpchar_larger		-				-				-				f f 1060	1042	0	0		0	_null_ _null_ ));
+DATA(insert ( 2797	n 0 tidlarger		-				tidlarger			-				-				-				f f 2800	27		0	0		0	_null_ _null_ ));
+DATA(insert ( 3526	n 0 enum_larger		-				enum_larger			-				-				-				f f 3519	3500	0	0		0	_null_ _null_ ));
+DATA(insert ( 3564	n 0 network_larger	-				network_larger		-				-				-				f f 1205	869		0	0		0	_null_ _null_ ));
 
 /* min */
-DATA(insert ( 2131	n 0 int8smaller		-				-				-				-				f f 412		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2132	n 0 int4smaller		-				-				-				-				f f 97		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2133	n 0 int2smaller		-				-				-				-				f f 95		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2134	n 0 oidsmaller		-				-				-				-				f f 609		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2135	n 0 float4smaller	-				-				-				-				f f 622		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2136	n 0 float8smaller	-				-				-				-				f f 672		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2137	n 0 int4smaller		-				-				-				-				f f 562		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2138	n 0 date_smaller	-				-				-				-				f f 1095	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2139	n 0 time_smaller	-				-				-				-				f f 1110	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2140	n 0 timetz_smaller	-				-				-				-				f f 1552	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2141	n 0 cashsmaller		-				-				-				-				f f 902		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2142	n 0 timestamp_smaller	-			-				-				-				f f 2062	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2143	n 0 timestamptz_smaller -			-				-				-				f f 1322	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2144	n 0 interval_smaller	-			-				-				-				f f 1332	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2145	n 0 text_smaller	-				-				-				-				f f 664		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2146	n 0 numeric_smaller -				-				-				-				f f 1754	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2051	n 0 array_smaller	-				-				-				-				f f 1072	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2245	n 0 bpchar_smaller	-				-				-				-				f f 1058	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2798	n 0 tidsmaller		-				-				-				-				f f 2799	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3527	n 0 enum_smaller	-				-				-				-				f f 3518	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3565	n 0 network_smaller -				-				-				-				f f 1203	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2131	n 0 int8smaller		-				int8smaller			-				-				-				f f 412		20		0	0		0	_null_ _null_ ));
+DATA(insert ( 2132	n 0 int4smaller		-				int4smaller			-				-				-				f f 97		23		0	0		0	_null_ _null_ ));
+DATA(insert ( 2133	n 0 int2smaller		-				int2smaller			-				-				-				f f 95		21		0	0		0	_null_ _null_ ));
+DATA(insert ( 2134	n 0 oidsmaller		-				oidsmaller			-				-				-				f f 609		26		0	0		0	_null_ _null_ ));
+DATA(insert ( 2135	n 0 float4smaller	-				float4smaller		-				-				-				f f 622		700		0	0		0	_null_ _null_ ));
+DATA(insert ( 2136	n 0 float8smaller	-				float8smaller		-				-				-				f f 672		701		0	0		0	_null_ _null_ ));
+DATA(insert ( 2137	n 0 int4smaller		-				int4smaller			-				-				-				f f 562		702		0	0		0	_null_ _null_ ));
+DATA(insert ( 2138	n 0 date_smaller	-				date_smaller		-				-				-				f f 1095	1082	0	0		0	_null_ _null_ ));
+DATA(insert ( 2139	n 0 time_smaller	-				time_smaller		-				-				-				f f 1110	1083	0	0		0	_null_ _null_ ));
+DATA(insert ( 2140	n 0 timetz_smaller	-				timetz_smaller		-				-				-				f f 1552	1266	0	0		0	_null_ _null_ ));
+DATA(insert ( 2141	n 0 cashsmaller		-				cashsmaller			-				-				-				f f 902		790		0	0		0	_null_ _null_ ));
+DATA(insert ( 2142	n 0 timestamp_smaller	-			timestamp_smaller	-				-				-				f f 2062	1114	0	0		0	_null_ _null_ ));
+DATA(insert ( 2143	n 0 timestamptz_smaller -			timestamptz_smaller	-				-				-				f f 1322	1184	0	0		0	_null_ _null_ ));
+DATA(insert ( 2144	n 0 interval_smaller	-			interval_smaller	-				-				-				f f 1332	1186	0	0		0	_null_ _null_ ));
+DATA(insert ( 2145	n 0 text_smaller	-				text_smaller		-				-				-				f f 664		25		0	0		0	_null_ _null_ ));
+DATA(insert ( 2146	n 0 numeric_smaller -				numeric_smaller		-				-				-				f f 1754	1700	0	0		0	_null_ _null_ ));
+DATA(insert ( 2051	n 0 array_smaller	-				array_smaller		-				-				-				f f 1072	2277	0	0		0	_null_ _null_ ));
+DATA(insert ( 2245	n 0 bpchar_smaller	-				bpchar_smaller		-				-				-				f f 1058	1042	0	0		0	_null_ _null_ ));
+DATA(insert ( 2798	n 0 tidsmaller		-				tidsmaller			-				-				-				f f 2799	27		0	0		0	_null_ _null_ ));
+DATA(insert ( 3527	n 0 enum_smaller	-				enum_smaller		-				-				-				f f 3518	3500	0	0		0	_null_ _null_ ));
+DATA(insert ( 3565	n 0 network_smaller -				network_smaller		-				-				-				f f 1203	869		0	0		0	_null_ _null_ ));
 
 /* count */
-DATA(insert ( 2147	n 0 int8inc_any		-				int8inc_any		int8dec_any		-				f f 0		20		0	20		0	"0" "0" ));
-DATA(insert ( 2803	n 0 int8inc			-				int8inc			int8dec			-				f f 0		20		0	20		0	"0" "0" ));
+DATA(insert ( 2147	n 0 int8inc_any		-				int8pl	int8inc_any		int8dec_any		-				f f 0		20		0	20		0	"0" "0" ));
+DATA(insert ( 2803	n 0 int8inc			-				int8pl	int8inc			int8dec			-				f f 0		20		0	20		0	"0" "0" ));
 
 /* var_pop */
-DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop		int8_accum		int8_accum_inv	numeric_var_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2719	n 0 int4_accum	numeric_poly_var_pop		int4_accum		int4_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2720	n 0 int2_accum	numeric_poly_var_pop		int2_accum		int2_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2721	n 0 float4_accum	float8_var_pop	-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2722	n 0 float8_accum	float8_var_pop	-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop numeric_accum numeric_accum_inv numeric_var_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop			-	int8_accum		int8_accum_inv	numeric_var_pop			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2719	n 0 int4_accum	numeric_poly_var_pop	-	int4_accum		int4_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2720	n 0 int2_accum	numeric_poly_var_pop	-	int2_accum		int2_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2721	n 0 float4_accum	float8_var_pop		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2722	n 0 float8_accum	float8_var_pop		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop		-	numeric_accum numeric_accum_inv numeric_var_pop			f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* var_samp */
-DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp	int8_accum		int8_accum_inv	numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2642	n 0 int4_accum	numeric_poly_var_samp		int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2643	n 0 int2_accum	numeric_poly_var_samp		int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2644	n 0 float4_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2645	n 0 float8_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp numeric_accum numeric_accum_inv numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp		-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2642	n 0 int4_accum	numeric_poly_var_samp	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2643	n 0 int2_accum	numeric_poly_var_samp	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2644	n 0 float4_accum	float8_var_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2645	n 0 float8_accum	float8_var_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp	-	numeric_accum	numeric_accum_inv numeric_var_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* variance: historical Postgres syntax for var_samp */
-DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp	int8_accum		int8_accum_inv	numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2149	n 0 int4_accum	numeric_poly_var_samp		int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2150	n 0 int2_accum	numeric_poly_var_samp		int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2151	n 0 float4_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2152	n 0 float8_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp numeric_accum numeric_accum_inv numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp		-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2149	n 0 int4_accum	numeric_poly_var_samp	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2150	n 0 int2_accum	numeric_poly_var_samp	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2151	n 0 float4_accum	float8_var_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2152	n 0 float8_accum	float8_var_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp	-	numeric_accum numeric_accum_inv numeric_var_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* stddev_pop */
-DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop	int8_accum	int8_accum_inv	numeric_stddev_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2725	n 0 int4_accum	numeric_poly_stddev_pop int4_accum	int4_accum_inv	numeric_poly_stddev_pop f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2726	n 0 int2_accum	numeric_poly_stddev_pop int2_accum	int2_accum_inv	numeric_poly_stddev_pop f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop numeric_accum numeric_accum_inv numeric_stddev_pop			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop		-	int8_accum	int8_accum_inv	numeric_stddev_pop		f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2725	n 0 int4_accum	numeric_poly_stddev_pop	-	int4_accum	int4_accum_inv	numeric_poly_stddev_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2726	n 0 int2_accum	numeric_poly_stddev_pop	-	int2_accum	int2_accum_inv	numeric_poly_stddev_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-	-				-				-					f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-	-				-				-					f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop	-	numeric_accum numeric_accum_inv numeric_stddev_pop	f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* stddev_samp */
-DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp		int8_accum	int8_accum_inv	numeric_stddev_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2713	n 0 int4_accum	numeric_poly_stddev_samp	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2714	n 0 int2_accum	numeric_poly_stddev_samp	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp numeric_accum numeric_accum_inv numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp			-	int8_accum	int8_accum_inv	numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2713	n 0 int4_accum	numeric_poly_stddev_samp	-	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2714	n 0 int2_accum	numeric_poly_stddev_samp	-	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp		-	numeric_accum numeric_accum_inv numeric_stddev_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* stddev: historical Postgres syntax for stddev_samp */
-DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp		int8_accum	int8_accum_inv	numeric_stddev_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2155	n 0 int4_accum	numeric_poly_stddev_samp	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2156	n 0 int2_accum	numeric_poly_stddev_samp	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp numeric_accum numeric_accum_inv numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp			-	int8_accum		int8_accum_inv	numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2155	n 0 int4_accum	numeric_poly_stddev_samp	-	int4_accum		int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2156	n 0 int2_accum	numeric_poly_stddev_samp	-	int2_accum		int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp		-	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp		-	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp		-	numeric_accum	numeric_accum_inv numeric_stddev_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* SQL2003 binary regression aggregates */
-DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-				-				-				f f 0	20		0	0		0	"0" _null_ ));
-DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-	-				-				-			f f 0	20		0	0		0	"0" _null_ ));
+DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
 
 /* boolean-and and boolean-or */
-DATA(insert ( 2517	n 0 booland_statefunc	-			bool_accum		bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2518	n 0 boolor_statefunc	-			bool_accum		bool_accum_inv	bool_anytrue	f f 59	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2519	n 0 booland_statefunc	-			bool_accum		bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2517	n 0 booland_statefunc	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2518	n 0 boolor_statefunc	-	-	bool_accum	bool_accum_inv	bool_anytrue	f f 59	16		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2519	n 0 booland_statefunc	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
 
 /* bitwise integer */
-DATA(insert ( 2236	n 0 int2and		-					-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2237	n 0 int2or		-					-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2238	n 0 int4and		-					-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2239	n 0 int4or		-					-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2240	n 0 int8and		-					-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2241	n 0 int8or		-					-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2242	n 0 bitand		-					-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
-DATA(insert ( 2243	n 0 bitor		-					-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
+DATA(insert ( 2236	n 0 int2and		-				int2and	-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
+DATA(insert ( 2237	n 0 int2or		-				int2or	-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
+DATA(insert ( 2238	n 0 int4and		-				int4and	-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
+DATA(insert ( 2239	n 0 int4or		-				int4or	-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
+DATA(insert ( 2240	n 0 int8and		-				int8and	-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
+DATA(insert ( 2241	n 0 int8or		-				int8or	-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
+DATA(insert ( 2242	n 0 bitand		-				bitand	-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
+DATA(insert ( 2243	n 0 bitor		-				bitor	-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
 
 /* xml */
-DATA(insert ( 2901	n 0 xmlconcat2	-					-				-				-				f f 0	142		0	0		0	_null_ _null_ ));
+DATA(insert ( 2901	n 0 xmlconcat2	-				-		-				-				-				f f 0	142		0	0		0	_null_ _null_ ));
 
 /* array */
-DATA(insert ( 2335	n 0 array_agg_transfn	array_agg_finalfn	-				-				-				t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn -		-				-				t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 2335	n 0 array_agg_transfn		array_agg_finalfn		-	-		-				-				t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn	-	-		-				-				t f 0	2281	0	0		0	_null_ _null_ ));
 
 /* text */
-DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
 
 /* bytea */
-DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-				-				-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-	-				-				-		f f 0	2281	0	0		0	_null_ _null_ ));
 
 /* json */
-DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
 
 /* jsonb */
-DATA(insert ( 3267	n 0 jsonb_agg_transfn	jsonb_agg_finalfn			-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3270	n 0 jsonb_object_agg_transfn jsonb_object_agg_finalfn -				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3267	n 0 jsonb_agg_transfn	jsonb_agg_finalfn				-	-				-				-			f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3270	n 0 jsonb_object_agg_transfn jsonb_object_agg_finalfn	-	-				-				-			f f 0	2281	0	0		0	_null_ _null_ ));
 
 /* ordered-set and hypothetical-set aggregates */
-DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
 
 
 /*
@@ -322,6 +325,7 @@ extern ObjectAddress AggregateCreate(const char *aggName,
 				Oid variadicArgType,
 				List *aggtransfnName,
 				List *aggfinalfnName,
+				List *aggcombinefnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index eb3591a..63d4b50 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1850,6 +1850,8 @@ typedef struct AggState
 	AggStatePerTrans curpertrans;	/* currently active trans state */
 	bool		input_done;		/* indicates end of input */
 	bool		agg_done;		/* indicates completion of Agg scan */
+	bool		combineStates;	/* input tuples contain transition states */
+	bool		finalizeAggs;	/* should we call the finalfn on agg states? */
 	int			projected_set;	/* The last projected grouping set */
 	int			current_set;	/* The current grouping set being evaluated */
 	Bitmapset  *grouped_cols;	/* grouped cols in current projection */
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 37086c6..9ae2a1b 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -726,6 +726,8 @@ typedef struct Agg
 	AggStrategy aggstrategy;
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
+	bool		combineStates;	/* input tuples contain transition states */
+	bool		finalizeAggs;	/* should we call the finalfn on agg states? */
 	Oid		   *grpOperators;	/* equality operators to compare with */
 	long		numGroups;		/* estimated number of groups in input */
 	List	   *groupingSets;	/* grouping sets to use */
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index 1fb8504..2c85972 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -59,9 +59,8 @@ extern Sort *make_sort_from_groupcols(PlannerInfo *root, List *groupcls,
 extern Agg *make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
 		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
-		 List *groupingSets,
-		 long numGroups,
-		 Plan *lefttree);
+		 List *groupingSets, long numGroups, bool combineStates,
+		 bool finalizeAggs, Plan *lefttree);
 extern WindowAgg *make_windowagg(PlannerInfo *root, List *tlist,
 			   List *windowFuncs, Index winref,
 			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
diff --git a/src/include/parser/parse_agg.h b/src/include/parser/parse_agg.h
index e2b3894..621b6b9 100644
--- a/src/include/parser/parse_agg.h
+++ b/src/include/parser/parse_agg.h
@@ -46,6 +46,12 @@ extern void build_aggregate_transfn_expr(Oid *agg_input_types,
 						Expr **transfnexpr,
 						Expr **invtransfnexpr);
 
+extern void build_aggregate_combinefn_expr(bool agg_variadic,
+										   Oid agg_state_type,
+										   Oid agg_input_collation,
+										   Oid combinefn_oid,
+										   Expr **combinefnexpr);
+
 extern void build_aggregate_finalfn_expr(Oid *agg_input_types,
 						int num_finalfn_inputs,
 						Oid agg_state_type,
diff --git a/src/test/regress/expected/create_aggregate.out b/src/test/regress/expected/create_aggregate.out
index 82a34fb..56643f2 100644
--- a/src/test/regress/expected/create_aggregate.out
+++ b/src/test/regress/expected/create_aggregate.out
@@ -101,6 +101,23 @@ CREATE AGGREGATE sumdouble (float8)
     msfunc = float8pl,
     minvfunc = float8mi
 );
+-- aggregate combine functions
+CREATE AGGREGATE mymax (int)
+(
+	stype = int4,
+	sfunc = int4larger,
+	cfunc = int4larger
+);
+-- Ensure all these functions made it into the catalog
+SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype
+FROM pg_aggregate
+WHERE aggfnoid = 'mymax'::REGPROC;
+ aggfnoid | aggtransfn | aggcombinefn | aggtranstype 
+----------+------------+--------------+--------------
+ mymax    | int4larger | int4larger   |           23
+(1 row)
+
+DROP AGGREGATE mymax (int);
 -- invalid: nonstrict inverse with strict forward function
 CREATE FUNCTION float8mi_n(float8, float8) RETURNS float8 AS
 $$ SELECT $1 - $2; $$
diff --git a/src/test/regress/sql/create_aggregate.sql b/src/test/regress/sql/create_aggregate.sql
index 0ec1572..0070382 100644
--- a/src/test/regress/sql/create_aggregate.sql
+++ b/src/test/regress/sql/create_aggregate.sql
@@ -115,6 +115,21 @@ CREATE AGGREGATE sumdouble (float8)
     minvfunc = float8mi
 );
 
+-- aggregate combine functions
+CREATE AGGREGATE mymax (int)
+(
+	stype = int4,
+	sfunc = int4larger,
+	cfunc = int4larger
+);
+
+-- Ensure all these functions made it into the catalog
+SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype
+FROM pg_aggregate
+WHERE aggfnoid = 'mymax'::REGPROC;
+
+DROP AGGREGATE mymax (int);
+
 -- invalid: nonstrict inverse with strict forward function
 
 CREATE FUNCTION float8mi_n(float8, float8) RETURNS float8 AS

diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index b2dc451..5524f1b 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -1228,6 +1228,7 @@ _copyAggref(const Aggref *from)
 
 	COPY_SCALAR_FIELD(aggfnoid);
 	COPY_SCALAR_FIELD(aggtype);
+	COPY_SCALAR_FIELD(aggtranstype);
 	COPY_SCALAR_FIELD(aggcollid);
 	COPY_SCALAR_FIELD(inputcollid);
 	COPY_NODE_FIELD(aggdirectargs);
@@ -1238,6 +1239,7 @@ _copyAggref(const Aggref *from)
 	COPY_SCALAR_FIELD(aggstar);
 	COPY_SCALAR_FIELD(aggvariadic);
 	COPY_SCALAR_FIELD(aggkind);
+	COPY_SCALAR_FIELD(aggskipfinalize);
 	COPY_SCALAR_FIELD(agglevelsup);
 	COPY_LOCATION_FIELD(location);
 
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 356fcaf..8bcbb75 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -191,6 +191,7 @@ _equalAggref(const Aggref *a, const Aggref *b)
 {
 	COMPARE_SCALAR_FIELD(aggfnoid);
 	COMPARE_SCALAR_FIELD(aggtype);
+	COMPARE_SCALAR_FIELD(aggtranstype);
 	COMPARE_SCALAR_FIELD(aggcollid);
 	COMPARE_SCALAR_FIELD(inputcollid);
 	COMPARE_NODE_FIELD(aggdirectargs);
@@ -201,6 +202,11 @@ _equalAggref(const Aggref *a, const Aggref *b)
 	COMPARE_SCALAR_FIELD(aggstar);
 	COMPARE_SCALAR_FIELD(aggvariadic);
 	COMPARE_SCALAR_FIELD(aggkind);
+
+	/* Commented out for now as this causes:
+	  "variable not found in subplan target list"
+	 COMPARE_SCALAR_FIELD(aggskipfinalize);
+	 */
 	COMPARE_SCALAR_FIELD(agglevelsup);
 	COMPARE_LOCATION_FIELD(location);
 
diff --git a/src/backend/nodes/nodeFuncs.c b/src/backend/nodes/nodeFuncs.c
index a11cb9f..5f547bd 100644
--- a/src/backend/nodes/nodeFuncs.c
+++ b/src/backend/nodes/nodeFuncs.c
@@ -57,7 +57,13 @@ exprType(const Node *expr)
 			type = ((const Param *) expr)->paramtype;
 			break;
 		case T_Aggref:
-			type = ((const Aggref *) expr)->aggtype;
+			{
+				Aggref *aggref = (Aggref *) expr;
+				if (aggref->aggskipfinalize)
+					type = aggref->aggtranstype;
+				else
+					type = aggref->aggtype;
+			}
 			break;
 		case T_GroupingFunc:
 			type = INT4OID;
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 6f6ccdc..6870e39 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -1016,6 +1016,7 @@ _outAggref(StringInfo str, const Aggref *node)
 
 	WRITE_OID_FIELD(aggfnoid);
 	WRITE_OID_FIELD(aggtype);
+	WRITE_OID_FIELD(aggtranstype);
 	WRITE_OID_FIELD(aggcollid);
 	WRITE_OID_FIELD(inputcollid);
 	WRITE_NODE_FIELD(aggdirectargs);
@@ -1026,6 +1027,7 @@ _outAggref(StringInfo str, const Aggref *node)
 	WRITE_BOOL_FIELD(aggstar);
 	WRITE_BOOL_FIELD(aggvariadic);
 	WRITE_CHAR_FIELD(aggkind);
+	WRITE_BOOL_FIELD(aggskipfinalize);
 	WRITE_UINT_FIELD(agglevelsup);
 	WRITE_LOCATION_FIELD(location);
 }
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 67d630f..c5c8b0d 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -134,7 +134,104 @@ static Plan *build_grouping_chain(PlannerInfo *root,
 					 AttrNumber *groupColIdx,
 					 AggClauseCosts *agg_costs,
 					 long numGroups,
-					 Plan *result_plan);
+					 Plan *result_plan,
+					 bool combineAggs);
+
+static List *
+make_aggregate_tlist(PlannerInfo *root,
+					 List *tlist,
+					 AttrNumber **groupColIdx)
+{
+	Query	   *parse = root->parse;
+	List	   *sub_tlist;
+	List	   *non_group_cols;
+	List	   *non_group_vars;
+	int			numCols;
+	ListCell   *tl;
+
+	*groupColIdx = NULL;
+
+	/*
+	 * Otherwise, we must build a tlist containing all grouping columns, plus
+	 * any other Vars mentioned in the targetlist and HAVING qual.
+	 */
+	sub_tlist = NIL;
+	non_group_cols = NIL;
+
+	numCols = list_length(parse->groupClause);
+	if (numCols > 0)
+	{
+		/*
+		 * If grouping, create sub_tlist entries for all GROUP BY columns, and
+		 * make an array showing where the group columns are in the sub_tlist.
+		 *
+		 * Note: with this implementation, the array entries will always be
+		 * 1..N, but we don't want callers to assume that.
+		 */
+		AttrNumber *grpColIdx;
+
+		grpColIdx = (AttrNumber *) palloc0(sizeof(AttrNumber) * numCols);
+		*groupColIdx = grpColIdx;
+
+		foreach(tl, tlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(tl);
+			int			colno;
+
+			colno = get_grouping_column_index(parse, tle);
+			if (colno >= 0)
+			{
+				/*
+				 * It's a grouping column, so add it to the result tlist and
+				 * remember its resno in grpColIdx[].
+				 */
+				TargetEntry *newtle;
+
+				newtle = makeTargetEntry((Expr *) copyObject(tle->expr),
+										 list_length(sub_tlist) + 1,
+										 tle->resname ? pstrdup(tle->resname) : NULL,
+										 tle->resjunk);
+				newtle->ressortgroupref = tle->ressortgroupref;
+				sub_tlist = lappend(sub_tlist, newtle);
+
+				Assert(grpColIdx[colno] == 0);	/* no dups expected */
+				grpColIdx[colno] = newtle->resno;
+			}
+			else
+			{
+				non_group_cols = lappend(non_group_cols, tle->expr);
+			}
+		}
+	}
+	else
+	{
+		foreach (tl, tlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(tl);
+			non_group_cols = lappend(non_group_cols, tle->expr);
+		}
+	}
+
+	/*
+	 * If there's a HAVING clause, we'll need need to ensure all Aggrefs from
+	 * there are also in the targetlist
+	 */
+	if (parse->havingQual)
+		non_group_cols = lappend(non_group_cols, parse->havingQual);
+
+
+	non_group_vars = pull_var_clause((Node *) non_group_cols,
+									 PVC_INCLUDE_AGGREGATES,
+									 PVC_INCLUDE_PLACEHOLDERS);
+
+	sub_tlist = add_to_flat_tlist(sub_tlist, non_group_vars);
+
+	/* clean up cruft */
+	list_free(non_group_vars);
+	list_free(non_group_cols);
+
+	return sub_tlist;
+}
 
 /*****************************************************************************
  *
@@ -1889,6 +1986,15 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			 * results.
 			 */
 			bool		need_sort_for_grouping = false;
+			bool		combineaggs;
+
+			/*
+			 * Enable partial aggregation test if all aggregates support
+			 * partial aggregation, and we have no grouping sets
+			 */
+			combineaggs = parse->groupingSets == NIL &&
+						  aggregates_allow_partial((Node *) tlist) &&
+						  aggregates_allow_partial(root->parse->havingQual);
 
 			result_plan = create_plan(root, best_path);
 			current_pathkeys = best_path->pathkeys;
@@ -1906,6 +2012,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 				need_tlist_eval = true;
 			}
 
+			if (combineaggs)
+				need_tlist_eval = true;
+
 			/*
 			 * create_plan returns a plan with just a "flat" tlist of required
 			 * Vars.  Usually we need to insert the sub_tlist as the tlist of
@@ -1984,20 +2093,83 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			 */
 			if (use_hashed_grouping)
 			{
-				/* Hashed aggregate plan --- no sort needed */
-				result_plan = (Plan *) make_agg(root,
-												tlist,
-												(List *) parse->havingQual,
-												AGG_HASHED,
-												&agg_costs,
-												numGroupCols,
-												groupColIdx,
-									extract_grouping_ops(parse->groupClause),
-												NIL,
-												numGroups,
-												false,
-												true,
-												result_plan);
+				if (combineaggs)
+				{
+					AttrNumber *groupColIdx;
+					List *aggtlist;
+
+					/* Hack hack */
+					aggtlist = make_aggregate_tlist(root, tlist, &groupColIdx);
+					{
+						ListCell *lc;
+						foreach(lc, aggtlist)
+						{
+							TargetEntry *tle = (TargetEntry *) lfirst(lc);
+							Aggref *aggref = (Aggref *) tle->expr;
+							if (IsA(aggref, Aggref))
+								aggref->aggskipfinalize = true;
+						}
+					}
+					/* End of hack */
+
+					/* Hashed aggregate plan --- no sort needed */
+					result_plan = (Plan *) make_agg(root,
+													aggtlist,
+													NIL,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													false,
+													false,
+													result_plan);
+
+					result_plan->targetlist = aggtlist;
+
+					/*
+					 * Also, account for the cost of evaluation of the sub_tlist.
+					 * See comments for add_tlist_costs_to_plan() for more info.
+					 */
+					add_tlist_costs_to_plan(root, result_plan, aggtlist);
+
+					aggtlist = make_aggregate_tlist(root, tlist, &groupColIdx);
+
+					result_plan = (Plan *) make_agg(root,
+													aggtlist,
+													(List *) parse->havingQual,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													true,
+													true,
+													result_plan);
+					result_plan->targetlist = tlist;
+
+				}
+				else
+				{
+					/* Hashed aggregate plan --- no sort needed */
+					result_plan = (Plan *) make_agg(root,
+													tlist,
+													(List *) parse->havingQual,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													false,
+													true,
+													result_plan);
+				}
 				/* Hashed aggregation produces randomly-ordered results */
 				current_pathkeys = NIL;
 			}
@@ -2023,7 +2195,8 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 												   groupColIdx,
 												   &agg_costs,
 												   numGroups,
-												   result_plan);
+												   result_plan,
+												   combineaggs);
 
 				/*
 				 * these are destroyed by build_grouping_chain, so make sure
@@ -2477,7 +2650,8 @@ build_grouping_chain(PlannerInfo *root,
 					 AttrNumber *groupColIdx,
 					 AggClauseCosts *agg_costs,
 					 long numGroups,
-					 Plan *result_plan)
+					 Plan *result_plan,
+					 bool combineAggs)
 {
 	AttrNumber *top_grpColIdx = groupColIdx;
 	List	   *chain = NIL;
@@ -2571,20 +2745,79 @@ build_grouping_chain(PlannerInfo *root,
 		else
 			numGroupCols = list_length(parse->groupClause);
 
-		result_plan = (Plan *) make_agg(root,
-										tlist,
-										(List *) parse->havingQual,
-								 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
-										agg_costs,
-										numGroupCols,
-										top_grpColIdx,
-										extract_grouping_ops(groupClause),
-										gsets,
-										numGroups,
-										false,
-										true,
-										result_plan);
+		if (combineAggs)
+		{
+			AttrNumber *groupColIdx;
+			List *aggtlist;
+
+			 /* Hack hack */
+			aggtlist = make_aggregate_tlist(root, tlist, &groupColIdx);
+			{
+				ListCell *lc;
+				foreach(lc, aggtlist)
+				{
+					TargetEntry *tle = (TargetEntry *) lfirst(lc);
+					Aggref *aggref = (Aggref *) tle->expr;
+					if (IsA(aggref, Aggref))
+						aggref->aggskipfinalize = true;
+				}
+			}
+
+			/* End of hack */
+			result_plan = (Plan *) make_agg(root,
+											aggtlist,
+											NIL,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											groupColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											false,
+											false,
+											result_plan);
+			result_plan->targetlist = aggtlist;
 
+			/*
+			 * Also, account for the cost of evaluation of the sub_tlist.
+			 * See comments for add_tlist_costs_to_plan() for more info.
+			 */
+			add_tlist_costs_to_plan(root, result_plan, aggtlist);
+
+			aggtlist  = make_aggregate_tlist(root, tlist, &groupColIdx);
+
+			result_plan = (Plan *) make_agg(root,
+											aggtlist,
+											(List *) parse->havingQual,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											groupColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											true,
+											true,
+											result_plan);
+			result_plan->targetlist = tlist;
+		}
+		else
+		{
+			result_plan = (Plan *) make_agg(root,
+											tlist,
+											(List *) parse->havingQual,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											top_grpColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											false,
+											true,
+											result_plan);
+		}
 		((Agg *) result_plan)->chain = chain;
 
 		/*
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 12e9290..fb423fc 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -139,6 +139,15 @@ static List *set_returning_clause_references(PlannerInfo *root,
 static bool fix_opfuncids_walker(Node *node, void *context);
 static bool extract_query_dependencies_walker(Node *node,
 								  PlannerInfo *context);
+static void set_agg_references(PlannerInfo *root, Plan *plan, int rtoffset);
+static Node *fix_combine_agg_expr(PlannerInfo *root,
+								  Node *node,
+								  indexed_tlist *subplan_itlist,
+								  Index newvarno,
+								  int rtoffset);
+static Node *fix_combine_agg_expr_mutator(Node *node,
+										  fix_upper_expr_context *context);
+
 
 /*****************************************************************************
  *
@@ -668,7 +677,7 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 			}
 			break;
 		case T_Agg:
-			set_upper_references(root, plan, rtoffset);
+			set_agg_references(root, plan, rtoffset);
 			break;
 		case T_Group:
 			set_upper_references(root, plan, rtoffset);
@@ -2432,3 +2441,211 @@ extract_query_dependencies_walker(Node *node, PlannerInfo *context)
 	return expression_tree_walker(node, extract_query_dependencies_walker,
 								  (void *) context);
 }
+
+/*
+ * set_upper_references
+ *	  Update the targetlist and quals of an upper-level plan node
+ *	  to refer to the tuples returned by its lefttree subplan.
+ *	  Also perform opcode lookup for these expressions, and
+ *	  add regclass OIDs to root->glob->relationOids.
+ *
+ * This is used for single-input plan types like Agg, Group, Result.
+ *
+ * In most cases, we have to match up individual Vars in the tlist and
+ * qual expressions with elements of the subplan's tlist (which was
+ * generated by flatten_tlist() from these selfsame expressions, so it
+ * should have all the required variables).  There is an important exception,
+ * however: GROUP BY and ORDER BY expressions will have been pushed into the
+ * subplan tlist unflattened.  If these values are also needed in the output
+ * then we want to reference the subplan tlist element rather than recomputing
+ * the expression.
+ */
+static void
+set_agg_references(PlannerInfo *root, Plan *plan, int rtoffset)
+{
+	Agg 	   *agg = (Agg*)plan;
+	Plan	   *subplan = plan->lefttree;
+	indexed_tlist *subplan_itlist;
+	List	   *output_targetlist;
+	ListCell   *l;
+
+	subplan_itlist = build_tlist_index(subplan->targetlist);
+
+	output_targetlist = NIL;
+
+	if (agg->combineStates)
+	{
+		foreach(l, plan->targetlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(l);
+			Node	   *newexpr;
+
+			/* If it's a non-Var sort/group item, first try to match by sortref */
+			if (tle->ressortgroupref != 0 && !IsA(tle->expr, Var))
+			{
+				newexpr = (Node *)
+					search_indexed_tlist_for_sortgroupref((Node *) tle->expr,
+														  tle->ressortgroupref,
+														  subplan_itlist,
+														  OUTER_VAR);
+				if (!newexpr)
+					newexpr = fix_combine_agg_expr(root,
+												 (Node *) tle->expr,
+												 subplan_itlist,
+												 OUTER_VAR,
+												 rtoffset);
+			}
+			else
+				newexpr = fix_combine_agg_expr(root,
+											 (Node *) tle->expr,
+											 subplan_itlist,
+											 OUTER_VAR,
+											 rtoffset);
+			tle = flatCopyTargetEntry(tle);
+			tle->expr = (Expr *) newexpr;
+			output_targetlist = lappend(output_targetlist, tle);
+		}
+	}
+	else
+	{
+		foreach(l, plan->targetlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(l);
+			Node	   *newexpr;
+
+			/* If it's a non-Var sort/group item, first try to match by sortref */
+			if (tle->ressortgroupref != 0 && !IsA(tle->expr, Var))
+			{
+				newexpr = (Node *)
+					search_indexed_tlist_for_sortgroupref((Node *) tle->expr,
+														  tle->ressortgroupref,
+														  subplan_itlist,
+														  OUTER_VAR);
+				if (!newexpr)
+					newexpr = fix_upper_expr(root,
+											 (Node *) tle->expr,
+											 subplan_itlist,
+											 OUTER_VAR,
+											 rtoffset);
+			}
+			else
+				newexpr = fix_upper_expr(root,
+										 (Node *) tle->expr,
+										 subplan_itlist,
+										 OUTER_VAR,
+										 rtoffset);
+			tle = flatCopyTargetEntry(tle);
+			tle->expr = (Expr *) newexpr;
+			output_targetlist = lappend(output_targetlist, tle);
+		}
+	}
+
+	plan->targetlist = output_targetlist;
+
+	plan->qual = (List *)
+		fix_upper_expr(root,
+					   (Node *) plan->qual,
+					   subplan_itlist,
+					   OUTER_VAR,
+					   rtoffset);
+
+	pfree(subplan_itlist);
+}
+
+
+/*
+ * This function is only used by combineAgg to set the Var nodes as args of
+ * Aggref reference output of a Gather plan.
+ */
+static Node *
+fix_combine_agg_expr(PlannerInfo *root,
+			   Node *node,
+			   indexed_tlist *subplan_itlist,
+			   Index newvarno,
+			   int rtoffset)
+{
+	fix_upper_expr_context context;
+
+	context.root = root;
+	context.subplan_itlist = subplan_itlist;
+	context.newvarno = newvarno;
+	context.rtoffset = rtoffset;
+	return fix_combine_agg_expr_mutator(node, &context);
+}
+
+static Node *
+fix_combine_agg_expr_mutator(Node *node, fix_upper_expr_context *context)
+{
+	Var		   *newvar;
+
+	if (node == NULL)
+		return NULL;
+	if (IsA(node, Var))
+	{
+		Var		   *var = (Var *) node;
+
+		newvar = search_indexed_tlist_for_var(var,
+											  context->subplan_itlist,
+											  context->newvarno,
+											  context->rtoffset);
+		if (!newvar)
+			elog(ERROR, "variable not found in subplan target list");
+		return (Node *) newvar;
+	}
+	if (IsA(node, Aggref))
+	{
+		TargetEntry *tle;
+		Aggref		*aggref = (Aggref*)node;
+		List	    *args = NIL;
+
+		tle = tlist_member(node, context->subplan_itlist->tlist);
+		if (tle)
+		{
+			/* Found a matching subplan output expression */
+			Var		   *newvar;
+			TargetEntry *newtle;
+
+			newvar = makeVarFromTargetEntry(context->newvarno, tle);
+			newvar->varnoold = 0;	/* wasn't ever a plain Var */
+			newvar->varoattno = 0;
+			newvar->vartype = aggref->aggtranstype; /* hack hack */
+
+			/* update the args in the aggref */
+
+			/* makeTargetEntry ,always set resno to one for finialize agg */
+			newtle = makeTargetEntry((Expr*)newvar,1,NULL,false);
+			args = lappend(args,newtle);
+
+			/*
+			 * Updated the args, let the newvar refer to the right position of
+			 * the agg function in the subplan
+			 */
+			aggref->args = args;
+
+			return (Node *) aggref;
+		}
+	}
+	if (IsA(node, PlaceHolderVar))
+	{
+		PlaceHolderVar *phv = (PlaceHolderVar *) node;
+
+		/* See if the PlaceHolderVar has bubbled up from a lower plan node */
+		if (context->subplan_itlist->has_ph_vars)
+		{
+			newvar = search_indexed_tlist_for_non_var((Node *) phv,
+													  context->subplan_itlist,
+													  context->newvarno);
+			if (newvar)
+				return (Node *) newvar;
+		}
+		/* If not supplied by input plan, evaluate the contained expr */
+		return fix_upper_expr_mutator((Node *) phv->phexpr, context);
+	}
+	if (IsA(node, Param))
+		return fix_param_node(context->root, (Param *) node);
+
+	fix_expr_common(context->root, node);
+	return expression_tree_mutator(node,
+								   fix_combine_agg_expr_mutator,
+								   (void *) context);
+}
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 00f5ce3..4d3a24e 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -445,6 +445,7 @@ partial_aggregate_walker(Node *node, void *context)
 				 aggref->aggfnoid);
 		aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
 		aggcombinefn = aggform->aggcombinefn;
+		aggref->aggtranstype = aggform->aggtranstype; /* Hack hack */
 		ReleaseSysCache(aggTuple);
 
 		/* Do we have a combine function? */
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index fa93a8c..5f37f14 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -3352,6 +3352,68 @@ numeric_avg_accum(PG_FUNCTION_ARGS)
 }
 
 /*
+ * Generic combine function for numeric aggregates
+ */
+Datum
+numeric_avg_combine(PG_FUNCTION_ARGS)
+{
+	NumericAggState *state1;
+	NumericAggState *state2;
+
+	state1 = PG_ARGISNULL(0) ? NULL : (NumericAggState *) PG_GETARG_POINTER(0);
+	state2 = PG_ARGISNULL(1) ? NULL : (NumericAggState *) PG_GETARG_POINTER(1);
+
+	if (state2 == NULL)
+		PG_RETURN_POINTER(state1);
+
+	/* manually copy all fields from state2 to state1 */
+	if (state1 == NULL)
+	{
+		MemoryContext old_context;
+
+		state1 = makeNumericAggState(fcinfo, false);
+		state1->N = state2->N;
+		state1->NaNcount = state2->NaNcount;
+		state1->maxScale = state2->maxScale;
+		state1->maxScaleCount = state2->maxScaleCount;
+
+		old_context = MemoryContextSwitchTo(state1->agg_context);
+
+		init_var(&state1->sumX);
+		set_var_from_var(&state2->sumX, &state1->sumX);
+
+		MemoryContextSwitchTo(old_context);
+
+		PG_RETURN_POINTER(state1);
+	}
+
+	if (state2->N > 0)
+	{
+		MemoryContext old_context;
+
+		state1->N += state2->N;
+		state1->NaNcount += state2->NaNcount;
+
+		if (state2->maxScale > state1->maxScale)
+			state1->maxScale = state2->maxScale;
+		else if (state2->maxScale == state1->maxScale)
+			state1->maxScale += state2->maxScale;
+
+		/* The rest of this needs to work in the aggregate context */
+		old_context = MemoryContextSwitchTo(state1->agg_context);
+
+		/* Accumulate sums */
+		add_var(&(state1->sumX), &(state2->sumX), &(state1->sumX));
+
+		if (state1->calcSumX2)
+			add_var(&(state1->sumX2), &(state2->sumX2), &(state1->sumX2));
+
+		MemoryContextSwitchTo(old_context);
+	}
+	PG_RETURN_POINTER(state1);
+}
+
+/*
  * Generic inverse transition function for numeric aggregates
  * (with or without requirement for X^2).
  */
diff --git a/src/include/catalog/pg_aggregate.h b/src/include/catalog/pg_aggregate.h
index b306f9b..6ea8fbb 100644
--- a/src/include/catalog/pg_aggregate.h
+++ b/src/include/catalog/pg_aggregate.h
@@ -145,7 +145,7 @@ DATA(insert ( 2110	n 0 float4pl		-					float4pl	-				-					-					f f 0	700		0	0
 DATA(insert ( 2111	n 0 float8pl		-					float8pl	-				-					-					f f 0	701		0	0		0	_null_ _null_ ));
 DATA(insert ( 2112	n 0 cash_pl			-					cash_pl		cash_pl			cash_mi				-					f f 0	790		0	790		0	_null_ _null_ ));
 DATA(insert ( 2113	n 0 interval_pl		-					interval_pl	interval_pl		interval_mi			-					f f 0	1186	0	1186	0	_null_ _null_ ));
-DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum		-		numeric_avg_accum	numeric_accum_inv	numeric_sum			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum		numeric_avg_combine	numeric_avg_accum	numeric_accum_inv	numeric_sum			f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* max */
 DATA(insert ( 2115	n 0 int8larger		-				int8larger			-				-				-				f f 413		20		0	0		0	_null_ _null_ ));
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index d8640db..f328007 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -2515,6 +2515,8 @@ DESCR("aggregate final function");
 DATA(insert OID = 1833 (  numeric_accum    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_accum _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
 DATA(insert OID = 2858 (  numeric_avg_accum    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_avg_accum _null_ _null_ _null_ ));
+DESCR("aggregate combine function");
+DATA(insert OID = 3317 (  numeric_avg_combine    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 2281" _null_ _null_ _null_ _null_ _null_ numeric_avg_combine _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
 DATA(insert OID = 3548 (  numeric_accum_inv    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_accum_inv _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 60c1ca2..81dd4f8 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -256,6 +256,7 @@ typedef struct Aggref
 	Expr		xpr;
 	Oid			aggfnoid;		/* pg_proc Oid of the aggregate */
 	Oid			aggtype;		/* type Oid of result of the aggregate */
+	Oid			aggtranstype;	 /* Hack hack */
 	Oid			aggcollid;		/* OID of collation of result */
 	Oid			inputcollid;	/* OID of collation that function should use */
 	List	   *aggdirectargs;	/* direct arguments, if an ordered-set agg */
@@ -267,6 +268,7 @@ typedef struct Aggref
 	bool		aggvariadic;	/* true if variadic arguments have been
 								 * combined into an array last argument */
 	char		aggkind;		/* aggregate kind (see pg_aggregate.h) */
+	bool		aggskipfinalize;/* TRUE if Aggref should skip finalization */
 	Index		agglevelsup;	/* > 0 if agg belongs to outer query */
 	int			location;		/* token location, or -1 if unknown */
 } Aggref;

diff --git a/doc/src/sgml/ref/create_aggregate.sgml b/doc/src/sgml/ref/create_aggregate.sgml
index eaa410b..4fb98b4 100644
--- a/doc/src/sgml/ref/create_aggregate.sgml
+++ b/doc/src/sgml/ref/create_aggregate.sgml
@@ -27,6 +27,7 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ <replacea
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">cfunc</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -45,6 +46,7 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ [ <replac
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">cfunc</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , HYPOTHETICAL ]
 )
@@ -58,6 +60,7 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">cfunc</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -105,12 +108,15 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
    functions:
    a state transition function
    <replaceable class="PARAMETER">sfunc</replaceable>,
-   and an optional final calculation function
-   <replaceable class="PARAMETER">ffunc</replaceable>.
+   an optional final calculation function
+   <replaceable class="PARAMETER">ffunc</replaceable>,
+   and an optional combine function
+   <replaceable class="PARAMETER">cfunc</replaceable>.
    These are used as follows:
 <programlisting>
 <replaceable class="PARAMETER">sfunc</replaceable>( internal-state, next-data-values ) ---> next-internal-state
 <replaceable class="PARAMETER">ffunc</replaceable>( internal-state ) ---> aggregate-value
+<replaceable class="PARAMETER">cfunc</replaceable>( internal-state, internal-state ) ---> next-internal-state
 </programlisting>
   </para>
 
@@ -128,6 +134,13 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
   </para>
 
   <para>
+   An aggregate function may also supply a combining function, which allows
+   the aggregation process to be broken down into multiple steps.  This
+   facilitates query optimization techniques such as parallel query,
+   pre-join aggregation and aggregation while sorting.
+  </para>
+
+  <para>
    An aggregate function can provide an initial condition,
    that is, an initial value for the internal state value.
    This is specified and stored in the database as a value of type
diff --git a/src/backend/catalog/pg_aggregate.c b/src/backend/catalog/pg_aggregate.c
index 121c27f..848a868 100644
--- a/src/backend/catalog/pg_aggregate.c
+++ b/src/backend/catalog/pg_aggregate.c
@@ -57,6 +57,7 @@ AggregateCreate(const char *aggName,
 				Oid variadicArgType,
 				List *aggtransfnName,
 				List *aggfinalfnName,
+				List *aggcombinefnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
@@ -77,6 +78,7 @@ AggregateCreate(const char *aggName,
 	Form_pg_proc proc;
 	Oid			transfn;
 	Oid			finalfn = InvalidOid;	/* can be omitted */
+	Oid			combinefn = InvalidOid;	/* can be omitted */
 	Oid			mtransfn = InvalidOid;	/* can be omitted */
 	Oid			minvtransfn = InvalidOid;		/* can be omitted */
 	Oid			mfinalfn = InvalidOid;	/* can be omitted */
@@ -396,6 +398,20 @@ AggregateCreate(const char *aggName,
 	}
 	Assert(OidIsValid(finaltype));
 
+	/* handle the combinefn, if supplied */
+	if (aggcombinefnName)
+	{
+		/*
+		 * Combine function must have 2 argument, each of which is the
+		 * trans type
+		 */
+		fnArgs[0] = aggTransType;
+		fnArgs[1] = aggTransType;
+
+		combinefn = lookup_agg_function(aggcombinefnName, 2, fnArgs,
+										variadicArgType, &finaltype);
+	}
+
 	/*
 	 * If finaltype (i.e. aggregate return type) is polymorphic, inputs must
 	 * be polymorphic also, else parser will fail to deduce result type.
@@ -567,6 +583,7 @@ AggregateCreate(const char *aggName,
 	values[Anum_pg_aggregate_aggnumdirectargs - 1] = Int16GetDatum(numDirectArgs);
 	values[Anum_pg_aggregate_aggtransfn - 1] = ObjectIdGetDatum(transfn);
 	values[Anum_pg_aggregate_aggfinalfn - 1] = ObjectIdGetDatum(finalfn);
+	values[Anum_pg_aggregate_aggcombinefn - 1] = ObjectIdGetDatum(combinefn);
 	values[Anum_pg_aggregate_aggmtransfn - 1] = ObjectIdGetDatum(mtransfn);
 	values[Anum_pg_aggregate_aggminvtransfn - 1] = ObjectIdGetDatum(minvtransfn);
 	values[Anum_pg_aggregate_aggmfinalfn - 1] = ObjectIdGetDatum(mfinalfn);
diff --git a/src/backend/commands/aggregatecmds.c b/src/backend/commands/aggregatecmds.c
index 894c89d..f680a55 100644
--- a/src/backend/commands/aggregatecmds.c
+++ b/src/backend/commands/aggregatecmds.c
@@ -61,6 +61,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	char		aggKind = AGGKIND_NORMAL;
 	List	   *transfuncName = NIL;
 	List	   *finalfuncName = NIL;
+	List	   *combinefuncName = NIL;
 	List	   *mtransfuncName = NIL;
 	List	   *minvtransfuncName = NIL;
 	List	   *mfinalfuncName = NIL;
@@ -124,6 +125,8 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 			transfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "finalfunc") == 0)
 			finalfuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "combinefunc") == 0)
+			combinefuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "msfunc") == 0)
 			mtransfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "minvfunc") == 0)
@@ -383,6 +386,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 						   variadicArgType,
 						   transfuncName,		/* step function name */
 						   finalfuncName,		/* final function name */
+						   combinefuncName,		/* combine function name */
 						   mtransfuncName,		/* fwd trans function name */
 						   minvtransfuncName,	/* inv trans function name */
 						   mfinalfuncName,		/* final function name */
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 12dae77..4a92bfc 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -908,25 +908,38 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			pname = sname = "Group";
 			break;
 		case T_Agg:
-			sname = "Aggregate";
-			switch (((Agg *) plan)->aggstrategy)
 			{
-				case AGG_PLAIN:
-					pname = "Aggregate";
-					strategy = "Plain";
-					break;
-				case AGG_SORTED:
-					pname = "GroupAggregate";
-					strategy = "Sorted";
-					break;
-				case AGG_HASHED:
-					pname = "HashAggregate";
-					strategy = "Hashed";
-					break;
-				default:
-					pname = "Aggregate ???";
-					strategy = "???";
-					break;
+				char	   *modifier;
+				Agg		   *agg = (Agg *) plan;
+
+				sname = "Aggregate";
+
+				if (agg->finalizeAggs == false)
+					modifier = "Partial ";
+				else if (agg->combineStates == true)
+					modifier = "Finalize ";
+				else
+					modifier = "";
+
+				switch (agg->aggstrategy)
+				{
+					case AGG_PLAIN:
+						pname = psprintf("%sAggregate", modifier);
+						strategy = "Plain";
+						break;
+					case AGG_SORTED:
+						pname = psprintf("%sGroupAggregate", modifier);
+						strategy = "Sorted";
+						break;
+					case AGG_HASHED:
+						pname = psprintf("%sHashAggregate", modifier);
+						strategy = "Hashed";
+						break;
+					default:
+						pname = "Aggregate ???";
+						strategy = "???";
+						break;
+				}
 			}
 			break;
 		case T_WindowAgg:
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index 2e36855..6bad1df 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -3,15 +3,40 @@
  * nodeAgg.c
  *	  Routines to handle aggregate nodes.
  *
- *	  ExecAgg evaluates each aggregate in the following steps:
+ *	  ExecAgg normally evaluates each aggregate in the following steps:
  *
  *		 transvalue = initcond
  *		 foreach input_tuple do
  *			transvalue = transfunc(transvalue, input_value(s))
  *		 result = finalfunc(transvalue, direct_argument(s))
  *
- *	  If a finalfunc is not supplied then the result is just the ending
- *	  value of transvalue.
+ *	  If a finalfunc is not supplied or finalizeAggs is false, then the result
+ *	  is just the ending value of transvalue.
+ *
+ *	  Other behavior is also supported and is controlled by the 'combineStates'
+ *	  and 'finalizeAggs' parameters. 'combineStates' controls whether the
+ *	  trans func or the combine func is used during aggregation. When
+ *	  'combineStates' is true we expect other (previously) aggregated states
+ *	  as input rather than input tuples. This mode facilitates multiple
+ *	  aggregate stages which allows us to support pushing aggregation down
+ *	  deeper into the plan rather than leaving it for the final stage. For
+ *	  example with a query such as:
+ *
+ *	  SELECT count(*) FROM (SELECT * FROM a UNION ALL SELECT * FROM b);
+ *
+ *	  with this functionality the planner has the flexibility to generate a
+ *	  plan which performs count(*) on table a and table b separately and then
+ *	  add a combine phase to combine both results. In this case the combine
+ *	  function would simply add both counts together.
+ *
+ *	  When multiple aggregate stages exist the planner should have set the
+ *	  'finalizeAggs' set to true only for the final aggregtion state, and
+ *	  each stage, apart from the very first one should have 'combineStates' set
+ *	  to true. This permits plans such as:
+ *
+ *		Finalize Aggregate
+ *			->  Partial Aggregate
+ *				->  Partial Aggregate
  *
  *	  If a normal aggregate call specifies DISTINCT or ORDER BY, we sort the
  *	  input tuples and eliminate duplicates (if required) before performing
@@ -197,7 +222,7 @@ typedef struct AggStatePerTransData
 	 */
 	int			numTransInputs;
 
-	/* Oid of the state transition function */
+	/* Oid of the state transition or combine function */
 	Oid			transfn_oid;
 
 	/* Oid of state value's datatype */
@@ -209,8 +234,8 @@ typedef struct AggStatePerTransData
 	List	   *aggdirectargs;	/* states of direct-argument expressions */
 
 	/*
-	 * fmgr lookup data for transition function.  Note in particular that the
-	 * fn_strict flag is kept here.
+	 * fmgr lookup data for transition function or combination function.  Note
+	 * in particular that the fn_strict flag is kept here.
 	 */
 	FmgrInfo	transfn;
 
@@ -421,6 +446,10 @@ static void advance_transition_function(AggState *aggstate,
 							AggStatePerTrans pertrans,
 							AggStatePerGroup pergroupstate);
 static void advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup);
+static void advance_combination_function(AggState *aggstate,
+							AggStatePerTrans pertrans,
+							AggStatePerGroup pergroupstate);
+static void combine_aggregates(AggState *aggstate, AggStatePerGroup pergroup);
 static void process_ordered_aggregate_single(AggState *aggstate,
 								 AggStatePerTrans pertrans,
 								 AggStatePerGroup pergroupstate);
@@ -796,6 +825,8 @@ advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
 	int			numGroupingSets = Max(aggstate->phase->numsets, 1);
 	int			numTrans = aggstate->numtrans;
 
+	Assert(!aggstate->combineStates);
+
 	for (transno = 0; transno < numTrans; transno++)
 	{
 		AggStatePerTrans pertrans = &aggstate->pertrans[transno];
@@ -879,6 +910,125 @@ advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
 	}
 }
 
+static void
+combine_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
+{
+	int			transno;
+	int			numTrans = aggstate->numtrans;
+
+	/* combine not supported with grouping sets */
+	Assert(aggstate->phase->numsets == 0);
+	Assert(aggstate->combineStates);
+
+	for (transno = 0; transno < numTrans; transno++)
+	{
+		AggStatePerTrans pertrans = &aggstate->pertrans[transno];
+		TupleTableSlot *slot;
+		FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
+		AggStatePerGroup pergroupstate = &pergroup[transno];
+
+		/* Evaluate the current input expressions for this aggregate */
+		slot = ExecProject(pertrans->evalproj, NULL);
+		Assert(slot->tts_nvalid >= 1);
+
+		fcinfo->arg[1] = slot->tts_values[0];
+		fcinfo->argnull[1] = slot->tts_isnull[0];
+
+		advance_combination_function(aggstate, pertrans, pergroupstate);
+	}
+}
+
+/*
+ * Perform combination of states between 2 aggregate states. Effectively this
+ * 'adds' two states together by whichever logic is defined in the aggregate
+ * function's combine function.
+ *
+ * Note that in this case transfn is set to the combination function. This
+ * perhaps should be changed to avoid confusion, but one field is ok for now
+ * as they'll never be needed at the same time.
+ */
+static void
+advance_combination_function(AggState *aggstate,
+							 AggStatePerTrans pertrans,
+							 AggStatePerGroup pergroupstate)
+{
+	FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
+	MemoryContext oldContext;
+	Datum		newVal;
+
+	if (pertrans->transfn.fn_strict)
+	{
+		/* if we're asked to merge to a NULL state, then do nothing */
+		if (fcinfo->argnull[1])
+			return;
+
+		if (pergroupstate->noTransValue)
+		{
+			/*
+			 * transValue has not been initialized. This is the first non-NULL
+			 * input value. We use it as the initial value for transValue. (We
+			 * already checked that the agg's input type is binary-compatible
+			 * with its transtype, so straight copy here is OK.)
+			 *
+			 * We must copy the datum into aggcontext if it is pass-by-ref. We
+			 * do not need to pfree the old transValue, since it's NULL.
+			 */
+			oldContext = MemoryContextSwitchTo(
+				aggstate->aggcontexts[aggstate->current_set]->ecxt_per_tuple_memory);
+			pergroupstate->transValue = datumCopy(fcinfo->arg[1],
+												  pertrans->transtypeByVal,
+												  pertrans->transtypeLen);
+
+			pergroupstate->transValueIsNull = false;
+			pergroupstate->noTransValue = false;
+			MemoryContextSwitchTo(oldContext);
+			return;
+		}
+	}
+
+	/* We run the combine functions in per-input-tuple memory context */
+	oldContext = MemoryContextSwitchTo(aggstate->tmpcontext->ecxt_per_tuple_memory);
+
+	/* set up aggstate->curpertrans for AggGetAggref() */
+	aggstate->curpertrans = pertrans;
+
+	/*
+	 * OK to call the combine function
+	 */
+	fcinfo->arg[0] = pergroupstate->transValue;
+	fcinfo->argnull[0] = pergroupstate->transValueIsNull;
+	fcinfo->isnull = false;		/* just in case combine func doesn't set it */
+
+	newVal = FunctionCallInvoke(fcinfo);
+
+	aggstate->curpertrans = NULL;
+
+	/*
+	 * If pass-by-ref datatype, must copy the new value into aggcontext and
+	 * pfree the prior transValue.  But if the combine function returned a
+	 * pointer to its first input, we don't need to do anything.
+	 */
+	if (!pertrans->transtypeByVal &&
+		DatumGetPointer(newVal) != DatumGetPointer(pergroupstate->transValue))
+	{
+		if (!fcinfo->isnull)
+		{
+			MemoryContextSwitchTo(aggstate->aggcontexts[aggstate->current_set]->ecxt_per_tuple_memory);
+			newVal = datumCopy(newVal,
+							   pertrans->transtypeByVal,
+							   pertrans->transtypeLen);
+		}
+		if (!pergroupstate->transValueIsNull)
+			pfree(DatumGetPointer(pergroupstate->transValue));
+	}
+
+	pergroupstate->transValue = newVal;
+	pergroupstate->transValueIsNull = fcinfo->isnull;
+
+	MemoryContextSwitchTo(oldContext);
+
+}
+
 
 /*
  * Run the transition function for a DISTINCT or ORDER BY aggregate
@@ -1278,8 +1428,14 @@ finalize_aggregates(AggState *aggstate,
 												pergroupstate);
 		}
 
-		finalize_aggregate(aggstate, peragg, pergroupstate,
-						   &aggvalues[aggno], &aggnulls[aggno]);
+		if (aggstate->finalizeAggs)
+			finalize_aggregate(aggstate, peragg, pergroupstate,
+							   &aggvalues[aggno], &aggnulls[aggno]);
+		else
+		{
+			aggvalues[aggno] = pergroupstate->transValue;
+			aggnulls[aggno] = pergroupstate->transValueIsNull;
+		}
 	}
 }
 
@@ -1811,7 +1967,10 @@ agg_retrieve_direct(AggState *aggstate)
 				 */
 				for (;;)
 				{
-					advance_aggregates(aggstate, pergroup);
+					if (!aggstate->combineStates)
+						advance_aggregates(aggstate, pergroup);
+					else
+						combine_aggregates(aggstate, pergroup);
 
 					/* Reset per-input-tuple context after each tuple */
 					ResetExprContext(tmpcontext);
@@ -1919,7 +2078,10 @@ agg_fill_hash_table(AggState *aggstate)
 		entry = lookup_hash_entry(aggstate, outerslot);
 
 		/* Advance the aggregates */
-		advance_aggregates(aggstate, entry->pergroup);
+		if (!aggstate->combineStates)
+			advance_aggregates(aggstate, entry->pergroup);
+		else
+			combine_aggregates(aggstate, entry->pergroup);
 
 		/* Reset per-input-tuple context after each tuple */
 		ResetExprContext(tmpcontext);
@@ -2051,6 +2213,8 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 	aggstate->pertrans = NULL;
 	aggstate->curpertrans = NULL;
 	aggstate->agg_done = false;
+	aggstate->combineStates = node->combineStates;
+	aggstate->finalizeAggs = node->finalizeAggs;
 	aggstate->input_done = false;
 	aggstate->pergroup = NULL;
 	aggstate->grp_firstTuple = NULL;
@@ -2402,7 +2566,21 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 						   get_func_name(aggref->aggfnoid));
 		InvokeFunctionExecuteHook(aggref->aggfnoid);
 
-		transfn_oid = aggform->aggtransfn;
+		/*
+		 * If this aggregation is performing state combines, then instead of
+		 * using the transition function, we'll use the combine function
+		 */
+		if (aggstate->combineStates)
+		{
+			transfn_oid = aggform->aggcombinefn;
+
+			/* If not set then the planner messed up */
+			if (!OidIsValid(transfn_oid))
+				elog(ERROR, "combinefn not set for aggregate function");
+		}
+		else
+			transfn_oid = aggform->aggtransfn;
+
 		peragg->finalfn_oid = finalfn_oid = aggform->aggfinalfn;
 
 		/* Check that aggregate owner has permission to call component fns */
@@ -2583,44 +2761,69 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 		pertrans->numTransInputs = numArguments;
 
 	/*
-	 * Set up infrastructure for calling the transfn
+	 * When combining states, we have no use at all for the aggregate
+	 * function's transfn. Instead we use the combinefn. However we do
+	 * reuse the transfnexpr for the combinefn, perhaps this should change
 	 */
-	build_aggregate_transfn_expr(inputTypes,
-								 numArguments,
-								 numDirectArgs,
-								 aggref->aggvariadic,
-								 aggtranstype,
-								 aggref->inputcollid,
-								 aggtransfn,
-								 InvalidOid,	/* invtrans is not needed here */
-								 &transfnexpr,
-								 NULL);
-	fmgr_info(aggtransfn, &pertrans->transfn);
-	fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
-
-	InitFunctionCallInfoData(pertrans->transfn_fcinfo,
-							 &pertrans->transfn,
-							 pertrans->numTransInputs + 1,
-							 pertrans->aggCollation,
-							 (void *) aggstate, NULL);
+	if (aggstate->combineStates)
+	{
+		build_aggregate_combinefn_expr(aggref->aggvariadic,
+									   aggtranstype,
+									   aggref->inputcollid,
+									   aggtransfn,
+									   &transfnexpr);
+		fmgr_info(aggtransfn, &pertrans->transfn);
+		fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
+
+		InitFunctionCallInfoData(pertrans->transfn_fcinfo,
+								 &pertrans->transfn,
+								 2,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
 
-	/*
-	 * If the transfn is strict and the initval is NULL, make sure input type
-	 * and transtype are the same (or at least binary-compatible), so that
-	 * it's OK to use the first aggregated input value as the initial
-	 * transValue.  This should have been checked at agg definition time, but
-	 * we must check again in case the transfn's strictness property has been
-	 * changed.
-	 */
-	if (pertrans->transfn.fn_strict && pertrans->initValueIsNull)
+	}
+	else
 	{
-		if (numArguments <= numDirectArgs ||
-			!IsBinaryCoercible(inputTypes[numDirectArgs],
-							   aggtranstype))
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
-					 errmsg("aggregate %u needs to have compatible input type and transition type",
-							aggref->aggfnoid)));
+		/*
+		 * Set up infrastructure for calling the transfn
+		 */
+		build_aggregate_transfn_expr(inputTypes,
+									 numArguments,
+									 numDirectArgs,
+									 aggref->aggvariadic,
+									 aggtranstype,
+									 aggref->inputcollid,
+									 aggtransfn,
+									 InvalidOid,	/* invtrans is not needed here */
+									 &transfnexpr,
+									 NULL);
+		fmgr_info(aggtransfn, &pertrans->transfn);
+		fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
+
+		InitFunctionCallInfoData(pertrans->transfn_fcinfo,
+								 &pertrans->transfn,
+								 pertrans->numTransInputs + 1,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+
+		/*
+		 * If the transfn is strict and the initval is NULL, make sure input type
+		 * and transtype are the same (or at least binary-compatible), so that
+		 * it's OK to use the first aggregated input value as the initial
+		 * transValue.  This should have been checked at agg definition time, but
+		 * we must check again in case the transfn's strictness property has been
+		 * changed.
+		 */
+		if (pertrans->transfn.fn_strict && pertrans->initValueIsNull)
+		{
+			if (numArguments <= numDirectArgs ||
+				!IsBinaryCoercible(inputTypes[numDirectArgs],
+								   aggtranstype))
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						 errmsg("aggregate %u needs to have compatible input type and transition type",
+								aggref->aggfnoid)));
+		}
 	}
 
 	/* get info about the state value's datatype */
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index ba04b72..b2dc451 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -865,6 +865,8 @@ _copyAgg(const Agg *from)
 
 	COPY_SCALAR_FIELD(aggstrategy);
 	COPY_SCALAR_FIELD(numCols);
+	COPY_SCALAR_FIELD(combineStates);
+	COPY_SCALAR_FIELD(finalizeAggs);
 	if (from->numCols > 0)
 	{
 		COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 63fae82..6f6ccdc 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -695,6 +695,9 @@ _outAgg(StringInfo str, const Agg *node)
 	for (i = 0; i < node->numCols; i++)
 		appendStringInfo(str, " %d", node->grpColIdx[i]);
 
+	WRITE_BOOL_FIELD(combineStates);
+	WRITE_BOOL_FIELD(finalizeAggs);
+
 	appendStringInfoString(str, " :grpOperators");
 	for (i = 0; i < node->numCols; i++)
 		appendStringInfo(str, " %u", node->grpOperators[i]);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 222e2ed..ec6790a 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1989,6 +1989,8 @@ _readAgg(void)
 	READ_ENUM_FIELD(aggstrategy, AggStrategy);
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
+	READ_BOOL_FIELD(combineStates);
+	READ_BOOL_FIELD(finalizeAggs);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 	READ_NODE_FIELD(groupingSets);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 32f903d..b34d635 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -1053,6 +1053,8 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path)
 								 groupOperators,
 								 NIL,
 								 numGroups,
+								 false,
+								 true,
 								 subplan);
 	}
 	else
@@ -4554,9 +4556,8 @@ Agg *
 make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
 		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
-		 List *groupingSets,
-		 long numGroups,
-		 Plan *lefttree)
+		 List *groupingSets, long numGroups, bool combineStates,
+		 bool finalizeAggs, Plan *lefttree)
 {
 	Agg		   *node = makeNode(Agg);
 	Plan	   *plan = &node->plan;
@@ -4565,6 +4566,8 @@ make_agg(PlannerInfo *root, List *tlist, List *qual,
 
 	node->aggstrategy = aggstrategy;
 	node->numCols = numGroupCols;
+	node->combineStates = combineStates;
+	node->finalizeAggs = finalizeAggs;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
 	node->numGroups = numGroups;
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 2c04f5c..67d630f 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -1995,6 +1995,8 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 									extract_grouping_ops(parse->groupClause),
 												NIL,
 												numGroups,
+												false,
+												true,
 												result_plan);
 				/* Hashed aggregation produces randomly-ordered results */
 				current_pathkeys = NIL;
@@ -2306,6 +2308,8 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 								 extract_grouping_ops(parse->distinctClause),
 											NIL,
 											numDistinctRows,
+											false,
+											true,
 											result_plan);
 			/* Hashed aggregation produces randomly-ordered results */
 			current_pathkeys = NIL;
@@ -2539,6 +2543,8 @@ build_grouping_chain(PlannerInfo *root,
 									 extract_grouping_ops(groupClause),
 									 gsets,
 									 numGroups,
+									 false,
+									 true,
 									 sort_plan);
 
 		sort_plan->lefttree = NULL;
@@ -2575,6 +2581,8 @@ build_grouping_chain(PlannerInfo *root,
 										extract_grouping_ops(groupClause),
 										gsets,
 										numGroups,
+										false,
+										true,
 										result_plan);
 
 		((Agg *) result_plan)->chain = chain;
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 2e55131..45de122 100644
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -775,6 +775,8 @@ make_union_unique(SetOperationStmt *op, Plan *plan,
 								 extract_grouping_ops(groupList),
 								 NIL,
 								 numGroups,
+								 false,
+								 true,
 								 plan);
 		/* Hashed aggregation produces randomly-ordered results */
 		*sortClauses = NIL;
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 915c8a4..00f5ce3 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -52,7 +52,6 @@
 #include "utils/syscache.h"
 #include "utils/typcache.h"
 
-
 typedef struct
 {
 	PlannerInfo *root;
@@ -93,6 +92,7 @@ typedef struct
 	bool		allow_restricted;
 } has_parallel_hazard_arg;
 
+static bool partial_aggregate_walker(Node *node, void *context);
 static bool contain_agg_clause_walker(Node *node, void *context);
 static bool count_agg_clauses_walker(Node *node,
 						 count_agg_clauses_context *context);
@@ -400,6 +400,64 @@ make_ands_implicit(Expr *clause)
  *****************************************************************************/
 
 /*
+ * aggregates_allow_partial
+ *		Recursively search for Aggref clauses and determine if each of them
+ *		support partial aggregation. Partial aggregation requires that the
+ *		aggregate does not have a DISTINCT or ORDER BY clause, and that it also
+ *		has a combine function set. Returns true if all found Aggrefs support
+ *		partial aggregation and false if any don't.
+ */
+bool
+aggregates_allow_partial(Node *clause)
+{
+	if (!partial_aggregate_walker(clause, NULL))
+		return true;
+	return false;
+}
+
+/*
+ * partial_aggregate_walker
+ *		Walker function for aggregates_allow_partial. Returns false if all
+ *		aggregates support partial aggregation and true if any don't.
+ */
+static bool
+partial_aggregate_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Aggref))
+	{
+		Aggref	   *aggref = (Aggref *) node;
+		HeapTuple	aggTuple;
+		Oid			aggcombinefn;
+		Form_pg_aggregate aggform;
+
+		Assert(aggref->agglevelsup == 0);
+
+		/* can't combine aggs with DISTINCT or ORDER BY */
+		if (aggref->aggdistinct || aggref->aggorder)
+			return true;	/* abort search */
+
+		aggTuple = SearchSysCache1(AGGFNOID,
+								   ObjectIdGetDatum(aggref->aggfnoid));
+		if (!HeapTupleIsValid(aggTuple))
+			elog(ERROR, "cache lookup failed for aggregate %u",
+				 aggref->aggfnoid);
+		aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
+		aggcombinefn = aggform->aggcombinefn;
+		ReleaseSysCache(aggTuple);
+
+		/* Do we have a combine function? */
+		if (!OidIsValid(aggcombinefn))
+			return true;	/* abort search */
+
+		return false; /* continue searching */
+	}
+	return expression_tree_walker(node, partial_aggregate_walker,
+								  (void *) context);
+}
+
+/*
  * contain_agg_clause
  *	  Recursively search for Aggref/GroupingFunc nodes within a clause.
  *
diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c
index 2c45bd6..96a7386 100644
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -1929,6 +1929,43 @@ build_aggregate_transfn_expr(Oid *agg_input_types,
 
 /*
  * Like build_aggregate_transfn_expr, but creates an expression tree for the
+ * combine function of an aggregate, rather than the transition function.
+ */
+void
+build_aggregate_combinefn_expr(bool agg_variadic,
+							   Oid agg_state_type,
+							   Oid agg_input_collation,
+							   Oid combinefn_oid,
+							   Expr **combinefnexpr)
+{
+	Param	   *argp;
+	List	   *args;
+	FuncExpr   *fexpr;
+
+	/* Build arg list to use in the combinefn FuncExpr node. */
+	argp = makeNode(Param);
+	argp->paramkind = PARAM_EXEC;
+	argp->paramid = -1;
+	argp->paramtype = agg_state_type;
+	argp->paramtypmod = -1;
+	argp->paramcollid = agg_input_collation;
+	argp->location = -1;
+
+	/* trans state type is arg 1 and 2 */
+	args = list_make2(argp, argp);
+
+	fexpr = makeFuncExpr(combinefn_oid,
+						 agg_state_type,
+						 args,
+						 InvalidOid,
+						 agg_input_collation,
+						 COERCE_EXPLICIT_CALL);
+	fexpr->funcvariadic = agg_variadic;
+	*combinefnexpr = (Expr *) fexpr;
+}
+
+/*
+ * Like build_aggregate_transfn_expr, but creates an expression tree for the
  * final function of an aggregate, rather than the transition function.
  */
 void
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 36863df..b676ed3 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -12279,6 +12279,7 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	PGresult   *res;
 	int			i_aggtransfn;
 	int			i_aggfinalfn;
+	int			i_aggcombinefn;
 	int			i_aggmtransfn;
 	int			i_aggminvtransfn;
 	int			i_aggmfinalfn;
@@ -12295,6 +12296,7 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	int			i_convertok;
 	const char *aggtransfn;
 	const char *aggfinalfn;
+	const char *aggcombinefn;
 	const char *aggmtransfn;
 	const char *aggminvtransfn;
 	const char *aggmfinalfn;
@@ -12325,7 +12327,26 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	selectSourceSchema(fout, agginfo->aggfn.dobj.namespace->dobj.name);
 
 	/* Get aggregate-specific details */
-	if (fout->remoteVersion >= 90400)
+	if (fout->remoteVersion >= 90600)
+	{
+		appendPQExpBuffer(query, "SELECT aggtransfn, "
+			"aggfinalfn, aggtranstype::pg_catalog.regtype, "
+			"aggcombinefn, aggmtransfn, aggminvtransfn, "
+			"aggmfinalfn, aggmtranstype::pg_catalog.regtype, "
+			"aggfinalextra, aggmfinalextra, "
+			"aggsortop::pg_catalog.regoperator, "
+			"(aggkind = 'h') AS hypothetical, "
+			"aggtransspace, agginitval, "
+			"aggmtransspace, aggminitval, "
+			"true AS convertok, "
+			"pg_catalog.pg_get_function_arguments(p.oid) AS funcargs, "
+			"pg_catalog.pg_get_function_identity_arguments(p.oid) AS funciargs "
+			"FROM pg_catalog.pg_aggregate a, pg_catalog.pg_proc p "
+			"WHERE a.aggfnoid = p.oid "
+			"AND p.oid = '%u'::pg_catalog.oid",
+			agginfo->aggfn.dobj.catId.oid);
+	}
+	else if (fout->remoteVersion >= 90400)
 	{
 		appendPQExpBuffer(query, "SELECT aggtransfn, "
 						  "aggfinalfn, aggtranstype::pg_catalog.regtype, "
@@ -12435,6 +12456,7 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 
 	i_aggtransfn = PQfnumber(res, "aggtransfn");
 	i_aggfinalfn = PQfnumber(res, "aggfinalfn");
+	i_aggcombinefn = PQfnumber(res, "aggcombinefn");
 	i_aggmtransfn = PQfnumber(res, "aggmtransfn");
 	i_aggminvtransfn = PQfnumber(res, "aggminvtransfn");
 	i_aggmfinalfn = PQfnumber(res, "aggmfinalfn");
@@ -12452,6 +12474,7 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 
 	aggtransfn = PQgetvalue(res, 0, i_aggtransfn);
 	aggfinalfn = PQgetvalue(res, 0, i_aggfinalfn);
+	aggcombinefn = PQgetvalue(res, 0, i_aggcombinefn);
 	aggmtransfn = PQgetvalue(res, 0, i_aggmtransfn);
 	aggminvtransfn = PQgetvalue(res, 0, i_aggminvtransfn);
 	aggmfinalfn = PQgetvalue(res, 0, i_aggmfinalfn);
@@ -12540,6 +12563,11 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 			appendPQExpBufferStr(details, ",\n    FINALFUNC_EXTRA");
 	}
 
+	if (strcmp(aggcombinefn, "-") != 0)
+	{
+		appendPQExpBuffer(details, ",\n    COMBINEFUNC = %s",	aggcombinefn);
+	}
+
 	if (strcmp(aggmtransfn, "-") != 0)
 	{
 		appendPQExpBuffer(details, ",\n    MSFUNC = %s,\n    MINVFUNC = %s,\n    MSTYPE = %s",
diff --git a/src/include/catalog/pg_aggregate.h b/src/include/catalog/pg_aggregate.h
index dd6079f..b306f9b 100644
--- a/src/include/catalog/pg_aggregate.h
+++ b/src/include/catalog/pg_aggregate.h
@@ -33,6 +33,7 @@
  *	aggnumdirectargs	number of arguments that are "direct" arguments
  *	aggtransfn			transition function
  *	aggfinalfn			final function (0 if none)
+ *	aggcombinefn		combine function (0 if none)
  *	aggmtransfn			forward function for moving-aggregate mode (0 if none)
  *	aggminvtransfn		inverse function for moving-aggregate mode (0 if none)
  *	aggmfinalfn			final function for moving-aggregate mode (0 if none)
@@ -56,6 +57,7 @@ CATALOG(pg_aggregate,2600) BKI_WITHOUT_OIDS
 	int16		aggnumdirectargs;
 	regproc		aggtransfn;
 	regproc		aggfinalfn;
+	regproc		aggcombinefn;
 	regproc		aggmtransfn;
 	regproc		aggminvtransfn;
 	regproc		aggmfinalfn;
@@ -85,24 +87,25 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  * ----------------
  */
 
-#define Natts_pg_aggregate					17
+#define Natts_pg_aggregate					18
 #define Anum_pg_aggregate_aggfnoid			1
 #define Anum_pg_aggregate_aggkind			2
 #define Anum_pg_aggregate_aggnumdirectargs	3
 #define Anum_pg_aggregate_aggtransfn		4
 #define Anum_pg_aggregate_aggfinalfn		5
-#define Anum_pg_aggregate_aggmtransfn		6
-#define Anum_pg_aggregate_aggminvtransfn	7
-#define Anum_pg_aggregate_aggmfinalfn		8
-#define Anum_pg_aggregate_aggfinalextra		9
-#define Anum_pg_aggregate_aggmfinalextra	10
-#define Anum_pg_aggregate_aggsortop			11
-#define Anum_pg_aggregate_aggtranstype		12
-#define Anum_pg_aggregate_aggtransspace		13
-#define Anum_pg_aggregate_aggmtranstype		14
-#define Anum_pg_aggregate_aggmtransspace	15
-#define Anum_pg_aggregate_agginitval		16
-#define Anum_pg_aggregate_aggminitval		17
+#define Anum_pg_aggregate_aggcombinefn		6
+#define Anum_pg_aggregate_aggmtransfn		7
+#define Anum_pg_aggregate_aggminvtransfn	8
+#define Anum_pg_aggregate_aggmfinalfn		9
+#define Anum_pg_aggregate_aggfinalextra		10
+#define Anum_pg_aggregate_aggmfinalextra	11
+#define Anum_pg_aggregate_aggsortop			12
+#define Anum_pg_aggregate_aggtranstype		13
+#define Anum_pg_aggregate_aggtransspace		14
+#define Anum_pg_aggregate_aggmtranstype		15
+#define Anum_pg_aggregate_aggmtransspace	16
+#define Anum_pg_aggregate_agginitval		17
+#define Anum_pg_aggregate_aggminitval		18
 
 /*
  * Symbolic values for aggkind column.  We distinguish normal aggregates
@@ -126,184 +129,184 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  */
 
 /* avg */
-DATA(insert ( 2100	n 0 int8_avg_accum	numeric_poly_avg		int8_avg_accum	int8_avg_accum_inv	numeric_poly_avg	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg		int4_avg_accum	int4_avg_accum_inv	int8_avg					f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg		int2_avg_accum	int2_avg_accum_inv	int8_avg					f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg	numeric_avg_accum numeric_accum_inv numeric_avg					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2104	n 0 float4_accum	float8_avg		-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2105	n 0 float8_accum	float8_avg		-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2106	n 0 interval_accum	interval_avg	interval_accum	interval_accum_inv interval_avg					f f 0	1187	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
+DATA(insert ( 2100	n 0 int8_avg_accum	numeric_poly_avg	-	int8_avg_accum	int8_avg_accum_inv	numeric_poly_avg	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg			-	int4_avg_accum	int4_avg_accum_inv	int8_avg			f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg			-	int2_avg_accum	int2_avg_accum_inv	int8_avg			f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg		-	numeric_avg_accum numeric_accum_inv numeric_avg			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2104	n 0 float4_accum	float8_avg			-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2105	n 0 float8_accum	float8_avg			-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2106	n 0 interval_accum	interval_avg		-	interval_accum	interval_accum_inv interval_avg			f f 0	1187	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
 
 /* sum */
-DATA(insert ( 2107	n 0 int8_avg_accum	numeric_poly_sum		int8_avg_accum	int8_avg_accum_inv numeric_poly_sum f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2108	n 0 int4_sum		-				int4_avg_accum	int4_avg_accum_inv int2int4_sum					f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2109	n 0 int2_sum		-				int2_avg_accum	int2_avg_accum_inv int2int4_sum					f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2110	n 0 float4pl		-				-				-				-								f f 0	700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2111	n 0 float8pl		-				-				-				-								f f 0	701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2112	n 0 cash_pl			-				cash_pl			cash_mi			-								f f 0	790		0	790		0	_null_ _null_ ));
-DATA(insert ( 2113	n 0 interval_pl		-				interval_pl		interval_mi		-								f f 0	1186	0	1186	0	_null_ _null_ ));
-DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum numeric_avg_accum numeric_accum_inv numeric_sum					f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2107	n 0 int8_avg_accum	numeric_poly_sum	-			int8_avg_accum	int8_avg_accum_inv	numeric_poly_sum	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2108	n 0 int4_sum		-					int8pl		int4_avg_accum	int4_avg_accum_inv	int2int4_sum		f f 0	20		0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2109	n 0 int2_sum		-					int8pl		int2_avg_accum	int2_avg_accum_inv	int2int4_sum		f f 0	20		0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2110	n 0 float4pl		-					float4pl	-				-					-					f f 0	700		0	0		0	_null_ _null_ ));
+DATA(insert ( 2111	n 0 float8pl		-					float8pl	-				-					-					f f 0	701		0	0		0	_null_ _null_ ));
+DATA(insert ( 2112	n 0 cash_pl			-					cash_pl		cash_pl			cash_mi				-					f f 0	790		0	790		0	_null_ _null_ ));
+DATA(insert ( 2113	n 0 interval_pl		-					interval_pl	interval_pl		interval_mi			-					f f 0	1186	0	1186	0	_null_ _null_ ));
+DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum		-		numeric_avg_accum	numeric_accum_inv	numeric_sum			f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* max */
-DATA(insert ( 2115	n 0 int8larger		-				-				-				-				f f 413		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2116	n 0 int4larger		-				-				-				-				f f 521		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2117	n 0 int2larger		-				-				-				-				f f 520		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2118	n 0 oidlarger		-				-				-				-				f f 610		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2119	n 0 float4larger	-				-				-				-				f f 623		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2120	n 0 float8larger	-				-				-				-				f f 674		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2121	n 0 int4larger		-				-				-				-				f f 563		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2122	n 0 date_larger		-				-				-				-				f f 1097	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2123	n 0 time_larger		-				-				-				-				f f 1112	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2124	n 0 timetz_larger	-				-				-				-				f f 1554	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2125	n 0 cashlarger		-				-				-				-				f f 903		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2126	n 0 timestamp_larger	-			-				-				-				f f 2064	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2127	n 0 timestamptz_larger	-			-				-				-				f f 1324	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2128	n 0 interval_larger -				-				-				-				f f 1334	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2129	n 0 text_larger		-				-				-				-				f f 666		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2130	n 0 numeric_larger	-				-				-				-				f f 1756	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2050	n 0 array_larger	-				-				-				-				f f 1073	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2244	n 0 bpchar_larger	-				-				-				-				f f 1060	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2797	n 0 tidlarger		-				-				-				-				f f 2800	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3526	n 0 enum_larger		-				-				-				-				f f 3519	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3564	n 0 network_larger	-				-				-				-				f f 1205	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2115	n 0 int8larger		-				int8larger			-				-				-				f f 413		20		0	0		0	_null_ _null_ ));
+DATA(insert ( 2116	n 0 int4larger		-				int4larger			-				-				-				f f 521		23		0	0		0	_null_ _null_ ));
+DATA(insert ( 2117	n 0 int2larger		-				int2larger			-				-				-				f f 520		21		0	0		0	_null_ _null_ ));
+DATA(insert ( 2118	n 0 oidlarger		-				oidlarger			-				-				-				f f 610		26		0	0		0	_null_ _null_ ));
+DATA(insert ( 2119	n 0 float4larger	-				float4larger		-				-				-				f f 623		700		0	0		0	_null_ _null_ ));
+DATA(insert ( 2120	n 0 float8larger	-				float8larger		-				-				-				f f 674		701		0	0		0	_null_ _null_ ));
+DATA(insert ( 2121	n 0 int4larger		-				int4larger			-				-				-				f f 563		702		0	0		0	_null_ _null_ ));
+DATA(insert ( 2122	n 0 date_larger		-				date_larger			-				-				-				f f 1097	1082	0	0		0	_null_ _null_ ));
+DATA(insert ( 2123	n 0 time_larger		-				time_larger			-				-				-				f f 1112	1083	0	0		0	_null_ _null_ ));
+DATA(insert ( 2124	n 0 timetz_larger	-				timetz_larger		-				-				-				f f 1554	1266	0	0		0	_null_ _null_ ));
+DATA(insert ( 2125	n 0 cashlarger		-				cashlarger			-				-				-				f f 903		790		0	0		0	_null_ _null_ ));
+DATA(insert ( 2126	n 0 timestamp_larger	-			timestamp_larger	-				-				-				f f 2064	1114	0	0		0	_null_ _null_ ));
+DATA(insert ( 2127	n 0 timestamptz_larger	-			timestamptz_larger	-				-				-				f f 1324	1184	0	0		0	_null_ _null_ ));
+DATA(insert ( 2128	n 0 interval_larger -				interval_larger		-				-				-				f f 1334	1186	0	0		0	_null_ _null_ ));
+DATA(insert ( 2129	n 0 text_larger		-				text_larger			-				-				-				f f 666		25		0	0		0	_null_ _null_ ));
+DATA(insert ( 2130	n 0 numeric_larger	-				numeric_larger		-				-				-				f f 1756	1700	0	0		0	_null_ _null_ ));
+DATA(insert ( 2050	n 0 array_larger	-				array_larger		-				-				-				f f 1073	2277	0	0		0	_null_ _null_ ));
+DATA(insert ( 2244	n 0 bpchar_larger	-				bpchar_larger		-				-				-				f f 1060	1042	0	0		0	_null_ _null_ ));
+DATA(insert ( 2797	n 0 tidlarger		-				tidlarger			-				-				-				f f 2800	27		0	0		0	_null_ _null_ ));
+DATA(insert ( 3526	n 0 enum_larger		-				enum_larger			-				-				-				f f 3519	3500	0	0		0	_null_ _null_ ));
+DATA(insert ( 3564	n 0 network_larger	-				network_larger		-				-				-				f f 1205	869		0	0		0	_null_ _null_ ));
 
 /* min */
-DATA(insert ( 2131	n 0 int8smaller		-				-				-				-				f f 412		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2132	n 0 int4smaller		-				-				-				-				f f 97		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2133	n 0 int2smaller		-				-				-				-				f f 95		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2134	n 0 oidsmaller		-				-				-				-				f f 609		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2135	n 0 float4smaller	-				-				-				-				f f 622		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2136	n 0 float8smaller	-				-				-				-				f f 672		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2137	n 0 int4smaller		-				-				-				-				f f 562		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2138	n 0 date_smaller	-				-				-				-				f f 1095	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2139	n 0 time_smaller	-				-				-				-				f f 1110	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2140	n 0 timetz_smaller	-				-				-				-				f f 1552	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2141	n 0 cashsmaller		-				-				-				-				f f 902		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2142	n 0 timestamp_smaller	-			-				-				-				f f 2062	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2143	n 0 timestamptz_smaller -			-				-				-				f f 1322	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2144	n 0 interval_smaller	-			-				-				-				f f 1332	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2145	n 0 text_smaller	-				-				-				-				f f 664		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2146	n 0 numeric_smaller -				-				-				-				f f 1754	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2051	n 0 array_smaller	-				-				-				-				f f 1072	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2245	n 0 bpchar_smaller	-				-				-				-				f f 1058	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2798	n 0 tidsmaller		-				-				-				-				f f 2799	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3527	n 0 enum_smaller	-				-				-				-				f f 3518	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3565	n 0 network_smaller -				-				-				-				f f 1203	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2131	n 0 int8smaller		-				int8smaller			-				-				-				f f 412		20		0	0		0	_null_ _null_ ));
+DATA(insert ( 2132	n 0 int4smaller		-				int4smaller			-				-				-				f f 97		23		0	0		0	_null_ _null_ ));
+DATA(insert ( 2133	n 0 int2smaller		-				int2smaller			-				-				-				f f 95		21		0	0		0	_null_ _null_ ));
+DATA(insert ( 2134	n 0 oidsmaller		-				oidsmaller			-				-				-				f f 609		26		0	0		0	_null_ _null_ ));
+DATA(insert ( 2135	n 0 float4smaller	-				float4smaller		-				-				-				f f 622		700		0	0		0	_null_ _null_ ));
+DATA(insert ( 2136	n 0 float8smaller	-				float8smaller		-				-				-				f f 672		701		0	0		0	_null_ _null_ ));
+DATA(insert ( 2137	n 0 int4smaller		-				int4smaller			-				-				-				f f 562		702		0	0		0	_null_ _null_ ));
+DATA(insert ( 2138	n 0 date_smaller	-				date_smaller		-				-				-				f f 1095	1082	0	0		0	_null_ _null_ ));
+DATA(insert ( 2139	n 0 time_smaller	-				time_smaller		-				-				-				f f 1110	1083	0	0		0	_null_ _null_ ));
+DATA(insert ( 2140	n 0 timetz_smaller	-				timetz_smaller		-				-				-				f f 1552	1266	0	0		0	_null_ _null_ ));
+DATA(insert ( 2141	n 0 cashsmaller		-				cashsmaller			-				-				-				f f 902		790		0	0		0	_null_ _null_ ));
+DATA(insert ( 2142	n 0 timestamp_smaller	-			timestamp_smaller	-				-				-				f f 2062	1114	0	0		0	_null_ _null_ ));
+DATA(insert ( 2143	n 0 timestamptz_smaller -			timestamptz_smaller	-				-				-				f f 1322	1184	0	0		0	_null_ _null_ ));
+DATA(insert ( 2144	n 0 interval_smaller	-			interval_smaller	-				-				-				f f 1332	1186	0	0		0	_null_ _null_ ));
+DATA(insert ( 2145	n 0 text_smaller	-				text_smaller		-				-				-				f f 664		25		0	0		0	_null_ _null_ ));
+DATA(insert ( 2146	n 0 numeric_smaller -				numeric_smaller		-				-				-				f f 1754	1700	0	0		0	_null_ _null_ ));
+DATA(insert ( 2051	n 0 array_smaller	-				array_smaller		-				-				-				f f 1072	2277	0	0		0	_null_ _null_ ));
+DATA(insert ( 2245	n 0 bpchar_smaller	-				bpchar_smaller		-				-				-				f f 1058	1042	0	0		0	_null_ _null_ ));
+DATA(insert ( 2798	n 0 tidsmaller		-				tidsmaller			-				-				-				f f 2799	27		0	0		0	_null_ _null_ ));
+DATA(insert ( 3527	n 0 enum_smaller	-				enum_smaller		-				-				-				f f 3518	3500	0	0		0	_null_ _null_ ));
+DATA(insert ( 3565	n 0 network_smaller -				network_smaller		-				-				-				f f 1203	869		0	0		0	_null_ _null_ ));
 
 /* count */
-DATA(insert ( 2147	n 0 int8inc_any		-				int8inc_any		int8dec_any		-				f f 0		20		0	20		0	"0" "0" ));
-DATA(insert ( 2803	n 0 int8inc			-				int8inc			int8dec			-				f f 0		20		0	20		0	"0" "0" ));
+DATA(insert ( 2147	n 0 int8inc_any		-				int8pl	int8inc_any		int8dec_any		-				f f 0		20		0	20		0	"0" "0" ));
+DATA(insert ( 2803	n 0 int8inc			-				int8pl	int8inc			int8dec			-				f f 0		20		0	20		0	"0" "0" ));
 
 /* var_pop */
-DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop		int8_accum		int8_accum_inv	numeric_var_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2719	n 0 int4_accum	numeric_poly_var_pop		int4_accum		int4_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2720	n 0 int2_accum	numeric_poly_var_pop		int2_accum		int2_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2721	n 0 float4_accum	float8_var_pop	-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2722	n 0 float8_accum	float8_var_pop	-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop numeric_accum numeric_accum_inv numeric_var_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop			-	int8_accum		int8_accum_inv	numeric_var_pop			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2719	n 0 int4_accum	numeric_poly_var_pop	-	int4_accum		int4_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2720	n 0 int2_accum	numeric_poly_var_pop	-	int2_accum		int2_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2721	n 0 float4_accum	float8_var_pop		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2722	n 0 float8_accum	float8_var_pop		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop		-	numeric_accum numeric_accum_inv numeric_var_pop			f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* var_samp */
-DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp	int8_accum		int8_accum_inv	numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2642	n 0 int4_accum	numeric_poly_var_samp		int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2643	n 0 int2_accum	numeric_poly_var_samp		int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2644	n 0 float4_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2645	n 0 float8_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp numeric_accum numeric_accum_inv numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp		-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2642	n 0 int4_accum	numeric_poly_var_samp	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2643	n 0 int2_accum	numeric_poly_var_samp	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2644	n 0 float4_accum	float8_var_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2645	n 0 float8_accum	float8_var_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp	-	numeric_accum	numeric_accum_inv numeric_var_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* variance: historical Postgres syntax for var_samp */
-DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp	int8_accum		int8_accum_inv	numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2149	n 0 int4_accum	numeric_poly_var_samp		int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2150	n 0 int2_accum	numeric_poly_var_samp		int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2151	n 0 float4_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2152	n 0 float8_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp numeric_accum numeric_accum_inv numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp		-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2149	n 0 int4_accum	numeric_poly_var_samp	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2150	n 0 int2_accum	numeric_poly_var_samp	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2151	n 0 float4_accum	float8_var_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2152	n 0 float8_accum	float8_var_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp	-	numeric_accum numeric_accum_inv numeric_var_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* stddev_pop */
-DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop	int8_accum	int8_accum_inv	numeric_stddev_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2725	n 0 int4_accum	numeric_poly_stddev_pop int4_accum	int4_accum_inv	numeric_poly_stddev_pop f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2726	n 0 int2_accum	numeric_poly_stddev_pop int2_accum	int2_accum_inv	numeric_poly_stddev_pop f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop numeric_accum numeric_accum_inv numeric_stddev_pop			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop		-	int8_accum	int8_accum_inv	numeric_stddev_pop		f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2725	n 0 int4_accum	numeric_poly_stddev_pop	-	int4_accum	int4_accum_inv	numeric_poly_stddev_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2726	n 0 int2_accum	numeric_poly_stddev_pop	-	int2_accum	int2_accum_inv	numeric_poly_stddev_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-	-				-				-					f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-	-				-				-					f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop	-	numeric_accum numeric_accum_inv numeric_stddev_pop	f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* stddev_samp */
-DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp		int8_accum	int8_accum_inv	numeric_stddev_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2713	n 0 int4_accum	numeric_poly_stddev_samp	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2714	n 0 int2_accum	numeric_poly_stddev_samp	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp numeric_accum numeric_accum_inv numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp			-	int8_accum	int8_accum_inv	numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2713	n 0 int4_accum	numeric_poly_stddev_samp	-	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2714	n 0 int2_accum	numeric_poly_stddev_samp	-	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp		-	numeric_accum numeric_accum_inv numeric_stddev_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* stddev: historical Postgres syntax for stddev_samp */
-DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp		int8_accum	int8_accum_inv	numeric_stddev_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2155	n 0 int4_accum	numeric_poly_stddev_samp	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2156	n 0 int2_accum	numeric_poly_stddev_samp	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp numeric_accum numeric_accum_inv numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp			-	int8_accum		int8_accum_inv	numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2155	n 0 int4_accum	numeric_poly_stddev_samp	-	int4_accum		int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2156	n 0 int2_accum	numeric_poly_stddev_samp	-	int2_accum		int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp		-	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp		-	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp		-	numeric_accum	numeric_accum_inv numeric_stddev_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* SQL2003 binary regression aggregates */
-DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-				-				-				f f 0	20		0	0		0	"0" _null_ ));
-DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-	-				-				-			f f 0	20		0	0		0	"0" _null_ ));
+DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
 
 /* boolean-and and boolean-or */
-DATA(insert ( 2517	n 0 booland_statefunc	-			bool_accum		bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2518	n 0 boolor_statefunc	-			bool_accum		bool_accum_inv	bool_anytrue	f f 59	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2519	n 0 booland_statefunc	-			bool_accum		bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2517	n 0 booland_statefunc	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2518	n 0 boolor_statefunc	-	-	bool_accum	bool_accum_inv	bool_anytrue	f f 59	16		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2519	n 0 booland_statefunc	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
 
 /* bitwise integer */
-DATA(insert ( 2236	n 0 int2and		-					-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2237	n 0 int2or		-					-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2238	n 0 int4and		-					-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2239	n 0 int4or		-					-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2240	n 0 int8and		-					-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2241	n 0 int8or		-					-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2242	n 0 bitand		-					-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
-DATA(insert ( 2243	n 0 bitor		-					-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
+DATA(insert ( 2236	n 0 int2and		-				int2and	-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
+DATA(insert ( 2237	n 0 int2or		-				int2or	-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
+DATA(insert ( 2238	n 0 int4and		-				int4and	-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
+DATA(insert ( 2239	n 0 int4or		-				int4or	-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
+DATA(insert ( 2240	n 0 int8and		-				int8and	-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
+DATA(insert ( 2241	n 0 int8or		-				int8or	-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
+DATA(insert ( 2242	n 0 bitand		-				bitand	-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
+DATA(insert ( 2243	n 0 bitor		-				bitor	-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
 
 /* xml */
-DATA(insert ( 2901	n 0 xmlconcat2	-					-				-				-				f f 0	142		0	0		0	_null_ _null_ ));
+DATA(insert ( 2901	n 0 xmlconcat2	-				-		-				-				-				f f 0	142		0	0		0	_null_ _null_ ));
 
 /* array */
-DATA(insert ( 2335	n 0 array_agg_transfn	array_agg_finalfn	-				-				-				t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn -		-				-				t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 2335	n 0 array_agg_transfn		array_agg_finalfn		-	-		-				-				t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn	-	-		-				-				t f 0	2281	0	0		0	_null_ _null_ ));
 
 /* text */
-DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
 
 /* bytea */
-DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-				-				-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-	-				-				-		f f 0	2281	0	0		0	_null_ _null_ ));
 
 /* json */
-DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
 
 /* jsonb */
-DATA(insert ( 3267	n 0 jsonb_agg_transfn	jsonb_agg_finalfn			-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3270	n 0 jsonb_object_agg_transfn jsonb_object_agg_finalfn -				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3267	n 0 jsonb_agg_transfn	jsonb_agg_finalfn				-	-				-				-			f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3270	n 0 jsonb_object_agg_transfn jsonb_object_agg_finalfn	-	-				-				-			f f 0	2281	0	0		0	_null_ _null_ ));
 
 /* ordered-set and hypothetical-set aggregates */
-DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
 
 
 /*
@@ -322,6 +325,7 @@ extern ObjectAddress AggregateCreate(const char *aggName,
 				Oid variadicArgType,
 				List *aggtransfnName,
 				List *aggfinalfnName,
+				List *aggcombinefnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 5ccf470..4243c0b 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1851,6 +1851,8 @@ typedef struct AggState
 	AggStatePerTrans curpertrans;	/* currently active trans state */
 	bool		input_done;		/* indicates end of input */
 	bool		agg_done;		/* indicates completion of Agg scan */
+	bool		combineStates;	/* input tuples contain transition states */
+	bool		finalizeAggs;	/* should we call the finalfn on agg states? */
 	int			projected_set;	/* The last projected grouping set */
 	int			current_set;	/* The current grouping set being evaluated */
 	Bitmapset  *grouped_cols;	/* grouped cols in current projection */
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 37086c6..9ae2a1b 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -726,6 +726,8 @@ typedef struct Agg
 	AggStrategy aggstrategy;
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
+	bool		combineStates;	/* input tuples contain transition states */
+	bool		finalizeAggs;	/* should we call the finalfn on agg states? */
 	Oid		   *grpOperators;	/* equality operators to compare with */
 	long		numGroups;		/* estimated number of groups in input */
 	List	   *groupingSets;	/* grouping sets to use */
diff --git a/src/include/optimizer/clauses.h b/src/include/optimizer/clauses.h
index 323f093..c7594d3 100644
--- a/src/include/optimizer/clauses.h
+++ b/src/include/optimizer/clauses.h
@@ -47,6 +47,7 @@ extern Node *make_and_qual(Node *qual1, Node *qual2);
 extern Expr *make_ands_explicit(List *andclauses);
 extern List *make_ands_implicit(Expr *clause);
 
+extern bool aggregates_allow_partial(Node *clause);
 extern bool contain_agg_clause(Node *clause);
 extern void count_agg_clauses(PlannerInfo *root, Node *clause,
 				  AggClauseCosts *costs);
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index f96e9ee..2989eac 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -60,9 +60,8 @@ extern Sort *make_sort_from_groupcols(PlannerInfo *root, List *groupcls,
 extern Agg *make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
 		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
-		 List *groupingSets,
-		 long numGroups,
-		 Plan *lefttree);
+		 List *groupingSets, long numGroups, bool combineStates,
+		 bool finalizeAggs, Plan *lefttree);
 extern WindowAgg *make_windowagg(PlannerInfo *root, List *tlist,
 			   List *windowFuncs, Index winref,
 			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
diff --git a/src/include/parser/parse_agg.h b/src/include/parser/parse_agg.h
index e2b3894..621b6b9 100644
--- a/src/include/parser/parse_agg.h
+++ b/src/include/parser/parse_agg.h
@@ -46,6 +46,12 @@ extern void build_aggregate_transfn_expr(Oid *agg_input_types,
 						Expr **transfnexpr,
 						Expr **invtransfnexpr);
 
+extern void build_aggregate_combinefn_expr(bool agg_variadic,
+										   Oid agg_state_type,
+										   Oid agg_input_collation,
+										   Oid combinefn_oid,
+										   Expr **combinefnexpr);
+
 extern void build_aggregate_finalfn_expr(Oid *agg_input_types,
 						int num_finalfn_inputs,
 						Oid agg_state_type,
diff --git a/src/test/regress/expected/create_aggregate.out b/src/test/regress/expected/create_aggregate.out
index 82a34fb..7f48b39 100644
--- a/src/test/regress/expected/create_aggregate.out
+++ b/src/test/regress/expected/create_aggregate.out
@@ -101,6 +101,23 @@ CREATE AGGREGATE sumdouble (float8)
     msfunc = float8pl,
     minvfunc = float8mi
 );
+-- aggregate combine functions
+CREATE AGGREGATE mymax (int)
+(
+	stype = int4,
+	sfunc = int4larger,
+	combinefunc = int4larger
+);
+-- Ensure all these functions made it into the catalog
+SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype
+FROM pg_aggregate
+WHERE aggfnoid = 'mymax'::REGPROC;
+ aggfnoid | aggtransfn | aggcombinefn | aggtranstype 
+----------+------------+--------------+--------------
+ mymax    | int4larger | int4larger   |           23
+(1 row)
+
+DROP AGGREGATE mymax (int);
 -- invalid: nonstrict inverse with strict forward function
 CREATE FUNCTION float8mi_n(float8, float8) RETURNS float8 AS
 $$ SELECT $1 - $2; $$
diff --git a/src/test/regress/sql/create_aggregate.sql b/src/test/regress/sql/create_aggregate.sql
index 0ec1572..cc80c75 100644
--- a/src/test/regress/sql/create_aggregate.sql
+++ b/src/test/regress/sql/create_aggregate.sql
@@ -115,6 +115,21 @@ CREATE AGGREGATE sumdouble (float8)
     minvfunc = float8mi
 );
 
+-- aggregate combine functions
+CREATE AGGREGATE mymax (int)
+(
+	stype = int4,
+	sfunc = int4larger,
+	combinefunc = int4larger
+);
+
+-- Ensure all these functions made it into the catalog
+SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype
+FROM pg_aggregate
+WHERE aggfnoid = 'mymax'::REGPROC;
+
+DROP AGGREGATE mymax (int);
+
 -- invalid: nonstrict inverse with strict forward function
 
 CREATE FUNCTION float8mi_n(float8, float8) RETURNS float8 AS

diff --git a/doc/src/sgml/ref/create_aggregate.sgml b/doc/src/sgml/ref/create_aggregate.sgml
index eaa410b..bb62c96 100644
--- a/doc/src/sgml/ref/create_aggregate.sgml
+++ b/doc/src/sgml/ref/create_aggregate.sgml
@@ -27,6 +27,10 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ <replacea
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
+    [ , SERIALFUNC = <replaceable class="PARAMETER">serialfunc</replaceable> ]
+    [ , DESERIALFUNC = <replaceable class="PARAMETER">deserialfunc</replaceable> ]
+    [ , SERIALTYPE = <replaceable class="PARAMETER">serialtype</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -45,6 +49,10 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ [ <replac
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
+    [ , SERIALFUNC = <replaceable class="PARAMETER">serialfunc</replaceable> ]
+    [ , DESERIALFUNC = <replaceable class="PARAMETER">deserialfunc</replaceable> ]
+    [ , SERIALTYPE = <replaceable class="PARAMETER">serialtype</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , HYPOTHETICAL ]
 )
@@ -58,6 +66,10 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
+    [ , SERIALFUNC = <replaceable class="PARAMETER">serialfunc</replaceable> ]
+    [ , DESERIALFUNC = <replaceable class="PARAMETER">deserialfunc</replaceable> ]
+    [ , SERIALTYPE = <replaceable class="PARAMETER">serialtype</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -105,12 +117,23 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
    functions:
    a state transition function
    <replaceable class="PARAMETER">sfunc</replaceable>,
-   and an optional final calculation function
-   <replaceable class="PARAMETER">ffunc</replaceable>.
+   an optional final calculation function
+   <replaceable class="PARAMETER">ffunc</replaceable>,
+   an optional combine function
+   <replaceable class="PARAMETER">combinefunc</replaceable>,
+   an optional serialization function
+   <replaceable class="PARAMETER">serialfunc</replaceable>,
+   an optional deserialization function
+   <replaceable class="PARAMETER">deserialfunc</replaceable>,
+   and an optional serialization type
+   <replaceable class="PARAMETER">serialtype</replaceable>.
    These are used as follows:
 <programlisting>
 <replaceable class="PARAMETER">sfunc</replaceable>( internal-state, next-data-values ) ---> next-internal-state
 <replaceable class="PARAMETER">ffunc</replaceable>( internal-state ) ---> aggregate-value
+<replaceable class="PARAMETER">combinefunc</replaceable>( internal-state, internal-state ) ---> next-internal-state
+<replaceable class="PARAMETER">serialfunc</replaceable>( internal-state ) ---> serialized-state
+<replaceable class="PARAMETER">deserialfunc</replaceable>( serialized-state ) ---> internal-state
 </programlisting>
   </para>
 
@@ -128,6 +151,27 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
   </para>
 
   <para>
+   An aggregate function may also supply a combining function, which allows
+   the aggregation process to be broken down into multiple steps.  This
+   facilitates query optimization techniques such as parallel query.
+  </para>
+
+  <para>
+  A serialization and deserialization function may also be supplied. These
+  functions are required in order to allow parallel aggregation for aggregates
+  with an <replaceable class="PARAMETER">stype</replaceable> of <literal>
+  INTERNAL</>. The <replaceable class="PARAMETER">serialfunc</replaceable>, if
+  present must transform the aggregate state into a value of
+  <replaceable class="PARAMETER">serialtype</replaceable>, whereas the 
+  <replaceable class="PARAMETER">deserialfunc</replaceable> performs the
+  opposite, transforming the aggregate state back into the
+  <replaceable class="PARAMETER">stype</replaceable>. This is required due to
+  the process model being unable to pass <literal>INTERNAL</literal> types
+  between different <productname>PostgreSQL</productname> processes. These
+  parameters are only valid when <replaceable class="PARAMETER">stype
+  </replaceable> is <literal>INTERNAL</>.
+
+  <para>
    An aggregate function can provide an initial condition,
    that is, an initial value for the internal state value.
    This is specified and stored in the database as a value of type
diff --git a/src/backend/catalog/pg_aggregate.c b/src/backend/catalog/pg_aggregate.c
index 121c27f..d781959 100644
--- a/src/backend/catalog/pg_aggregate.c
+++ b/src/backend/catalog/pg_aggregate.c
@@ -57,6 +57,9 @@ AggregateCreate(const char *aggName,
 				Oid variadicArgType,
 				List *aggtransfnName,
 				List *aggfinalfnName,
+				List *aggcombinefnName,
+				List *aggserialfnName,
+				List *aggdeserialfnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
@@ -64,6 +67,7 @@ AggregateCreate(const char *aggName,
 				bool mfinalfnExtraArgs,
 				List *aggsortopName,
 				Oid aggTransType,
+				Oid aggSerialType,
 				int32 aggTransSpace,
 				Oid aggmTransType,
 				int32 aggmTransSpace,
@@ -77,6 +81,9 @@ AggregateCreate(const char *aggName,
 	Form_pg_proc proc;
 	Oid			transfn;
 	Oid			finalfn = InvalidOid;	/* can be omitted */
+	Oid			combinefn = InvalidOid;	/* can be omitted */
+	Oid			serialfn = InvalidOid;	/* can be omitted */
+	Oid			deserialfn = InvalidOid;	/* can be omitted */
 	Oid			mtransfn = InvalidOid;	/* can be omitted */
 	Oid			minvtransfn = InvalidOid;		/* can be omitted */
 	Oid			mfinalfn = InvalidOid;	/* can be omitted */
@@ -396,6 +403,83 @@ AggregateCreate(const char *aggName,
 	}
 	Assert(OidIsValid(finaltype));
 
+	/* handle the combinefn, if supplied */
+	if (aggcombinefnName)
+	{
+		Oid combineType;
+
+		/*
+		 * Combine function must have 2 argument, each of which is the
+		 * trans type
+		 */
+		fnArgs[0] = aggTransType;
+		fnArgs[1] = aggTransType;
+
+		combinefn = lookup_agg_function(aggcombinefnName, 2, fnArgs,
+										variadicArgType, &combineType);
+
+		/* Ensure the return type matches the aggregates trans type */
+		if (combineType != aggTransType)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+			errmsg("return type of combine function %s is not %s",
+				   NameListToString(aggcombinefnName),
+				   format_type_be(aggTransType))));
+	}
+
+	/*
+	 * Validate the serial function, if present. We must ensure that the return
+	 * type of this function is the same as the specified serialType, and that
+	 * indeed a serialType was actually also specified.
+	 */
+	if (aggserialfnName)
+	{
+		/* check that we also got a serial type */
+		if (!OidIsValid(aggSerialType))
+			ereport(ERROR,
+				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+				 errmsg("must specify serialtype when specifying serialfunc")));
+
+		fnArgs[0] = aggTransType;
+
+		serialfn = lookup_agg_function(aggserialfnName, 1,
+									   fnArgs, variadicArgType,
+									   &rettype);
+
+		if (rettype != aggSerialType)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("return type of serial function %s is not %s",
+							NameListToString(aggserialfnName),
+							format_type_be(aggSerialType))));
+	}
+
+	/*
+	 * Validate the deserial function, if present. We must ensure that the
+	 * return type of this function is the same as the transType.
+	 */
+	if (aggdeserialfnName)
+	{
+		/* check that we also got a serial type */
+		if (!OidIsValid(aggSerialType))
+			ereport(ERROR,
+				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+				 errmsg("must specify serialtype when specifying deserialfunc")));
+
+		fnArgs[0] = aggSerialType;
+
+		deserialfn = lookup_agg_function(aggdeserialfnName, 1,
+										 fnArgs, variadicArgType,
+										 &rettype);
+
+		if (rettype != aggTransType)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("return type of deserial function %s is not %s",
+							NameListToString(aggdeserialfnName),
+							format_type_be(aggTransType))));
+	}
+
 	/*
 	 * If finaltype (i.e. aggregate return type) is polymorphic, inputs must
 	 * be polymorphic also, else parser will fail to deduce result type.
@@ -567,6 +651,9 @@ AggregateCreate(const char *aggName,
 	values[Anum_pg_aggregate_aggnumdirectargs - 1] = Int16GetDatum(numDirectArgs);
 	values[Anum_pg_aggregate_aggtransfn - 1] = ObjectIdGetDatum(transfn);
 	values[Anum_pg_aggregate_aggfinalfn - 1] = ObjectIdGetDatum(finalfn);
+	values[Anum_pg_aggregate_aggcombinefn - 1] = ObjectIdGetDatum(combinefn);
+	values[Anum_pg_aggregate_aggserialfn - 1] = ObjectIdGetDatum(serialfn);
+	values[Anum_pg_aggregate_aggdeserialfn - 1] = ObjectIdGetDatum(deserialfn);
 	values[Anum_pg_aggregate_aggmtransfn - 1] = ObjectIdGetDatum(mtransfn);
 	values[Anum_pg_aggregate_aggminvtransfn - 1] = ObjectIdGetDatum(minvtransfn);
 	values[Anum_pg_aggregate_aggmfinalfn - 1] = ObjectIdGetDatum(mfinalfn);
@@ -574,6 +661,7 @@ AggregateCreate(const char *aggName,
 	values[Anum_pg_aggregate_aggmfinalextra - 1] = BoolGetDatum(mfinalfnExtraArgs);
 	values[Anum_pg_aggregate_aggsortop - 1] = ObjectIdGetDatum(sortop);
 	values[Anum_pg_aggregate_aggtranstype - 1] = ObjectIdGetDatum(aggTransType);
+	values[Anum_pg_aggregate_aggserialtype - 1] = ObjectIdGetDatum(aggSerialType);
 	values[Anum_pg_aggregate_aggtransspace - 1] = Int32GetDatum(aggTransSpace);
 	values[Anum_pg_aggregate_aggmtranstype - 1] = ObjectIdGetDatum(aggmTransType);
 	values[Anum_pg_aggregate_aggmtransspace - 1] = Int32GetDatum(aggmTransSpace);
@@ -600,7 +688,8 @@ AggregateCreate(const char *aggName,
 	 * Create dependencies for the aggregate (above and beyond those already
 	 * made by ProcedureCreate).  Note: we don't need an explicit dependency
 	 * on aggTransType since we depend on it indirectly through transfn.
-	 * Likewise for aggmTransType if any.
+	 * Likewise for aggmTransType using the mtransfunc, and also for
+	 * aggSerialType using the serialfn, if they exist.
 	 */
 
 	/* Depends on transition function */
@@ -618,6 +707,33 @@ AggregateCreate(const char *aggName,
 		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
 	}
 
+	/* Depends on combine function, if any */
+	if (OidIsValid(combinefn))
+	{
+		referenced.classId = ProcedureRelationId;
+		referenced.objectId = combinefn;
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
+	/* Depends on serial function, if any */
+	if (OidIsValid(serialfn))
+	{
+		referenced.classId = ProcedureRelationId;
+		referenced.objectId = serialfn;
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
+	/* Depends on deserial function, if any */
+	if (OidIsValid(deserialfn))
+	{
+		referenced.classId = ProcedureRelationId;
+		referenced.objectId = deserialfn;
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
 	/* Depends on forward transition function, if any */
 	if (OidIsValid(mtransfn))
 	{
diff --git a/src/backend/commands/aggregatecmds.c b/src/backend/commands/aggregatecmds.c
index 894c89d..415cb19 100644
--- a/src/backend/commands/aggregatecmds.c
+++ b/src/backend/commands/aggregatecmds.c
@@ -61,6 +61,9 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	char		aggKind = AGGKIND_NORMAL;
 	List	   *transfuncName = NIL;
 	List	   *finalfuncName = NIL;
+	List	   *combinefuncName = NIL;
+	List	   *serialfuncName = NIL;
+	List	   *deserialfuncName = NIL;
 	List	   *mtransfuncName = NIL;
 	List	   *minvtransfuncName = NIL;
 	List	   *mfinalfuncName = NIL;
@@ -69,6 +72,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	List	   *sortoperatorName = NIL;
 	TypeName   *baseType = NULL;
 	TypeName   *transType = NULL;
+	TypeName   *serialType = NULL;
 	TypeName   *mtransType = NULL;
 	int32		transSpace = 0;
 	int32		mtransSpace = 0;
@@ -83,8 +87,10 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	List	   *parameterDefaults;
 	Oid			variadicArgType;
 	Oid			transTypeId;
+	Oid			serialTypeId = InvalidOid;
 	Oid			mtransTypeId = InvalidOid;
 	char		transTypeType;
+	char		serialTypeType = 0;
 	char		mtransTypeType = 0;
 	ListCell   *pl;
 
@@ -124,6 +130,12 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 			transfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "finalfunc") == 0)
 			finalfuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "combinefunc") == 0)
+			combinefuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "serialfunc") == 0)
+			serialfuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "deserialfunc") == 0)
+			deserialfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "msfunc") == 0)
 			mtransfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "minvfunc") == 0)
@@ -151,6 +163,8 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 		}
 		else if (pg_strcasecmp(defel->defname, "stype") == 0)
 			transType = defGetTypeName(defel);
+		else if (pg_strcasecmp(defel->defname, "serialtype") == 0)
+			serialType = defGetTypeName(defel);
 		else if (pg_strcasecmp(defel->defname, "stype1") == 0)
 			transType = defGetTypeName(defel);
 		else if (pg_strcasecmp(defel->defname, "sspace") == 0)
@@ -316,6 +330,51 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 							format_type_be(transTypeId))));
 	}
 
+	if (serialType)
+	{
+		/*
+		 * There's little point in having a serial/deserial function on
+		 * aggregates that don't have an internal state, so let's just disallow
+		 * this as it may help clear up any confusion or needless authoring of
+		 * these functions.
+		 */
+		if (transTypeId != INTERNALOID)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("a serialtype must only be specified when stype is \"%s\"",
+						 format_type_be(INTERNALOID))));
+
+		serialTypeId = typenameTypeId(NULL, serialType);
+		serialTypeType = get_typtype(serialTypeId);
+
+		/*
+		 * We disallow INTERNAL serialType as the whole point of the
+		 * serialzed types is to allow the aggregate state to be output,
+		 * and we cannot output INTERNAL. This check, combined with the one
+		 * above ensures that the trans type and serial type are not the same.
+		 */
+		if (serialTypeId == INTERNALOID)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						errmsg("aggregate serial data type cannot be \"%s\"",
+							format_type_be(serialTypeId))));
+
+		/*
+		 * If serialType is specified then serialfuncName and deserialfuncName
+		 * must be present; if not, then none of the serialization options
+		 * should have been specified.
+		 */
+		if (serialfuncName == NIL)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("aggregate serialfunc must be specified when serialtype is specified")));
+
+		if (deserialfuncName == NIL)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("aggregate deserialfunc must be specified when serialtype is specified")));
+	}
+
 	/*
 	 * If a moving-aggregate transtype is specified, look that up.  Same
 	 * restrictions as for transtype.
@@ -383,6 +442,9 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 						   variadicArgType,
 						   transfuncName,		/* step function name */
 						   finalfuncName,		/* final function name */
+						   combinefuncName,		/* combine function name */
+						   serialfuncName,		/* serial function name */
+						   deserialfuncName,	/* deserial function name */
 						   mtransfuncName,		/* fwd trans function name */
 						   minvtransfuncName,	/* inv trans function name */
 						   mfinalfuncName,		/* final function name */
@@ -390,6 +452,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 						   mfinalfuncExtraArgs,
 						   sortoperatorName,	/* sort operator name */
 						   transTypeId, /* transition data type */
+						   serialTypeId, /* serial data type */
 						   transSpace,	/* transition space */
 						   mtransTypeId,		/* transition data type */
 						   mtransSpace, /* transition space */
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 12dae77..4a92bfc 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -908,25 +908,38 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			pname = sname = "Group";
 			break;
 		case T_Agg:
-			sname = "Aggregate";
-			switch (((Agg *) plan)->aggstrategy)
 			{
-				case AGG_PLAIN:
-					pname = "Aggregate";
-					strategy = "Plain";
-					break;
-				case AGG_SORTED:
-					pname = "GroupAggregate";
-					strategy = "Sorted";
-					break;
-				case AGG_HASHED:
-					pname = "HashAggregate";
-					strategy = "Hashed";
-					break;
-				default:
-					pname = "Aggregate ???";
-					strategy = "???";
-					break;
+				char	   *modifier;
+				Agg		   *agg = (Agg *) plan;
+
+				sname = "Aggregate";
+
+				if (agg->finalizeAggs == false)
+					modifier = "Partial ";
+				else if (agg->combineStates == true)
+					modifier = "Finalize ";
+				else
+					modifier = "";
+
+				switch (agg->aggstrategy)
+				{
+					case AGG_PLAIN:
+						pname = psprintf("%sAggregate", modifier);
+						strategy = "Plain";
+						break;
+					case AGG_SORTED:
+						pname = psprintf("%sGroupAggregate", modifier);
+						strategy = "Sorted";
+						break;
+					case AGG_HASHED:
+						pname = psprintf("%sHashAggregate", modifier);
+						strategy = "Hashed";
+						break;
+					default:
+						pname = "Aggregate ???";
+						strategy = "???";
+						break;
+				}
 			}
 			break;
 		case T_WindowAgg:
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index 2e36855..8589ee8 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -3,15 +3,57 @@
  * nodeAgg.c
  *	  Routines to handle aggregate nodes.
  *
- *	  ExecAgg evaluates each aggregate in the following steps:
+ *	  ExecAgg normally evaluates each aggregate in the following steps:
  *
  *		 transvalue = initcond
  *		 foreach input_tuple do
  *			transvalue = transfunc(transvalue, input_value(s))
  *		 result = finalfunc(transvalue, direct_argument(s))
  *
- *	  If a finalfunc is not supplied then the result is just the ending
- *	  value of transvalue.
+ *	  If a finalfunc is not supplied or finalizeAggs is false, then the result
+ *	  is just the ending value of transvalue.
+ *
+ *	  Other behavior is also supported and is controlled by the 'combineStates',
+ *	  'finalizeAggs' and 'serialStates' parameters. 'combineStates' controls
+ *	  whether the trans func or the combine func is used during aggregation.
+ *	  When 'combineStates' is true we expect other (previously) aggregated
+ *	  states as input rather than input tuples. This mode facilitates multiple
+ *	  aggregate stages which allows us to support pushing aggregation down
+ *	  deeper into the plan rather than leaving it for the final stage. For
+ *	  example with a query such as:
+ *
+ *	  SELECT count(*) FROM (SELECT * FROM a UNION ALL SELECT * FROM b);
+ *
+ *	  with this functionality the planner has the flexibility to generate a
+ *	  plan which performs count(*) on table a and table b separately and then
+ *	  add a combine phase to combine both results. In this case the combine
+ *	  function would simply add both counts together.
+ *
+ *	  When multiple aggregate stages exist the planner should have set the
+ *	  'finalizeAggs' to true only for the final aggregtion state, and each
+ *	  stage, apart from the very first one should have 'combineStates' set to
+ *	  true. This permits plans such as:
+ *
+ *		Finalize Aggregate
+ *			->  Partial Aggregate
+ *				->  Partial Aggregate
+ *
+ *	  Combine functions which use pass-by-ref states should be careful to
+ *	  always update the 1st state parameter by adding the 2nd parameter to it,
+ *	  rather than the other way around. If the 1st state is NULL, then it's not
+ *	  sufficient to simply return the 2nd state, as the memory context is
+ *	  incorrect. Instead a new state should be created in the correct aggregate
+ *	  memory context and the 2nd state should be copied over.
+ *
+ *	  The 'serialStates' option can be used to allow multi-stage aggregation
+ *	  for aggregates with an INTERNAL state type. When this mode is disabled
+ *	  only a pointer to the INTERNAL aggregate states are passed around the
+ *	  executor. This behaviour does not suit a parallel environment where the
+ *	  process is unable to dereference pointers for memory which belongs to a
+ *	  worker process. Enabling this mode causes the INTERNAL states to be
+ *	  serialized and deserialized as and when required, which of course
+ *	  requires that the aggregate function also have a 'serialfunc' and
+ *	  'deserialfunc' function specified.
  *
  *	  If a normal aggregate call specifies DISTINCT or ORDER BY, we sort the
  *	  input tuples and eliminate duplicates (if required) before performing
@@ -134,6 +176,7 @@
 #include "catalog/objectaccess.h"
 #include "catalog/pg_aggregate.h"
 #include "catalog/pg_proc.h"
+#include "catalog/pg_type.h"
 #include "executor/executor.h"
 #include "executor/nodeAgg.h"
 #include "miscadmin.h"
@@ -197,9 +240,15 @@ typedef struct AggStatePerTransData
 	 */
 	int			numTransInputs;
 
-	/* Oid of the state transition function */
+	/* Oid of the state transition or combine function */
 	Oid			transfn_oid;
 
+	/* Oid of the serial function or InvalidOid */
+	Oid			serialfn_oid;
+
+	/* Oid of the deserial function or InvalidOid */
+	Oid			deserialfn_oid;
+
 	/* Oid of state value's datatype */
 	Oid			aggtranstype;
 
@@ -209,11 +258,17 @@ typedef struct AggStatePerTransData
 	List	   *aggdirectargs;	/* states of direct-argument expressions */
 
 	/*
-	 * fmgr lookup data for transition function.  Note in particular that the
-	 * fn_strict flag is kept here.
+	 * fmgr lookup data for transition function or combination function.  Note
+	 * in particular that the fn_strict flag is kept here.
 	 */
 	FmgrInfo	transfn;
 
+	/* fmgr lookup data for serial function */
+	FmgrInfo	serialfn;
+
+	/* fmgr lookup data for deserial function */
+	FmgrInfo	deserialfn;
+
 	/* Input collation derived for aggregate */
 	Oid			aggCollation;
 
@@ -294,6 +349,11 @@ typedef struct AggStatePerTransData
 	 * worth the extra space consumption.
 	 */
 	FunctionCallInfoData transfn_fcinfo;
+
+	/* Likewise for serial and deserial functions */
+	FunctionCallInfoData serialfn_fcinfo;
+
+	FunctionCallInfoData deserialfn_fcinfo;
 }	AggStatePerTransData;
 
 /*
@@ -421,6 +481,10 @@ static void advance_transition_function(AggState *aggstate,
 							AggStatePerTrans pertrans,
 							AggStatePerGroup pergroupstate);
 static void advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup);
+static void advance_combination_function(AggState *aggstate,
+							AggStatePerTrans pertrans,
+							AggStatePerGroup pergroupstate);
+static void combine_aggregates(AggState *aggstate, AggStatePerGroup pergroup);
 static void process_ordered_aggregate_single(AggState *aggstate,
 								 AggStatePerTrans pertrans,
 								 AggStatePerGroup pergroupstate);
@@ -451,14 +515,17 @@ static Datum GetAggInitVal(Datum textInitVal, Oid transtype);
 static void build_pertrans_for_aggref(AggStatePerTrans pertrans,
 						  AggState *aggsate, EState *estate,
 						  Aggref *aggref, Oid aggtransfn, Oid aggtranstype,
-						  Datum initValue, bool initValueIsNull,
-						  Oid *inputTypes, int numArguments);
+						  Oid aggserialtype, Oid aggserialfn,
+						  Oid aggdeserialfn, Datum initValue,
+						  bool initValueIsNull, Oid *inputTypes,
+						  int numArguments);
 static int find_compatible_peragg(Aggref *newagg, AggState *aggstate,
 					   int lastaggno, List **same_input_transnos);
 static int find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 						 Oid aggtransfn, Oid aggtranstype,
+						 Oid aggserialfn, Oid aggdeserialfn,
 						 Datum initValue, bool initValueIsNull,
-						 List *possible_matches);
+						 List *transnos);
 
 
 /*
@@ -796,6 +863,8 @@ advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
 	int			numGroupingSets = Max(aggstate->phase->numsets, 1);
 	int			numTrans = aggstate->numtrans;
 
+	Assert(!aggstate->combineStates);
+
 	for (transno = 0; transno < numTrans; transno++)
 	{
 		AggStatePerTrans pertrans = &aggstate->pertrans[transno];
@@ -879,6 +948,152 @@ advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
 	}
 }
 
+/*
+ * combine_aggregates is used when running in 'combineState' mode. This
+ * advances each aggregate transition state by adding another transition state
+ * to it.
+ */
+static void
+combine_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
+{
+	int			transno;
+	int			numTrans = aggstate->numtrans;
+
+	/* combine not supported with grouping sets */
+	Assert(aggstate->phase->numsets == 0);
+	Assert(aggstate->combineStates);
+
+	for (transno = 0; transno < numTrans; transno++)
+	{
+		AggStatePerTrans pertrans = &aggstate->pertrans[transno];
+		TupleTableSlot *slot;
+		FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
+		AggStatePerGroup pergroupstate = &pergroup[transno];
+
+		/* Evaluate the current input expressions for this aggregate */
+		slot = ExecProject(pertrans->evalproj, NULL);
+		Assert(slot->tts_nvalid >= 1);
+
+		/*
+		 * deserialfn_oid will be set if we must deserialize the input state
+		 * before calling the combine function
+		 */
+		if (OidIsValid(pertrans->deserialfn_oid))
+		{
+			/* don't call a strict deserial function with NULL input */
+			if (pertrans->deserialfn.fn_strict && slot->tts_isnull[0] == true)
+				continue;
+			else
+			{
+				FunctionCallInfo dsinfo = &pertrans->deserialfn_fcinfo;
+				dsinfo->arg[0] = slot->tts_values[0];
+				dsinfo->argnull[0] = slot->tts_isnull[0];
+
+				fcinfo->arg[1] = FunctionCallInvoke(dsinfo);
+				fcinfo->argnull[1] = dsinfo->isnull;
+			}
+		}
+		else
+		{
+			fcinfo->arg[1] = slot->tts_values[0];
+			fcinfo->argnull[1] = slot->tts_isnull[0];
+		}
+
+		advance_combination_function(aggstate, pertrans, pergroupstate);
+	}
+}
+
+/*
+ * Perform combination of states between 2 aggregate states. Effectively this
+ * 'adds' two states together by whichever logic is defined in the aggregate
+ * function's combine function.
+ *
+ * Note that in this case transfn is set to the combination function. This
+ * perhaps should be changed to avoid confusion, but one field is ok for now
+ * as they'll never be needed at the same time.
+ */
+static void
+advance_combination_function(AggState *aggstate,
+							 AggStatePerTrans pertrans,
+							 AggStatePerGroup pergroupstate)
+{
+	FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
+	MemoryContext oldContext;
+	Datum		newVal;
+
+	if (pertrans->transfn.fn_strict)
+	{
+		/* if we're asked to merge to a NULL state, then do nothing */
+		if (fcinfo->argnull[1])
+			return;
+
+		if (pergroupstate->noTransValue)
+		{
+			/*
+			 * transValue has not yet been initialized.  If pass-by-ref
+			 * datatype we must copy the combining state value into aggcontext.
+			 */
+			if (!pertrans->transtypeByVal)
+			{
+				oldContext = MemoryContextSwitchTo(
+					aggstate->aggcontexts[aggstate->current_set]->ecxt_per_tuple_memory);
+				pergroupstate->transValue = datumCopy(fcinfo->arg[1],
+													  pertrans->transtypeByVal,
+													  pertrans->transtypeLen);
+				MemoryContextSwitchTo(oldContext);
+			}
+			else
+				pergroupstate->transValue = fcinfo->arg[1];
+
+			pergroupstate->transValueIsNull = false;
+			pergroupstate->noTransValue = false;
+			return;
+		}
+	}
+
+	/* We run the combine functions in per-input-tuple memory context */
+	oldContext = MemoryContextSwitchTo(aggstate->tmpcontext->ecxt_per_tuple_memory);
+
+	/* set up aggstate->curpertrans for AggGetAggref() */
+	aggstate->curpertrans = pertrans;
+
+	/*
+	 * OK to call the combine function
+	 */
+	fcinfo->arg[0] = pergroupstate->transValue;
+	fcinfo->argnull[0] = pergroupstate->transValueIsNull;
+	fcinfo->isnull = false;		/* just in case combine func doesn't set it */
+
+	newVal = FunctionCallInvoke(fcinfo);
+
+	aggstate->curpertrans = NULL;
+
+	/*
+	 * If pass-by-ref datatype, must copy the new value into aggcontext and
+	 * pfree the prior transValue.  But if the combine function returned a
+	 * pointer to its first input, we don't need to do anything.
+	 */
+	if (!pertrans->transtypeByVal &&
+		DatumGetPointer(newVal) != DatumGetPointer(pergroupstate->transValue))
+	{
+		if (!fcinfo->isnull)
+		{
+			MemoryContextSwitchTo(aggstate->aggcontexts[aggstate->current_set]->ecxt_per_tuple_memory);
+			newVal = datumCopy(newVal,
+							   pertrans->transtypeByVal,
+							   pertrans->transtypeLen);
+		}
+		if (!pergroupstate->transValueIsNull)
+			pfree(DatumGetPointer(pergroupstate->transValue));
+	}
+
+	pergroupstate->transValue = newVal;
+	pergroupstate->transValueIsNull = fcinfo->isnull;
+
+	MemoryContextSwitchTo(oldContext);
+
+}
+
 
 /*
  * Run the transition function for a DISTINCT or ORDER BY aggregate
@@ -1278,8 +1493,35 @@ finalize_aggregates(AggState *aggstate,
 												pergroupstate);
 		}
 
-		finalize_aggregate(aggstate, peragg, pergroupstate,
-						   &aggvalues[aggno], &aggnulls[aggno]);
+		if (aggstate->finalizeAggs)
+			finalize_aggregate(aggstate, peragg, pergroupstate,
+							   &aggvalues[aggno], &aggnulls[aggno]);
+
+		/*
+		 * serialfn_oid will be set if we must serialize the input state
+		 * before calling the combine function on the state.
+		 */
+		else if (OidIsValid(pertrans->serialfn_oid))
+		{
+			/* don't call a strict serial function with NULL input */
+			if (pertrans->serialfn.fn_strict &&
+				pergroupstate->transValueIsNull)
+				continue;
+			else
+			{
+				FunctionCallInfo fcinfo = &pertrans->serialfn_fcinfo;
+				fcinfo->arg[0] = pergroupstate->transValue;
+				fcinfo->argnull[0] = pergroupstate->transValueIsNull;
+
+				aggvalues[aggno] = FunctionCallInvoke(fcinfo);
+				aggnulls[aggno] = fcinfo->isnull;
+			}
+		}
+		else
+		{
+			aggvalues[aggno] = pergroupstate->transValue;
+			aggnulls[aggno] = pergroupstate->transValueIsNull;
+		}
 	}
 }
 
@@ -1811,7 +2053,10 @@ agg_retrieve_direct(AggState *aggstate)
 				 */
 				for (;;)
 				{
-					advance_aggregates(aggstate, pergroup);
+					if (!aggstate->combineStates)
+						advance_aggregates(aggstate, pergroup);
+					else
+						combine_aggregates(aggstate, pergroup);
 
 					/* Reset per-input-tuple context after each tuple */
 					ResetExprContext(tmpcontext);
@@ -1919,7 +2164,10 @@ agg_fill_hash_table(AggState *aggstate)
 		entry = lookup_hash_entry(aggstate, outerslot);
 
 		/* Advance the aggregates */
-		advance_aggregates(aggstate, entry->pergroup);
+		if (!aggstate->combineStates)
+			advance_aggregates(aggstate, entry->pergroup);
+		else
+			combine_aggregates(aggstate, entry->pergroup);
 
 		/* Reset per-input-tuple context after each tuple */
 		ResetExprContext(tmpcontext);
@@ -2051,6 +2299,9 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 	aggstate->pertrans = NULL;
 	aggstate->curpertrans = NULL;
 	aggstate->agg_done = false;
+	aggstate->combineStates = node->combineStates;
+	aggstate->finalizeAggs = node->finalizeAggs;
+	aggstate->serialStates = node->serialStates;
 	aggstate->input_done = false;
 	aggstate->pergroup = NULL;
 	aggstate->grp_firstTuple = NULL;
@@ -2359,6 +2610,9 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 		AclResult	aclresult;
 		Oid			transfn_oid,
 					finalfn_oid;
+		Oid			serialtype_oid,
+					serialfn_oid,
+					deserialfn_oid;
 		Expr	   *finalfnexpr;
 		Oid			aggtranstype;
 		Datum		textInitVal;
@@ -2402,8 +2656,67 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 						   get_func_name(aggref->aggfnoid));
 		InvokeFunctionExecuteHook(aggref->aggfnoid);
 
-		transfn_oid = aggform->aggtransfn;
-		peragg->finalfn_oid = finalfn_oid = aggform->aggfinalfn;
+		/*
+		 * If this aggregation is performing state combines, then instead of
+		 * using the transition function, we'll use the combine function
+		 */
+		if (aggstate->combineStates)
+		{
+			transfn_oid = aggform->aggcombinefn;
+
+			/* If not set then the planner messed up */
+			if (!OidIsValid(transfn_oid))
+				elog(ERROR, "combinefn not set for aggregate function");
+		}
+		else
+			transfn_oid = aggform->aggtransfn;
+
+		/* Final function only required if we're finalizing the aggregates */
+		if (aggstate->finalizeAggs)
+			peragg->finalfn_oid = finalfn_oid = aggform->aggfinalfn;
+		else
+			peragg->finalfn_oid = finalfn_oid = InvalidOid;
+
+		serialtype_oid = InvalidOid;
+		serialfn_oid = InvalidOid;
+		deserialfn_oid = InvalidOid;
+
+		/*
+		 * Determine if we require serialization or deserialization of the
+		 * aggregate states. This is only required if the aggregate state is
+		 * internal.
+		 */
+		if (aggstate->serialStates && aggform->aggtranstype == INTERNALOID)
+		{
+			/*
+			 * The planner should only have generated an agg node with
+			 * serialStates if every aggregate with an INTERNAL state has a
+			 * serial type, serial function and deserial function. Let's ensure
+			 * it didn't mess that up.
+			 */
+			if (!OidIsValid(aggform->aggserialtype))
+				elog(ERROR, "serial type not set during serialStates aggregation step");
+
+			if (!OidIsValid(aggform->aggserialfn))
+				elog(ERROR, "serial func not set during serialStates aggregation step");
+
+			if (!OidIsValid(aggform->aggdeserialfn))
+				elog(ERROR, "deserial func not set during serialStates aggregation step");
+
+			/* serial func only required when not finalizing aggs */
+			if (!aggstate->finalizeAggs)
+			{
+				serialfn_oid = aggform->aggserialfn;
+				serialtype_oid = aggform->aggserialtype;
+			}
+
+			/* deserial func only required when combining states */
+			if (aggstate->combineStates)
+			{
+				deserialfn_oid = aggform->aggdeserialfn;
+				serialtype_oid = aggform->aggserialtype;
+			}
+		}
 
 		/* Check that aggregate owner has permission to call component fns */
 		{
@@ -2433,6 +2746,24 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 								   get_func_name(finalfn_oid));
 				InvokeFunctionExecuteHook(finalfn_oid);
 			}
+			if (OidIsValid(serialfn_oid))
+			{
+				aclresult = pg_proc_aclcheck(serialfn_oid, aggOwner,
+											 ACL_EXECUTE);
+				if (aclresult != ACLCHECK_OK)
+					aclcheck_error(aclresult, ACL_KIND_PROC,
+								   get_func_name(serialfn_oid));
+				InvokeFunctionExecuteHook(serialfn_oid);
+			}
+			if (OidIsValid(deserialfn_oid))
+			{
+				aclresult = pg_proc_aclcheck(deserialfn_oid, aggOwner,
+											 ACL_EXECUTE);
+				if (aclresult != ACLCHECK_OK)
+					aclcheck_error(aclresult, ACL_KIND_PROC,
+								   get_func_name(deserialfn_oid));
+				InvokeFunctionExecuteHook(deserialfn_oid);
+			}
 		}
 
 		/*
@@ -2459,7 +2790,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 
 		/*
 		 * build expression trees using actual argument & result types for the
-		 * finalfn, if it exists
+		 * finalfn, if it exists and is required.
 		 */
 		if (OidIsValid(finalfn_oid))
 		{
@@ -2474,10 +2805,11 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 			fmgr_info_set_expr((Node *) finalfnexpr, &peragg->finalfn);
 		}
 
-		/* get info about the result type's datatype */
-		get_typlenbyval(aggref->aggtype,
-						&peragg->resulttypeLen,
-						&peragg->resulttypeByVal);
+		/* when finalizing we get info about the final result's datatype */
+		if (aggstate->finalizeAggs)
+			get_typlenbyval(aggref->aggtype,
+							&peragg->resulttypeLen,
+							&peragg->resulttypeByVal);
 
 		/*
 		 * initval is potentially null, so don't try to access it as a struct
@@ -2501,7 +2833,8 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 		 */
 		existing_transno = find_compatible_pertrans(aggstate, aggref,
 													transfn_oid, aggtranstype,
-												  initValue, initValueIsNull,
+												  serialfn_oid, deserialfn_oid,
+													initValue, initValueIsNull,
 													same_input_transnos);
 		if (existing_transno != -1)
 		{
@@ -2517,8 +2850,10 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 			pertrans = &pertransstates[++transno];
 			build_pertrans_for_aggref(pertrans, aggstate, estate,
 									  aggref, transfn_oid, aggtranstype,
-									  initValue, initValueIsNull,
-									  inputTypes, numArguments);
+									  serialtype_oid, serialfn_oid,
+									  deserialfn_oid, initValue,
+									  initValueIsNull, inputTypes,
+									  numArguments);
 			peragg->transno = transno;
 		}
 		ReleaseSysCache(aggTuple);
@@ -2546,12 +2881,15 @@ static void
 build_pertrans_for_aggref(AggStatePerTrans pertrans,
 						  AggState *aggstate, EState *estate,
 						  Aggref *aggref,
-						  Oid aggtransfn, Oid aggtranstype,
+						  Oid aggtransfn, Oid aggtranstype, Oid aggserialtype,
+						  Oid aggserialfn, Oid aggdeserialfn,
 						  Datum initValue, bool initValueIsNull,
 						  Oid *inputTypes, int numArguments)
 {
 	int			numGroupingSets = Max(aggstate->maxsets, 1);
 	Expr	   *transfnexpr;
+	Expr	   *serialfnexpr = NULL;
+	Expr	   *deserialfnexpr = NULL;
 	ListCell   *lc;
 	int			numInputs;
 	int			numDirectArgs;
@@ -2565,6 +2903,8 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 	pertrans->aggref = aggref;
 	pertrans->aggCollation = aggref->inputcollid;
 	pertrans->transfn_oid = aggtransfn;
+	pertrans->serialfn_oid = aggserialfn;
+	pertrans->deserialfn_oid = aggdeserialfn;
 	pertrans->initValue = initValue;
 	pertrans->initValueIsNull = initValueIsNull;
 
@@ -2583,44 +2923,68 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 		pertrans->numTransInputs = numArguments;
 
 	/*
-	 * Set up infrastructure for calling the transfn
+	 * When combining states, we have no use at all for the aggregate
+	 * function's transfn. Instead we use the combinefn. However we do
+	 * reuse the transfnexpr for the combinefn, perhaps this should change
 	 */
-	build_aggregate_transfn_expr(inputTypes,
-								 numArguments,
-								 numDirectArgs,
-								 aggref->aggvariadic,
-								 aggtranstype,
-								 aggref->inputcollid,
-								 aggtransfn,
-								 InvalidOid,	/* invtrans is not needed here */
-								 &transfnexpr,
-								 NULL);
-	fmgr_info(aggtransfn, &pertrans->transfn);
-	fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
-
-	InitFunctionCallInfoData(pertrans->transfn_fcinfo,
-							 &pertrans->transfn,
-							 pertrans->numTransInputs + 1,
-							 pertrans->aggCollation,
-							 (void *) aggstate, NULL);
+	if (aggstate->combineStates)
+	{
+		build_aggregate_combinefn_expr(aggtranstype,
+									   aggref->inputcollid,
+									   aggtransfn,
+									   &transfnexpr);
+		fmgr_info(aggtransfn, &pertrans->transfn);
+		fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
+
+		InitFunctionCallInfoData(pertrans->transfn_fcinfo,
+								 &pertrans->transfn,
+								 2,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
 
-	/*
-	 * If the transfn is strict and the initval is NULL, make sure input type
-	 * and transtype are the same (or at least binary-compatible), so that
-	 * it's OK to use the first aggregated input value as the initial
-	 * transValue.  This should have been checked at agg definition time, but
-	 * we must check again in case the transfn's strictness property has been
-	 * changed.
-	 */
-	if (pertrans->transfn.fn_strict && pertrans->initValueIsNull)
+	}
+	else
 	{
-		if (numArguments <= numDirectArgs ||
-			!IsBinaryCoercible(inputTypes[numDirectArgs],
-							   aggtranstype))
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
-					 errmsg("aggregate %u needs to have compatible input type and transition type",
-							aggref->aggfnoid)));
+		/*
+		 * Set up infrastructure for calling the transfn
+		 */
+		build_aggregate_transfn_expr(inputTypes,
+									 numArguments,
+									 numDirectArgs,
+									 aggref->aggvariadic,
+									 aggtranstype,
+									 aggref->inputcollid,
+									 aggtransfn,
+									 InvalidOid,	/* invtrans is not needed here */
+									 &transfnexpr,
+									 NULL);
+		fmgr_info(aggtransfn, &pertrans->transfn);
+		fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
+
+		InitFunctionCallInfoData(pertrans->transfn_fcinfo,
+								 &pertrans->transfn,
+								 pertrans->numTransInputs + 1,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+
+		/*
+		 * If the transfn is strict and the initval is NULL, make sure input type
+		 * and transtype are the same (or at least binary-compatible), so that
+		 * it's OK to use the first aggregated input value as the initial
+		 * transValue.  This should have been checked at agg definition time, but
+		 * we must check again in case the transfn's strictness property has been
+		 * changed.
+		 */
+		if (pertrans->transfn.fn_strict && pertrans->initValueIsNull)
+		{
+			if (numArguments <= numDirectArgs ||
+				!IsBinaryCoercible(inputTypes[numDirectArgs],
+								   aggtranstype))
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						 errmsg("aggregate %u needs to have compatible input type and transition type",
+								aggref->aggfnoid)));
+		}
 	}
 
 	/* get info about the state value's datatype */
@@ -2628,6 +2992,41 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 					&pertrans->transtypeLen,
 					&pertrans->transtypeByVal);
 
+	if (OidIsValid(aggserialfn))
+	{
+		build_aggregate_serialfn_expr(aggtranstype,
+									  aggserialtype,
+									  aggref->inputcollid,
+									  aggserialfn,
+									  &serialfnexpr);
+		fmgr_info(aggserialfn, &pertrans->serialfn);
+		fmgr_info_set_expr((Node *) serialfnexpr, &pertrans->serialfn);
+
+		InitFunctionCallInfoData(pertrans->serialfn_fcinfo,
+								 &pertrans->serialfn,
+								 1,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+	}
+
+	if (OidIsValid(aggdeserialfn))
+	{
+		build_aggregate_serialfn_expr(aggtranstype,
+									  aggserialtype,
+									  aggref->inputcollid,
+									  aggdeserialfn,
+									  &deserialfnexpr);
+		fmgr_info(aggdeserialfn, &pertrans->deserialfn);
+		fmgr_info_set_expr((Node *) deserialfnexpr, &pertrans->deserialfn);
+
+		InitFunctionCallInfoData(pertrans->deserialfn_fcinfo,
+								 &pertrans->deserialfn,
+								 1,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+
+	}
+
 	/*
 	 * Get a tupledesc corresponding to the aggregated inputs (including sort
 	 * expressions) of the agg.
@@ -2874,6 +3273,7 @@ find_compatible_peragg(Aggref *newagg, AggState *aggstate,
 static int
 find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 						 Oid aggtransfn, Oid aggtranstype,
+						 Oid aggserialfn, Oid aggdeserialfn,
 						 Datum initValue, bool initValueIsNull,
 						 List *transnos)
 {
@@ -2892,6 +3292,14 @@ find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 			aggtranstype != pertrans->aggtranstype)
 			continue;
 
+		/*
+		 * serial and deserial functions must match, if present. Remember that
+		 * these will be InvalidOid if they're not required for this agg node
+		 */
+		if (aggserialfn != pertrans->serialfn_oid ||
+			aggdeserialfn != pertrans->deserialfn_oid)
+			continue;
+
 		/* Check that the initial condition matches, too. */
 		if (initValueIsNull && pertrans->initValueIsNull)
 			return transno;
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index ba04b72..130cbe6 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -865,6 +865,9 @@ _copyAgg(const Agg *from)
 
 	COPY_SCALAR_FIELD(aggstrategy);
 	COPY_SCALAR_FIELD(numCols);
+	COPY_SCALAR_FIELD(combineStates);
+	COPY_SCALAR_FIELD(finalizeAggs);
+	COPY_SCALAR_FIELD(serialStates);
 	if (from->numCols > 0)
 	{
 		COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 63fae82..08af15e 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -695,6 +695,10 @@ _outAgg(StringInfo str, const Agg *node)
 	for (i = 0; i < node->numCols; i++)
 		appendStringInfo(str, " %d", node->grpColIdx[i]);
 
+	WRITE_BOOL_FIELD(combineStates);
+	WRITE_BOOL_FIELD(finalizeAggs);
+	WRITE_BOOL_FIELD(serialStates);
+
 	appendStringInfoString(str, " :grpOperators");
 	for (i = 0; i < node->numCols; i++)
 		appendStringInfo(str, " %u", node->grpOperators[i]);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 222e2ed..0620043 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1989,6 +1989,9 @@ _readAgg(void)
 	READ_ENUM_FIELD(aggstrategy, AggStrategy);
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
+	READ_BOOL_FIELD(combineStates);
+	READ_BOOL_FIELD(finalizeAggs);
+	READ_BOOL_FIELD(serialStates);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 	READ_NODE_FIELD(groupingSets);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 32f903d..f79167a 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -1053,6 +1053,9 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path)
 								 groupOperators,
 								 NIL,
 								 numGroups,
+								 false,
+								 true,
+								 false,
 								 subplan);
 	}
 	else
@@ -4554,9 +4557,8 @@ Agg *
 make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
 		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
-		 List *groupingSets,
-		 long numGroups,
-		 Plan *lefttree)
+		 List *groupingSets, long numGroups, bool combineStates,
+		 bool finalizeAggs, bool serialStates, Plan *lefttree)
 {
 	Agg		   *node = makeNode(Agg);
 	Plan	   *plan = &node->plan;
@@ -4565,6 +4567,9 @@ make_agg(PlannerInfo *root, List *tlist, List *qual,
 
 	node->aggstrategy = aggstrategy;
 	node->numCols = numGroupCols;
+	node->combineStates = combineStates;
+	node->finalizeAggs = finalizeAggs;
+	node->serialStates = serialStates;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
 	node->numGroups = numGroups;
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 2c04f5c..6897c1f 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -1995,6 +1995,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 									extract_grouping_ops(parse->groupClause),
 												NIL,
 												numGroups,
+												false,
+												true,
+												false,
 												result_plan);
 				/* Hashed aggregation produces randomly-ordered results */
 				current_pathkeys = NIL;
@@ -2306,6 +2309,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 								 extract_grouping_ops(parse->distinctClause),
 											NIL,
 											numDistinctRows,
+											false,
+											true,
+											false,
 											result_plan);
 			/* Hashed aggregation produces randomly-ordered results */
 			current_pathkeys = NIL;
@@ -2539,6 +2545,9 @@ build_grouping_chain(PlannerInfo *root,
 									 extract_grouping_ops(groupClause),
 									 gsets,
 									 numGroups,
+									 false,
+									 true,
+									 false,
 									 sort_plan);
 
 		sort_plan->lefttree = NULL;
@@ -2575,6 +2584,9 @@ build_grouping_chain(PlannerInfo *root,
 										extract_grouping_ops(groupClause),
 										gsets,
 										numGroups,
+										false,
+										true,
+										false,
 										result_plan);
 
 		((Agg *) result_plan)->chain = chain;
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 12e9290..1f23f49 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -15,7 +15,9 @@
  */
 #include "postgres.h"
 
+#include "access/htup_details.h"
 #include "access/transam.h"
+#include "catalog/pg_aggregate.h"
 #include "catalog/pg_type.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
@@ -139,6 +141,18 @@ static List *set_returning_clause_references(PlannerInfo *root,
 static bool fix_opfuncids_walker(Node *node, void *context);
 static bool extract_query_dependencies_walker(Node *node,
 								  PlannerInfo *context);
+static void set_combineagg_references(PlannerInfo *root, Plan *plan,
+									  int rtoffset);
+static Node *fix_combine_agg_expr(PlannerInfo *root,
+								  Node *node,
+								  indexed_tlist *subplan_itlist,
+								  Index newvarno,
+								  int rtoffset);
+static Node *fix_combine_agg_expr_mutator(Node *node,
+										  fix_upper_expr_context *context);
+static void set_partialagg_aggref_types(PlannerInfo *root, Plan *plan,
+										bool serializeStates);
+
 
 /*****************************************************************************
  *
@@ -668,8 +682,24 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 			}
 			break;
 		case T_Agg:
-			set_upper_references(root, plan, rtoffset);
-			break;
+			{
+				Agg *aggplan = (Agg *) plan;
+
+				/*
+				 * For partial aggregation we must adjust the return types of
+				 * the Aggrefs
+				 */
+				if (!aggplan->finalizeAggs)
+					set_partialagg_aggref_types(root, plan,
+												aggplan->serialStates);
+
+				if (aggplan->combineStates)
+					set_combineagg_references(root, plan, rtoffset);
+				else
+					set_upper_references(root, plan, rtoffset);
+
+				break;
+			}
 		case T_Group:
 			set_upper_references(root, plan, rtoffset);
 			break;
@@ -2432,3 +2462,199 @@ extract_query_dependencies_walker(Node *node, PlannerInfo *context)
 	return expression_tree_walker(node, extract_query_dependencies_walker,
 								  (void *) context);
 }
+
+static void
+set_combineagg_references(PlannerInfo *root, Plan *plan, int rtoffset)
+{
+	Plan	   *subplan = plan->lefttree;
+	indexed_tlist *subplan_itlist;
+	List	   *output_targetlist;
+	ListCell   *l;
+
+	Assert(IsA(plan, Agg));
+	Assert(((Agg *) plan)->combineStates);
+
+	subplan_itlist = build_tlist_index(subplan->targetlist);
+
+	output_targetlist = NIL;
+
+	foreach(l, plan->targetlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(l);
+		Node	   *newexpr;
+
+		/* If it's a non-Var sort/group item, first try to match by sortref */
+		if (tle->ressortgroupref != 0 && !IsA(tle->expr, Var))
+		{
+			newexpr = (Node *)
+				search_indexed_tlist_for_sortgroupref((Node *) tle->expr,
+														tle->ressortgroupref,
+														subplan_itlist,
+														OUTER_VAR);
+			if (!newexpr)
+				newexpr = fix_combine_agg_expr(root,
+												(Node *) tle->expr,
+												subplan_itlist,
+												OUTER_VAR,
+												rtoffset);
+		}
+		else
+			newexpr = fix_combine_agg_expr(root,
+											(Node *) tle->expr,
+											subplan_itlist,
+											OUTER_VAR,
+											rtoffset);
+		tle = flatCopyTargetEntry(tle);
+		tle->expr = (Expr *) newexpr;
+		output_targetlist = lappend(output_targetlist, tle);
+	}
+
+	plan->targetlist = output_targetlist;
+
+	plan->qual = (List *)
+		fix_upper_expr(root,
+					   (Node *) plan->qual,
+					   subplan_itlist,
+					   OUTER_VAR,
+					   rtoffset);
+
+	pfree(subplan_itlist);
+}
+
+
+/*
+ * Adjust the Aggref'a args to reference the correct Aggref target in the outer
+ * subplan.
+ */
+static Node *
+fix_combine_agg_expr(PlannerInfo *root,
+			   Node *node,
+			   indexed_tlist *subplan_itlist,
+			   Index newvarno,
+			   int rtoffset)
+{
+	fix_upper_expr_context context;
+
+	context.root = root;
+	context.subplan_itlist = subplan_itlist;
+	context.newvarno = newvarno;
+	context.rtoffset = rtoffset;
+	return fix_combine_agg_expr_mutator(node, &context);
+}
+
+static Node *
+fix_combine_agg_expr_mutator(Node *node, fix_upper_expr_context *context)
+{
+	Var		   *newvar;
+
+	if (node == NULL)
+		return NULL;
+	if (IsA(node, Var))
+	{
+		Var		   *var = (Var *) node;
+
+		newvar = search_indexed_tlist_for_var(var,
+											  context->subplan_itlist,
+											  context->newvarno,
+											  context->rtoffset);
+		if (!newvar)
+			elog(ERROR, "variable not found in subplan target list");
+		return (Node *) newvar;
+	}
+	if (IsA(node, Aggref))
+	{
+		TargetEntry *tle;
+		Aggref		*aggref = (Aggref*) node;
+
+		tle = tlist_member(node, context->subplan_itlist->tlist);
+		if (tle)
+		{
+			/* Found a matching subplan output expression */
+			Var		   *newvar;
+			TargetEntry *newtle;
+
+			newvar = makeVarFromTargetEntry(context->newvarno, tle);
+			newvar->varnoold = 0;	/* wasn't ever a plain Var */
+			newvar->varoattno = 0;
+
+			/* update the args in the aggref */
+
+			/* makeTargetEntry ,always set resno to one for finialize agg */
+			newtle = makeTargetEntry((Expr*) newvar, 1, NULL, false);
+
+			/*
+			 * Updated the args, let the newvar refer to the right position of
+			 * the agg function in the subplan
+			 */
+			aggref->args = list_make1(newtle);
+
+			return (Node *) aggref;
+		}
+		else
+			elog(ERROR, "aggref not found in subplan target list");
+	}
+	if (IsA(node, PlaceHolderVar))
+	{
+		PlaceHolderVar *phv = (PlaceHolderVar *) node;
+
+		/* See if the PlaceHolderVar has bubbled up from a lower plan node */
+		if (context->subplan_itlist->has_ph_vars)
+		{
+			newvar = search_indexed_tlist_for_non_var((Node *) phv,
+													  context->subplan_itlist,
+													  context->newvarno);
+			if (newvar)
+				return (Node *) newvar;
+		}
+		/* If not supplied by input plan, evaluate the contained expr */
+		return fix_upper_expr_mutator((Node *) phv->phexpr, context);
+	}
+	if (IsA(node, Param))
+		return fix_param_node(context->root, (Param *) node);
+
+	fix_expr_common(context->root, node);
+	return expression_tree_mutator(node,
+								   fix_combine_agg_expr_mutator,
+								   (void *) context);
+}
+
+/* XXX is this really the best place and way to do this? */
+static void
+set_partialagg_aggref_types(PlannerInfo *root, Plan *plan, bool serializeStates)
+{
+	ListCell *l;
+
+	foreach(l, plan->targetlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(l);
+
+		if (IsA(tle->expr, Aggref))
+		{
+			Aggref *aggref = (Aggref *) tle->expr;
+			HeapTuple	aggTuple;
+			Form_pg_aggregate aggform;
+
+			aggTuple = SearchSysCache1(AGGFNOID,
+									   ObjectIdGetDatum(aggref->aggfnoid));
+			if (!HeapTupleIsValid(aggTuple))
+				elog(ERROR, "cache lookup failed for aggregate %u",
+					 aggref->aggfnoid);
+			aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
+
+			/*
+			 * For partial aggregate nodes the return type of the Aggref
+			 * depends on if we're performing a serialization of the partially
+			 * aggregated states or not. If we are then the return type should
+			 * be the serial type rather than the trans type. We only require
+			 * this behavior for aggregates with INTERNAL trans types.
+			 */
+			if (serializeStates && OidIsValid(aggform->aggserialtype) &&
+				aggform->aggtranstype == INTERNALOID)
+				aggref->aggtype = aggform->aggserialtype;
+			else
+				aggref->aggtype = aggform->aggtranstype;
+
+			ReleaseSysCache(aggTuple);
+		}
+	}
+}
\ No newline at end of file
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 2e55131..a4500c4 100644
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -775,6 +775,9 @@ make_union_unique(SetOperationStmt *op, Plan *plan,
 								 extract_grouping_ops(groupList),
 								 NIL,
 								 numGroups,
+								 false,
+								 true,
+								 false,
 								 plan);
 		/* Hashed aggregation produces randomly-ordered results */
 		*sortClauses = NIL;
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 915c8a4..e34842d 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -52,6 +52,10 @@
 #include "utils/syscache.h"
 #include "utils/typcache.h"
 
+typedef struct
+{
+	PartialAggType allowedtype;
+} partial_agg_context;
 
 typedef struct
 {
@@ -93,6 +97,7 @@ typedef struct
 	bool		allow_restricted;
 } has_parallel_hazard_arg;
 
+static bool partial_aggregate_walker(Node *node, void *context);
 static bool contain_agg_clause_walker(Node *node, void *context);
 static bool count_agg_clauses_walker(Node *node,
 						 count_agg_clauses_context *context);
@@ -400,6 +405,89 @@ make_ands_implicit(Expr *clause)
  *****************************************************************************/
 
 /*
+ * aggregates_allow_partial
+ *		Recursively search for Aggref clauses and determine the maximum
+ *		'degree' of partial aggregation which can be supported. Partial
+ *		aggregation requires that each aggregate does not have a DISTINCT or
+ *		ORDER BY clause, and that it also has a combine function set. For
+ *		aggregates with an INTERNAL trans type we only can support all types of
+ *		partial aggregation when the aggregate has a serial and deserial
+ *		function set. If this is not present then we can only support, at most
+ *		partial aggregation in the context of a single backend process, as
+ *		internal state pointers cannot be dereferenced from another backend
+ *		process.
+ */
+PartialAggType
+aggregates_allow_partial(Node *clause)
+{
+	partial_agg_context context;
+
+	/* initially any type is ok, until we find Aggrefs which say otherwise */
+	context.allowedtype = PAT_ANY;
+
+	if (!partial_aggregate_walker(clause, &context))
+		return context.allowedtype;
+	return context.allowedtype;
+}
+
+static bool
+partial_aggregate_walker(Node *node, partial_agg_context *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Aggref))
+	{
+		Aggref	   *aggref = (Aggref *) node;
+		HeapTuple	aggTuple;
+		Form_pg_aggregate aggform;
+
+		Assert(aggref->agglevelsup == 0);
+
+		/*
+		 * We can't perform partial aggregation with Aggrefs containing a
+		 * DISTINCT or ORDER BY clause.
+		 */
+		if (aggref->aggdistinct || aggref->aggorder)
+		{
+			context->allowedtype = PAT_DISABLED;
+			return true;	/* abort search */
+		}
+		aggTuple = SearchSysCache1(AGGFNOID,
+								   ObjectIdGetDatum(aggref->aggfnoid));
+		if (!HeapTupleIsValid(aggTuple))
+			elog(ERROR, "cache lookup failed for aggregate %u",
+				 aggref->aggfnoid);
+		aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
+
+		/*
+		 * If there is no combine func, then partial aggregation is not
+		 * possible.
+		 */
+		if (!OidIsValid(aggform->aggcombinefn))
+		{
+			ReleaseSysCache(aggTuple);
+			context->allowedtype = PAT_DISABLED;
+			return true;	/* abort search */
+		}
+
+		/*
+		 * Any aggs with an internal transtype must have a serial type, serial
+		 * func and deserial func, otherwise we can only support internal mode.
+		 */
+		if (aggform->aggtranstype == INTERNALOID &&
+			(!OidIsValid(aggform->aggserialtype) ||
+			 !OidIsValid(aggform->aggserialfn) ||
+			 !OidIsValid(aggform->aggdeserialfn)))
+			context->allowedtype = PAT_INTERNAL_ONLY;
+
+		ReleaseSysCache(aggTuple);
+		return false; /* continue searching */
+	}
+	return expression_tree_walker(node, partial_aggregate_walker,
+								  (void *) context);
+}
+
+/*
  * contain_agg_clause
  *	  Recursively search for Aggref/GroupingFunc nodes within a clause.
  *
diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c
index 2c45bd6..7c5df77 100644
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -1929,6 +1929,116 @@ build_aggregate_transfn_expr(Oid *agg_input_types,
 
 /*
  * Like build_aggregate_transfn_expr, but creates an expression tree for the
+ * combine function of an aggregate, rather than the transition function.
+ */
+void
+build_aggregate_combinefn_expr(Oid agg_state_type,
+							   Oid agg_input_collation,
+							   Oid combinefn_oid,
+							   Expr **combinefnexpr)
+{
+	Param	   *argp;
+	List	   *args;
+	FuncExpr   *fexpr;
+
+	/* Build arg list to use in the combinefn FuncExpr node. */
+	argp = makeNode(Param);
+	argp->paramkind = PARAM_EXEC;
+	argp->paramid = -1;
+	argp->paramtype = agg_state_type;
+	argp->paramtypmod = -1;
+	argp->paramcollid = agg_input_collation;
+	argp->location = -1;
+
+	/* transition state type is arg 1 and 2 */
+	args = list_make2(argp, argp);
+
+	fexpr = makeFuncExpr(combinefn_oid,
+						 agg_state_type,
+						 args,
+						 InvalidOid,
+						 agg_input_collation,
+						 COERCE_EXPLICIT_CALL);
+	fexpr->funcvariadic = false;
+	*combinefnexpr = (Expr *) fexpr;
+}
+
+/*
+ * Like build_aggregate_transfn_expr, but creates an expression tree for the
+ * serial function of an aggregate, rather than the transition function.
+ */
+void
+build_aggregate_serialfn_expr(Oid agg_state_type,
+							  Oid agg_serial_type,
+							  Oid agg_input_collation,
+							  Oid serialfn_oid,
+							  Expr **serialfnexpr)
+{
+	Param	   *argp;
+	List	   *args;
+	FuncExpr   *fexpr;
+
+	/* Build arg list to use in the serialfn FuncExpr node. */
+	argp = makeNode(Param);
+	argp->paramkind = PARAM_EXEC;
+	argp->paramid = -1;
+	argp->paramtype = agg_state_type;
+	argp->paramtypmod = -1;
+	argp->paramcollid = agg_input_collation;
+	argp->location = -1;
+
+	/* takes a single arg of the transition state type */
+	args = list_make1(argp);
+
+	fexpr = makeFuncExpr(serialfn_oid,
+						 agg_serial_type,
+						 args,
+						 InvalidOid,
+						 agg_input_collation,
+						 COERCE_EXPLICIT_CALL);
+	fexpr->funcvariadic = false;
+	*serialfnexpr = (Expr *) fexpr;
+}
+
+/*
+ * Like build_aggregate_transfn_expr, but creates an expression tree for the
+ * deserial function of an aggregate, rather than the transition function.
+ */
+void
+build_aggregate_deserialfn_expr(Oid agg_state_type,
+								Oid agg_serial_type,
+								Oid agg_input_collation,
+								Oid deserialfn_oid,
+								Expr **deserialfnexpr)
+{
+	Param	   *argp;
+	List	   *args;
+	FuncExpr   *fexpr;
+
+	/* Build arg list to use in the serialfn FuncExpr node. */
+	argp = makeNode(Param);
+	argp->paramkind = PARAM_EXEC;
+	argp->paramid = -1;
+	argp->paramtype = agg_serial_type;
+	argp->paramtypmod = -1;
+	argp->paramcollid = agg_input_collation;
+	argp->location = -1;
+
+	/* takes a single arg of the serial type */
+	args = list_make1(argp);
+
+	fexpr = makeFuncExpr(deserialfn_oid,
+						 agg_state_type,
+						 args,
+						 InvalidOid,
+						 agg_input_collation,
+						 COERCE_EXPLICIT_CALL);
+	fexpr->funcvariadic = false;
+	*deserialfnexpr = (Expr *) fexpr;
+}
+
+/*
+ * Like build_aggregate_transfn_expr, but creates an expression tree for the
  * final function of an aggregate, rather than the transition function.
  */
 void
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index fa93a8c..d04bfa6 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -3352,6 +3352,175 @@ numeric_avg_accum(PG_FUNCTION_ARGS)
 }
 
 /*
+ * Generic combine function for numeric aggregates without requirement for X^2
+ */
+Datum
+numeric_avg_combine(PG_FUNCTION_ARGS)
+{
+	NumericAggState *state1;
+	NumericAggState *state2;
+
+	state1 = PG_ARGISNULL(0) ? NULL : (NumericAggState *) PG_GETARG_POINTER(0);
+	state2 = PG_ARGISNULL(1) ? NULL : (NumericAggState *) PG_GETARG_POINTER(1);
+
+	if (state2 == NULL)
+		PG_RETURN_POINTER(state1);
+
+	/* manually copy all fields from state2 to state1 */
+	if (state1 == NULL)
+	{
+		MemoryContext old_context;
+
+		state1 = makeNumericAggState(fcinfo, false);
+		state1->N = state2->N;
+		state1->NaNcount = state2->NaNcount;
+		state1->maxScale = state2->maxScale;
+		state1->maxScaleCount = state2->maxScaleCount;
+
+		old_context = MemoryContextSwitchTo(state1->agg_context);
+
+		init_var(&state1->sumX);
+		set_var_from_var(&state2->sumX, &state1->sumX);
+
+		MemoryContextSwitchTo(old_context);
+
+		PG_RETURN_POINTER(state1);
+	}
+
+	if (state2->N > 0)
+	{
+		MemoryContext old_context;
+
+		state1->N += state2->N;
+		state1->NaNcount += state2->NaNcount;
+
+		/*
+		 * XXX do we care about these? They're really only needed for moving
+		 * aggregates.
+		 */
+		if (state2->maxScale > state1->maxScale)
+			state1->maxScale = state2->maxScale;
+		else if (state2->maxScale == state1->maxScale)
+			state1->maxScale += state2->maxScale;
+
+		/* The rest of this needs to work in the aggregate context */
+		old_context = MemoryContextSwitchTo(state1->agg_context);
+
+		/* Accumulate sums */
+		add_var(&(state1->sumX), &(state2->sumX), &(state1->sumX));
+
+		if (state1->calcSumX2)
+			add_var(&(state1->sumX2), &(state2->sumX2), &(state1->sumX2));
+
+		MemoryContextSwitchTo(old_context);
+	}
+	PG_RETURN_POINTER(state1);
+}
+
+/*
+ * numeric_avg_serialize
+ *		Serialize NumericAggState into text.
+ *		numeric_avg_deserialize(numeric_avg_serialize(state)) must result in
+ *		a state which matches the original input state.
+ */
+Datum
+numeric_avg_serialize(PG_FUNCTION_ARGS)
+{
+	NumericAggState *state;
+	StringInfoData string;
+	MemoryContext agg_context;
+	MemoryContext old_context;
+	text	   *result;
+
+	/* Ensure we disallow calling when not in aggregate context */
+	if (!AggCheckCallContext(fcinfo, &agg_context))
+		elog(ERROR, "aggregate function called in non-aggregate context");
+
+	state = (NumericAggState *) PG_GETARG_POINTER(0);
+
+	initStringInfo(&string);
+
+	/*
+	 * Transform the NumericAggState into a string with the following format:
+	 * "N sumX maxScale maxScaleCount NaNcount"
+	 * XXX perhaps we can come up with a more efficient format for this.
+	 */
+	appendStringInfo(&string, INT64_FORMAT " %s %d " INT64_FORMAT " " INT64_FORMAT,
+			state->N, get_str_from_var(&state->sumX), state->maxScale,
+			state->maxScaleCount, state->NaNcount);
+
+	old_context = MemoryContextSwitchTo(agg_context);
+
+	result = cstring_to_text_with_len(string.data, string.len);
+
+	MemoryContextSwitchTo(old_context);
+
+	PG_RETURN_TEXT_P(result);
+}
+
+/*
+ * numeric_avg_deserialize
+ *		deserialize Text into NumericAggState
+ *		numeric_avg_serialize(numeric_avg_deserialize(text)) must result in
+ *		text which matches the original input text.
+ */
+Datum
+numeric_avg_deserialize(PG_FUNCTION_ARGS)
+{
+	NumericAggState *result;
+	MemoryContext agg_context;
+	MemoryContext old_context;
+	Numeric		tmp;
+	text	   *sstate;
+	char	   *state;
+	char	   *token[5];
+	int			i;
+
+	if (!AggCheckCallContext(fcinfo, &agg_context))
+		elog(ERROR, "aggregate function called in non-aggregate context");
+
+	sstate = PG_GETARG_TEXT_P(0);
+	state = text_to_cstring(sstate);
+
+	token[0] = strtok(state, " ");
+
+	if (!token[0])
+		elog(ERROR, "invalid serialization format");
+
+	for (i = 1; i < 5; i++)
+	{
+		token[i] = strtok(NULL, " ");
+		if (!token[i])
+			elog(ERROR, "invalid serialization format");
+	}
+
+	old_context = MemoryContextSwitchTo(agg_context);
+
+	/*
+	 * Transform string into a NumericAggState. The string is in the format:
+	 * "N sumX maxScale maxScaleCount NaNcount"
+	 */
+	result = makeNumericAggState(fcinfo, false);
+
+	scanint8(token[0], false, &result->N);
+
+	tmp = DatumGetNumeric(DirectFunctionCall3(numeric_in,
+						  CStringGetDatum(token[1]),
+						  ObjectIdGetDatum(0),
+						  Int32GetDatum(-1)));
+	init_var_from_num(tmp, &result->sumX);
+
+	result->maxScale = pg_atoi(token[2], sizeof(int32), 0);
+	scanint8(token[3], false, &result->maxScaleCount);
+	scanint8(token[4], false, &result->NaNcount);
+
+	MemoryContextSwitchTo(old_context);
+
+	pfree(state);
+	PG_RETURN_POINTER(result);
+}
+
+/*
  * Generic inverse transition function for numeric aggregates
  * (with or without requirement for X^2).
  */
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 36863df..f6b9862 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -12279,6 +12279,9 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	PGresult   *res;
 	int			i_aggtransfn;
 	int			i_aggfinalfn;
+	int			i_aggcombinefn;
+	int			i_aggserialfn;
+	int			i_aggdeserialfn;
 	int			i_aggmtransfn;
 	int			i_aggminvtransfn;
 	int			i_aggmfinalfn;
@@ -12287,6 +12290,7 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	int			i_aggsortop;
 	int			i_hypothetical;
 	int			i_aggtranstype;
+	int			i_aggserialtype;
 	int			i_aggtransspace;
 	int			i_aggmtranstype;
 	int			i_aggmtransspace;
@@ -12295,6 +12299,9 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	int			i_convertok;
 	const char *aggtransfn;
 	const char *aggfinalfn;
+	const char *aggcombinefn;
+	const char *aggserialfn;
+	const char *aggdeserialfn;
 	const char *aggmtransfn;
 	const char *aggminvtransfn;
 	const char *aggmfinalfn;
@@ -12304,6 +12311,7 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	char	   *aggsortconvop;
 	bool		hypothetical;
 	const char *aggtranstype;
+	const char *aggserialtype;
 	const char *aggtransspace;
 	const char *aggmtranstype;
 	const char *aggmtransspace;
@@ -12325,7 +12333,27 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	selectSourceSchema(fout, agginfo->aggfn.dobj.namespace->dobj.name);
 
 	/* Get aggregate-specific details */
-	if (fout->remoteVersion >= 90400)
+	if (fout->remoteVersion >= 90600)
+	{
+		appendPQExpBuffer(query, "SELECT aggtransfn, "
+			"aggfinalfn, aggtranstype::pg_catalog.regtype, "
+			"aggcombinefn, aggserialfn, aggdeserialfn, aggmtransfn, "
+			"aggminvtransfn, aggmfinalfn, aggmtranstype::pg_catalog.regtype, "
+			"aggfinalextra, aggmfinalextra, "
+			"aggsortop::pg_catalog.regoperator, "
+			"aggserialtype::pg_catalog.regtype, "
+			"(aggkind = 'h') AS hypothetical, "
+			"aggtransspace, agginitval, "
+			"aggmtransspace, aggminitval, "
+			"true AS convertok, "
+			"pg_catalog.pg_get_function_arguments(p.oid) AS funcargs, "
+			"pg_catalog.pg_get_function_identity_arguments(p.oid) AS funciargs "
+			"FROM pg_catalog.pg_aggregate a, pg_catalog.pg_proc p "
+			"WHERE a.aggfnoid = p.oid "
+			"AND p.oid = '%u'::pg_catalog.oid",
+			agginfo->aggfn.dobj.catId.oid);
+	}
+	else if (fout->remoteVersion >= 90400)
 	{
 		appendPQExpBuffer(query, "SELECT aggtransfn, "
 						  "aggfinalfn, aggtranstype::pg_catalog.regtype, "
@@ -12435,12 +12463,16 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 
 	i_aggtransfn = PQfnumber(res, "aggtransfn");
 	i_aggfinalfn = PQfnumber(res, "aggfinalfn");
+	i_aggcombinefn = PQfnumber(res, "aggcombinefn");
+	i_aggserialfn = PQfnumber(res, "aggserialfn");
+	i_aggdeserialfn = PQfnumber(res, "aggdeserialfn");
 	i_aggmtransfn = PQfnumber(res, "aggmtransfn");
 	i_aggminvtransfn = PQfnumber(res, "aggminvtransfn");
 	i_aggmfinalfn = PQfnumber(res, "aggmfinalfn");
 	i_aggfinalextra = PQfnumber(res, "aggfinalextra");
 	i_aggmfinalextra = PQfnumber(res, "aggmfinalextra");
 	i_aggsortop = PQfnumber(res, "aggsortop");
+	i_aggserialtype = PQfnumber(res, "aggserialtype");
 	i_hypothetical = PQfnumber(res, "hypothetical");
 	i_aggtranstype = PQfnumber(res, "aggtranstype");
 	i_aggtransspace = PQfnumber(res, "aggtransspace");
@@ -12452,6 +12484,9 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 
 	aggtransfn = PQgetvalue(res, 0, i_aggtransfn);
 	aggfinalfn = PQgetvalue(res, 0, i_aggfinalfn);
+	aggcombinefn = PQgetvalue(res, 0, i_aggcombinefn);
+	aggserialfn = PQgetvalue(res, 0, i_aggserialfn);
+	aggdeserialfn = PQgetvalue(res, 0, i_aggdeserialfn);
 	aggmtransfn = PQgetvalue(res, 0, i_aggmtransfn);
 	aggminvtransfn = PQgetvalue(res, 0, i_aggminvtransfn);
 	aggmfinalfn = PQgetvalue(res, 0, i_aggmfinalfn);
@@ -12460,6 +12495,7 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	aggsortop = PQgetvalue(res, 0, i_aggsortop);
 	hypothetical = (PQgetvalue(res, 0, i_hypothetical)[0] == 't');
 	aggtranstype = PQgetvalue(res, 0, i_aggtranstype);
+	aggserialtype = PQgetvalue(res, 0, i_aggserialtype);
 	aggtransspace = PQgetvalue(res, 0, i_aggtransspace);
 	aggmtranstype = PQgetvalue(res, 0, i_aggmtranstype);
 	aggmtransspace = PQgetvalue(res, 0, i_aggmtransspace);
@@ -12540,6 +12576,18 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 			appendPQExpBufferStr(details, ",\n    FINALFUNC_EXTRA");
 	}
 
+	if (strcmp(aggcombinefn, "-") != 0)
+	{
+		appendPQExpBuffer(details, ",\n    COMBINEFUNC = %s",	aggcombinefn);
+	}
+
+	if (strcmp(aggserialfn, "-") != 0)
+	{
+		appendPQExpBuffer(details, ",\n    SERIALFUNC = %s",	aggserialfn);
+		appendPQExpBuffer(details, ",\n    DESERIALFUNC = %s",	aggdeserialfn);
+		appendPQExpBuffer(details, ",\n    SERIALTYPE = %s",	aggserialtype);
+	}
+
 	if (strcmp(aggmtransfn, "-") != 0)
 	{
 		appendPQExpBuffer(details, ",\n    MSFUNC = %s,\n    MINVFUNC = %s,\n    MSTYPE = %s",
diff --git a/src/include/catalog/pg_aggregate.h b/src/include/catalog/pg_aggregate.h
index dd6079f..3fe6cf0 100644
--- a/src/include/catalog/pg_aggregate.h
+++ b/src/include/catalog/pg_aggregate.h
@@ -33,6 +33,9 @@
  *	aggnumdirectargs	number of arguments that are "direct" arguments
  *	aggtransfn			transition function
  *	aggfinalfn			final function (0 if none)
+ *	aggcombinefn		combine function (0 if none)
+ *	aggserialfn			function to convert transtype into serialtype
+ *	aggdeserialfn		function to convert serialtype into transtype
  *	aggmtransfn			forward function for moving-aggregate mode (0 if none)
  *	aggminvtransfn		inverse function for moving-aggregate mode (0 if none)
  *	aggmfinalfn			final function for moving-aggregate mode (0 if none)
@@ -42,6 +45,7 @@
  *	aggtranstype		type of aggregate's transition (state) data
  *	aggtransspace		estimated size of state data (0 for default estimate)
  *	aggmtranstype		type of moving-aggregate state data (0 if none)
+ *	aggserialtype		datatype to serialize state to. (0 if none)
  *	aggmtransspace		estimated size of moving-agg state (0 for default est)
  *	agginitval			initial value for transition state (can be NULL)
  *	aggminitval			initial value for moving-agg state (can be NULL)
@@ -56,6 +60,9 @@ CATALOG(pg_aggregate,2600) BKI_WITHOUT_OIDS
 	int16		aggnumdirectargs;
 	regproc		aggtransfn;
 	regproc		aggfinalfn;
+	regproc		aggcombinefn;
+	regproc		aggserialfn;
+	regproc		aggdeserialfn;
 	regproc		aggmtransfn;
 	regproc		aggminvtransfn;
 	regproc		aggmfinalfn;
@@ -63,6 +70,7 @@ CATALOG(pg_aggregate,2600) BKI_WITHOUT_OIDS
 	bool		aggmfinalextra;
 	Oid			aggsortop;
 	Oid			aggtranstype;
+	Oid			aggserialtype;
 	int32		aggtransspace;
 	Oid			aggmtranstype;
 	int32		aggmtransspace;
@@ -85,24 +93,28 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  * ----------------
  */
 
-#define Natts_pg_aggregate					17
+#define Natts_pg_aggregate					21
 #define Anum_pg_aggregate_aggfnoid			1
 #define Anum_pg_aggregate_aggkind			2
 #define Anum_pg_aggregate_aggnumdirectargs	3
 #define Anum_pg_aggregate_aggtransfn		4
 #define Anum_pg_aggregate_aggfinalfn		5
-#define Anum_pg_aggregate_aggmtransfn		6
-#define Anum_pg_aggregate_aggminvtransfn	7
-#define Anum_pg_aggregate_aggmfinalfn		8
-#define Anum_pg_aggregate_aggfinalextra		9
-#define Anum_pg_aggregate_aggmfinalextra	10
-#define Anum_pg_aggregate_aggsortop			11
-#define Anum_pg_aggregate_aggtranstype		12
-#define Anum_pg_aggregate_aggtransspace		13
-#define Anum_pg_aggregate_aggmtranstype		14
-#define Anum_pg_aggregate_aggmtransspace	15
-#define Anum_pg_aggregate_agginitval		16
-#define Anum_pg_aggregate_aggminitval		17
+#define Anum_pg_aggregate_aggcombinefn		6
+#define Anum_pg_aggregate_aggserialfn		7
+#define Anum_pg_aggregate_aggdeserialfn		8
+#define Anum_pg_aggregate_aggmtransfn		9
+#define Anum_pg_aggregate_aggminvtransfn	10
+#define Anum_pg_aggregate_aggmfinalfn		11
+#define Anum_pg_aggregate_aggfinalextra		12
+#define Anum_pg_aggregate_aggmfinalextra	13
+#define Anum_pg_aggregate_aggsortop			14
+#define Anum_pg_aggregate_aggtranstype		15
+#define Anum_pg_aggregate_aggserialtype		16
+#define Anum_pg_aggregate_aggtransspace		17
+#define Anum_pg_aggregate_aggmtranstype		18
+#define Anum_pg_aggregate_aggmtransspace	19
+#define Anum_pg_aggregate_agginitval		20
+#define Anum_pg_aggregate_aggminitval		21
 
 /*
  * Symbolic values for aggkind column.  We distinguish normal aggregates
@@ -126,184 +138,184 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  */
 
 /* avg */
-DATA(insert ( 2100	n 0 int8_avg_accum	numeric_poly_avg		int8_avg_accum	int8_avg_accum_inv	numeric_poly_avg	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg		int4_avg_accum	int4_avg_accum_inv	int8_avg					f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg		int2_avg_accum	int2_avg_accum_inv	int8_avg					f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg	numeric_avg_accum numeric_accum_inv numeric_avg					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2104	n 0 float4_accum	float8_avg		-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2105	n 0 float8_accum	float8_avg		-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2106	n 0 interval_accum	interval_avg	interval_accum	interval_accum_inv interval_avg					f f 0	1187	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
+DATA(insert ( 2100	n 0 int8_avg_accum	numeric_poly_avg	-					-	-	int8_avg_accum	int8_avg_accum_inv	numeric_poly_avg	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg			-					-	-	int4_avg_accum	int4_avg_accum_inv	int8_avg			f f 0	1016	0	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg			-					-	-	int2_avg_accum	int2_avg_accum_inv	int8_avg			f f 0	1016	0	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg		numeric_avg_combine	numeric_avg_serialize	numeric_avg_deserialize	numeric_avg_accum numeric_accum_inv numeric_avg			f f 0	2281	25	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2104	n 0 float4_accum	float8_avg			-					-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2105	n 0 float8_accum	float8_avg			-					-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2106	n 0 interval_accum	interval_avg		-					-	-	interval_accum	interval_accum_inv interval_avg			f f 0	1187	0	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
 
 /* sum */
-DATA(insert ( 2107	n 0 int8_avg_accum	numeric_poly_sum		int8_avg_accum	int8_avg_accum_inv numeric_poly_sum f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2108	n 0 int4_sum		-				int4_avg_accum	int4_avg_accum_inv int2int4_sum					f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2109	n 0 int2_sum		-				int2_avg_accum	int2_avg_accum_inv int2int4_sum					f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2110	n 0 float4pl		-				-				-				-								f f 0	700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2111	n 0 float8pl		-				-				-				-								f f 0	701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2112	n 0 cash_pl			-				cash_pl			cash_mi			-								f f 0	790		0	790		0	_null_ _null_ ));
-DATA(insert ( 2113	n 0 interval_pl		-				interval_pl		interval_mi		-								f f 0	1186	0	1186	0	_null_ _null_ ));
-DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum numeric_avg_accum numeric_accum_inv numeric_sum					f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2107	n 0 int8_avg_accum	numeric_poly_sum	-					-	-	int8_avg_accum	int8_avg_accum_inv	numeric_poly_sum	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2108	n 0 int4_sum		-					int8pl				-	-	int4_avg_accum	int4_avg_accum_inv	int2int4_sum		f f 0	20		0	0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2109	n 0 int2_sum		-					int8pl				-	-	int2_avg_accum	int2_avg_accum_inv	int2int4_sum		f f 0	20		0	0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2110	n 0 float4pl		-					float4pl			-	-	-				-					-					f f 0	700		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2111	n 0 float8pl		-					float8pl			-	-	-				-					-					f f 0	701		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2112	n 0 cash_pl			-					cash_pl				-	-	cash_pl			cash_mi				-					f f 0	790		0	0	790		0	_null_ _null_ ));
+DATA(insert ( 2113	n 0 interval_pl		-					interval_pl			-	-	interval_pl		interval_mi			-					f f 0	1186	0	0	1186	0	_null_ _null_ ));
+DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum		numeric_avg_combine	numeric_avg_serialize	numeric_avg_deserialize	numeric_avg_accum	numeric_accum_inv	numeric_sum		f f 0	2281	25	128 2281	128 _null_ _null_ ));
 
 /* max */
-DATA(insert ( 2115	n 0 int8larger		-				-				-				-				f f 413		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2116	n 0 int4larger		-				-				-				-				f f 521		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2117	n 0 int2larger		-				-				-				-				f f 520		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2118	n 0 oidlarger		-				-				-				-				f f 610		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2119	n 0 float4larger	-				-				-				-				f f 623		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2120	n 0 float8larger	-				-				-				-				f f 674		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2121	n 0 int4larger		-				-				-				-				f f 563		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2122	n 0 date_larger		-				-				-				-				f f 1097	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2123	n 0 time_larger		-				-				-				-				f f 1112	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2124	n 0 timetz_larger	-				-				-				-				f f 1554	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2125	n 0 cashlarger		-				-				-				-				f f 903		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2126	n 0 timestamp_larger	-			-				-				-				f f 2064	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2127	n 0 timestamptz_larger	-			-				-				-				f f 1324	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2128	n 0 interval_larger -				-				-				-				f f 1334	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2129	n 0 text_larger		-				-				-				-				f f 666		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2130	n 0 numeric_larger	-				-				-				-				f f 1756	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2050	n 0 array_larger	-				-				-				-				f f 1073	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2244	n 0 bpchar_larger	-				-				-				-				f f 1060	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2797	n 0 tidlarger		-				-				-				-				f f 2800	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3526	n 0 enum_larger		-				-				-				-				f f 3519	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3564	n 0 network_larger	-				-				-				-				f f 1205	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2115	n 0 int8larger		-				int8larger			-	-	-				-				-				f f 413		20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2116	n 0 int4larger		-				int4larger			-	-	-				-				-				f f 521		23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2117	n 0 int2larger		-				int2larger			-	-	-				-				-				f f 520		21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2118	n 0 oidlarger		-				oidlarger			-	-	-				-				-				f f 610		26		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2119	n 0 float4larger	-				float4larger		-	-	-				-				-				f f 623		700		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2120	n 0 float8larger	-				float8larger		-	-	-				-				-				f f 674		701		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2121	n 0 int4larger		-				int4larger			-	-	-				-				-				f f 563		702		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2122	n 0 date_larger		-				date_larger			-	-	-				-				-				f f 1097	1082	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2123	n 0 time_larger		-				time_larger			-	-	-				-				-				f f 1112	1083	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2124	n 0 timetz_larger	-				timetz_larger		-	-	-				-				-				f f 1554	1266	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2125	n 0 cashlarger		-				cashlarger			-	-	-				-				-				f f 903		790		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2126	n 0 timestamp_larger	-			timestamp_larger	-	-	-				-				-				f f 2064	1114	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2127	n 0 timestamptz_larger	-			timestamptz_larger	-	-	-				-				-				f f 1324	1184	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2128	n 0 interval_larger -				interval_larger		-	-	-				-				-				f f 1334	1186	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2129	n 0 text_larger		-				text_larger			-	-	-				-				-				f f 666		25		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2130	n 0 numeric_larger	-				numeric_larger		-	-	-				-				-				f f 1756	1700	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2050	n 0 array_larger	-				array_larger		-	-	-				-				-				f f 1073	2277	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2244	n 0 bpchar_larger	-				bpchar_larger		-	-	-				-				-				f f 1060	1042	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2797	n 0 tidlarger		-				tidlarger			-	-	-				-				-				f f 2800	27		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3526	n 0 enum_larger		-				enum_larger			-	-	-				-				-				f f 3519	3500	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3564	n 0 network_larger	-				network_larger		-	-	-				-				-				f f 1205	869		0	0	0		0	_null_ _null_ ));
 
 /* min */
-DATA(insert ( 2131	n 0 int8smaller		-				-				-				-				f f 412		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2132	n 0 int4smaller		-				-				-				-				f f 97		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2133	n 0 int2smaller		-				-				-				-				f f 95		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2134	n 0 oidsmaller		-				-				-				-				f f 609		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2135	n 0 float4smaller	-				-				-				-				f f 622		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2136	n 0 float8smaller	-				-				-				-				f f 672		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2137	n 0 int4smaller		-				-				-				-				f f 562		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2138	n 0 date_smaller	-				-				-				-				f f 1095	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2139	n 0 time_smaller	-				-				-				-				f f 1110	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2140	n 0 timetz_smaller	-				-				-				-				f f 1552	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2141	n 0 cashsmaller		-				-				-				-				f f 902		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2142	n 0 timestamp_smaller	-			-				-				-				f f 2062	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2143	n 0 timestamptz_smaller -			-				-				-				f f 1322	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2144	n 0 interval_smaller	-			-				-				-				f f 1332	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2145	n 0 text_smaller	-				-				-				-				f f 664		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2146	n 0 numeric_smaller -				-				-				-				f f 1754	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2051	n 0 array_smaller	-				-				-				-				f f 1072	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2245	n 0 bpchar_smaller	-				-				-				-				f f 1058	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2798	n 0 tidsmaller		-				-				-				-				f f 2799	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3527	n 0 enum_smaller	-				-				-				-				f f 3518	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3565	n 0 network_smaller -				-				-				-				f f 1203	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2131	n 0 int8smaller		-				int8smaller			-	-	-				-				-				f f 412		20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2132	n 0 int4smaller		-				int4smaller			-	-	-				-				-				f f 97		23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2133	n 0 int2smaller		-				int2smaller			-	-	-				-				-				f f 95		21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2134	n 0 oidsmaller		-				oidsmaller			-	-	-				-				-				f f 609		26		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2135	n 0 float4smaller	-				float4smaller		-	-	-				-				-				f f 622		700		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2136	n 0 float8smaller	-				float8smaller		-	-	-				-				-				f f 672		701		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2137	n 0 int4smaller		-				int4smaller			-	-	-				-				-				f f 562		702		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2138	n 0 date_smaller	-				date_smaller		-	-	-				-				-				f f 1095	1082	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2139	n 0 time_smaller	-				time_smaller		-	-	-				-				-				f f 1110	1083	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2140	n 0 timetz_smaller	-				timetz_smaller		-	-	-				-				-				f f 1552	1266	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2141	n 0 cashsmaller		-				cashsmaller			-	-	-				-				-				f f 902		790		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2142	n 0 timestamp_smaller	-			timestamp_smaller	-	-	-				-				-				f f 2062	1114	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2143	n 0 timestamptz_smaller -			timestamptz_smaller	-	-	-				-				-				f f 1322	1184	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2144	n 0 interval_smaller	-			interval_smaller	-	-	-				-				-				f f 1332	1186	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2145	n 0 text_smaller	-				text_smaller		-	-	-				-				-				f f 664		25		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2146	n 0 numeric_smaller -				numeric_smaller		-	-	-				-				-				f f 1754	1700	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2051	n 0 array_smaller	-				array_smaller		-	-	-				-				-				f f 1072	2277	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2245	n 0 bpchar_smaller	-				bpchar_smaller		-	-	-				-				-				f f 1058	1042	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2798	n 0 tidsmaller		-				tidsmaller			-	-	-				-				-				f f 2799	27		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3527	n 0 enum_smaller	-				enum_smaller		-	-	-				-				-				f f 3518	3500	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3565	n 0 network_smaller -				network_smaller		-	-	-				-				-				f f 1203	869		0	0	0		0	_null_ _null_ ));
 
 /* count */
-DATA(insert ( 2147	n 0 int8inc_any		-				int8inc_any		int8dec_any		-				f f 0		20		0	20		0	"0" "0" ));
-DATA(insert ( 2803	n 0 int8inc			-				int8inc			int8dec			-				f f 0		20		0	20		0	"0" "0" ));
+DATA(insert ( 2147	n 0 int8inc_any		-				int8pl	-	-	int8inc_any		int8dec_any		-				f f 0		20		0	0	20		0	"0" "0" ));
+DATA(insert ( 2803	n 0 int8inc			-				int8pl	-	-	int8inc			int8dec			-				f f 0		20		0	0	20		0	"0" "0" ));
 
 /* var_pop */
-DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop		int8_accum		int8_accum_inv	numeric_var_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2719	n 0 int4_accum	numeric_poly_var_pop		int4_accum		int4_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2720	n 0 int2_accum	numeric_poly_var_pop		int2_accum		int2_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2721	n 0 float4_accum	float8_var_pop	-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2722	n 0 float8_accum	float8_var_pop	-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop numeric_accum numeric_accum_inv numeric_var_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop			-	-	-	int8_accum		int8_accum_inv	numeric_var_pop			f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2719	n 0 int4_accum	numeric_poly_var_pop	-	-	-	int4_accum		int4_accum_inv	numeric_poly_var_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2720	n 0 int2_accum	numeric_poly_var_pop	-	-	-	int2_accum		int2_accum_inv	numeric_poly_var_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2721	n 0 float4_accum	float8_var_pop		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2722	n 0 float8_accum	float8_var_pop		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop		-	-	-	numeric_accum numeric_accum_inv numeric_var_pop			f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* var_samp */
-DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp	int8_accum		int8_accum_inv	numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2642	n 0 int4_accum	numeric_poly_var_samp		int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2643	n 0 int2_accum	numeric_poly_var_samp		int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2644	n 0 float4_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2645	n 0 float8_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp numeric_accum numeric_accum_inv numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp		-	-	-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2642	n 0 int4_accum	numeric_poly_var_samp	-	-	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2643	n 0 int2_accum	numeric_poly_var_samp	-	-	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2644	n 0 float4_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2645	n 0 float8_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp	-	-	-	numeric_accum	numeric_accum_inv numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* variance: historical Postgres syntax for var_samp */
-DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp	int8_accum		int8_accum_inv	numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2149	n 0 int4_accum	numeric_poly_var_samp		int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2150	n 0 int2_accum	numeric_poly_var_samp		int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2151	n 0 float4_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2152	n 0 float8_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp numeric_accum numeric_accum_inv numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp		-	-	-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2149	n 0 int4_accum	numeric_poly_var_samp	-	-	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2150	n 0 int2_accum	numeric_poly_var_samp	-	-	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2151	n 0 float4_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2152	n 0 float8_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp	-	-	-	numeric_accum numeric_accum_inv numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* stddev_pop */
-DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop	int8_accum	int8_accum_inv	numeric_stddev_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2725	n 0 int4_accum	numeric_poly_stddev_pop int4_accum	int4_accum_inv	numeric_poly_stddev_pop f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2726	n 0 int2_accum	numeric_poly_stddev_pop int2_accum	int2_accum_inv	numeric_poly_stddev_pop f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop numeric_accum numeric_accum_inv numeric_stddev_pop			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop		-	-	-	int8_accum	int8_accum_inv	numeric_stddev_pop		f f 0	2281	0	128	2281	128 _null_ _null_ ));
+DATA(insert ( 2725	n 0 int4_accum	numeric_poly_stddev_pop	-	-	-	int4_accum	int4_accum_inv	numeric_poly_stddev_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2726	n 0 int2_accum	numeric_poly_stddev_pop	-	-	-	int2_accum	int2_accum_inv	numeric_poly_stddev_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-	-	-	-				-				-					f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-	-	-	-				-				-					f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop	-	-	-	numeric_accum numeric_accum_inv numeric_stddev_pop	f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* stddev_samp */
-DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp		int8_accum	int8_accum_inv	numeric_stddev_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2713	n 0 int4_accum	numeric_poly_stddev_samp	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2714	n 0 int2_accum	numeric_poly_stddev_samp	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp numeric_accum numeric_accum_inv numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp			-	-	-	int8_accum	int8_accum_inv	numeric_stddev_samp			f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2713	n 0 int4_accum	numeric_poly_stddev_samp	-	-	-	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2714	n 0 int2_accum	numeric_poly_stddev_samp	-	-	-	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp		-	-	-	numeric_accum numeric_accum_inv numeric_stddev_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* stddev: historical Postgres syntax for stddev_samp */
-DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp		int8_accum	int8_accum_inv	numeric_stddev_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2155	n 0 int4_accum	numeric_poly_stddev_samp	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2156	n 0 int2_accum	numeric_poly_stddev_samp	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp numeric_accum numeric_accum_inv numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp			-	-	-	int8_accum		int8_accum_inv	numeric_stddev_samp			f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2155	n 0 int4_accum	numeric_poly_stddev_samp	-	-	-	int4_accum		int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2156	n 0 int2_accum	numeric_poly_stddev_samp	-	-	-	int2_accum		int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp		-	-	-	-				-				-							f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp		-	-	-	-				-				-							f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp		-	-	-	numeric_accum	numeric_accum_inv numeric_stddev_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* SQL2003 binary regression aggregates */
-DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-				-				-				f f 0	20		0	0		0	"0" _null_ ));
-DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-	-	-	-				-				-			f f 0	20		0	0	0		0	"0" _null_ ));
+DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
 
 /* boolean-and and boolean-or */
-DATA(insert ( 2517	n 0 booland_statefunc	-			bool_accum		bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2518	n 0 boolor_statefunc	-			bool_accum		bool_accum_inv	bool_anytrue	f f 59	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2519	n 0 booland_statefunc	-			bool_accum		bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2517	n 0 booland_statefunc	-	-	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16	0		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2518	n 0 boolor_statefunc	-	-	-	-	bool_accum	bool_accum_inv	bool_anytrue	f f 59	16	0		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2519	n 0 booland_statefunc	-	-	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16	0		0	2281	16	_null_ _null_ ));
 
 /* bitwise integer */
-DATA(insert ( 2236	n 0 int2and		-					-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2237	n 0 int2or		-					-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2238	n 0 int4and		-					-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2239	n 0 int4or		-					-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2240	n 0 int8and		-					-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2241	n 0 int8or		-					-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2242	n 0 bitand		-					-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
-DATA(insert ( 2243	n 0 bitor		-					-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
+DATA(insert ( 2236	n 0 int2and		-				int2and	-	-	-				-				-				f f 0	21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2237	n 0 int2or		-				int2or	-	-	-				-				-				f f 0	21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2238	n 0 int4and		-				int4and	-	-	-				-				-				f f 0	23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2239	n 0 int4or		-				int4or	-	-	-				-				-				f f 0	23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2240	n 0 int8and		-				int8and	-	-	-				-				-				f f 0	20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2241	n 0 int8or		-				int8or	-	-	-				-				-				f f 0	20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2242	n 0 bitand		-				bitand	-	-	-				-				-				f f 0	1560	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2243	n 0 bitor		-				bitor	-	-	-				-				-				f f 0	1560	0	0	0		0	_null_ _null_ ));
 
 /* xml */
-DATA(insert ( 2901	n 0 xmlconcat2	-					-				-				-				f f 0	142		0	0		0	_null_ _null_ ));
+DATA(insert ( 2901	n 0 xmlconcat2	-				-		-	-	-				-				-				f f 0	142		0	0	0		0	_null_ _null_ ));
 
 /* array */
-DATA(insert ( 2335	n 0 array_agg_transfn	array_agg_finalfn	-				-				-				t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn -		-				-				t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 2335	n 0 array_agg_transfn		array_agg_finalfn		-	-	-	-		-				-				t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn	-	-	-	-		-				-				t f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* text */
-DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-	-	-	-				-				-				f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* bytea */
-DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-				-				-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-	-	-	-				-				-		f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* json */
-DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-	-	-	-				-				-				f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -	-	-	-				-				-				f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* jsonb */
-DATA(insert ( 3267	n 0 jsonb_agg_transfn	jsonb_agg_finalfn			-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3270	n 0 jsonb_object_agg_transfn jsonb_object_agg_finalfn -				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3267	n 0 jsonb_agg_transfn	jsonb_agg_finalfn				-	-	-	-				-				-			f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3270	n 0 jsonb_object_agg_transfn jsonb_object_agg_finalfn	-	-	-	-				-				-			f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* ordered-set and hypothetical-set aggregates */
-DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
 
 
 /*
@@ -322,6 +334,9 @@ extern ObjectAddress AggregateCreate(const char *aggName,
 				Oid variadicArgType,
 				List *aggtransfnName,
 				List *aggfinalfnName,
+				List *aggcombinefnName,
+				List *aggserialfnName,
+				List *aggdeserialfnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
@@ -329,6 +344,7 @@ extern ObjectAddress AggregateCreate(const char *aggName,
 				bool mfinalfnExtraArgs,
 				List *aggsortopName,
 				Oid aggTransType,
+				Oid aggSerialType,
 				int32 aggTransSpace,
 				Oid aggmTransType,
 				int32 aggmTransSpace,
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index d8640db..afe81ab 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -2515,6 +2515,12 @@ DESCR("aggregate final function");
 DATA(insert OID = 1833 (  numeric_accum    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_accum _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
 DATA(insert OID = 2858 (  numeric_avg_accum    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_avg_accum _null_ _null_ _null_ ));
+DESCR("aggregate combine function");
+DATA(insert OID = 3317 (  numeric_avg_combine    PGNSP PGUID 12 1 0 0 0 f f f f t f i s 2 0 2281 "2281 2281" _null_ _null_ _null_ _null_ _null_ numeric_avg_combine _null_ _null_ _null_ ));
+DESCR("aggregate serial function");
+DATA(insert OID = 3318 (  numeric_avg_serialize    PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 25 "2281" _null_ _null_ _null_ _null_ _null_ numeric_avg_serialize _null_ _null_ _null_ ));
+DESCR("aggregate deserial function");
+DATA(insert OID = 3319 (  numeric_avg_deserialize    PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 2281 "25" _null_ _null_ _null_ _null_ _null_ numeric_avg_deserialize _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
 DATA(insert OID = 3548 (  numeric_accum_inv    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_accum_inv _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 5ccf470..4dad0ae5 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1851,6 +1851,9 @@ typedef struct AggState
 	AggStatePerTrans curpertrans;	/* currently active trans state */
 	bool		input_done;		/* indicates end of input */
 	bool		agg_done;		/* indicates completion of Agg scan */
+	bool		combineStates;	/* input tuples contain transition states */
+	bool		finalizeAggs;	/* should we call the finalfn on agg states? */
+	bool		serialStates;	/* should partial states be serialized? */
 	int			projected_set;	/* The last projected grouping set */
 	int			current_set;	/* The current grouping set being evaluated */
 	Bitmapset  *grouped_cols;	/* grouped cols in current projection */
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 37086c6..3082114 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -726,6 +726,9 @@ typedef struct Agg
 	AggStrategy aggstrategy;
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
+	bool		combineStates;	/* input tuples contain transition states */
+	bool		finalizeAggs;	/* should we call the finalfn on agg states? */
+	bool		serialStates;	/* should partial states be serialized? */
 	Oid		   *grpOperators;	/* equality operators to compare with */
 	long		numGroups;		/* estimated number of groups in input */
 	List	   *groupingSets;	/* grouping sets to use */
diff --git a/src/include/optimizer/clauses.h b/src/include/optimizer/clauses.h
index 323f093..8097087 100644
--- a/src/include/optimizer/clauses.h
+++ b/src/include/optimizer/clauses.h
@@ -27,6 +27,25 @@ typedef struct
 	List	  **windowFuncs;	/* lists of WindowFuncs for each winref */
 } WindowFuncLists;
 
+/*
+ * PartialAggType
+ *	PartialAggType stores whether partial aggregation is allowed and
+ *	which context it is allowed in. We require three states here as there are
+ *	two different contexts in which partial aggregation is safe. For aggregates
+ *	which have an 'stype' of INTERNAL, within a single backend process it is
+ *	okay to pass a pointer to the aggregate state, as the memory to which the
+ *	pointer points to will belong to the same process. In cases where the
+ *	aggregate state must be passed between different processes, for example
+ *	during parallel aggregation, passing the pointer is not okay due to the
+ *	fact that the memory being referenced won't be accessible from another
+ *	process.
+ */
+typedef enum
+{
+	PAT_ANY = 0,		/* Any type of partial aggregation is ok. */
+	PAT_INTERNAL_ONLY,	/* Some aggregates support only internal mode. */
+	PAT_DISABLED		/* Some aggregates don't support partial mode at all */
+} PartialAggType;
 
 extern Expr *make_opclause(Oid opno, Oid opresulttype, bool opretset,
 			  Expr *leftop, Expr *rightop,
@@ -47,6 +66,7 @@ extern Node *make_and_qual(Node *qual1, Node *qual2);
 extern Expr *make_ands_explicit(List *andclauses);
 extern List *make_ands_implicit(Expr *clause);
 
+extern PartialAggType aggregates_allow_partial(Node *clause);
 extern bool contain_agg_clause(Node *clause);
 extern void count_agg_clauses(PlannerInfo *root, Node *clause,
 				  AggClauseCosts *costs);
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index f96e9ee..421fa5d 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -60,9 +60,8 @@ extern Sort *make_sort_from_groupcols(PlannerInfo *root, List *groupcls,
 extern Agg *make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
 		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
-		 List *groupingSets,
-		 long numGroups,
-		 Plan *lefttree);
+		 List *groupingSets, long numGroups, bool combineStates,
+		 bool finalizeAggs, bool serialStates, Plan *lefttree);
 extern WindowAgg *make_windowagg(PlannerInfo *root, List *tlist,
 			   List *windowFuncs, Index winref,
 			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
diff --git a/src/include/parser/parse_agg.h b/src/include/parser/parse_agg.h
index e2b3894..a79bc72 100644
--- a/src/include/parser/parse_agg.h
+++ b/src/include/parser/parse_agg.h
@@ -46,6 +46,23 @@ extern void build_aggregate_transfn_expr(Oid *agg_input_types,
 						Expr **transfnexpr,
 						Expr **invtransfnexpr);
 
+extern void build_aggregate_combinefn_expr(Oid agg_state_type,
+										   Oid agg_input_collation,
+										   Oid combinefn_oid,
+										   Expr **combinefnexpr);
+
+extern void build_aggregate_serialfn_expr(Oid agg_state_type,
+										  Oid agg_serial_type,
+										  Oid agg_input_collation,
+										  Oid serialfn_oid,
+										  Expr **serialfnexpr);
+
+extern void build_aggregate_deserialfn_expr(Oid agg_state_type,
+											Oid agg_serial_type,
+											Oid agg_input_collation,
+											Oid deserialfn_oid,
+											Expr **deserialfnexpr);
+
 extern void build_aggregate_finalfn_expr(Oid *agg_input_types,
 						int num_finalfn_inputs,
 						Oid agg_state_type,
diff --git a/src/test/regress/expected/create_aggregate.out b/src/test/regress/expected/create_aggregate.out
index 82a34fb..14f73c4 100644
--- a/src/test/regress/expected/create_aggregate.out
+++ b/src/test/regress/expected/create_aggregate.out
@@ -101,6 +101,93 @@ CREATE AGGREGATE sumdouble (float8)
     msfunc = float8pl,
     minvfunc = float8mi
 );
+-- aggregate combine and serialization functions
+-- Ensure stype and serialtype can't be the same
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = internal
+);
+ERROR:  aggregate serial data type cannot be "internal"
+-- if serialtype is specified we need a serialfunc and deserialfunc
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text
+);
+ERROR:  aggregate serialfunc must be specified when serialtype is specified
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize
+);
+ERROR:  aggregate deserialfunc must be specified when serialtype is specified
+-- serialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_deserialize,
+	deserialfunc = numeric_avg_deserialize
+);
+ERROR:  function numeric_avg_deserialize(internal) does not exist
+-- deserialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_serialize
+);
+ERROR:  function numeric_avg_serialize(text) does not exist
+-- ensure return type of serialfunc is checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = bytea,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize
+);
+ERROR:  return type of serial function numeric_avg_serialize is not bytea
+-- ensure combine function parameters are checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = int4larger
+);
+ERROR:  function int4larger(internal, internal) does not exist
+-- ensure create aggregate works.
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	finalfunc = numeric_avg,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = numeric_avg_combine
+);
+-- Ensure all these functions made it into the catalog
+SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype,aggserialfn,aggdeserialfn,aggserialtype
+FROM pg_aggregate
+WHERE aggfnoid = 'myavg'::REGPROC;
+ aggfnoid |    aggtransfn     |    aggcombinefn     | aggtranstype |      aggserialfn      |      aggdeserialfn      | aggserialtype 
+----------+-------------------+---------------------+--------------+-----------------------+-------------------------+---------------
+ myavg    | numeric_avg_accum | numeric_avg_combine |         2281 | numeric_avg_serialize | numeric_avg_deserialize |            25
+(1 row)
+
+DROP AGGREGATE myavg (numeric);
 -- invalid: nonstrict inverse with strict forward function
 CREATE FUNCTION float8mi_n(float8, float8) RETURNS float8 AS
 $$ SELECT $1 - $2; $$
diff --git a/src/test/regress/sql/create_aggregate.sql b/src/test/regress/sql/create_aggregate.sql
index 0ec1572..8395e5d 100644
--- a/src/test/regress/sql/create_aggregate.sql
+++ b/src/test/regress/sql/create_aggregate.sql
@@ -115,6 +115,92 @@ CREATE AGGREGATE sumdouble (float8)
     minvfunc = float8mi
 );
 
+-- aggregate combine and serialization functions
+
+-- Ensure stype and serialtype can't be the same
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = internal
+);
+
+-- if serialtype is specified we need a serialfunc and deserialfunc
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text
+);
+
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize
+);
+
+-- serialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_deserialize,
+	deserialfunc = numeric_avg_deserialize
+);
+
+-- deserialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_serialize
+);
+
+-- ensure return type of serialfunc is checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = bytea,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize
+);
+
+-- ensure combine function parameters are checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = int4larger
+);
+
+-- ensure create aggregate works.
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	finalfunc = numeric_avg,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = numeric_avg_combine
+);
+
+-- Ensure all these functions made it into the catalog
+SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype,aggserialfn,aggdeserialfn,aggserialtype
+FROM pg_aggregate
+WHERE aggfnoid = 'myavg'::REGPROC;
+
+DROP AGGREGATE myavg (numeric);
+
 -- invalid: nonstrict inverse with strict forward function
 
 CREATE FUNCTION float8mi_n(float8, float8) RETURNS float8 AS

diff --git b/src/backend/optimizer/plan/planner.c a/src/backend/optimizer/plan/planner.c
index 6897c1f..95faefb 100644
--- b/src/backend/optimizer/plan/planner.c
+++ a/src/backend/optimizer/plan/planner.c
@@ -134,7 +134,104 @@ static Plan *build_grouping_chain(PlannerInfo *root,
 					 AttrNumber *groupColIdx,
 					 AggClauseCosts *agg_costs,
 					 long numGroups,
-					 Plan *result_plan);
+					 Plan *result_plan,
+					 PartialAggType partialaggtype);
+
+static List *
+make_aggregate_tlist(PlannerInfo *root,
+					 List *tlist,
+					 AttrNumber **groupColIdx)
+{
+	Query	   *parse = root->parse;
+	List	   *sub_tlist;
+	List	   *non_group_cols;
+	List	   *non_group_vars;
+	int			numCols;
+	ListCell   *tl;
+
+	*groupColIdx = NULL;
+
+	/*
+	 * Otherwise, we must build a tlist containing all grouping columns, plus
+	 * any other Vars mentioned in the targetlist and HAVING qual.
+	 */
+	sub_tlist = NIL;
+	non_group_cols = NIL;
+
+	numCols = list_length(parse->groupClause);
+	if (numCols > 0)
+	{
+		/*
+		 * If grouping, create sub_tlist entries for all GROUP BY columns, and
+		 * make an array showing where the group columns are in the sub_tlist.
+		 *
+		 * Note: with this implementation, the array entries will always be
+		 * 1..N, but we don't want callers to assume that.
+		 */
+		AttrNumber *grpColIdx;
+
+		grpColIdx = (AttrNumber *) palloc0(sizeof(AttrNumber) * numCols);
+		*groupColIdx = grpColIdx;
+
+		foreach(tl, tlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(tl);
+			int			colno;
+
+			colno = get_grouping_column_index(parse, tle);
+			if (colno >= 0)
+			{
+				/*
+				 * It's a grouping column, so add it to the result tlist and
+				 * remember its resno in grpColIdx[].
+				 */
+				TargetEntry *newtle;
+
+				newtle = makeTargetEntry((Expr *) copyObject(tle->expr),
+										 list_length(sub_tlist) + 1,
+										 NULL,
+										 tle->resjunk);
+				newtle->ressortgroupref = tle->ressortgroupref;
+				sub_tlist = lappend(sub_tlist, newtle);
+
+				Assert(grpColIdx[colno] == 0);	/* no dups expected */
+				grpColIdx[colno] = newtle->resno;
+			}
+			else
+			{
+				non_group_cols = lappend(non_group_cols, tle->expr);
+			}
+		}
+	}
+	else
+	{
+		foreach(tl, tlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(tl);
+			non_group_cols = lappend(non_group_cols, tle->expr);
+		}
+	}
+
+	/*
+	 * If there's a HAVING clause, we'll need need to ensure all Aggrefs from
+	 * there are also in the targetlist
+	 */
+	if (parse->havingQual)
+		non_group_cols = lappend(non_group_cols, parse->havingQual);
+
+
+	non_group_vars = pull_var_clause((Node *) non_group_cols,
+									 PVC_INCLUDE_AGGREGATES,
+									 PVC_INCLUDE_PLACEHOLDERS);
+
+	sub_tlist = add_to_flat_tlist(sub_tlist, non_group_vars);
+
+	/* clean up cruft */
+	list_free(non_group_vars);
+	list_free(non_group_cols);
+
+	return sub_tlist;
+}
 
 /*****************************************************************************
  *
@@ -1889,6 +1986,19 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			 * results.
 			 */
 			bool		need_sort_for_grouping = false;
+			PartialAggType partialaggtype;
+
+			/* Determine the level of partial aggregation we can use */
+			if (parse->groupingSets)
+				partialaggtype = PAT_DISABLED;
+			else
+			{
+				partialaggtype = aggregates_allow_partial((Node *) tlist);
+
+				if (partialaggtype != PAT_DISABLED)
+					partialaggtype = Min(partialaggtype,
+							aggregates_allow_partial(root->parse->havingQual));
+			}
 
 			result_plan = create_plan(root, best_path);
 			current_pathkeys = best_path->pathkeys;
@@ -1906,6 +2016,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 				need_tlist_eval = true;
 			}
 
+			if (partialaggtype != PAT_DISABLED)
+				need_tlist_eval = true;
+
 			/*
 			 * create_plan returns a plan with just a "flat" tlist of required
 			 * Vars.  Usually we need to insert the sub_tlist as the tlist of
@@ -1984,21 +2097,74 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			 */
 			if (use_hashed_grouping)
 			{
-				/* Hashed aggregate plan --- no sort needed */
-				result_plan = (Plan *) make_agg(root,
-												tlist,
-												(List *) parse->havingQual,
-												AGG_HASHED,
-												&agg_costs,
-												numGroupCols,
-												groupColIdx,
-									extract_grouping_ops(parse->groupClause),
-												NIL,
-												numGroups,
-												false,
-												true,
-												false,
-												result_plan);
+				if (partialaggtype != PAT_DISABLED)
+				{
+					AttrNumber *groupColIdx;
+					List *aggtlist;
+
+					aggtlist = make_aggregate_tlist(root, tlist, &groupColIdx);
+
+					/* Hashed aggregate plan --- no sort needed */
+					result_plan = (Plan *) make_agg(root,
+													aggtlist,
+													NIL,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													false,
+													false,
+													true,
+													result_plan);
+
+					result_plan->targetlist = aggtlist;
+
+					/*
+					 * Also, account for the cost of evaluation of the sub_tlist.
+					 * See comments for add_tlist_costs_to_plan() for more info.
+					 */
+					add_tlist_costs_to_plan(root, result_plan, aggtlist);
+
+					aggtlist  = make_aggregate_tlist(root, tlist, &groupColIdx);
+
+					result_plan = (Plan *) make_agg(root,
+													aggtlist,
+													(List *) parse->havingQual,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													true,
+													true,
+													true,
+													result_plan);
+					result_plan->targetlist = tlist;
+
+				}
+				else
+				{
+					/* Hashed aggregate plan --- no sort needed */
+					result_plan = (Plan *) make_agg(root,
+													tlist,
+													(List *) parse->havingQual,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													false,
+													true,
+													false,
+													result_plan);
+				}
 				/* Hashed aggregation produces randomly-ordered results */
 				current_pathkeys = NIL;
 			}
@@ -2024,7 +2190,8 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 												   groupColIdx,
 												   &agg_costs,
 												   numGroups,
-												   result_plan);
+												   result_plan,
+												   partialaggtype);
 
 				/*
 				 * these are destroyed by build_grouping_chain, so make sure
@@ -2479,7 +2646,8 @@ build_grouping_chain(PlannerInfo *root,
 					 AttrNumber *groupColIdx,
 					 AggClauseCosts *agg_costs,
 					 long numGroups,
-					 Plan *result_plan)
+					 Plan *result_plan,
+					 PartialAggType partialaggtype)
 {
 	AttrNumber *top_grpColIdx = groupColIdx;
 	List	   *chain = NIL;
@@ -2574,21 +2742,70 @@ build_grouping_chain(PlannerInfo *root,
 		else
 			numGroupCols = list_length(parse->groupClause);
 
-		result_plan = (Plan *) make_agg(root,
-										tlist,
-										(List *) parse->havingQual,
-								 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
-										agg_costs,
-										numGroupCols,
-										top_grpColIdx,
-										extract_grouping_ops(groupClause),
-										gsets,
-										numGroups,
-										false,
-										true,
-										false,
-										result_plan);
+		if (partialaggtype != PAT_DISABLED)
+		{
+			AttrNumber *groupColIdx;
+			List *aggtlist;
+
+			aggtlist = make_aggregate_tlist(root, tlist, &groupColIdx);
 
+			result_plan = (Plan *) make_agg(root,
+											aggtlist,
+											NIL,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											groupColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											false,
+											false,
+											true,
+											result_plan);
+			result_plan->targetlist = aggtlist;
+
+			/*
+			 * Also, account for the cost of evaluation of the sub_tlist.
+			 * See comments for add_tlist_costs_to_plan() for more info.
+			 */
+			add_tlist_costs_to_plan(root, result_plan, aggtlist);
+
+			aggtlist  = make_aggregate_tlist(root, tlist, &groupColIdx);
+
+			result_plan = (Plan *) make_agg(root,
+											aggtlist,
+											(List *) parse->havingQual,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											groupColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											true,
+											true,
+											true,
+											result_plan);
+			result_plan->targetlist = tlist;
+		}
+		else
+		{
+			result_plan = (Plan *) make_agg(root,
+											tlist,
+											(List *) parse->havingQual,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											top_grpColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											false,
+											true,
+											false,
+											result_plan);
+		}
 		((Agg *) result_plan)->chain = chain;
 
 		/*

diff --git a/doc/src/sgml/ref/create_aggregate.sgml b/doc/src/sgml/ref/create_aggregate.sgml
index eaa410b..bb62c96 100644
--- a/doc/src/sgml/ref/create_aggregate.sgml
+++ b/doc/src/sgml/ref/create_aggregate.sgml
@@ -27,6 +27,10 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ <replacea
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
+    [ , SERIALFUNC = <replaceable class="PARAMETER">serialfunc</replaceable> ]
+    [ , DESERIALFUNC = <replaceable class="PARAMETER">deserialfunc</replaceable> ]
+    [ , SERIALTYPE = <replaceable class="PARAMETER">serialtype</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -45,6 +49,10 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ [ <replac
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
+    [ , SERIALFUNC = <replaceable class="PARAMETER">serialfunc</replaceable> ]
+    [ , DESERIALFUNC = <replaceable class="PARAMETER">deserialfunc</replaceable> ]
+    [ , SERIALTYPE = <replaceable class="PARAMETER">serialtype</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , HYPOTHETICAL ]
 )
@@ -58,6 +66,10 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
+    [ , SERIALFUNC = <replaceable class="PARAMETER">serialfunc</replaceable> ]
+    [ , DESERIALFUNC = <replaceable class="PARAMETER">deserialfunc</replaceable> ]
+    [ , SERIALTYPE = <replaceable class="PARAMETER">serialtype</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -105,12 +117,23 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
    functions:
    a state transition function
    <replaceable class="PARAMETER">sfunc</replaceable>,
-   and an optional final calculation function
-   <replaceable class="PARAMETER">ffunc</replaceable>.
+   an optional final calculation function
+   <replaceable class="PARAMETER">ffunc</replaceable>,
+   an optional combine function
+   <replaceable class="PARAMETER">combinefunc</replaceable>,
+   an optional serialization function
+   <replaceable class="PARAMETER">serialfunc</replaceable>,
+   an optional deserialization function
+   <replaceable class="PARAMETER">deserialfunc</replaceable>,
+   and an optional serialization type
+   <replaceable class="PARAMETER">serialtype</replaceable>.
    These are used as follows:
 <programlisting>
 <replaceable class="PARAMETER">sfunc</replaceable>( internal-state, next-data-values ) ---> next-internal-state
 <replaceable class="PARAMETER">ffunc</replaceable>( internal-state ) ---> aggregate-value
+<replaceable class="PARAMETER">combinefunc</replaceable>( internal-state, internal-state ) ---> next-internal-state
+<replaceable class="PARAMETER">serialfunc</replaceable>( internal-state ) ---> serialized-state
+<replaceable class="PARAMETER">deserialfunc</replaceable>( serialized-state ) ---> internal-state
 </programlisting>
   </para>
 
@@ -128,6 +151,27 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
   </para>
 
   <para>
+   An aggregate function may also supply a combining function, which allows
+   the aggregation process to be broken down into multiple steps.  This
+   facilitates query optimization techniques such as parallel query.
+  </para>
+
+  <para>
+  A serialization and deserialization function may also be supplied. These
+  functions are required in order to allow parallel aggregation for aggregates
+  with an <replaceable class="PARAMETER">stype</replaceable> of <literal>
+  INTERNAL</>. The <replaceable class="PARAMETER">serialfunc</replaceable>, if
+  present must transform the aggregate state into a value of
+  <replaceable class="PARAMETER">serialtype</replaceable>, whereas the 
+  <replaceable class="PARAMETER">deserialfunc</replaceable> performs the
+  opposite, transforming the aggregate state back into the
+  <replaceable class="PARAMETER">stype</replaceable>. This is required due to
+  the process model being unable to pass <literal>INTERNAL</literal> types
+  between different <productname>PostgreSQL</productname> processes. These
+  parameters are only valid when <replaceable class="PARAMETER">stype
+  </replaceable> is <literal>INTERNAL</>.
+
+  <para>
    An aggregate function can provide an initial condition,
    that is, an initial value for the internal state value.
    This is specified and stored in the database as a value of type
diff --git a/src/backend/catalog/pg_aggregate.c b/src/backend/catalog/pg_aggregate.c
index 1d845ec..d971109 100644
--- a/src/backend/catalog/pg_aggregate.c
+++ b/src/backend/catalog/pg_aggregate.c
@@ -57,6 +57,9 @@ AggregateCreate(const char *aggName,
 				Oid variadicArgType,
 				List *aggtransfnName,
 				List *aggfinalfnName,
+				List *aggcombinefnName,
+				List *aggserialfnName,
+				List *aggdeserialfnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
@@ -64,6 +67,7 @@ AggregateCreate(const char *aggName,
 				bool mfinalfnExtraArgs,
 				List *aggsortopName,
 				Oid aggTransType,
+				Oid aggSerialType,
 				int32 aggTransSpace,
 				Oid aggmTransType,
 				int32 aggmTransSpace,
@@ -77,6 +81,9 @@ AggregateCreate(const char *aggName,
 	Form_pg_proc proc;
 	Oid			transfn;
 	Oid			finalfn = InvalidOid;	/* can be omitted */
+	Oid			combinefn = InvalidOid;	/* can be omitted */
+	Oid			serialfn = InvalidOid;	/* can be omitted */
+	Oid			deserialfn = InvalidOid;	/* can be omitted */
 	Oid			mtransfn = InvalidOid;	/* can be omitted */
 	Oid			minvtransfn = InvalidOid;		/* can be omitted */
 	Oid			mfinalfn = InvalidOid;	/* can be omitted */
@@ -396,6 +403,83 @@ AggregateCreate(const char *aggName,
 	}
 	Assert(OidIsValid(finaltype));
 
+	/* handle the combinefn, if supplied */
+	if (aggcombinefnName)
+	{
+		Oid combineType;
+
+		/*
+		 * Combine function must have 2 argument, each of which is the
+		 * trans type
+		 */
+		fnArgs[0] = aggTransType;
+		fnArgs[1] = aggTransType;
+
+		combinefn = lookup_agg_function(aggcombinefnName, 2, fnArgs,
+										variadicArgType, &combineType);
+
+		/* Ensure the return type matches the aggregates trans type */
+		if (combineType != aggTransType)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+			errmsg("return type of combine function %s is not %s",
+				   NameListToString(aggcombinefnName),
+				   format_type_be(aggTransType))));
+	}
+
+	/*
+	 * Validate the serial function, if present. We must ensure that the return
+	 * type of this function is the same as the specified serialType, and that
+	 * indeed a serialType was actually also specified.
+	 */
+	if (aggserialfnName)
+	{
+		/* check that we also got a serial type */
+		if (!OidIsValid(aggSerialType))
+			ereport(ERROR,
+				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+				 errmsg("must specify serialtype when specifying serialfunc")));
+
+		fnArgs[0] = aggTransType;
+
+		serialfn = lookup_agg_function(aggserialfnName, 1,
+									   fnArgs, variadicArgType,
+									   &rettype);
+
+		if (rettype != aggSerialType)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("return type of serial function %s is not %s",
+							NameListToString(aggserialfnName),
+							format_type_be(aggSerialType))));
+	}
+
+	/*
+	 * Validate the deserial function, if present. We must ensure that the
+	 * return type of this function is the same as the transType.
+	 */
+	if (aggdeserialfnName)
+	{
+		/* check that we also got a serial type */
+		if (!OidIsValid(aggSerialType))
+			ereport(ERROR,
+				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+				 errmsg("must specify serialtype when specifying deserialfunc")));
+
+		fnArgs[0] = aggSerialType;
+
+		deserialfn = lookup_agg_function(aggdeserialfnName, 1,
+										 fnArgs, variadicArgType,
+										 &rettype);
+
+		if (rettype != aggTransType)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("return type of deserial function %s is not %s",
+							NameListToString(aggdeserialfnName),
+							format_type_be(aggTransType))));
+	}
+
 	/*
 	 * If finaltype (i.e. aggregate return type) is polymorphic, inputs must
 	 * be polymorphic also, else parser will fail to deduce result type.
@@ -567,6 +651,9 @@ AggregateCreate(const char *aggName,
 	values[Anum_pg_aggregate_aggnumdirectargs - 1] = Int16GetDatum(numDirectArgs);
 	values[Anum_pg_aggregate_aggtransfn - 1] = ObjectIdGetDatum(transfn);
 	values[Anum_pg_aggregate_aggfinalfn - 1] = ObjectIdGetDatum(finalfn);
+	values[Anum_pg_aggregate_aggcombinefn - 1] = ObjectIdGetDatum(combinefn);
+	values[Anum_pg_aggregate_aggserialfn - 1] = ObjectIdGetDatum(serialfn);
+	values[Anum_pg_aggregate_aggdeserialfn - 1] = ObjectIdGetDatum(deserialfn);
 	values[Anum_pg_aggregate_aggmtransfn - 1] = ObjectIdGetDatum(mtransfn);
 	values[Anum_pg_aggregate_aggminvtransfn - 1] = ObjectIdGetDatum(minvtransfn);
 	values[Anum_pg_aggregate_aggmfinalfn - 1] = ObjectIdGetDatum(mfinalfn);
@@ -574,6 +661,7 @@ AggregateCreate(const char *aggName,
 	values[Anum_pg_aggregate_aggmfinalextra - 1] = BoolGetDatum(mfinalfnExtraArgs);
 	values[Anum_pg_aggregate_aggsortop - 1] = ObjectIdGetDatum(sortop);
 	values[Anum_pg_aggregate_aggtranstype - 1] = ObjectIdGetDatum(aggTransType);
+	values[Anum_pg_aggregate_aggserialtype - 1] = ObjectIdGetDatum(aggSerialType);
 	values[Anum_pg_aggregate_aggtransspace - 1] = Int32GetDatum(aggTransSpace);
 	values[Anum_pg_aggregate_aggmtranstype - 1] = ObjectIdGetDatum(aggmTransType);
 	values[Anum_pg_aggregate_aggmtransspace - 1] = Int32GetDatum(aggmTransSpace);
@@ -600,7 +688,8 @@ AggregateCreate(const char *aggName,
 	 * Create dependencies for the aggregate (above and beyond those already
 	 * made by ProcedureCreate).  Note: we don't need an explicit dependency
 	 * on aggTransType since we depend on it indirectly through transfn.
-	 * Likewise for aggmTransType if any.
+	 * Likewise for aggmTransType using the mtransfunc, and also for
+	 * aggSerialType using the serialfn, if they exist.
 	 */
 
 	/* Depends on transition function */
@@ -618,6 +707,33 @@ AggregateCreate(const char *aggName,
 		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
 	}
 
+	/* Depends on combine function, if any */
+	if (OidIsValid(combinefn))
+	{
+		referenced.classId = ProcedureRelationId;
+		referenced.objectId = combinefn;
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
+	/* Depends on serial function, if any */
+	if (OidIsValid(serialfn))
+	{
+		referenced.classId = ProcedureRelationId;
+		referenced.objectId = serialfn;
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
+	/* Depends on deserial function, if any */
+	if (OidIsValid(deserialfn))
+	{
+		referenced.classId = ProcedureRelationId;
+		referenced.objectId = deserialfn;
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
 	/* Depends on forward transition function, if any */
 	if (OidIsValid(mtransfn))
 	{
diff --git a/src/backend/commands/aggregatecmds.c b/src/backend/commands/aggregatecmds.c
index 441b3aa..76102f3 100644
--- a/src/backend/commands/aggregatecmds.c
+++ b/src/backend/commands/aggregatecmds.c
@@ -61,6 +61,9 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	char		aggKind = AGGKIND_NORMAL;
 	List	   *transfuncName = NIL;
 	List	   *finalfuncName = NIL;
+	List	   *combinefuncName = NIL;
+	List	   *serialfuncName = NIL;
+	List	   *deserialfuncName = NIL;
 	List	   *mtransfuncName = NIL;
 	List	   *minvtransfuncName = NIL;
 	List	   *mfinalfuncName = NIL;
@@ -69,6 +72,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	List	   *sortoperatorName = NIL;
 	TypeName   *baseType = NULL;
 	TypeName   *transType = NULL;
+	TypeName   *serialType = NULL;
 	TypeName   *mtransType = NULL;
 	int32		transSpace = 0;
 	int32		mtransSpace = 0;
@@ -83,8 +87,10 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	List	   *parameterDefaults;
 	Oid			variadicArgType;
 	Oid			transTypeId;
+	Oid			serialTypeId = InvalidOid;
 	Oid			mtransTypeId = InvalidOid;
 	char		transTypeType;
+	char		serialTypeType = 0;
 	char		mtransTypeType = 0;
 	ListCell   *pl;
 
@@ -124,6 +130,12 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 			transfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "finalfunc") == 0)
 			finalfuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "combinefunc") == 0)
+			combinefuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "serialfunc") == 0)
+			serialfuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "deserialfunc") == 0)
+			deserialfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "msfunc") == 0)
 			mtransfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "minvfunc") == 0)
@@ -151,6 +163,8 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 		}
 		else if (pg_strcasecmp(defel->defname, "stype") == 0)
 			transType = defGetTypeName(defel);
+		else if (pg_strcasecmp(defel->defname, "serialtype") == 0)
+			serialType = defGetTypeName(defel);
 		else if (pg_strcasecmp(defel->defname, "stype1") == 0)
 			transType = defGetTypeName(defel);
 		else if (pg_strcasecmp(defel->defname, "sspace") == 0)
@@ -316,6 +330,51 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 							format_type_be(transTypeId))));
 	}
 
+	if (serialType)
+	{
+		/*
+		 * There's little point in having a serial/deserial function on
+		 * aggregates that don't have an internal state, so let's just disallow
+		 * this as it may help clear up any confusion or needless authoring of
+		 * these functions.
+		 */
+		if (transTypeId != INTERNALOID)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("a serialtype must only be specified when stype is \"%s\"",
+						 format_type_be(INTERNALOID))));
+
+		serialTypeId = typenameTypeId(NULL, serialType);
+		serialTypeType = get_typtype(serialTypeId);
+
+		/*
+		 * We disallow INTERNAL serialType as the whole point of the
+		 * serialzed types is to allow the aggregate state to be output,
+		 * and we cannot output INTERNAL. This check, combined with the one
+		 * above ensures that the trans type and serial type are not the same.
+		 */
+		if (serialTypeId == INTERNALOID)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						errmsg("aggregate serial data type cannot be \"%s\"",
+							format_type_be(serialTypeId))));
+
+		/*
+		 * If serialType is specified then serialfuncName and deserialfuncName
+		 * must be present; if not, then none of the serialization options
+		 * should have been specified.
+		 */
+		if (serialfuncName == NIL)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("aggregate serialfunc must be specified when serialtype is specified")));
+
+		if (deserialfuncName == NIL)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("aggregate deserialfunc must be specified when serialtype is specified")));
+	}
+
 	/*
 	 * If a moving-aggregate transtype is specified, look that up.  Same
 	 * restrictions as for transtype.
@@ -383,6 +442,9 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 						   variadicArgType,
 						   transfuncName,		/* step function name */
 						   finalfuncName,		/* final function name */
+						   combinefuncName,		/* combine function name */
+						   serialfuncName,		/* serial function name */
+						   deserialfuncName,	/* deserial function name */
 						   mtransfuncName,		/* fwd trans function name */
 						   minvtransfuncName,	/* inv trans function name */
 						   mfinalfuncName,		/* final function name */
@@ -390,6 +452,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 						   mfinalfuncExtraArgs,
 						   sortoperatorName,	/* sort operator name */
 						   transTypeId, /* transition data type */
+						   serialTypeId, /* serial data type */
 						   transSpace,	/* transition space */
 						   mtransTypeId,		/* transition data type */
 						   mtransSpace, /* transition space */
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 9827c39..58b5012 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -908,25 +908,38 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			pname = sname = "Group";
 			break;
 		case T_Agg:
-			sname = "Aggregate";
-			switch (((Agg *) plan)->aggstrategy)
 			{
-				case AGG_PLAIN:
-					pname = "Aggregate";
-					strategy = "Plain";
-					break;
-				case AGG_SORTED:
-					pname = "GroupAggregate";
-					strategy = "Sorted";
-					break;
-				case AGG_HASHED:
-					pname = "HashAggregate";
-					strategy = "Hashed";
-					break;
-				default:
-					pname = "Aggregate ???";
-					strategy = "???";
-					break;
+				char	   *modifier;
+				Agg		   *agg = (Agg *) plan;
+
+				sname = "Aggregate";
+
+				if (agg->finalizeAggs == false)
+					modifier = "Partial ";
+				else if (agg->combineStates == true)
+					modifier = "Finalize ";
+				else
+					modifier = "";
+
+				switch (agg->aggstrategy)
+				{
+					case AGG_PLAIN:
+						pname = psprintf("%sAggregate", modifier);
+						strategy = "Plain";
+						break;
+					case AGG_SORTED:
+						pname = psprintf("%sGroupAggregate", modifier);
+						strategy = "Sorted";
+						break;
+					case AGG_HASHED:
+						pname = psprintf("%sHashAggregate", modifier);
+						strategy = "Hashed";
+						break;
+					default:
+						pname = "Aggregate ???";
+						strategy = "???";
+						break;
+				}
 			}
 			break;
 		case T_WindowAgg:
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index f49114a..d0cc643 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -3,15 +3,57 @@
  * nodeAgg.c
  *	  Routines to handle aggregate nodes.
  *
- *	  ExecAgg evaluates each aggregate in the following steps:
+ *	  ExecAgg normally evaluates each aggregate in the following steps:
  *
  *		 transvalue = initcond
  *		 foreach input_tuple do
  *			transvalue = transfunc(transvalue, input_value(s))
  *		 result = finalfunc(transvalue, direct_argument(s))
  *
- *	  If a finalfunc is not supplied then the result is just the ending
- *	  value of transvalue.
+ *	  If a finalfunc is not supplied or finalizeAggs is false, then the result
+ *	  is just the ending value of transvalue.
+ *
+ *	  Other behavior is also supported and is controlled by the 'combineStates',
+ *	  'finalizeAggs' and 'serialStates' parameters. 'combineStates' controls
+ *	  whether the trans func or the combine func is used during aggregation.
+ *	  When 'combineStates' is true we expect other (previously) aggregated
+ *	  states as input rather than input tuples. This mode facilitates multiple
+ *	  aggregate stages which allows us to support pushing aggregation down
+ *	  deeper into the plan rather than leaving it for the final stage. For
+ *	  example with a query such as:
+ *
+ *	  SELECT count(*) FROM (SELECT * FROM a UNION ALL SELECT * FROM b);
+ *
+ *	  with this functionality the planner has the flexibility to generate a
+ *	  plan which performs count(*) on table a and table b separately and then
+ *	  add a combine phase to combine both results. In this case the combine
+ *	  function would simply add both counts together.
+ *
+ *	  When multiple aggregate stages exist the planner should have set the
+ *	  'finalizeAggs' to true only for the final aggregtion state, and each
+ *	  stage, apart from the very first one should have 'combineStates' set to
+ *	  true. This permits plans such as:
+ *
+ *		Finalize Aggregate
+ *			->  Partial Aggregate
+ *				->  Partial Aggregate
+ *
+ *	  Combine functions which use pass-by-ref states should be careful to
+ *	  always update the 1st state parameter by adding the 2nd parameter to it,
+ *	  rather than the other way around. If the 1st state is NULL, then it's not
+ *	  sufficient to simply return the 2nd state, as the memory context is
+ *	  incorrect. Instead a new state should be created in the correct aggregate
+ *	  memory context and the 2nd state should be copied over.
+ *
+ *	  The 'serialStates' option can be used to allow multi-stage aggregation
+ *	  for aggregates with an INTERNAL state type. When this mode is disabled
+ *	  only a pointer to the INTERNAL aggregate states are passed around the
+ *	  executor. This behaviour does not suit a parallel environment where the
+ *	  process is unable to dereference pointers for memory which belongs to a
+ *	  worker process. Enabling this mode causes the INTERNAL states to be
+ *	  serialized and deserialized as and when required, which of course
+ *	  requires that the aggregate function also have a 'serialfunc' and
+ *	  'deserialfunc' function specified.
  *
  *	  If a normal aggregate call specifies DISTINCT or ORDER BY, we sort the
  *	  input tuples and eliminate duplicates (if required) before performing
@@ -134,6 +176,7 @@
 #include "catalog/objectaccess.h"
 #include "catalog/pg_aggregate.h"
 #include "catalog/pg_proc.h"
+#include "catalog/pg_type.h"
 #include "executor/executor.h"
 #include "executor/nodeAgg.h"
 #include "miscadmin.h"
@@ -197,9 +240,15 @@ typedef struct AggStatePerTransData
 	 */
 	int			numTransInputs;
 
-	/* Oid of the state transition function */
+	/* Oid of the state transition or combine function */
 	Oid			transfn_oid;
 
+	/* Oid of the serial function or InvalidOid */
+	Oid			serialfn_oid;
+
+	/* Oid of the deserial function or InvalidOid */
+	Oid			deserialfn_oid;
+
 	/* Oid of state value's datatype */
 	Oid			aggtranstype;
 
@@ -209,11 +258,17 @@ typedef struct AggStatePerTransData
 	List	   *aggdirectargs;	/* states of direct-argument expressions */
 
 	/*
-	 * fmgr lookup data for transition function.  Note in particular that the
-	 * fn_strict flag is kept here.
+	 * fmgr lookup data for transition function or combination function.  Note
+	 * in particular that the fn_strict flag is kept here.
 	 */
 	FmgrInfo	transfn;
 
+	/* fmgr lookup data for serial function */
+	FmgrInfo	serialfn;
+
+	/* fmgr lookup data for deserial function */
+	FmgrInfo	deserialfn;
+
 	/* Input collation derived for aggregate */
 	Oid			aggCollation;
 
@@ -294,6 +349,11 @@ typedef struct AggStatePerTransData
 	 * worth the extra space consumption.
 	 */
 	FunctionCallInfoData transfn_fcinfo;
+
+	/* Likewise for serial and deserial functions */
+	FunctionCallInfoData serialfn_fcinfo;
+
+	FunctionCallInfoData deserialfn_fcinfo;
 }	AggStatePerTransData;
 
 /*
@@ -421,6 +481,10 @@ static void advance_transition_function(AggState *aggstate,
 							AggStatePerTrans pertrans,
 							AggStatePerGroup pergroupstate);
 static void advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup);
+static void advance_combination_function(AggState *aggstate,
+							AggStatePerTrans pertrans,
+							AggStatePerGroup pergroupstate);
+static void combine_aggregates(AggState *aggstate, AggStatePerGroup pergroup);
 static void process_ordered_aggregate_single(AggState *aggstate,
 								 AggStatePerTrans pertrans,
 								 AggStatePerGroup pergroupstate);
@@ -451,14 +515,17 @@ static Datum GetAggInitVal(Datum textInitVal, Oid transtype);
 static void build_pertrans_for_aggref(AggStatePerTrans pertrans,
 						  AggState *aggsate, EState *estate,
 						  Aggref *aggref, Oid aggtransfn, Oid aggtranstype,
-						  Datum initValue, bool initValueIsNull,
-						  Oid *inputTypes, int numArguments);
+						  Oid aggserialtype, Oid aggserialfn,
+						  Oid aggdeserialfn, Datum initValue,
+						  bool initValueIsNull, Oid *inputTypes,
+						  int numArguments);
 static int find_compatible_peragg(Aggref *newagg, AggState *aggstate,
 					   int lastaggno, List **same_input_transnos);
 static int find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 						 Oid aggtransfn, Oid aggtranstype,
+						 Oid aggserialfn, Oid aggdeserialfn,
 						 Datum initValue, bool initValueIsNull,
-						 List *possible_matches);
+						 List *transnos);
 
 
 /*
@@ -796,6 +863,8 @@ advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
 	int			numGroupingSets = Max(aggstate->phase->numsets, 1);
 	int			numTrans = aggstate->numtrans;
 
+	Assert(!aggstate->combineStates);
+
 	for (transno = 0; transno < numTrans; transno++)
 	{
 		AggStatePerTrans pertrans = &aggstate->pertrans[transno];
@@ -879,6 +948,152 @@ advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
 	}
 }
 
+/*
+ * combine_aggregates is used when running in 'combineState' mode. This
+ * advances each aggregate transition state by adding another transition state
+ * to it.
+ */
+static void
+combine_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
+{
+	int			transno;
+	int			numTrans = aggstate->numtrans;
+
+	/* combine not supported with grouping sets */
+	Assert(aggstate->phase->numsets == 0);
+	Assert(aggstate->combineStates);
+
+	for (transno = 0; transno < numTrans; transno++)
+	{
+		AggStatePerTrans pertrans = &aggstate->pertrans[transno];
+		TupleTableSlot *slot;
+		FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
+		AggStatePerGroup pergroupstate = &pergroup[transno];
+
+		/* Evaluate the current input expressions for this aggregate */
+		slot = ExecProject(pertrans->evalproj, NULL);
+		Assert(slot->tts_nvalid >= 1);
+
+		/*
+		 * deserialfn_oid will be set if we must deserialize the input state
+		 * before calling the combine function
+		 */
+		if (OidIsValid(pertrans->deserialfn_oid))
+		{
+			/* don't call a strict deserial function with NULL input */
+			if (pertrans->deserialfn.fn_strict && slot->tts_isnull[0] == true)
+				continue;
+			else
+			{
+				FunctionCallInfo dsinfo = &pertrans->deserialfn_fcinfo;
+				dsinfo->arg[0] = slot->tts_values[0];
+				dsinfo->argnull[0] = slot->tts_isnull[0];
+
+				fcinfo->arg[1] = FunctionCallInvoke(dsinfo);
+				fcinfo->argnull[1] = dsinfo->isnull;
+			}
+		}
+		else
+		{
+			fcinfo->arg[1] = slot->tts_values[0];
+			fcinfo->argnull[1] = slot->tts_isnull[0];
+		}
+
+		advance_combination_function(aggstate, pertrans, pergroupstate);
+	}
+}
+
+/*
+ * Perform combination of states between 2 aggregate states. Effectively this
+ * 'adds' two states together by whichever logic is defined in the aggregate
+ * function's combine function.
+ *
+ * Note that in this case transfn is set to the combination function. This
+ * perhaps should be changed to avoid confusion, but one field is ok for now
+ * as they'll never be needed at the same time.
+ */
+static void
+advance_combination_function(AggState *aggstate,
+							 AggStatePerTrans pertrans,
+							 AggStatePerGroup pergroupstate)
+{
+	FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
+	MemoryContext oldContext;
+	Datum		newVal;
+
+	if (pertrans->transfn.fn_strict)
+	{
+		/* if we're asked to merge to a NULL state, then do nothing */
+		if (fcinfo->argnull[1])
+			return;
+
+		if (pergroupstate->noTransValue)
+		{
+			/*
+			 * transValue has not yet been initialized.  If pass-by-ref
+			 * datatype we must copy the combining state value into aggcontext.
+			 */
+			if (!pertrans->transtypeByVal)
+			{
+				oldContext = MemoryContextSwitchTo(
+					aggstate->aggcontexts[aggstate->current_set]->ecxt_per_tuple_memory);
+				pergroupstate->transValue = datumCopy(fcinfo->arg[1],
+													  pertrans->transtypeByVal,
+													  pertrans->transtypeLen);
+				MemoryContextSwitchTo(oldContext);
+			}
+			else
+				pergroupstate->transValue = fcinfo->arg[1];
+
+			pergroupstate->transValueIsNull = false;
+			pergroupstate->noTransValue = false;
+			return;
+		}
+	}
+
+	/* We run the combine functions in per-input-tuple memory context */
+	oldContext = MemoryContextSwitchTo(aggstate->tmpcontext->ecxt_per_tuple_memory);
+
+	/* set up aggstate->curpertrans for AggGetAggref() */
+	aggstate->curpertrans = pertrans;
+
+	/*
+	 * OK to call the combine function
+	 */
+	fcinfo->arg[0] = pergroupstate->transValue;
+	fcinfo->argnull[0] = pergroupstate->transValueIsNull;
+	fcinfo->isnull = false;		/* just in case combine func doesn't set it */
+
+	newVal = FunctionCallInvoke(fcinfo);
+
+	aggstate->curpertrans = NULL;
+
+	/*
+	 * If pass-by-ref datatype, must copy the new value into aggcontext and
+	 * pfree the prior transValue.  But if the combine function returned a
+	 * pointer to its first input, we don't need to do anything.
+	 */
+	if (!pertrans->transtypeByVal &&
+		DatumGetPointer(newVal) != DatumGetPointer(pergroupstate->transValue))
+	{
+		if (!fcinfo->isnull)
+		{
+			MemoryContextSwitchTo(aggstate->aggcontexts[aggstate->current_set]->ecxt_per_tuple_memory);
+			newVal = datumCopy(newVal,
+							   pertrans->transtypeByVal,
+							   pertrans->transtypeLen);
+		}
+		if (!pergroupstate->transValueIsNull)
+			pfree(DatumGetPointer(pergroupstate->transValue));
+	}
+
+	pergroupstate->transValue = newVal;
+	pergroupstate->transValueIsNull = fcinfo->isnull;
+
+	MemoryContextSwitchTo(oldContext);
+
+}
+
 
 /*
  * Run the transition function for a DISTINCT or ORDER BY aggregate
@@ -1278,8 +1493,35 @@ finalize_aggregates(AggState *aggstate,
 												pergroupstate);
 		}
 
-		finalize_aggregate(aggstate, peragg, pergroupstate,
-						   &aggvalues[aggno], &aggnulls[aggno]);
+		if (aggstate->finalizeAggs)
+			finalize_aggregate(aggstate, peragg, pergroupstate,
+							   &aggvalues[aggno], &aggnulls[aggno]);
+
+		/*
+		 * serialfn_oid will be set if we must serialize the input state
+		 * before calling the combine function on the state.
+		 */
+		else if (OidIsValid(pertrans->serialfn_oid))
+		{
+			/* don't call a strict serial function with NULL input */
+			if (pertrans->serialfn.fn_strict &&
+				pergroupstate->transValueIsNull)
+				continue;
+			else
+			{
+				FunctionCallInfo fcinfo = &pertrans->serialfn_fcinfo;
+				fcinfo->arg[0] = pergroupstate->transValue;
+				fcinfo->argnull[0] = pergroupstate->transValueIsNull;
+
+				aggvalues[aggno] = FunctionCallInvoke(fcinfo);
+				aggnulls[aggno] = fcinfo->isnull;
+			}
+		}
+		else
+		{
+			aggvalues[aggno] = pergroupstate->transValue;
+			aggnulls[aggno] = pergroupstate->transValueIsNull;
+		}
 	}
 }
 
@@ -1811,7 +2053,10 @@ agg_retrieve_direct(AggState *aggstate)
 				 */
 				for (;;)
 				{
-					advance_aggregates(aggstate, pergroup);
+					if (!aggstate->combineStates)
+						advance_aggregates(aggstate, pergroup);
+					else
+						combine_aggregates(aggstate, pergroup);
 
 					/* Reset per-input-tuple context after each tuple */
 					ResetExprContext(tmpcontext);
@@ -1919,7 +2164,10 @@ agg_fill_hash_table(AggState *aggstate)
 		entry = lookup_hash_entry(aggstate, outerslot);
 
 		/* Advance the aggregates */
-		advance_aggregates(aggstate, entry->pergroup);
+		if (!aggstate->combineStates)
+			advance_aggregates(aggstate, entry->pergroup);
+		else
+			combine_aggregates(aggstate, entry->pergroup);
 
 		/* Reset per-input-tuple context after each tuple */
 		ResetExprContext(tmpcontext);
@@ -2051,6 +2299,9 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 	aggstate->pertrans = NULL;
 	aggstate->curpertrans = NULL;
 	aggstate->agg_done = false;
+	aggstate->combineStates = node->combineStates;
+	aggstate->finalizeAggs = node->finalizeAggs;
+	aggstate->serialStates = node->serialStates;
 	aggstate->input_done = false;
 	aggstate->pergroup = NULL;
 	aggstate->grp_firstTuple = NULL;
@@ -2359,6 +2610,9 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 		AclResult	aclresult;
 		Oid			transfn_oid,
 					finalfn_oid;
+		Oid			serialtype_oid,
+					serialfn_oid,
+					deserialfn_oid;
 		Expr	   *finalfnexpr;
 		Oid			aggtranstype;
 		Datum		textInitVal;
@@ -2402,8 +2656,67 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 						   get_func_name(aggref->aggfnoid));
 		InvokeFunctionExecuteHook(aggref->aggfnoid);
 
-		transfn_oid = aggform->aggtransfn;
-		peragg->finalfn_oid = finalfn_oid = aggform->aggfinalfn;
+		/*
+		 * If this aggregation is performing state combines, then instead of
+		 * using the transition function, we'll use the combine function
+		 */
+		if (aggstate->combineStates)
+		{
+			transfn_oid = aggform->aggcombinefn;
+
+			/* If not set then the planner messed up */
+			if (!OidIsValid(transfn_oid))
+				elog(ERROR, "combinefn not set for aggregate function");
+		}
+		else
+			transfn_oid = aggform->aggtransfn;
+
+		/* Final function only required if we're finalizing the aggregates */
+		if (aggstate->finalizeAggs)
+			peragg->finalfn_oid = finalfn_oid = aggform->aggfinalfn;
+		else
+			peragg->finalfn_oid = finalfn_oid = InvalidOid;
+
+		serialtype_oid = InvalidOid;
+		serialfn_oid = InvalidOid;
+		deserialfn_oid = InvalidOid;
+
+		/*
+		 * Determine if we require serialization or deserialization of the
+		 * aggregate states. This is only required if the aggregate state is
+		 * internal.
+		 */
+		if (aggstate->serialStates && aggform->aggtranstype == INTERNALOID)
+		{
+			/*
+			 * The planner should only have generated an agg node with
+			 * serialStates if every aggregate with an INTERNAL state has a
+			 * serial type, serial function and deserial function. Let's ensure
+			 * it didn't mess that up.
+			 */
+			if (!OidIsValid(aggform->aggserialtype))
+				elog(ERROR, "serial type not set during serialStates aggregation step");
+
+			if (!OidIsValid(aggform->aggserialfn))
+				elog(ERROR, "serial func not set during serialStates aggregation step");
+
+			if (!OidIsValid(aggform->aggdeserialfn))
+				elog(ERROR, "deserial func not set during serialStates aggregation step");
+
+			/* serial func only required when not finalizing aggs */
+			if (!aggstate->finalizeAggs)
+			{
+				serialfn_oid = aggform->aggserialfn;
+				serialtype_oid = aggform->aggserialtype;
+			}
+
+			/* deserial func only required when combining states */
+			if (aggstate->combineStates)
+			{
+				deserialfn_oid = aggform->aggdeserialfn;
+				serialtype_oid = aggform->aggserialtype;
+			}
+		}
 
 		/* Check that aggregate owner has permission to call component fns */
 		{
@@ -2433,6 +2746,24 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 								   get_func_name(finalfn_oid));
 				InvokeFunctionExecuteHook(finalfn_oid);
 			}
+			if (OidIsValid(serialfn_oid))
+			{
+				aclresult = pg_proc_aclcheck(serialfn_oid, aggOwner,
+											 ACL_EXECUTE);
+				if (aclresult != ACLCHECK_OK)
+					aclcheck_error(aclresult, ACL_KIND_PROC,
+								   get_func_name(serialfn_oid));
+				InvokeFunctionExecuteHook(serialfn_oid);
+			}
+			if (OidIsValid(deserialfn_oid))
+			{
+				aclresult = pg_proc_aclcheck(deserialfn_oid, aggOwner,
+											 ACL_EXECUTE);
+				if (aclresult != ACLCHECK_OK)
+					aclcheck_error(aclresult, ACL_KIND_PROC,
+								   get_func_name(deserialfn_oid));
+				InvokeFunctionExecuteHook(deserialfn_oid);
+			}
 		}
 
 		/*
@@ -2459,7 +2790,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 
 		/*
 		 * build expression trees using actual argument & result types for the
-		 * finalfn, if it exists
+		 * finalfn, if it exists and is required.
 		 */
 		if (OidIsValid(finalfn_oid))
 		{
@@ -2474,10 +2805,11 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 			fmgr_info_set_expr((Node *) finalfnexpr, &peragg->finalfn);
 		}
 
-		/* get info about the result type's datatype */
-		get_typlenbyval(aggref->aggtype,
-						&peragg->resulttypeLen,
-						&peragg->resulttypeByVal);
+		/* when finalizing we get info about the final result's datatype */
+		if (aggstate->finalizeAggs)
+			get_typlenbyval(aggref->aggtype,
+							&peragg->resulttypeLen,
+							&peragg->resulttypeByVal);
 
 		/*
 		 * initval is potentially null, so don't try to access it as a struct
@@ -2501,7 +2833,8 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 		 */
 		existing_transno = find_compatible_pertrans(aggstate, aggref,
 													transfn_oid, aggtranstype,
-												  initValue, initValueIsNull,
+												  serialfn_oid, deserialfn_oid,
+													initValue, initValueIsNull,
 													same_input_transnos);
 		if (existing_transno != -1)
 		{
@@ -2517,8 +2850,10 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 			pertrans = &pertransstates[++transno];
 			build_pertrans_for_aggref(pertrans, aggstate, estate,
 									  aggref, transfn_oid, aggtranstype,
-									  initValue, initValueIsNull,
-									  inputTypes, numArguments);
+									  serialtype_oid, serialfn_oid,
+									  deserialfn_oid, initValue,
+									  initValueIsNull, inputTypes,
+									  numArguments);
 			peragg->transno = transno;
 		}
 		ReleaseSysCache(aggTuple);
@@ -2546,12 +2881,15 @@ static void
 build_pertrans_for_aggref(AggStatePerTrans pertrans,
 						  AggState *aggstate, EState *estate,
 						  Aggref *aggref,
-						  Oid aggtransfn, Oid aggtranstype,
+						  Oid aggtransfn, Oid aggtranstype, Oid aggserialtype,
+						  Oid aggserialfn, Oid aggdeserialfn,
 						  Datum initValue, bool initValueIsNull,
 						  Oid *inputTypes, int numArguments)
 {
 	int			numGroupingSets = Max(aggstate->maxsets, 1);
 	Expr	   *transfnexpr;
+	Expr	   *serialfnexpr = NULL;
+	Expr	   *deserialfnexpr = NULL;
 	ListCell   *lc;
 	int			numInputs;
 	int			numDirectArgs;
@@ -2565,6 +2903,8 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 	pertrans->aggref = aggref;
 	pertrans->aggCollation = aggref->inputcollid;
 	pertrans->transfn_oid = aggtransfn;
+	pertrans->serialfn_oid = aggserialfn;
+	pertrans->deserialfn_oid = aggdeserialfn;
 	pertrans->initValue = initValue;
 	pertrans->initValueIsNull = initValueIsNull;
 
@@ -2583,44 +2923,68 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 		pertrans->numTransInputs = numArguments;
 
 	/*
-	 * Set up infrastructure for calling the transfn
+	 * When combining states, we have no use at all for the aggregate
+	 * function's transfn. Instead we use the combinefn. However we do
+	 * reuse the transfnexpr for the combinefn, perhaps this should change
 	 */
-	build_aggregate_transfn_expr(inputTypes,
-								 numArguments,
-								 numDirectArgs,
-								 aggref->aggvariadic,
-								 aggtranstype,
-								 aggref->inputcollid,
-								 aggtransfn,
-								 InvalidOid,	/* invtrans is not needed here */
-								 &transfnexpr,
-								 NULL);
-	fmgr_info(aggtransfn, &pertrans->transfn);
-	fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
-
-	InitFunctionCallInfoData(pertrans->transfn_fcinfo,
-							 &pertrans->transfn,
-							 pertrans->numTransInputs + 1,
-							 pertrans->aggCollation,
-							 (void *) aggstate, NULL);
+	if (aggstate->combineStates)
+	{
+		build_aggregate_combinefn_expr(aggtranstype,
+									   aggref->inputcollid,
+									   aggtransfn,
+									   &transfnexpr);
+		fmgr_info(aggtransfn, &pertrans->transfn);
+		fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
+
+		InitFunctionCallInfoData(pertrans->transfn_fcinfo,
+								 &pertrans->transfn,
+								 2,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
 
-	/*
-	 * If the transfn is strict and the initval is NULL, make sure input type
-	 * and transtype are the same (or at least binary-compatible), so that
-	 * it's OK to use the first aggregated input value as the initial
-	 * transValue.  This should have been checked at agg definition time, but
-	 * we must check again in case the transfn's strictness property has been
-	 * changed.
-	 */
-	if (pertrans->transfn.fn_strict && pertrans->initValueIsNull)
+	}
+	else
 	{
-		if (numArguments <= numDirectArgs ||
-			!IsBinaryCoercible(inputTypes[numDirectArgs],
-							   aggtranstype))
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
-					 errmsg("aggregate %u needs to have compatible input type and transition type",
-							aggref->aggfnoid)));
+		/*
+		 * Set up infrastructure for calling the transfn
+		 */
+		build_aggregate_transfn_expr(inputTypes,
+									 numArguments,
+									 numDirectArgs,
+									 aggref->aggvariadic,
+									 aggtranstype,
+									 aggref->inputcollid,
+									 aggtransfn,
+									 InvalidOid,	/* invtrans is not needed here */
+									 &transfnexpr,
+									 NULL);
+		fmgr_info(aggtransfn, &pertrans->transfn);
+		fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
+
+		InitFunctionCallInfoData(pertrans->transfn_fcinfo,
+								 &pertrans->transfn,
+								 pertrans->numTransInputs + 1,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+
+		/*
+		 * If the transfn is strict and the initval is NULL, make sure input type
+		 * and transtype are the same (or at least binary-compatible), so that
+		 * it's OK to use the first aggregated input value as the initial
+		 * transValue.  This should have been checked at agg definition time, but
+		 * we must check again in case the transfn's strictness property has been
+		 * changed.
+		 */
+		if (pertrans->transfn.fn_strict && pertrans->initValueIsNull)
+		{
+			if (numArguments <= numDirectArgs ||
+				!IsBinaryCoercible(inputTypes[numDirectArgs],
+								   aggtranstype))
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						 errmsg("aggregate %u needs to have compatible input type and transition type",
+								aggref->aggfnoid)));
+		}
 	}
 
 	/* get info about the state value's datatype */
@@ -2628,6 +2992,41 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 					&pertrans->transtypeLen,
 					&pertrans->transtypeByVal);
 
+	if (OidIsValid(aggserialfn))
+	{
+		build_aggregate_serialfn_expr(aggtranstype,
+									  aggserialtype,
+									  aggref->inputcollid,
+									  aggserialfn,
+									  &serialfnexpr);
+		fmgr_info(aggserialfn, &pertrans->serialfn);
+		fmgr_info_set_expr((Node *) serialfnexpr, &pertrans->serialfn);
+
+		InitFunctionCallInfoData(pertrans->serialfn_fcinfo,
+								 &pertrans->serialfn,
+								 1,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+	}
+
+	if (OidIsValid(aggdeserialfn))
+	{
+		build_aggregate_serialfn_expr(aggtranstype,
+									  aggserialtype,
+									  aggref->inputcollid,
+									  aggdeserialfn,
+									  &deserialfnexpr);
+		fmgr_info(aggdeserialfn, &pertrans->deserialfn);
+		fmgr_info_set_expr((Node *) deserialfnexpr, &pertrans->deserialfn);
+
+		InitFunctionCallInfoData(pertrans->deserialfn_fcinfo,
+								 &pertrans->deserialfn,
+								 1,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+
+	}
+
 	/*
 	 * Get a tupledesc corresponding to the aggregated inputs (including sort
 	 * expressions) of the agg.
@@ -2874,6 +3273,7 @@ find_compatible_peragg(Aggref *newagg, AggState *aggstate,
 static int
 find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 						 Oid aggtransfn, Oid aggtranstype,
+						 Oid aggserialfn, Oid aggdeserialfn,
 						 Datum initValue, bool initValueIsNull,
 						 List *transnos)
 {
@@ -2892,6 +3292,14 @@ find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 			aggtranstype != pertrans->aggtranstype)
 			continue;
 
+		/*
+		 * serial and deserial functions must match, if present. Remember that
+		 * these will be InvalidOid if they're not required for this agg node
+		 */
+		if (aggserialfn != pertrans->serialfn_oid ||
+			aggdeserialfn != pertrans->deserialfn_oid)
+			continue;
+
 		/* Check that the initial condition matches, too. */
 		if (initValueIsNull && pertrans->initValueIsNull)
 			return transno;
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index f47e0da..7e880fc 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -865,6 +865,9 @@ _copyAgg(const Agg *from)
 
 	COPY_SCALAR_FIELD(aggstrategy);
 	COPY_SCALAR_FIELD(numCols);
+	COPY_SCALAR_FIELD(combineStates);
+	COPY_SCALAR_FIELD(finalizeAggs);
+	COPY_SCALAR_FIELD(serialStates);
 	if (from->numCols > 0)
 	{
 		COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index d95e151..4cb78fa 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -695,6 +695,10 @@ _outAgg(StringInfo str, const Agg *node)
 	for (i = 0; i < node->numCols; i++)
 		appendStringInfo(str, " %d", node->grpColIdx[i]);
 
+	WRITE_BOOL_FIELD(combineStates);
+	WRITE_BOOL_FIELD(finalizeAggs);
+	WRITE_BOOL_FIELD(serialStates);
+
 	appendStringInfoString(str, " :grpOperators");
 	for (i = 0; i < node->numCols; i++)
 		appendStringInfo(str, " %u", node->grpOperators[i]);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 719a52c..d85f6db 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1989,6 +1989,9 @@ _readAgg(void)
 	READ_ENUM_FIELD(aggstrategy, AggStrategy);
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
+	READ_BOOL_FIELD(combineStates);
+	READ_BOOL_FIELD(finalizeAggs);
+	READ_BOOL_FIELD(serialStates);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 	READ_NODE_FIELD(groupingSets);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 953aa62..896a888 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -1054,6 +1054,9 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path)
 								 groupOperators,
 								 NIL,
 								 numGroups,
+								 false,
+								 true,
+								 false,
 								 subplan);
 	}
 	else
@@ -4557,9 +4560,8 @@ Agg *
 make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
 		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
-		 List *groupingSets,
-		 long numGroups,
-		 Plan *lefttree)
+		 List *groupingSets, long numGroups, bool combineStates,
+		 bool finalizeAggs, bool serialStates, Plan *lefttree)
 {
 	Agg		   *node = makeNode(Agg);
 	Plan	   *plan = &node->plan;
@@ -4568,6 +4570,9 @@ make_agg(PlannerInfo *root, List *tlist, List *qual,
 
 	node->aggstrategy = aggstrategy;
 	node->numCols = numGroupCols;
+	node->combineStates = combineStates;
+	node->finalizeAggs = finalizeAggs;
+	node->serialStates = serialStates;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
 	node->numGroups = numGroups;
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 147c4de..08a914e 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -2009,6 +2009,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 									extract_grouping_ops(parse->groupClause),
 												NIL,
 												numGroups,
+												false,
+												true,
+												false,
 												result_plan);
 				/* Hashed aggregation produces randomly-ordered results */
 				current_pathkeys = NIL;
@@ -2323,6 +2326,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 								 extract_grouping_ops(parse->distinctClause),
 											NIL,
 											numDistinctRows,
+											false,
+											true,
+											false,
 											result_plan);
 			/* Hashed aggregation produces randomly-ordered results */
 			current_pathkeys = NIL;
@@ -2556,6 +2562,9 @@ build_grouping_chain(PlannerInfo *root,
 									 extract_grouping_ops(groupClause),
 									 gsets,
 									 numGroups,
+									 false,
+									 true,
+									 false,
 									 sort_plan);
 
 		sort_plan->lefttree = NULL;
@@ -2592,6 +2601,9 @@ build_grouping_chain(PlannerInfo *root,
 										extract_grouping_ops(groupClause),
 										gsets,
 										numGroups,
+										false,
+										true,
+										false,
 										result_plan);
 
 		((Agg *) result_plan)->chain = chain;
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 615f3a2..007fc0f 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -15,7 +15,9 @@
  */
 #include "postgres.h"
 
+#include "access/htup_details.h"
 #include "access/transam.h"
+#include "catalog/pg_aggregate.h"
 #include "catalog/pg_type.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
@@ -139,6 +141,18 @@ static List *set_returning_clause_references(PlannerInfo *root,
 static bool fix_opfuncids_walker(Node *node, void *context);
 static bool extract_query_dependencies_walker(Node *node,
 								  PlannerInfo *context);
+static void set_combineagg_references(PlannerInfo *root, Plan *plan,
+									  int rtoffset);
+static Node *fix_combine_agg_expr(PlannerInfo *root,
+								  Node *node,
+								  indexed_tlist *subplan_itlist,
+								  Index newvarno,
+								  int rtoffset);
+static Node *fix_combine_agg_expr_mutator(Node *node,
+										  fix_upper_expr_context *context);
+static void set_partialagg_aggref_types(PlannerInfo *root, Plan *plan,
+										bool serializeStates);
+
 
 /*****************************************************************************
  *
@@ -668,8 +682,24 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 			}
 			break;
 		case T_Agg:
-			set_upper_references(root, plan, rtoffset);
-			break;
+			{
+				Agg *aggplan = (Agg *) plan;
+
+				/*
+				 * For partial aggregation we must adjust the return types of
+				 * the Aggrefs
+				 */
+				if (!aggplan->finalizeAggs)
+					set_partialagg_aggref_types(root, plan,
+												aggplan->serialStates);
+
+				if (aggplan->combineStates)
+					set_combineagg_references(root, plan, rtoffset);
+				else
+					set_upper_references(root, plan, rtoffset);
+
+				break;
+			}
 		case T_Group:
 			set_upper_references(root, plan, rtoffset);
 			break;
@@ -2432,3 +2462,199 @@ extract_query_dependencies_walker(Node *node, PlannerInfo *context)
 	return expression_tree_walker(node, extract_query_dependencies_walker,
 								  (void *) context);
 }
+
+static void
+set_combineagg_references(PlannerInfo *root, Plan *plan, int rtoffset)
+{
+	Plan	   *subplan = plan->lefttree;
+	indexed_tlist *subplan_itlist;
+	List	   *output_targetlist;
+	ListCell   *l;
+
+	Assert(IsA(plan, Agg));
+	Assert(((Agg *) plan)->combineStates);
+
+	subplan_itlist = build_tlist_index(subplan->targetlist);
+
+	output_targetlist = NIL;
+
+	foreach(l, plan->targetlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(l);
+		Node	   *newexpr;
+
+		/* If it's a non-Var sort/group item, first try to match by sortref */
+		if (tle->ressortgroupref != 0 && !IsA(tle->expr, Var))
+		{
+			newexpr = (Node *)
+				search_indexed_tlist_for_sortgroupref((Node *) tle->expr,
+														tle->ressortgroupref,
+														subplan_itlist,
+														OUTER_VAR);
+			if (!newexpr)
+				newexpr = fix_combine_agg_expr(root,
+												(Node *) tle->expr,
+												subplan_itlist,
+												OUTER_VAR,
+												rtoffset);
+		}
+		else
+			newexpr = fix_combine_agg_expr(root,
+											(Node *) tle->expr,
+											subplan_itlist,
+											OUTER_VAR,
+											rtoffset);
+		tle = flatCopyTargetEntry(tle);
+		tle->expr = (Expr *) newexpr;
+		output_targetlist = lappend(output_targetlist, tle);
+	}
+
+	plan->targetlist = output_targetlist;
+
+	plan->qual = (List *)
+		fix_upper_expr(root,
+					   (Node *) plan->qual,
+					   subplan_itlist,
+					   OUTER_VAR,
+					   rtoffset);
+
+	pfree(subplan_itlist);
+}
+
+
+/*
+ * Adjust the Aggref'a args to reference the correct Aggref target in the outer
+ * subplan.
+ */
+static Node *
+fix_combine_agg_expr(PlannerInfo *root,
+			   Node *node,
+			   indexed_tlist *subplan_itlist,
+			   Index newvarno,
+			   int rtoffset)
+{
+	fix_upper_expr_context context;
+
+	context.root = root;
+	context.subplan_itlist = subplan_itlist;
+	context.newvarno = newvarno;
+	context.rtoffset = rtoffset;
+	return fix_combine_agg_expr_mutator(node, &context);
+}
+
+static Node *
+fix_combine_agg_expr_mutator(Node *node, fix_upper_expr_context *context)
+{
+	Var		   *newvar;
+
+	if (node == NULL)
+		return NULL;
+	if (IsA(node, Var))
+	{
+		Var		   *var = (Var *) node;
+
+		newvar = search_indexed_tlist_for_var(var,
+											  context->subplan_itlist,
+											  context->newvarno,
+											  context->rtoffset);
+		if (!newvar)
+			elog(ERROR, "variable not found in subplan target list");
+		return (Node *) newvar;
+	}
+	if (IsA(node, Aggref))
+	{
+		TargetEntry *tle;
+		Aggref		*aggref = (Aggref*) node;
+
+		tle = tlist_member(node, context->subplan_itlist->tlist);
+		if (tle)
+		{
+			/* Found a matching subplan output expression */
+			Var		   *newvar;
+			TargetEntry *newtle;
+
+			newvar = makeVarFromTargetEntry(context->newvarno, tle);
+			newvar->varnoold = 0;	/* wasn't ever a plain Var */
+			newvar->varoattno = 0;
+
+			/* update the args in the aggref */
+
+			/* makeTargetEntry ,always set resno to one for finialize agg */
+			newtle = makeTargetEntry((Expr*) newvar, 1, NULL, false);
+
+			/*
+			 * Updated the args, let the newvar refer to the right position of
+			 * the agg function in the subplan
+			 */
+			aggref->args = list_make1(newtle);
+
+			return (Node *) aggref;
+		}
+		else
+			elog(ERROR, "aggref not found in subplan target list");
+	}
+	if (IsA(node, PlaceHolderVar))
+	{
+		PlaceHolderVar *phv = (PlaceHolderVar *) node;
+
+		/* See if the PlaceHolderVar has bubbled up from a lower plan node */
+		if (context->subplan_itlist->has_ph_vars)
+		{
+			newvar = search_indexed_tlist_for_non_var((Node *) phv,
+													  context->subplan_itlist,
+													  context->newvarno);
+			if (newvar)
+				return (Node *) newvar;
+		}
+		/* If not supplied by input plan, evaluate the contained expr */
+		return fix_upper_expr_mutator((Node *) phv->phexpr, context);
+	}
+	if (IsA(node, Param))
+		return fix_param_node(context->root, (Param *) node);
+
+	fix_expr_common(context->root, node);
+	return expression_tree_mutator(node,
+								   fix_combine_agg_expr_mutator,
+								   (void *) context);
+}
+
+/* XXX is this really the best place and way to do this? */
+static void
+set_partialagg_aggref_types(PlannerInfo *root, Plan *plan, bool serializeStates)
+{
+	ListCell *l;
+
+	foreach(l, plan->targetlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(l);
+
+		if (IsA(tle->expr, Aggref))
+		{
+			Aggref *aggref = (Aggref *) tle->expr;
+			HeapTuple	aggTuple;
+			Form_pg_aggregate aggform;
+
+			aggTuple = SearchSysCache1(AGGFNOID,
+									   ObjectIdGetDatum(aggref->aggfnoid));
+			if (!HeapTupleIsValid(aggTuple))
+				elog(ERROR, "cache lookup failed for aggregate %u",
+					 aggref->aggfnoid);
+			aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
+
+			/*
+			 * For partial aggregate nodes the return type of the Aggref
+			 * depends on if we're performing a serialization of the partially
+			 * aggregated states or not. If we are then the return type should
+			 * be the serial type rather than the trans type. We only require
+			 * this behavior for aggregates with INTERNAL trans types.
+			 */
+			if (serializeStates && OidIsValid(aggform->aggserialtype) &&
+				aggform->aggtranstype == INTERNALOID)
+				aggref->aggtype = aggform->aggserialtype;
+			else
+				aggref->aggtype = aggform->aggtranstype;
+
+			ReleaseSysCache(aggTuple);
+		}
+	}
+}
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 694e9ed..ab2f1a8 100644
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -775,6 +775,9 @@ make_union_unique(SetOperationStmt *op, Plan *plan,
 								 extract_grouping_ops(groupList),
 								 NIL,
 								 numGroups,
+								 false,
+								 true,
+								 false,
 								 plan);
 		/* Hashed aggregation produces randomly-ordered results */
 		*sortClauses = NIL;
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index ace8b38..a9012b6 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -52,6 +52,10 @@
 #include "utils/syscache.h"
 #include "utils/typcache.h"
 
+typedef struct
+{
+	PartialAggType allowedtype;
+} partial_agg_context;
 
 typedef struct
 {
@@ -93,6 +97,7 @@ typedef struct
 	bool		allow_restricted;
 } has_parallel_hazard_arg;
 
+static bool partial_aggregate_walker(Node *node, void *context);
 static bool contain_agg_clause_walker(Node *node, void *context);
 static bool count_agg_clauses_walker(Node *node,
 						 count_agg_clauses_context *context);
@@ -400,6 +405,89 @@ make_ands_implicit(Expr *clause)
  *****************************************************************************/
 
 /*
+ * aggregates_allow_partial
+ *		Recursively search for Aggref clauses and determine the maximum
+ *		'degree' of partial aggregation which can be supported. Partial
+ *		aggregation requires that each aggregate does not have a DISTINCT or
+ *		ORDER BY clause, and that it also has a combine function set. For
+ *		aggregates with an INTERNAL trans type we only can support all types of
+ *		partial aggregation when the aggregate has a serial and deserial
+ *		function set. If this is not present then we can only support, at most
+ *		partial aggregation in the context of a single backend process, as
+ *		internal state pointers cannot be dereferenced from another backend
+ *		process.
+ */
+PartialAggType
+aggregates_allow_partial(Node *clause)
+{
+	partial_agg_context context;
+
+	/* initially any type is ok, until we find Aggrefs which say otherwise */
+	context.allowedtype = PAT_ANY;
+
+	if (!partial_aggregate_walker(clause, &context))
+		return context.allowedtype;
+	return context.allowedtype;
+}
+
+static bool
+partial_aggregate_walker(Node *node, partial_agg_context *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Aggref))
+	{
+		Aggref	   *aggref = (Aggref *) node;
+		HeapTuple	aggTuple;
+		Form_pg_aggregate aggform;
+
+		Assert(aggref->agglevelsup == 0);
+
+		/*
+		 * We can't perform partial aggregation with Aggrefs containing a
+		 * DISTINCT or ORDER BY clause.
+		 */
+		if (aggref->aggdistinct || aggref->aggorder)
+		{
+			context->allowedtype = PAT_DISABLED;
+			return true;	/* abort search */
+		}
+		aggTuple = SearchSysCache1(AGGFNOID,
+								   ObjectIdGetDatum(aggref->aggfnoid));
+		if (!HeapTupleIsValid(aggTuple))
+			elog(ERROR, "cache lookup failed for aggregate %u",
+				 aggref->aggfnoid);
+		aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
+
+		/*
+		 * If there is no combine func, then partial aggregation is not
+		 * possible.
+		 */
+		if (!OidIsValid(aggform->aggcombinefn))
+		{
+			ReleaseSysCache(aggTuple);
+			context->allowedtype = PAT_DISABLED;
+			return true;	/* abort search */
+		}
+
+		/*
+		 * Any aggs with an internal transtype must have a serial type, serial
+		 * func and deserial func, otherwise we can only support internal mode.
+		 */
+		if (aggform->aggtranstype == INTERNALOID &&
+			(!OidIsValid(aggform->aggserialtype) ||
+			 !OidIsValid(aggform->aggserialfn) ||
+			 !OidIsValid(aggform->aggdeserialfn)))
+			context->allowedtype = PAT_INTERNAL_ONLY;
+
+		ReleaseSysCache(aggTuple);
+		return false; /* continue searching */
+	}
+	return expression_tree_walker(node, partial_aggregate_walker,
+								  (void *) context);
+}
+
+/*
  * contain_agg_clause
  *	  Recursively search for Aggref/GroupingFunc nodes within a clause.
  *
diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c
index b718169..ca3823a 100644
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -1929,6 +1929,116 @@ build_aggregate_transfn_expr(Oid *agg_input_types,
 
 /*
  * Like build_aggregate_transfn_expr, but creates an expression tree for the
+ * combine function of an aggregate, rather than the transition function.
+ */
+void
+build_aggregate_combinefn_expr(Oid agg_state_type,
+							   Oid agg_input_collation,
+							   Oid combinefn_oid,
+							   Expr **combinefnexpr)
+{
+	Param	   *argp;
+	List	   *args;
+	FuncExpr   *fexpr;
+
+	/* Build arg list to use in the combinefn FuncExpr node. */
+	argp = makeNode(Param);
+	argp->paramkind = PARAM_EXEC;
+	argp->paramid = -1;
+	argp->paramtype = agg_state_type;
+	argp->paramtypmod = -1;
+	argp->paramcollid = agg_input_collation;
+	argp->location = -1;
+
+	/* transition state type is arg 1 and 2 */
+	args = list_make2(argp, argp);
+
+	fexpr = makeFuncExpr(combinefn_oid,
+						 agg_state_type,
+						 args,
+						 InvalidOid,
+						 agg_input_collation,
+						 COERCE_EXPLICIT_CALL);
+	fexpr->funcvariadic = false;
+	*combinefnexpr = (Expr *) fexpr;
+}
+
+/*
+ * Like build_aggregate_transfn_expr, but creates an expression tree for the
+ * serial function of an aggregate, rather than the transition function.
+ */
+void
+build_aggregate_serialfn_expr(Oid agg_state_type,
+							  Oid agg_serial_type,
+							  Oid agg_input_collation,
+							  Oid serialfn_oid,
+							  Expr **serialfnexpr)
+{
+	Param	   *argp;
+	List	   *args;
+	FuncExpr   *fexpr;
+
+	/* Build arg list to use in the serialfn FuncExpr node. */
+	argp = makeNode(Param);
+	argp->paramkind = PARAM_EXEC;
+	argp->paramid = -1;
+	argp->paramtype = agg_state_type;
+	argp->paramtypmod = -1;
+	argp->paramcollid = agg_input_collation;
+	argp->location = -1;
+
+	/* takes a single arg of the transition state type */
+	args = list_make1(argp);
+
+	fexpr = makeFuncExpr(serialfn_oid,
+						 agg_serial_type,
+						 args,
+						 InvalidOid,
+						 agg_input_collation,
+						 COERCE_EXPLICIT_CALL);
+	fexpr->funcvariadic = false;
+	*serialfnexpr = (Expr *) fexpr;
+}
+
+/*
+ * Like build_aggregate_transfn_expr, but creates an expression tree for the
+ * deserial function of an aggregate, rather than the transition function.
+ */
+void
+build_aggregate_deserialfn_expr(Oid agg_state_type,
+								Oid agg_serial_type,
+								Oid agg_input_collation,
+								Oid deserialfn_oid,
+								Expr **deserialfnexpr)
+{
+	Param	   *argp;
+	List	   *args;
+	FuncExpr   *fexpr;
+
+	/* Build arg list to use in the serialfn FuncExpr node. */
+	argp = makeNode(Param);
+	argp->paramkind = PARAM_EXEC;
+	argp->paramid = -1;
+	argp->paramtype = agg_serial_type;
+	argp->paramtypmod = -1;
+	argp->paramcollid = agg_input_collation;
+	argp->location = -1;
+
+	/* takes a single arg of the serial type */
+	args = list_make1(argp);
+
+	fexpr = makeFuncExpr(deserialfn_oid,
+						 agg_state_type,
+						 args,
+						 InvalidOid,
+						 agg_input_collation,
+						 COERCE_EXPLICIT_CALL);
+	fexpr->funcvariadic = false;
+	*deserialfnexpr = (Expr *) fexpr;
+}
+
+/*
+ * Like build_aggregate_transfn_expr, but creates an expression tree for the
  * final function of an aggregate, rather than the transition function.
  */
 void
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index 07b2645..3947cba 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -3369,6 +3369,175 @@ numeric_avg_accum(PG_FUNCTION_ARGS)
 }
 
 /*
+ * Generic combine function for numeric aggregates without requirement for X^2
+ */
+Datum
+numeric_avg_combine(PG_FUNCTION_ARGS)
+{
+	NumericAggState *state1;
+	NumericAggState *state2;
+
+	state1 = PG_ARGISNULL(0) ? NULL : (NumericAggState *) PG_GETARG_POINTER(0);
+	state2 = PG_ARGISNULL(1) ? NULL : (NumericAggState *) PG_GETARG_POINTER(1);
+
+	if (state2 == NULL)
+		PG_RETURN_POINTER(state1);
+
+	/* manually copy all fields from state2 to state1 */
+	if (state1 == NULL)
+	{
+		MemoryContext old_context;
+
+		state1 = makeNumericAggState(fcinfo, false);
+		state1->N = state2->N;
+		state1->NaNcount = state2->NaNcount;
+		state1->maxScale = state2->maxScale;
+		state1->maxScaleCount = state2->maxScaleCount;
+
+		old_context = MemoryContextSwitchTo(state1->agg_context);
+
+		init_var(&state1->sumX);
+		set_var_from_var(&state2->sumX, &state1->sumX);
+
+		MemoryContextSwitchTo(old_context);
+
+		PG_RETURN_POINTER(state1);
+	}
+
+	if (state2->N > 0)
+	{
+		MemoryContext old_context;
+
+		state1->N += state2->N;
+		state1->NaNcount += state2->NaNcount;
+
+		/*
+		 * XXX do we care about these? They're really only needed for moving
+		 * aggregates.
+		 */
+		if (state2->maxScale > state1->maxScale)
+			state1->maxScale = state2->maxScale;
+		else if (state2->maxScale == state1->maxScale)
+			state1->maxScale += state2->maxScale;
+
+		/* The rest of this needs to work in the aggregate context */
+		old_context = MemoryContextSwitchTo(state1->agg_context);
+
+		/* Accumulate sums */
+		add_var(&(state1->sumX), &(state2->sumX), &(state1->sumX));
+
+		if (state1->calcSumX2)
+			add_var(&(state1->sumX2), &(state2->sumX2), &(state1->sumX2));
+
+		MemoryContextSwitchTo(old_context);
+	}
+	PG_RETURN_POINTER(state1);
+}
+
+/*
+ * numeric_avg_serialize
+ *		Serialize NumericAggState into text.
+ *		numeric_avg_deserialize(numeric_avg_serialize(state)) must result in
+ *		a state which matches the original input state.
+ */
+Datum
+numeric_avg_serialize(PG_FUNCTION_ARGS)
+{
+	NumericAggState *state;
+	StringInfoData string;
+	MemoryContext agg_context;
+	MemoryContext old_context;
+	text	   *result;
+
+	/* Ensure we disallow calling when not in aggregate context */
+	if (!AggCheckCallContext(fcinfo, &agg_context))
+		elog(ERROR, "aggregate function called in non-aggregate context");
+
+	state = (NumericAggState *) PG_GETARG_POINTER(0);
+
+	initStringInfo(&string);
+
+	/*
+	 * Transform the NumericAggState into a string with the following format:
+	 * "N sumX maxScale maxScaleCount NaNcount"
+	 * XXX perhaps we can come up with a more efficient format for this.
+	 */
+	appendStringInfo(&string, INT64_FORMAT " %s %d " INT64_FORMAT " " INT64_FORMAT,
+			state->N, get_str_from_var(&state->sumX), state->maxScale,
+			state->maxScaleCount, state->NaNcount);
+
+	old_context = MemoryContextSwitchTo(agg_context);
+
+	result = cstring_to_text_with_len(string.data, string.len);
+
+	MemoryContextSwitchTo(old_context);
+
+	PG_RETURN_TEXT_P(result);
+}
+
+/*
+ * numeric_avg_deserialize
+ *		deserialize Text into NumericAggState
+ *		numeric_avg_serialize(numeric_avg_deserialize(text)) must result in
+ *		text which matches the original input text.
+ */
+Datum
+numeric_avg_deserialize(PG_FUNCTION_ARGS)
+{
+	NumericAggState *result;
+	MemoryContext agg_context;
+	MemoryContext old_context;
+	Numeric		tmp;
+	text	   *sstate;
+	char	   *state;
+	char	   *token[5];
+	int			i;
+
+	if (!AggCheckCallContext(fcinfo, &agg_context))
+		elog(ERROR, "aggregate function called in non-aggregate context");
+
+	sstate = PG_GETARG_TEXT_P(0);
+	state = text_to_cstring(sstate);
+
+	token[0] = strtok(state, " ");
+
+	if (!token[0])
+		elog(ERROR, "invalid serialization format");
+
+	for (i = 1; i < 5; i++)
+	{
+		token[i] = strtok(NULL, " ");
+		if (!token[i])
+			elog(ERROR, "invalid serialization format");
+	}
+
+	old_context = MemoryContextSwitchTo(agg_context);
+
+	/*
+	 * Transform string into a NumericAggState. The string is in the format:
+	 * "N sumX maxScale maxScaleCount NaNcount"
+	 */
+	result = makeNumericAggState(fcinfo, false);
+
+	scanint8(token[0], false, &result->N);
+
+	tmp = DatumGetNumeric(DirectFunctionCall3(numeric_in,
+						  CStringGetDatum(token[1]),
+						  ObjectIdGetDatum(0),
+						  Int32GetDatum(-1)));
+	init_var_from_num(tmp, &result->sumX);
+
+	result->maxScale = pg_atoi(token[2], sizeof(int32), 0);
+	scanint8(token[3], false, &result->maxScaleCount);
+	scanint8(token[4], false, &result->NaNcount);
+
+	MemoryContextSwitchTo(old_context);
+
+	pfree(state);
+	PG_RETURN_POINTER(result);
+}
+
+/*
  * Generic inverse transition function for numeric aggregates
  * (with or without requirement for X^2).
  */
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 56c0528..e8fefdb 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -12283,6 +12283,9 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	PGresult   *res;
 	int			i_aggtransfn;
 	int			i_aggfinalfn;
+	int			i_aggcombinefn;
+	int			i_aggserialfn;
+	int			i_aggdeserialfn;
 	int			i_aggmtransfn;
 	int			i_aggminvtransfn;
 	int			i_aggmfinalfn;
@@ -12291,6 +12294,7 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	int			i_aggsortop;
 	int			i_hypothetical;
 	int			i_aggtranstype;
+	int			i_aggserialtype;
 	int			i_aggtransspace;
 	int			i_aggmtranstype;
 	int			i_aggmtransspace;
@@ -12299,6 +12303,9 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	int			i_convertok;
 	const char *aggtransfn;
 	const char *aggfinalfn;
+	const char *aggcombinefn;
+	const char *aggserialfn;
+	const char *aggdeserialfn;
 	const char *aggmtransfn;
 	const char *aggminvtransfn;
 	const char *aggmfinalfn;
@@ -12308,6 +12315,7 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	char	   *aggsortconvop;
 	bool		hypothetical;
 	const char *aggtranstype;
+	const char *aggserialtype;
 	const char *aggtransspace;
 	const char *aggmtranstype;
 	const char *aggmtransspace;
@@ -12329,7 +12337,27 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	selectSourceSchema(fout, agginfo->aggfn.dobj.namespace->dobj.name);
 
 	/* Get aggregate-specific details */
-	if (fout->remoteVersion >= 90400)
+	if (fout->remoteVersion >= 90600)
+	{
+		appendPQExpBuffer(query, "SELECT aggtransfn, "
+			"aggfinalfn, aggtranstype::pg_catalog.regtype, "
+			"aggcombinefn, aggserialfn, aggdeserialfn, aggmtransfn, "
+			"aggminvtransfn, aggmfinalfn, aggmtranstype::pg_catalog.regtype, "
+			"aggfinalextra, aggmfinalextra, "
+			"aggsortop::pg_catalog.regoperator, "
+			"aggserialtype::pg_catalog.regtype, "
+			"(aggkind = 'h') AS hypothetical, "
+			"aggtransspace, agginitval, "
+			"aggmtransspace, aggminitval, "
+			"true AS convertok, "
+			"pg_catalog.pg_get_function_arguments(p.oid) AS funcargs, "
+			"pg_catalog.pg_get_function_identity_arguments(p.oid) AS funciargs "
+			"FROM pg_catalog.pg_aggregate a, pg_catalog.pg_proc p "
+			"WHERE a.aggfnoid = p.oid "
+			"AND p.oid = '%u'::pg_catalog.oid",
+			agginfo->aggfn.dobj.catId.oid);
+	}
+	else if (fout->remoteVersion >= 90400)
 	{
 		appendPQExpBuffer(query, "SELECT aggtransfn, "
 						  "aggfinalfn, aggtranstype::pg_catalog.regtype, "
@@ -12439,12 +12467,16 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 
 	i_aggtransfn = PQfnumber(res, "aggtransfn");
 	i_aggfinalfn = PQfnumber(res, "aggfinalfn");
+	i_aggcombinefn = PQfnumber(res, "aggcombinefn");
+	i_aggserialfn = PQfnumber(res, "aggserialfn");
+	i_aggdeserialfn = PQfnumber(res, "aggdeserialfn");
 	i_aggmtransfn = PQfnumber(res, "aggmtransfn");
 	i_aggminvtransfn = PQfnumber(res, "aggminvtransfn");
 	i_aggmfinalfn = PQfnumber(res, "aggmfinalfn");
 	i_aggfinalextra = PQfnumber(res, "aggfinalextra");
 	i_aggmfinalextra = PQfnumber(res, "aggmfinalextra");
 	i_aggsortop = PQfnumber(res, "aggsortop");
+	i_aggserialtype = PQfnumber(res, "aggserialtype");
 	i_hypothetical = PQfnumber(res, "hypothetical");
 	i_aggtranstype = PQfnumber(res, "aggtranstype");
 	i_aggtransspace = PQfnumber(res, "aggtransspace");
@@ -12456,6 +12488,9 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 
 	aggtransfn = PQgetvalue(res, 0, i_aggtransfn);
 	aggfinalfn = PQgetvalue(res, 0, i_aggfinalfn);
+	aggcombinefn = PQgetvalue(res, 0, i_aggcombinefn);
+	aggserialfn = PQgetvalue(res, 0, i_aggserialfn);
+	aggdeserialfn = PQgetvalue(res, 0, i_aggdeserialfn);
 	aggmtransfn = PQgetvalue(res, 0, i_aggmtransfn);
 	aggminvtransfn = PQgetvalue(res, 0, i_aggminvtransfn);
 	aggmfinalfn = PQgetvalue(res, 0, i_aggmfinalfn);
@@ -12464,6 +12499,7 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 	aggsortop = PQgetvalue(res, 0, i_aggsortop);
 	hypothetical = (PQgetvalue(res, 0, i_hypothetical)[0] == 't');
 	aggtranstype = PQgetvalue(res, 0, i_aggtranstype);
+	aggserialtype = PQgetvalue(res, 0, i_aggserialtype);
 	aggtransspace = PQgetvalue(res, 0, i_aggtransspace);
 	aggmtranstype = PQgetvalue(res, 0, i_aggmtranstype);
 	aggmtransspace = PQgetvalue(res, 0, i_aggmtransspace);
@@ -12544,6 +12580,18 @@ dumpAgg(Archive *fout, DumpOptions *dopt, AggInfo *agginfo)
 			appendPQExpBufferStr(details, ",\n    FINALFUNC_EXTRA");
 	}
 
+	if (strcmp(aggcombinefn, "-") != 0)
+	{
+		appendPQExpBuffer(details, ",\n    COMBINEFUNC = %s",	aggcombinefn);
+	}
+
+	if (strcmp(aggserialfn, "-") != 0)
+	{
+		appendPQExpBuffer(details, ",\n    SERIALFUNC = %s",	aggserialfn);
+		appendPQExpBuffer(details, ",\n    DESERIALFUNC = %s",	aggdeserialfn);
+		appendPQExpBuffer(details, ",\n    SERIALTYPE = %s",	aggserialtype);
+	}
+
 	if (strcmp(aggmtransfn, "-") != 0)
 	{
 		appendPQExpBuffer(details, ",\n    MSFUNC = %s,\n    MINVFUNC = %s,\n    MSTYPE = %s",
diff --git a/src/include/catalog/pg_aggregate.h b/src/include/catalog/pg_aggregate.h
index 28b0669..ed2ee92 100644
--- a/src/include/catalog/pg_aggregate.h
+++ b/src/include/catalog/pg_aggregate.h
@@ -33,6 +33,9 @@
  *	aggnumdirectargs	number of arguments that are "direct" arguments
  *	aggtransfn			transition function
  *	aggfinalfn			final function (0 if none)
+ *	aggcombinefn		combine function (0 if none)
+ *	aggserialfn			function to convert transtype into serialtype
+ *	aggdeserialfn		function to convert serialtype into transtype
  *	aggmtransfn			forward function for moving-aggregate mode (0 if none)
  *	aggminvtransfn		inverse function for moving-aggregate mode (0 if none)
  *	aggmfinalfn			final function for moving-aggregate mode (0 if none)
@@ -42,6 +45,7 @@
  *	aggtranstype		type of aggregate's transition (state) data
  *	aggtransspace		estimated size of state data (0 for default estimate)
  *	aggmtranstype		type of moving-aggregate state data (0 if none)
+ *	aggserialtype		datatype to serialize state to. (0 if none)
  *	aggmtransspace		estimated size of moving-agg state (0 for default est)
  *	agginitval			initial value for transition state (can be NULL)
  *	aggminitval			initial value for moving-agg state (can be NULL)
@@ -56,6 +60,9 @@ CATALOG(pg_aggregate,2600) BKI_WITHOUT_OIDS
 	int16		aggnumdirectargs;
 	regproc		aggtransfn;
 	regproc		aggfinalfn;
+	regproc		aggcombinefn;
+	regproc		aggserialfn;
+	regproc		aggdeserialfn;
 	regproc		aggmtransfn;
 	regproc		aggminvtransfn;
 	regproc		aggmfinalfn;
@@ -63,6 +70,7 @@ CATALOG(pg_aggregate,2600) BKI_WITHOUT_OIDS
 	bool		aggmfinalextra;
 	Oid			aggsortop;
 	Oid			aggtranstype;
+	Oid			aggserialtype;
 	int32		aggtransspace;
 	Oid			aggmtranstype;
 	int32		aggmtransspace;
@@ -85,24 +93,28 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  * ----------------
  */
 
-#define Natts_pg_aggregate					17
+#define Natts_pg_aggregate					21
 #define Anum_pg_aggregate_aggfnoid			1
 #define Anum_pg_aggregate_aggkind			2
 #define Anum_pg_aggregate_aggnumdirectargs	3
 #define Anum_pg_aggregate_aggtransfn		4
 #define Anum_pg_aggregate_aggfinalfn		5
-#define Anum_pg_aggregate_aggmtransfn		6
-#define Anum_pg_aggregate_aggminvtransfn	7
-#define Anum_pg_aggregate_aggmfinalfn		8
-#define Anum_pg_aggregate_aggfinalextra		9
-#define Anum_pg_aggregate_aggmfinalextra	10
-#define Anum_pg_aggregate_aggsortop			11
-#define Anum_pg_aggregate_aggtranstype		12
-#define Anum_pg_aggregate_aggtransspace		13
-#define Anum_pg_aggregate_aggmtranstype		14
-#define Anum_pg_aggregate_aggmtransspace	15
-#define Anum_pg_aggregate_agginitval		16
-#define Anum_pg_aggregate_aggminitval		17
+#define Anum_pg_aggregate_aggcombinefn		6
+#define Anum_pg_aggregate_aggserialfn		7
+#define Anum_pg_aggregate_aggdeserialfn		8
+#define Anum_pg_aggregate_aggmtransfn		9
+#define Anum_pg_aggregate_aggminvtransfn	10
+#define Anum_pg_aggregate_aggmfinalfn		11
+#define Anum_pg_aggregate_aggfinalextra		12
+#define Anum_pg_aggregate_aggmfinalextra	13
+#define Anum_pg_aggregate_aggsortop			14
+#define Anum_pg_aggregate_aggtranstype		15
+#define Anum_pg_aggregate_aggserialtype		16
+#define Anum_pg_aggregate_aggtransspace		17
+#define Anum_pg_aggregate_aggmtranstype		18
+#define Anum_pg_aggregate_aggmtransspace	19
+#define Anum_pg_aggregate_agginitval		20
+#define Anum_pg_aggregate_aggminitval		21
 
 /*
  * Symbolic values for aggkind column.  We distinguish normal aggregates
@@ -126,184 +138,184 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  */
 
 /* avg */
-DATA(insert ( 2100	n 0 int8_avg_accum	numeric_poly_avg		int8_avg_accum	int8_avg_accum_inv	numeric_poly_avg	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg		int4_avg_accum	int4_avg_accum_inv	int8_avg					f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg		int2_avg_accum	int2_avg_accum_inv	int8_avg					f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg	numeric_avg_accum numeric_accum_inv numeric_avg					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2104	n 0 float4_accum	float8_avg		-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2105	n 0 float8_accum	float8_avg		-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2106	n 0 interval_accum	interval_avg	interval_accum	interval_accum_inv interval_avg					f f 0	1187	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
+DATA(insert ( 2100	n 0 int8_avg_accum	numeric_poly_avg	-					-	-	int8_avg_accum	int8_avg_accum_inv	numeric_poly_avg	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg			-					-	-	int4_avg_accum	int4_avg_accum_inv	int8_avg			f f 0	1016	0	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg			-					-	-	int2_avg_accum	int2_avg_accum_inv	int8_avg			f f 0	1016	0	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg		numeric_avg_combine	numeric_avg_serialize	numeric_avg_deserialize	numeric_avg_accum numeric_accum_inv numeric_avg			f f 0	2281	25	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2104	n 0 float4_accum	float8_avg			-					-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2105	n 0 float8_accum	float8_avg			-					-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2106	n 0 interval_accum	interval_avg		-					-	-	interval_accum	interval_accum_inv interval_avg			f f 0	1187	0	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
 
 /* sum */
-DATA(insert ( 2107	n 0 int8_avg_accum	numeric_poly_sum		int8_avg_accum	int8_avg_accum_inv numeric_poly_sum f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2108	n 0 int4_sum		-				int4_avg_accum	int4_avg_accum_inv int2int4_sum					f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2109	n 0 int2_sum		-				int2_avg_accum	int2_avg_accum_inv int2int4_sum					f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2110	n 0 float4pl		-				-				-				-								f f 0	700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2111	n 0 float8pl		-				-				-				-								f f 0	701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2112	n 0 cash_pl			-				cash_pl			cash_mi			-								f f 0	790		0	790		0	_null_ _null_ ));
-DATA(insert ( 2113	n 0 interval_pl		-				interval_pl		interval_mi		-								f f 0	1186	0	1186	0	_null_ _null_ ));
-DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum numeric_avg_accum numeric_accum_inv numeric_sum					f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2107	n 0 int8_avg_accum	numeric_poly_sum	-					-	-	int8_avg_accum	int8_avg_accum_inv	numeric_poly_sum	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2108	n 0 int4_sum		-					int8pl				-	-	int4_avg_accum	int4_avg_accum_inv	int2int4_sum		f f 0	20		0	0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2109	n 0 int2_sum		-					int8pl				-	-	int2_avg_accum	int2_avg_accum_inv	int2int4_sum		f f 0	20		0	0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2110	n 0 float4pl		-					float4pl			-	-	-				-					-					f f 0	700		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2111	n 0 float8pl		-					float8pl			-	-	-				-					-					f f 0	701		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2112	n 0 cash_pl			-					cash_pl				-	-	cash_pl			cash_mi				-					f f 0	790		0	0	790		0	_null_ _null_ ));
+DATA(insert ( 2113	n 0 interval_pl		-					interval_pl			-	-	interval_pl		interval_mi			-					f f 0	1186	0	0	1186	0	_null_ _null_ ));
+DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum		numeric_avg_combine	numeric_avg_serialize	numeric_avg_deserialize	numeric_avg_accum	numeric_accum_inv	numeric_sum		f f 0	2281	25	128 2281	128 _null_ _null_ ));
 
 /* max */
-DATA(insert ( 2115	n 0 int8larger		-				-				-				-				f f 413		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2116	n 0 int4larger		-				-				-				-				f f 521		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2117	n 0 int2larger		-				-				-				-				f f 520		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2118	n 0 oidlarger		-				-				-				-				f f 610		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2119	n 0 float4larger	-				-				-				-				f f 623		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2120	n 0 float8larger	-				-				-				-				f f 674		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2121	n 0 int4larger		-				-				-				-				f f 563		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2122	n 0 date_larger		-				-				-				-				f f 1097	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2123	n 0 time_larger		-				-				-				-				f f 1112	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2124	n 0 timetz_larger	-				-				-				-				f f 1554	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2125	n 0 cashlarger		-				-				-				-				f f 903		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2126	n 0 timestamp_larger	-			-				-				-				f f 2064	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2127	n 0 timestamptz_larger	-			-				-				-				f f 1324	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2128	n 0 interval_larger -				-				-				-				f f 1334	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2129	n 0 text_larger		-				-				-				-				f f 666		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2130	n 0 numeric_larger	-				-				-				-				f f 1756	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2050	n 0 array_larger	-				-				-				-				f f 1073	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2244	n 0 bpchar_larger	-				-				-				-				f f 1060	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2797	n 0 tidlarger		-				-				-				-				f f 2800	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3526	n 0 enum_larger		-				-				-				-				f f 3519	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3564	n 0 network_larger	-				-				-				-				f f 1205	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2115	n 0 int8larger		-				int8larger			-	-	-				-				-				f f 413		20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2116	n 0 int4larger		-				int4larger			-	-	-				-				-				f f 521		23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2117	n 0 int2larger		-				int2larger			-	-	-				-				-				f f 520		21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2118	n 0 oidlarger		-				oidlarger			-	-	-				-				-				f f 610		26		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2119	n 0 float4larger	-				float4larger		-	-	-				-				-				f f 623		700		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2120	n 0 float8larger	-				float8larger		-	-	-				-				-				f f 674		701		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2121	n 0 int4larger		-				int4larger			-	-	-				-				-				f f 563		702		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2122	n 0 date_larger		-				date_larger			-	-	-				-				-				f f 1097	1082	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2123	n 0 time_larger		-				time_larger			-	-	-				-				-				f f 1112	1083	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2124	n 0 timetz_larger	-				timetz_larger		-	-	-				-				-				f f 1554	1266	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2125	n 0 cashlarger		-				cashlarger			-	-	-				-				-				f f 903		790		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2126	n 0 timestamp_larger	-			timestamp_larger	-	-	-				-				-				f f 2064	1114	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2127	n 0 timestamptz_larger	-			timestamptz_larger	-	-	-				-				-				f f 1324	1184	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2128	n 0 interval_larger -				interval_larger		-	-	-				-				-				f f 1334	1186	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2129	n 0 text_larger		-				text_larger			-	-	-				-				-				f f 666		25		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2130	n 0 numeric_larger	-				numeric_larger		-	-	-				-				-				f f 1756	1700	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2050	n 0 array_larger	-				array_larger		-	-	-				-				-				f f 1073	2277	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2244	n 0 bpchar_larger	-				bpchar_larger		-	-	-				-				-				f f 1060	1042	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2797	n 0 tidlarger		-				tidlarger			-	-	-				-				-				f f 2800	27		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3526	n 0 enum_larger		-				enum_larger			-	-	-				-				-				f f 3519	3500	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3564	n 0 network_larger	-				network_larger		-	-	-				-				-				f f 1205	869		0	0	0		0	_null_ _null_ ));
 
 /* min */
-DATA(insert ( 2131	n 0 int8smaller		-				-				-				-				f f 412		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2132	n 0 int4smaller		-				-				-				-				f f 97		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2133	n 0 int2smaller		-				-				-				-				f f 95		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2134	n 0 oidsmaller		-				-				-				-				f f 609		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2135	n 0 float4smaller	-				-				-				-				f f 622		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2136	n 0 float8smaller	-				-				-				-				f f 672		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2137	n 0 int4smaller		-				-				-				-				f f 562		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2138	n 0 date_smaller	-				-				-				-				f f 1095	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2139	n 0 time_smaller	-				-				-				-				f f 1110	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2140	n 0 timetz_smaller	-				-				-				-				f f 1552	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2141	n 0 cashsmaller		-				-				-				-				f f 902		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2142	n 0 timestamp_smaller	-			-				-				-				f f 2062	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2143	n 0 timestamptz_smaller -			-				-				-				f f 1322	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2144	n 0 interval_smaller	-			-				-				-				f f 1332	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2145	n 0 text_smaller	-				-				-				-				f f 664		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2146	n 0 numeric_smaller -				-				-				-				f f 1754	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2051	n 0 array_smaller	-				-				-				-				f f 1072	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2245	n 0 bpchar_smaller	-				-				-				-				f f 1058	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2798	n 0 tidsmaller		-				-				-				-				f f 2799	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3527	n 0 enum_smaller	-				-				-				-				f f 3518	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3565	n 0 network_smaller -				-				-				-				f f 1203	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2131	n 0 int8smaller		-				int8smaller			-	-	-				-				-				f f 412		20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2132	n 0 int4smaller		-				int4smaller			-	-	-				-				-				f f 97		23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2133	n 0 int2smaller		-				int2smaller			-	-	-				-				-				f f 95		21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2134	n 0 oidsmaller		-				oidsmaller			-	-	-				-				-				f f 609		26		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2135	n 0 float4smaller	-				float4smaller		-	-	-				-				-				f f 622		700		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2136	n 0 float8smaller	-				float8smaller		-	-	-				-				-				f f 672		701		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2137	n 0 int4smaller		-				int4smaller			-	-	-				-				-				f f 562		702		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2138	n 0 date_smaller	-				date_smaller		-	-	-				-				-				f f 1095	1082	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2139	n 0 time_smaller	-				time_smaller		-	-	-				-				-				f f 1110	1083	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2140	n 0 timetz_smaller	-				timetz_smaller		-	-	-				-				-				f f 1552	1266	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2141	n 0 cashsmaller		-				cashsmaller			-	-	-				-				-				f f 902		790		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2142	n 0 timestamp_smaller	-			timestamp_smaller	-	-	-				-				-				f f 2062	1114	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2143	n 0 timestamptz_smaller -			timestamptz_smaller	-	-	-				-				-				f f 1322	1184	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2144	n 0 interval_smaller	-			interval_smaller	-	-	-				-				-				f f 1332	1186	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2145	n 0 text_smaller	-				text_smaller		-	-	-				-				-				f f 664		25		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2146	n 0 numeric_smaller -				numeric_smaller		-	-	-				-				-				f f 1754	1700	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2051	n 0 array_smaller	-				array_smaller		-	-	-				-				-				f f 1072	2277	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2245	n 0 bpchar_smaller	-				bpchar_smaller		-	-	-				-				-				f f 1058	1042	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2798	n 0 tidsmaller		-				tidsmaller			-	-	-				-				-				f f 2799	27		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3527	n 0 enum_smaller	-				enum_smaller		-	-	-				-				-				f f 3518	3500	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3565	n 0 network_smaller -				network_smaller		-	-	-				-				-				f f 1203	869		0	0	0		0	_null_ _null_ ));
 
 /* count */
-DATA(insert ( 2147	n 0 int8inc_any		-				int8inc_any		int8dec_any		-				f f 0		20		0	20		0	"0" "0" ));
-DATA(insert ( 2803	n 0 int8inc			-				int8inc			int8dec			-				f f 0		20		0	20		0	"0" "0" ));
+DATA(insert ( 2147	n 0 int8inc_any		-				int8pl	-	-	int8inc_any		int8dec_any		-				f f 0		20		0	0	20		0	"0" "0" ));
+DATA(insert ( 2803	n 0 int8inc			-				int8pl	-	-	int8inc			int8dec			-				f f 0		20		0	0	20		0	"0" "0" ));
 
 /* var_pop */
-DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop		int8_accum		int8_accum_inv	numeric_var_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2719	n 0 int4_accum	numeric_poly_var_pop		int4_accum		int4_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2720	n 0 int2_accum	numeric_poly_var_pop		int2_accum		int2_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2721	n 0 float4_accum	float8_var_pop	-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2722	n 0 float8_accum	float8_var_pop	-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop numeric_accum numeric_accum_inv numeric_var_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop			-	-	-	int8_accum		int8_accum_inv	numeric_var_pop			f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2719	n 0 int4_accum	numeric_poly_var_pop	-	-	-	int4_accum		int4_accum_inv	numeric_poly_var_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2720	n 0 int2_accum	numeric_poly_var_pop	-	-	-	int2_accum		int2_accum_inv	numeric_poly_var_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2721	n 0 float4_accum	float8_var_pop		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2722	n 0 float8_accum	float8_var_pop		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop		-	-	-	numeric_accum numeric_accum_inv numeric_var_pop			f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* var_samp */
-DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp	int8_accum		int8_accum_inv	numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2642	n 0 int4_accum	numeric_poly_var_samp		int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2643	n 0 int2_accum	numeric_poly_var_samp		int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2644	n 0 float4_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2645	n 0 float8_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp numeric_accum numeric_accum_inv numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp		-	-	-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2642	n 0 int4_accum	numeric_poly_var_samp	-	-	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2643	n 0 int2_accum	numeric_poly_var_samp	-	-	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2644	n 0 float4_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2645	n 0 float8_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp	-	-	-	numeric_accum	numeric_accum_inv numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* variance: historical Postgres syntax for var_samp */
-DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp	int8_accum		int8_accum_inv	numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2149	n 0 int4_accum	numeric_poly_var_samp		int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2150	n 0 int2_accum	numeric_poly_var_samp		int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2151	n 0 float4_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2152	n 0 float8_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp numeric_accum numeric_accum_inv numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp		-	-	-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2149	n 0 int4_accum	numeric_poly_var_samp	-	-	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2150	n 0 int2_accum	numeric_poly_var_samp	-	-	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2151	n 0 float4_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2152	n 0 float8_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp	-	-	-	numeric_accum numeric_accum_inv numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* stddev_pop */
-DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop	int8_accum	int8_accum_inv	numeric_stddev_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2725	n 0 int4_accum	numeric_poly_stddev_pop int4_accum	int4_accum_inv	numeric_poly_stddev_pop f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2726	n 0 int2_accum	numeric_poly_stddev_pop int2_accum	int2_accum_inv	numeric_poly_stddev_pop f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop numeric_accum numeric_accum_inv numeric_stddev_pop			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop		-	-	-	int8_accum	int8_accum_inv	numeric_stddev_pop		f f 0	2281	0	128	2281	128 _null_ _null_ ));
+DATA(insert ( 2725	n 0 int4_accum	numeric_poly_stddev_pop	-	-	-	int4_accum	int4_accum_inv	numeric_poly_stddev_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2726	n 0 int2_accum	numeric_poly_stddev_pop	-	-	-	int2_accum	int2_accum_inv	numeric_poly_stddev_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-	-	-	-				-				-					f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-	-	-	-				-				-					f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop	-	-	-	numeric_accum numeric_accum_inv numeric_stddev_pop	f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* stddev_samp */
-DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp		int8_accum	int8_accum_inv	numeric_stddev_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2713	n 0 int4_accum	numeric_poly_stddev_samp	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2714	n 0 int2_accum	numeric_poly_stddev_samp	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp numeric_accum numeric_accum_inv numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp			-	-	-	int8_accum	int8_accum_inv	numeric_stddev_samp			f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2713	n 0 int4_accum	numeric_poly_stddev_samp	-	-	-	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2714	n 0 int2_accum	numeric_poly_stddev_samp	-	-	-	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp		-	-	-	numeric_accum numeric_accum_inv numeric_stddev_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* stddev: historical Postgres syntax for stddev_samp */
-DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp		int8_accum	int8_accum_inv	numeric_stddev_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2155	n 0 int4_accum	numeric_poly_stddev_samp	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2156	n 0 int2_accum	numeric_poly_stddev_samp	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp numeric_accum numeric_accum_inv numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp			-	-	-	int8_accum		int8_accum_inv	numeric_stddev_samp			f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2155	n 0 int4_accum	numeric_poly_stddev_samp	-	-	-	int4_accum		int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2156	n 0 int2_accum	numeric_poly_stddev_samp	-	-	-	int2_accum		int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp		-	-	-	-				-				-							f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp		-	-	-	-				-				-							f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp		-	-	-	numeric_accum	numeric_accum_inv numeric_stddev_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* SQL2003 binary regression aggregates */
-DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-				-				-				f f 0	20		0	0		0	"0" _null_ ));
-DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-	-	-	-				-				-			f f 0	20		0	0	0		0	"0" _null_ ));
+DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
 
 /* boolean-and and boolean-or */
-DATA(insert ( 2517	n 0 booland_statefunc	-			bool_accum		bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2518	n 0 boolor_statefunc	-			bool_accum		bool_accum_inv	bool_anytrue	f f 59	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2519	n 0 booland_statefunc	-			bool_accum		bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2517	n 0 booland_statefunc	-	-	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16	0		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2518	n 0 boolor_statefunc	-	-	-	-	bool_accum	bool_accum_inv	bool_anytrue	f f 59	16	0		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2519	n 0 booland_statefunc	-	-	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16	0		0	2281	16	_null_ _null_ ));
 
 /* bitwise integer */
-DATA(insert ( 2236	n 0 int2and		-					-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2237	n 0 int2or		-					-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2238	n 0 int4and		-					-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2239	n 0 int4or		-					-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2240	n 0 int8and		-					-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2241	n 0 int8or		-					-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2242	n 0 bitand		-					-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
-DATA(insert ( 2243	n 0 bitor		-					-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
+DATA(insert ( 2236	n 0 int2and		-				int2and	-	-	-				-				-				f f 0	21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2237	n 0 int2or		-				int2or	-	-	-				-				-				f f 0	21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2238	n 0 int4and		-				int4and	-	-	-				-				-				f f 0	23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2239	n 0 int4or		-				int4or	-	-	-				-				-				f f 0	23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2240	n 0 int8and		-				int8and	-	-	-				-				-				f f 0	20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2241	n 0 int8or		-				int8or	-	-	-				-				-				f f 0	20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2242	n 0 bitand		-				bitand	-	-	-				-				-				f f 0	1560	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2243	n 0 bitor		-				bitor	-	-	-				-				-				f f 0	1560	0	0	0		0	_null_ _null_ ));
 
 /* xml */
-DATA(insert ( 2901	n 0 xmlconcat2	-					-				-				-				f f 0	142		0	0		0	_null_ _null_ ));
+DATA(insert ( 2901	n 0 xmlconcat2	-				-		-	-	-				-				-				f f 0	142		0	0	0		0	_null_ _null_ ));
 
 /* array */
-DATA(insert ( 2335	n 0 array_agg_transfn	array_agg_finalfn	-				-				-				t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn -		-				-				t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 2335	n 0 array_agg_transfn		array_agg_finalfn		-	-	-	-		-				-				t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn	-	-	-	-		-				-				t f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* text */
-DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-	-	-	-				-				-				f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* bytea */
-DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-				-				-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-	-	-	-				-				-		f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* json */
-DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-	-	-	-				-				-				f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -	-	-	-				-				-				f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* jsonb */
-DATA(insert ( 3267	n 0 jsonb_agg_transfn	jsonb_agg_finalfn			-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3270	n 0 jsonb_object_agg_transfn jsonb_object_agg_finalfn -				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3267	n 0 jsonb_agg_transfn	jsonb_agg_finalfn				-	-	-	-				-				-			f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3270	n 0 jsonb_object_agg_transfn jsonb_object_agg_finalfn	-	-	-	-				-				-			f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* ordered-set and hypothetical-set aggregates */
-DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
 
 
 /*
@@ -322,6 +334,9 @@ extern ObjectAddress AggregateCreate(const char *aggName,
 				Oid variadicArgType,
 				List *aggtransfnName,
 				List *aggfinalfnName,
+				List *aggcombinefnName,
+				List *aggserialfnName,
+				List *aggdeserialfnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
@@ -329,6 +344,7 @@ extern ObjectAddress AggregateCreate(const char *aggName,
 				bool mfinalfnExtraArgs,
 				List *aggsortopName,
 				Oid aggTransType,
+				Oid aggSerialType,
 				int32 aggTransSpace,
 				Oid aggmTransType,
 				int32 aggmTransSpace,
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 86b09a1..af7468b 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -2517,6 +2517,12 @@ DESCR("aggregate final function");
 DATA(insert OID = 1833 (  numeric_accum    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_accum _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
 DATA(insert OID = 2858 (  numeric_avg_accum    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_avg_accum _null_ _null_ _null_ ));
+DESCR("aggregate combine function");
+DATA(insert OID = 3318 (  numeric_avg_combine    PGNSP PGUID 12 1 0 0 0 f f f f t f i s 2 0 2281 "2281 2281" _null_ _null_ _null_ _null_ _null_ numeric_avg_combine _null_ _null_ _null_ ));
+DESCR("aggregate serial function");
+DATA(insert OID = 3319 (  numeric_avg_serialize    PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 25 "2281" _null_ _null_ _null_ _null_ _null_ numeric_avg_serialize _null_ _null_ _null_ ));
+DESCR("aggregate deserial function");
+DATA(insert OID = 3320 (  numeric_avg_deserialize    PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 2281 "25" _null_ _null_ _null_ _null_ _null_ numeric_avg_deserialize _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
 DATA(insert OID = 3548 (  numeric_accum_inv    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_accum_inv _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index bfa5125..69a1dad 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1851,6 +1851,9 @@ typedef struct AggState
 	AggStatePerTrans curpertrans;	/* currently active trans state */
 	bool		input_done;		/* indicates end of input */
 	bool		agg_done;		/* indicates completion of Agg scan */
+	bool		combineStates;	/* input tuples contain transition states */
+	bool		finalizeAggs;	/* should we call the finalfn on agg states? */
+	bool		serialStates;	/* should partial states be serialized? */
 	int			projected_set;	/* The last projected grouping set */
 	int			current_set;	/* The current grouping set being evaluated */
 	Bitmapset  *grouped_cols;	/* grouped cols in current projection */
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index c92579b..b5d0e56 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -726,6 +726,9 @@ typedef struct Agg
 	AggStrategy aggstrategy;
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
+	bool		combineStates;	/* input tuples contain transition states */
+	bool		finalizeAggs;	/* should we call the finalfn on agg states? */
+	bool		serialStates;	/* should partial states be serialized? */
 	Oid		   *grpOperators;	/* equality operators to compare with */
 	long		numGroups;		/* estimated number of groups in input */
 	List	   *groupingSets;	/* grouping sets to use */
diff --git a/src/include/optimizer/clauses.h b/src/include/optimizer/clauses.h
index 3b3fd0f..d381ff0 100644
--- a/src/include/optimizer/clauses.h
+++ b/src/include/optimizer/clauses.h
@@ -27,6 +27,25 @@ typedef struct
 	List	  **windowFuncs;	/* lists of WindowFuncs for each winref */
 } WindowFuncLists;
 
+/*
+ * PartialAggType
+ *	PartialAggType stores whether partial aggregation is allowed and
+ *	which context it is allowed in. We require three states here as there are
+ *	two different contexts in which partial aggregation is safe. For aggregates
+ *	which have an 'stype' of INTERNAL, within a single backend process it is
+ *	okay to pass a pointer to the aggregate state, as the memory to which the
+ *	pointer points to will belong to the same process. In cases where the
+ *	aggregate state must be passed between different processes, for example
+ *	during parallel aggregation, passing the pointer is not okay due to the
+ *	fact that the memory being referenced won't be accessible from another
+ *	process.
+ */
+typedef enum
+{
+	PAT_ANY = 0,		/* Any type of partial aggregation is ok. */
+	PAT_INTERNAL_ONLY,	/* Some aggregates support only internal mode. */
+	PAT_DISABLED		/* Some aggregates don't support partial mode at all */
+} PartialAggType;
 
 extern Expr *make_opclause(Oid opno, Oid opresulttype, bool opretset,
 			  Expr *leftop, Expr *rightop,
@@ -47,6 +66,7 @@ extern Node *make_and_qual(Node *qual1, Node *qual2);
 extern Expr *make_ands_explicit(List *andclauses);
 extern List *make_ands_implicit(Expr *clause);
 
+extern PartialAggType aggregates_allow_partial(Node *clause);
 extern bool contain_agg_clause(Node *clause);
 extern void count_agg_clauses(PlannerInfo *root, Node *clause,
 				  AggClauseCosts *costs);
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index 275054f..c1819f6 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -60,9 +60,8 @@ extern Sort *make_sort_from_groupcols(PlannerInfo *root, List *groupcls,
 extern Agg *make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
 		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
-		 List *groupingSets,
-		 long numGroups,
-		 Plan *lefttree);
+		 List *groupingSets, long numGroups, bool combineStates,
+		 bool finalizeAggs, bool serialStates, Plan *lefttree);
 extern WindowAgg *make_windowagg(PlannerInfo *root, List *tlist,
 			   List *windowFuncs, Index winref,
 			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
diff --git a/src/include/parser/parse_agg.h b/src/include/parser/parse_agg.h
index 3e336b9..43be714 100644
--- a/src/include/parser/parse_agg.h
+++ b/src/include/parser/parse_agg.h
@@ -46,6 +46,23 @@ extern void build_aggregate_transfn_expr(Oid *agg_input_types,
 						Expr **transfnexpr,
 						Expr **invtransfnexpr);
 
+extern void build_aggregate_combinefn_expr(Oid agg_state_type,
+										   Oid agg_input_collation,
+										   Oid combinefn_oid,
+										   Expr **combinefnexpr);
+
+extern void build_aggregate_serialfn_expr(Oid agg_state_type,
+										  Oid agg_serial_type,
+										  Oid agg_input_collation,
+										  Oid serialfn_oid,
+										  Expr **serialfnexpr);
+
+extern void build_aggregate_deserialfn_expr(Oid agg_state_type,
+											Oid agg_serial_type,
+											Oid agg_input_collation,
+											Oid deserialfn_oid,
+											Expr **deserialfnexpr);
+
 extern void build_aggregate_finalfn_expr(Oid *agg_input_types,
 						int num_finalfn_inputs,
 						Oid agg_state_type,
diff --git a/src/test/regress/expected/create_aggregate.out b/src/test/regress/expected/create_aggregate.out
index 82a34fb..14f73c4 100644
--- a/src/test/regress/expected/create_aggregate.out
+++ b/src/test/regress/expected/create_aggregate.out
@@ -101,6 +101,93 @@ CREATE AGGREGATE sumdouble (float8)
     msfunc = float8pl,
     minvfunc = float8mi
 );
+-- aggregate combine and serialization functions
+-- Ensure stype and serialtype can't be the same
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = internal
+);
+ERROR:  aggregate serial data type cannot be "internal"
+-- if serialtype is specified we need a serialfunc and deserialfunc
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text
+);
+ERROR:  aggregate serialfunc must be specified when serialtype is specified
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize
+);
+ERROR:  aggregate deserialfunc must be specified when serialtype is specified
+-- serialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_deserialize,
+	deserialfunc = numeric_avg_deserialize
+);
+ERROR:  function numeric_avg_deserialize(internal) does not exist
+-- deserialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_serialize
+);
+ERROR:  function numeric_avg_serialize(text) does not exist
+-- ensure return type of serialfunc is checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = bytea,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize
+);
+ERROR:  return type of serial function numeric_avg_serialize is not bytea
+-- ensure combine function parameters are checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = int4larger
+);
+ERROR:  function int4larger(internal, internal) does not exist
+-- ensure create aggregate works.
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	finalfunc = numeric_avg,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = numeric_avg_combine
+);
+-- Ensure all these functions made it into the catalog
+SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype,aggserialfn,aggdeserialfn,aggserialtype
+FROM pg_aggregate
+WHERE aggfnoid = 'myavg'::REGPROC;
+ aggfnoid |    aggtransfn     |    aggcombinefn     | aggtranstype |      aggserialfn      |      aggdeserialfn      | aggserialtype 
+----------+-------------------+---------------------+--------------+-----------------------+-------------------------+---------------
+ myavg    | numeric_avg_accum | numeric_avg_combine |         2281 | numeric_avg_serialize | numeric_avg_deserialize |            25
+(1 row)
+
+DROP AGGREGATE myavg (numeric);
 -- invalid: nonstrict inverse with strict forward function
 CREATE FUNCTION float8mi_n(float8, float8) RETURNS float8 AS
 $$ SELECT $1 - $2; $$
diff --git a/src/test/regress/sql/create_aggregate.sql b/src/test/regress/sql/create_aggregate.sql
index 0ec1572..8395e5d 100644
--- a/src/test/regress/sql/create_aggregate.sql
+++ b/src/test/regress/sql/create_aggregate.sql
@@ -115,6 +115,92 @@ CREATE AGGREGATE sumdouble (float8)
     minvfunc = float8mi
 );
 
+-- aggregate combine and serialization functions
+
+-- Ensure stype and serialtype can't be the same
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = internal
+);
+
+-- if serialtype is specified we need a serialfunc and deserialfunc
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text
+);
+
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize
+);
+
+-- serialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_deserialize,
+	deserialfunc = numeric_avg_deserialize
+);
+
+-- deserialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_serialize
+);
+
+-- ensure return type of serialfunc is checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = bytea,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize
+);
+
+-- ensure combine function parameters are checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = int4larger
+);
+
+-- ensure create aggregate works.
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	finalfunc = numeric_avg,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = numeric_avg_combine
+);
+
+-- Ensure all these functions made it into the catalog
+SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype,aggserialfn,aggdeserialfn,aggserialtype
+FROM pg_aggregate
+WHERE aggfnoid = 'myavg'::REGPROC;
+
+DROP AGGREGATE myavg (numeric);
+
 -- invalid: nonstrict inverse with strict forward function
 
 CREATE FUNCTION float8mi_n(float8, float8) RETURNS float8 AS

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 08a914e..8f08f19 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -134,7 +134,104 @@ static Plan *build_grouping_chain(PlannerInfo *root,
 					 AttrNumber *groupColIdx,
 					 AggClauseCosts *agg_costs,
 					 long numGroups,
-					 Plan *result_plan);
+					 Plan *result_plan,
+					 PartialAggType partialaggtype);
+
+static List *
+make_aggregate_tlist(PlannerInfo *root,
+					 List *tlist,
+					 AttrNumber **groupColIdx)
+{
+	Query	   *parse = root->parse;
+	List	   *sub_tlist;
+	List	   *non_group_cols;
+	List	   *non_group_vars;
+	int			numCols;
+	ListCell   *tl;
+
+	*groupColIdx = NULL;
+
+	/*
+	 * Otherwise, we must build a tlist containing all grouping columns, plus
+	 * any other Vars mentioned in the targetlist and HAVING qual.
+	 */
+	sub_tlist = NIL;
+	non_group_cols = NIL;
+
+	numCols = list_length(parse->groupClause);
+	if (numCols > 0)
+	{
+		/*
+		 * If grouping, create sub_tlist entries for all GROUP BY columns, and
+		 * make an array showing where the group columns are in the sub_tlist.
+		 *
+		 * Note: with this implementation, the array entries will always be
+		 * 1..N, but we don't want callers to assume that.
+		 */
+		AttrNumber *grpColIdx;
+
+		grpColIdx = (AttrNumber *) palloc0(sizeof(AttrNumber) * numCols);
+		*groupColIdx = grpColIdx;
+
+		foreach(tl, tlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(tl);
+			int			colno;
+
+			colno = get_grouping_column_index(parse, tle);
+			if (colno >= 0)
+			{
+				/*
+				 * It's a grouping column, so add it to the result tlist and
+				 * remember its resno in grpColIdx[].
+				 */
+				TargetEntry *newtle;
+
+				newtle = makeTargetEntry((Expr *) copyObject(tle->expr),
+										 list_length(sub_tlist) + 1,
+										 NULL,
+										 tle->resjunk);
+				newtle->ressortgroupref = tle->ressortgroupref;
+				sub_tlist = lappend(sub_tlist, newtle);
+
+				Assert(grpColIdx[colno] == 0);	/* no dups expected */
+				grpColIdx[colno] = newtle->resno;
+			}
+			else
+			{
+				non_group_cols = lappend(non_group_cols, tle->expr);
+			}
+		}
+	}
+	else
+	{
+		foreach(tl, tlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(tl);
+			non_group_cols = lappend(non_group_cols, tle->expr);
+		}
+	}
+
+	/*
+	 * If there's a HAVING clause, we'll need need to ensure all Aggrefs from
+	 * there are also in the targetlist
+	 */
+	if (parse->havingQual)
+		non_group_cols = lappend(non_group_cols, parse->havingQual);
+
+
+	non_group_vars = pull_var_clause((Node *) non_group_cols,
+									 PVC_INCLUDE_AGGREGATES,
+									 PVC_INCLUDE_PLACEHOLDERS);
+
+	sub_tlist = add_to_flat_tlist(sub_tlist, non_group_vars);
+
+	/* clean up cruft */
+	list_free(non_group_vars);
+	list_free(non_group_cols);
+
+	return sub_tlist;
+}
 
 /*****************************************************************************
  *
@@ -1900,6 +1997,19 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			AttrNumber *groupColIdx = NULL;
 			bool		need_tlist_eval = true;
 			bool		need_sort_for_grouping = false;
+			PartialAggType partialaggtype;
+
+			/* Determine the level of partial aggregation we can use */
+			if (parse->groupingSets)
+				partialaggtype = PAT_DISABLED;
+			else
+			{
+				partialaggtype = aggregates_allow_partial((Node *) tlist);
+
+				if (partialaggtype != PAT_DISABLED)
+					partialaggtype = Min(partialaggtype,
+							aggregates_allow_partial(root->parse->havingQual));
+			}
 
 			result_plan = create_plan(root, best_path);
 			current_pathkeys = best_path->pathkeys;
@@ -1917,6 +2027,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 											   &groupColIdx,
 											   &need_tlist_eval);
 
+			if (partialaggtype != PAT_DISABLED)
+				need_tlist_eval = true;
+
 			/*
 			 * create_plan returns a plan with just a "flat" tlist of required
 			 * Vars.  Usually we need to insert the sub_tlist as the tlist of
@@ -1998,21 +2111,74 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			 */
 			if (use_hashed_grouping)
 			{
-				/* Hashed aggregate plan --- no sort needed */
-				result_plan = (Plan *) make_agg(root,
-												tlist,
-												(List *) parse->havingQual,
-												AGG_HASHED,
-												&agg_costs,
-												numGroupCols,
-												groupColIdx,
-									extract_grouping_ops(parse->groupClause),
-												NIL,
-												numGroups,
-												false,
-												true,
-												false,
-												result_plan);
+				if (partialaggtype != PAT_DISABLED)
+				{
+					AttrNumber *groupColIdx;
+					List *aggtlist;
+
+					aggtlist = make_aggregate_tlist(root, tlist, &groupColIdx);
+
+					/* Hashed aggregate plan --- no sort needed */
+					result_plan = (Plan *) make_agg(root,
+													aggtlist,
+													NIL,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													false,
+													false,
+													true,
+													result_plan);
+
+					result_plan->targetlist = aggtlist;
+
+					/*
+					 * Also, account for the cost of evaluation of the sub_tlist.
+					 * See comments for add_tlist_costs_to_plan() for more info.
+					 */
+					add_tlist_costs_to_plan(root, result_plan, aggtlist);
+
+					aggtlist  = make_aggregate_tlist(root, tlist, &groupColIdx);
+
+					result_plan = (Plan *) make_agg(root,
+													aggtlist,
+													(List *) parse->havingQual,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													true,
+													true,
+													true,
+													result_plan);
+					result_plan->targetlist = tlist;
+
+				}
+				else
+				{
+					/* Hashed aggregate plan --- no sort needed */
+					result_plan = (Plan *) make_agg(root,
+													tlist,
+													(List *) parse->havingQual,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													false,
+													true,
+													false,
+													result_plan);
+				}
 				/* Hashed aggregation produces randomly-ordered results */
 				current_pathkeys = NIL;
 			}
@@ -2041,7 +2207,8 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 												   groupColIdx,
 												   &agg_costs,
 												   numGroups,
-												   result_plan);
+												   result_plan,
+												   partialaggtype);
 
 				/*
 				 * these are destroyed by build_grouping_chain, so make sure
@@ -2496,7 +2663,8 @@ build_grouping_chain(PlannerInfo *root,
 					 AttrNumber *groupColIdx,
 					 AggClauseCosts *agg_costs,
 					 long numGroups,
-					 Plan *result_plan)
+					 Plan *result_plan,
+					 PartialAggType partialaggtype)
 {
 	AttrNumber *top_grpColIdx = groupColIdx;
 	List	   *chain = NIL;
@@ -2591,21 +2759,70 @@ build_grouping_chain(PlannerInfo *root,
 		else
 			numGroupCols = list_length(parse->groupClause);
 
-		result_plan = (Plan *) make_agg(root,
-										tlist,
-										(List *) parse->havingQual,
-								 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
-										agg_costs,
-										numGroupCols,
-										top_grpColIdx,
-										extract_grouping_ops(groupClause),
-										gsets,
-										numGroups,
-										false,
-										true,
-										false,
-										result_plan);
+		if (partialaggtype != PAT_DISABLED)
+		{
+			AttrNumber *groupColIdx;
+			List *aggtlist;
+
+			aggtlist = make_aggregate_tlist(root, tlist, &groupColIdx);
+
+			result_plan = (Plan *) make_agg(root,
+											aggtlist,
+											NIL,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											groupColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											false,
+											false,
+											true,
+											result_plan);
+			result_plan->targetlist = aggtlist;
+
+			/*
+			 * Also, account for the cost of evaluation of the sub_tlist.
+			 * See comments for add_tlist_costs_to_plan() for more info.
+			 */
+			add_tlist_costs_to_plan(root, result_plan, aggtlist);
+
+			aggtlist  = make_aggregate_tlist(root, tlist, &groupColIdx);
 
+			result_plan = (Plan *) make_agg(root,
+											aggtlist,
+											(List *) parse->havingQual,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											groupColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											true,
+											true,
+											true,
+											result_plan);
+			result_plan->targetlist = tlist;
+		}
+		else
+		{
+			result_plan = (Plan *) make_agg(root,
+											tlist,
+											(List *) parse->havingQual,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											top_grpColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											false,
+											true,
+											false,
+											result_plan);
+		}
 		((Agg *) result_plan)->chain = chain;
 
 		/*

diff --git a/doc/src/sgml/ref/create_aggregate.sgml b/doc/src/sgml/ref/create_aggregate.sgml
index eaa410b..bb62c96 100644
--- a/doc/src/sgml/ref/create_aggregate.sgml
+++ b/doc/src/sgml/ref/create_aggregate.sgml
@@ -27,6 +27,10 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ <replacea
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
+    [ , SERIALFUNC = <replaceable class="PARAMETER">serialfunc</replaceable> ]
+    [ , DESERIALFUNC = <replaceable class="PARAMETER">deserialfunc</replaceable> ]
+    [ , SERIALTYPE = <replaceable class="PARAMETER">serialtype</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -45,6 +49,10 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ [ <replac
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
+    [ , SERIALFUNC = <replaceable class="PARAMETER">serialfunc</replaceable> ]
+    [ , DESERIALFUNC = <replaceable class="PARAMETER">deserialfunc</replaceable> ]
+    [ , SERIALTYPE = <replaceable class="PARAMETER">serialtype</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , HYPOTHETICAL ]
 )
@@ -58,6 +66,10 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
+    [ , SERIALFUNC = <replaceable class="PARAMETER">serialfunc</replaceable> ]
+    [ , DESERIALFUNC = <replaceable class="PARAMETER">deserialfunc</replaceable> ]
+    [ , SERIALTYPE = <replaceable class="PARAMETER">serialtype</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -105,12 +117,23 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
    functions:
    a state transition function
    <replaceable class="PARAMETER">sfunc</replaceable>,
-   and an optional final calculation function
-   <replaceable class="PARAMETER">ffunc</replaceable>.
+   an optional final calculation function
+   <replaceable class="PARAMETER">ffunc</replaceable>,
+   an optional combine function
+   <replaceable class="PARAMETER">combinefunc</replaceable>,
+   an optional serialization function
+   <replaceable class="PARAMETER">serialfunc</replaceable>,
+   an optional deserialization function
+   <replaceable class="PARAMETER">deserialfunc</replaceable>,
+   and an optional serialization type
+   <replaceable class="PARAMETER">serialtype</replaceable>.
    These are used as follows:
 <programlisting>
 <replaceable class="PARAMETER">sfunc</replaceable>( internal-state, next-data-values ) ---> next-internal-state
 <replaceable class="PARAMETER">ffunc</replaceable>( internal-state ) ---> aggregate-value
+<replaceable class="PARAMETER">combinefunc</replaceable>( internal-state, internal-state ) ---> next-internal-state
+<replaceable class="PARAMETER">serialfunc</replaceable>( internal-state ) ---> serialized-state
+<replaceable class="PARAMETER">deserialfunc</replaceable>( serialized-state ) ---> internal-state
 </programlisting>
   </para>
 
@@ -128,6 +151,27 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
   </para>
 
   <para>
+   An aggregate function may also supply a combining function, which allows
+   the aggregation process to be broken down into multiple steps.  This
+   facilitates query optimization techniques such as parallel query.
+  </para>
+
+  <para>
+  A serialization and deserialization function may also be supplied. These
+  functions are required in order to allow parallel aggregation for aggregates
+  with an <replaceable class="PARAMETER">stype</replaceable> of <literal>
+  INTERNAL</>. The <replaceable class="PARAMETER">serialfunc</replaceable>, if
+  present must transform the aggregate state into a value of
+  <replaceable class="PARAMETER">serialtype</replaceable>, whereas the 
+  <replaceable class="PARAMETER">deserialfunc</replaceable> performs the
+  opposite, transforming the aggregate state back into the
+  <replaceable class="PARAMETER">stype</replaceable>. This is required due to
+  the process model being unable to pass <literal>INTERNAL</literal> types
+  between different <productname>PostgreSQL</productname> processes. These
+  parameters are only valid when <replaceable class="PARAMETER">stype
+  </replaceable> is <literal>INTERNAL</>.
+
+  <para>
    An aggregate function can provide an initial condition,
    that is, an initial value for the internal state value.
    This is specified and stored in the database as a value of type
diff --git a/src/backend/catalog/pg_aggregate.c b/src/backend/catalog/pg_aggregate.c
index 1d845ec..d971109 100644
--- a/src/backend/catalog/pg_aggregate.c
+++ b/src/backend/catalog/pg_aggregate.c
@@ -57,6 +57,9 @@ AggregateCreate(const char *aggName,
 				Oid variadicArgType,
 				List *aggtransfnName,
 				List *aggfinalfnName,
+				List *aggcombinefnName,
+				List *aggserialfnName,
+				List *aggdeserialfnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
@@ -64,6 +67,7 @@ AggregateCreate(const char *aggName,
 				bool mfinalfnExtraArgs,
 				List *aggsortopName,
 				Oid aggTransType,
+				Oid aggSerialType,
 				int32 aggTransSpace,
 				Oid aggmTransType,
 				int32 aggmTransSpace,
@@ -77,6 +81,9 @@ AggregateCreate(const char *aggName,
 	Form_pg_proc proc;
 	Oid			transfn;
 	Oid			finalfn = InvalidOid;	/* can be omitted */
+	Oid			combinefn = InvalidOid;	/* can be omitted */
+	Oid			serialfn = InvalidOid;	/* can be omitted */
+	Oid			deserialfn = InvalidOid;	/* can be omitted */
 	Oid			mtransfn = InvalidOid;	/* can be omitted */
 	Oid			minvtransfn = InvalidOid;		/* can be omitted */
 	Oid			mfinalfn = InvalidOid;	/* can be omitted */
@@ -396,6 +403,83 @@ AggregateCreate(const char *aggName,
 	}
 	Assert(OidIsValid(finaltype));
 
+	/* handle the combinefn, if supplied */
+	if (aggcombinefnName)
+	{
+		Oid combineType;
+
+		/*
+		 * Combine function must have 2 argument, each of which is the
+		 * trans type
+		 */
+		fnArgs[0] = aggTransType;
+		fnArgs[1] = aggTransType;
+
+		combinefn = lookup_agg_function(aggcombinefnName, 2, fnArgs,
+										variadicArgType, &combineType);
+
+		/* Ensure the return type matches the aggregates trans type */
+		if (combineType != aggTransType)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+			errmsg("return type of combine function %s is not %s",
+				   NameListToString(aggcombinefnName),
+				   format_type_be(aggTransType))));
+	}
+
+	/*
+	 * Validate the serial function, if present. We must ensure that the return
+	 * type of this function is the same as the specified serialType, and that
+	 * indeed a serialType was actually also specified.
+	 */
+	if (aggserialfnName)
+	{
+		/* check that we also got a serial type */
+		if (!OidIsValid(aggSerialType))
+			ereport(ERROR,
+				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+				 errmsg("must specify serialtype when specifying serialfunc")));
+
+		fnArgs[0] = aggTransType;
+
+		serialfn = lookup_agg_function(aggserialfnName, 1,
+									   fnArgs, variadicArgType,
+									   &rettype);
+
+		if (rettype != aggSerialType)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("return type of serial function %s is not %s",
+							NameListToString(aggserialfnName),
+							format_type_be(aggSerialType))));
+	}
+
+	/*
+	 * Validate the deserial function, if present. We must ensure that the
+	 * return type of this function is the same as the transType.
+	 */
+	if (aggdeserialfnName)
+	{
+		/* check that we also got a serial type */
+		if (!OidIsValid(aggSerialType))
+			ereport(ERROR,
+				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+				 errmsg("must specify serialtype when specifying deserialfunc")));
+
+		fnArgs[0] = aggSerialType;
+
+		deserialfn = lookup_agg_function(aggdeserialfnName, 1,
+										 fnArgs, variadicArgType,
+										 &rettype);
+
+		if (rettype != aggTransType)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("return type of deserial function %s is not %s",
+							NameListToString(aggdeserialfnName),
+							format_type_be(aggTransType))));
+	}
+
 	/*
 	 * If finaltype (i.e. aggregate return type) is polymorphic, inputs must
 	 * be polymorphic also, else parser will fail to deduce result type.
@@ -567,6 +651,9 @@ AggregateCreate(const char *aggName,
 	values[Anum_pg_aggregate_aggnumdirectargs - 1] = Int16GetDatum(numDirectArgs);
 	values[Anum_pg_aggregate_aggtransfn - 1] = ObjectIdGetDatum(transfn);
 	values[Anum_pg_aggregate_aggfinalfn - 1] = ObjectIdGetDatum(finalfn);
+	values[Anum_pg_aggregate_aggcombinefn - 1] = ObjectIdGetDatum(combinefn);
+	values[Anum_pg_aggregate_aggserialfn - 1] = ObjectIdGetDatum(serialfn);
+	values[Anum_pg_aggregate_aggdeserialfn - 1] = ObjectIdGetDatum(deserialfn);
 	values[Anum_pg_aggregate_aggmtransfn - 1] = ObjectIdGetDatum(mtransfn);
 	values[Anum_pg_aggregate_aggminvtransfn - 1] = ObjectIdGetDatum(minvtransfn);
 	values[Anum_pg_aggregate_aggmfinalfn - 1] = ObjectIdGetDatum(mfinalfn);
@@ -574,6 +661,7 @@ AggregateCreate(const char *aggName,
 	values[Anum_pg_aggregate_aggmfinalextra - 1] = BoolGetDatum(mfinalfnExtraArgs);
 	values[Anum_pg_aggregate_aggsortop - 1] = ObjectIdGetDatum(sortop);
 	values[Anum_pg_aggregate_aggtranstype - 1] = ObjectIdGetDatum(aggTransType);
+	values[Anum_pg_aggregate_aggserialtype - 1] = ObjectIdGetDatum(aggSerialType);
 	values[Anum_pg_aggregate_aggtransspace - 1] = Int32GetDatum(aggTransSpace);
 	values[Anum_pg_aggregate_aggmtranstype - 1] = ObjectIdGetDatum(aggmTransType);
 	values[Anum_pg_aggregate_aggmtransspace - 1] = Int32GetDatum(aggmTransSpace);
@@ -600,7 +688,8 @@ AggregateCreate(const char *aggName,
 	 * Create dependencies for the aggregate (above and beyond those already
 	 * made by ProcedureCreate).  Note: we don't need an explicit dependency
 	 * on aggTransType since we depend on it indirectly through transfn.
-	 * Likewise for aggmTransType if any.
+	 * Likewise for aggmTransType using the mtransfunc, and also for
+	 * aggSerialType using the serialfn, if they exist.
 	 */
 
 	/* Depends on transition function */
@@ -618,6 +707,33 @@ AggregateCreate(const char *aggName,
 		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
 	}
 
+	/* Depends on combine function, if any */
+	if (OidIsValid(combinefn))
+	{
+		referenced.classId = ProcedureRelationId;
+		referenced.objectId = combinefn;
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
+	/* Depends on serial function, if any */
+	if (OidIsValid(serialfn))
+	{
+		referenced.classId = ProcedureRelationId;
+		referenced.objectId = serialfn;
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
+	/* Depends on deserial function, if any */
+	if (OidIsValid(deserialfn))
+	{
+		referenced.classId = ProcedureRelationId;
+		referenced.objectId = deserialfn;
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
 	/* Depends on forward transition function, if any */
 	if (OidIsValid(mtransfn))
 	{
diff --git a/src/backend/commands/aggregatecmds.c b/src/backend/commands/aggregatecmds.c
index 441b3aa..76102f3 100644
--- a/src/backend/commands/aggregatecmds.c
+++ b/src/backend/commands/aggregatecmds.c
@@ -61,6 +61,9 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	char		aggKind = AGGKIND_NORMAL;
 	List	   *transfuncName = NIL;
 	List	   *finalfuncName = NIL;
+	List	   *combinefuncName = NIL;
+	List	   *serialfuncName = NIL;
+	List	   *deserialfuncName = NIL;
 	List	   *mtransfuncName = NIL;
 	List	   *minvtransfuncName = NIL;
 	List	   *mfinalfuncName = NIL;
@@ -69,6 +72,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	List	   *sortoperatorName = NIL;
 	TypeName   *baseType = NULL;
 	TypeName   *transType = NULL;
+	TypeName   *serialType = NULL;
 	TypeName   *mtransType = NULL;
 	int32		transSpace = 0;
 	int32		mtransSpace = 0;
@@ -83,8 +87,10 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	List	   *parameterDefaults;
 	Oid			variadicArgType;
 	Oid			transTypeId;
+	Oid			serialTypeId = InvalidOid;
 	Oid			mtransTypeId = InvalidOid;
 	char		transTypeType;
+	char		serialTypeType = 0;
 	char		mtransTypeType = 0;
 	ListCell   *pl;
 
@@ -124,6 +130,12 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 			transfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "finalfunc") == 0)
 			finalfuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "combinefunc") == 0)
+			combinefuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "serialfunc") == 0)
+			serialfuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "deserialfunc") == 0)
+			deserialfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "msfunc") == 0)
 			mtransfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "minvfunc") == 0)
@@ -151,6 +163,8 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 		}
 		else if (pg_strcasecmp(defel->defname, "stype") == 0)
 			transType = defGetTypeName(defel);
+		else if (pg_strcasecmp(defel->defname, "serialtype") == 0)
+			serialType = defGetTypeName(defel);
 		else if (pg_strcasecmp(defel->defname, "stype1") == 0)
 			transType = defGetTypeName(defel);
 		else if (pg_strcasecmp(defel->defname, "sspace") == 0)
@@ -316,6 +330,51 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 							format_type_be(transTypeId))));
 	}
 
+	if (serialType)
+	{
+		/*
+		 * There's little point in having a serial/deserial function on
+		 * aggregates that don't have an internal state, so let's just disallow
+		 * this as it may help clear up any confusion or needless authoring of
+		 * these functions.
+		 */
+		if (transTypeId != INTERNALOID)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("a serialtype must only be specified when stype is \"%s\"",
+						 format_type_be(INTERNALOID))));
+
+		serialTypeId = typenameTypeId(NULL, serialType);
+		serialTypeType = get_typtype(serialTypeId);
+
+		/*
+		 * We disallow INTERNAL serialType as the whole point of the
+		 * serialzed types is to allow the aggregate state to be output,
+		 * and we cannot output INTERNAL. This check, combined with the one
+		 * above ensures that the trans type and serial type are not the same.
+		 */
+		if (serialTypeId == INTERNALOID)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						errmsg("aggregate serial data type cannot be \"%s\"",
+							format_type_be(serialTypeId))));
+
+		/*
+		 * If serialType is specified then serialfuncName and deserialfuncName
+		 * must be present; if not, then none of the serialization options
+		 * should have been specified.
+		 */
+		if (serialfuncName == NIL)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("aggregate serialfunc must be specified when serialtype is specified")));
+
+		if (deserialfuncName == NIL)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("aggregate deserialfunc must be specified when serialtype is specified")));
+	}
+
 	/*
 	 * If a moving-aggregate transtype is specified, look that up.  Same
 	 * restrictions as for transtype.
@@ -383,6 +442,9 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 						   variadicArgType,
 						   transfuncName,		/* step function name */
 						   finalfuncName,		/* final function name */
+						   combinefuncName,		/* combine function name */
+						   serialfuncName,		/* serial function name */
+						   deserialfuncName,	/* deserial function name */
 						   mtransfuncName,		/* fwd trans function name */
 						   minvtransfuncName,	/* inv trans function name */
 						   mfinalfuncName,		/* final function name */
@@ -390,6 +452,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 						   mfinalfuncExtraArgs,
 						   sortoperatorName,	/* sort operator name */
 						   transTypeId, /* transition data type */
+						   serialTypeId, /* serial data type */
 						   transSpace,	/* transition space */
 						   mtransTypeId,		/* transition data type */
 						   mtransSpace, /* transition space */
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 9827c39..58b5012 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -908,25 +908,38 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			pname = sname = "Group";
 			break;
 		case T_Agg:
-			sname = "Aggregate";
-			switch (((Agg *) plan)->aggstrategy)
 			{
-				case AGG_PLAIN:
-					pname = "Aggregate";
-					strategy = "Plain";
-					break;
-				case AGG_SORTED:
-					pname = "GroupAggregate";
-					strategy = "Sorted";
-					break;
-				case AGG_HASHED:
-					pname = "HashAggregate";
-					strategy = "Hashed";
-					break;
-				default:
-					pname = "Aggregate ???";
-					strategy = "???";
-					break;
+				char	   *modifier;
+				Agg		   *agg = (Agg *) plan;
+
+				sname = "Aggregate";
+
+				if (agg->finalizeAggs == false)
+					modifier = "Partial ";
+				else if (agg->combineStates == true)
+					modifier = "Finalize ";
+				else
+					modifier = "";
+
+				switch (agg->aggstrategy)
+				{
+					case AGG_PLAIN:
+						pname = psprintf("%sAggregate", modifier);
+						strategy = "Plain";
+						break;
+					case AGG_SORTED:
+						pname = psprintf("%sGroupAggregate", modifier);
+						strategy = "Sorted";
+						break;
+					case AGG_HASHED:
+						pname = psprintf("%sHashAggregate", modifier);
+						strategy = "Hashed";
+						break;
+					default:
+						pname = "Aggregate ???";
+						strategy = "???";
+						break;
+				}
 			}
 			break;
 		case T_WindowAgg:
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index f49114a..d0cc643 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -3,15 +3,57 @@
  * nodeAgg.c
  *	  Routines to handle aggregate nodes.
  *
- *	  ExecAgg evaluates each aggregate in the following steps:
+ *	  ExecAgg normally evaluates each aggregate in the following steps:
  *
  *		 transvalue = initcond
  *		 foreach input_tuple do
  *			transvalue = transfunc(transvalue, input_value(s))
  *		 result = finalfunc(transvalue, direct_argument(s))
  *
- *	  If a finalfunc is not supplied then the result is just the ending
- *	  value of transvalue.
+ *	  If a finalfunc is not supplied or finalizeAggs is false, then the result
+ *	  is just the ending value of transvalue.
+ *
+ *	  Other behavior is also supported and is controlled by the 'combineStates',
+ *	  'finalizeAggs' and 'serialStates' parameters. 'combineStates' controls
+ *	  whether the trans func or the combine func is used during aggregation.
+ *	  When 'combineStates' is true we expect other (previously) aggregated
+ *	  states as input rather than input tuples. This mode facilitates multiple
+ *	  aggregate stages which allows us to support pushing aggregation down
+ *	  deeper into the plan rather than leaving it for the final stage. For
+ *	  example with a query such as:
+ *
+ *	  SELECT count(*) FROM (SELECT * FROM a UNION ALL SELECT * FROM b);
+ *
+ *	  with this functionality the planner has the flexibility to generate a
+ *	  plan which performs count(*) on table a and table b separately and then
+ *	  add a combine phase to combine both results. In this case the combine
+ *	  function would simply add both counts together.
+ *
+ *	  When multiple aggregate stages exist the planner should have set the
+ *	  'finalizeAggs' to true only for the final aggregtion state, and each
+ *	  stage, apart from the very first one should have 'combineStates' set to
+ *	  true. This permits plans such as:
+ *
+ *		Finalize Aggregate
+ *			->  Partial Aggregate
+ *				->  Partial Aggregate
+ *
+ *	  Combine functions which use pass-by-ref states should be careful to
+ *	  always update the 1st state parameter by adding the 2nd parameter to it,
+ *	  rather than the other way around. If the 1st state is NULL, then it's not
+ *	  sufficient to simply return the 2nd state, as the memory context is
+ *	  incorrect. Instead a new state should be created in the correct aggregate
+ *	  memory context and the 2nd state should be copied over.
+ *
+ *	  The 'serialStates' option can be used to allow multi-stage aggregation
+ *	  for aggregates with an INTERNAL state type. When this mode is disabled
+ *	  only a pointer to the INTERNAL aggregate states are passed around the
+ *	  executor. This behaviour does not suit a parallel environment where the
+ *	  process is unable to dereference pointers for memory which belongs to a
+ *	  worker process. Enabling this mode causes the INTERNAL states to be
+ *	  serialized and deserialized as and when required, which of course
+ *	  requires that the aggregate function also have a 'serialfunc' and
+ *	  'deserialfunc' function specified.
  *
  *	  If a normal aggregate call specifies DISTINCT or ORDER BY, we sort the
  *	  input tuples and eliminate duplicates (if required) before performing
@@ -134,6 +176,7 @@
 #include "catalog/objectaccess.h"
 #include "catalog/pg_aggregate.h"
 #include "catalog/pg_proc.h"
+#include "catalog/pg_type.h"
 #include "executor/executor.h"
 #include "executor/nodeAgg.h"
 #include "miscadmin.h"
@@ -197,9 +240,15 @@ typedef struct AggStatePerTransData
 	 */
 	int			numTransInputs;
 
-	/* Oid of the state transition function */
+	/* Oid of the state transition or combine function */
 	Oid			transfn_oid;
 
+	/* Oid of the serial function or InvalidOid */
+	Oid			serialfn_oid;
+
+	/* Oid of the deserial function or InvalidOid */
+	Oid			deserialfn_oid;
+
 	/* Oid of state value's datatype */
 	Oid			aggtranstype;
 
@@ -209,11 +258,17 @@ typedef struct AggStatePerTransData
 	List	   *aggdirectargs;	/* states of direct-argument expressions */
 
 	/*
-	 * fmgr lookup data for transition function.  Note in particular that the
-	 * fn_strict flag is kept here.
+	 * fmgr lookup data for transition function or combination function.  Note
+	 * in particular that the fn_strict flag is kept here.
 	 */
 	FmgrInfo	transfn;
 
+	/* fmgr lookup data for serial function */
+	FmgrInfo	serialfn;
+
+	/* fmgr lookup data for deserial function */
+	FmgrInfo	deserialfn;
+
 	/* Input collation derived for aggregate */
 	Oid			aggCollation;
 
@@ -294,6 +349,11 @@ typedef struct AggStatePerTransData
 	 * worth the extra space consumption.
 	 */
 	FunctionCallInfoData transfn_fcinfo;
+
+	/* Likewise for serial and deserial functions */
+	FunctionCallInfoData serialfn_fcinfo;
+
+	FunctionCallInfoData deserialfn_fcinfo;
 }	AggStatePerTransData;
 
 /*
@@ -421,6 +481,10 @@ static void advance_transition_function(AggState *aggstate,
 							AggStatePerTrans pertrans,
 							AggStatePerGroup pergroupstate);
 static void advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup);
+static void advance_combination_function(AggState *aggstate,
+							AggStatePerTrans pertrans,
+							AggStatePerGroup pergroupstate);
+static void combine_aggregates(AggState *aggstate, AggStatePerGroup pergroup);
 static void process_ordered_aggregate_single(AggState *aggstate,
 								 AggStatePerTrans pertrans,
 								 AggStatePerGroup pergroupstate);
@@ -451,14 +515,17 @@ static Datum GetAggInitVal(Datum textInitVal, Oid transtype);
 static void build_pertrans_for_aggref(AggStatePerTrans pertrans,
 						  AggState *aggsate, EState *estate,
 						  Aggref *aggref, Oid aggtransfn, Oid aggtranstype,
-						  Datum initValue, bool initValueIsNull,
-						  Oid *inputTypes, int numArguments);
+						  Oid aggserialtype, Oid aggserialfn,
+						  Oid aggdeserialfn, Datum initValue,
+						  bool initValueIsNull, Oid *inputTypes,
+						  int numArguments);
 static int find_compatible_peragg(Aggref *newagg, AggState *aggstate,
 					   int lastaggno, List **same_input_transnos);
 static int find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 						 Oid aggtransfn, Oid aggtranstype,
+						 Oid aggserialfn, Oid aggdeserialfn,
 						 Datum initValue, bool initValueIsNull,
-						 List *possible_matches);
+						 List *transnos);
 
 
 /*
@@ -796,6 +863,8 @@ advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
 	int			numGroupingSets = Max(aggstate->phase->numsets, 1);
 	int			numTrans = aggstate->numtrans;
 
+	Assert(!aggstate->combineStates);
+
 	for (transno = 0; transno < numTrans; transno++)
 	{
 		AggStatePerTrans pertrans = &aggstate->pertrans[transno];
@@ -879,6 +948,152 @@ advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
 	}
 }
 
+/*
+ * combine_aggregates is used when running in 'combineState' mode. This
+ * advances each aggregate transition state by adding another transition state
+ * to it.
+ */
+static void
+combine_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
+{
+	int			transno;
+	int			numTrans = aggstate->numtrans;
+
+	/* combine not supported with grouping sets */
+	Assert(aggstate->phase->numsets == 0);
+	Assert(aggstate->combineStates);
+
+	for (transno = 0; transno < numTrans; transno++)
+	{
+		AggStatePerTrans pertrans = &aggstate->pertrans[transno];
+		TupleTableSlot *slot;
+		FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
+		AggStatePerGroup pergroupstate = &pergroup[transno];
+
+		/* Evaluate the current input expressions for this aggregate */
+		slot = ExecProject(pertrans->evalproj, NULL);
+		Assert(slot->tts_nvalid >= 1);
+
+		/*
+		 * deserialfn_oid will be set if we must deserialize the input state
+		 * before calling the combine function
+		 */
+		if (OidIsValid(pertrans->deserialfn_oid))
+		{
+			/* don't call a strict deserial function with NULL input */
+			if (pertrans->deserialfn.fn_strict && slot->tts_isnull[0] == true)
+				continue;
+			else
+			{
+				FunctionCallInfo dsinfo = &pertrans->deserialfn_fcinfo;
+				dsinfo->arg[0] = slot->tts_values[0];
+				dsinfo->argnull[0] = slot->tts_isnull[0];
+
+				fcinfo->arg[1] = FunctionCallInvoke(dsinfo);
+				fcinfo->argnull[1] = dsinfo->isnull;
+			}
+		}
+		else
+		{
+			fcinfo->arg[1] = slot->tts_values[0];
+			fcinfo->argnull[1] = slot->tts_isnull[0];
+		}
+
+		advance_combination_function(aggstate, pertrans, pergroupstate);
+	}
+}
+
+/*
+ * Perform combination of states between 2 aggregate states. Effectively this
+ * 'adds' two states together by whichever logic is defined in the aggregate
+ * function's combine function.
+ *
+ * Note that in this case transfn is set to the combination function. This
+ * perhaps should be changed to avoid confusion, but one field is ok for now
+ * as they'll never be needed at the same time.
+ */
+static void
+advance_combination_function(AggState *aggstate,
+							 AggStatePerTrans pertrans,
+							 AggStatePerGroup pergroupstate)
+{
+	FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
+	MemoryContext oldContext;
+	Datum		newVal;
+
+	if (pertrans->transfn.fn_strict)
+	{
+		/* if we're asked to merge to a NULL state, then do nothing */
+		if (fcinfo->argnull[1])
+			return;
+
+		if (pergroupstate->noTransValue)
+		{
+			/*
+			 * transValue has not yet been initialized.  If pass-by-ref
+			 * datatype we must copy the combining state value into aggcontext.
+			 */
+			if (!pertrans->transtypeByVal)
+			{
+				oldContext = MemoryContextSwitchTo(
+					aggstate->aggcontexts[aggstate->current_set]->ecxt_per_tuple_memory);
+				pergroupstate->transValue = datumCopy(fcinfo->arg[1],
+													  pertrans->transtypeByVal,
+													  pertrans->transtypeLen);
+				MemoryContextSwitchTo(oldContext);
+			}
+			else
+				pergroupstate->transValue = fcinfo->arg[1];
+
+			pergroupstate->transValueIsNull = false;
+			pergroupstate->noTransValue = false;
+			return;
+		}
+	}
+
+	/* We run the combine functions in per-input-tuple memory context */
+	oldContext = MemoryContextSwitchTo(aggstate->tmpcontext->ecxt_per_tuple_memory);
+
+	/* set up aggstate->curpertrans for AggGetAggref() */
+	aggstate->curpertrans = pertrans;
+
+	/*
+	 * OK to call the combine function
+	 */
+	fcinfo->arg[0] = pergroupstate->transValue;
+	fcinfo->argnull[0] = pergroupstate->transValueIsNull;
+	fcinfo->isnull = false;		/* just in case combine func doesn't set it */
+
+	newVal = FunctionCallInvoke(fcinfo);
+
+	aggstate->curpertrans = NULL;
+
+	/*
+	 * If pass-by-ref datatype, must copy the new value into aggcontext and
+	 * pfree the prior transValue.  But if the combine function returned a
+	 * pointer to its first input, we don't need to do anything.
+	 */
+	if (!pertrans->transtypeByVal &&
+		DatumGetPointer(newVal) != DatumGetPointer(pergroupstate->transValue))
+	{
+		if (!fcinfo->isnull)
+		{
+			MemoryContextSwitchTo(aggstate->aggcontexts[aggstate->current_set]->ecxt_per_tuple_memory);
+			newVal = datumCopy(newVal,
+							   pertrans->transtypeByVal,
+							   pertrans->transtypeLen);
+		}
+		if (!pergroupstate->transValueIsNull)
+			pfree(DatumGetPointer(pergroupstate->transValue));
+	}
+
+	pergroupstate->transValue = newVal;
+	pergroupstate->transValueIsNull = fcinfo->isnull;
+
+	MemoryContextSwitchTo(oldContext);
+
+}
+
 
 /*
  * Run the transition function for a DISTINCT or ORDER BY aggregate
@@ -1278,8 +1493,35 @@ finalize_aggregates(AggState *aggstate,
 												pergroupstate);
 		}
 
-		finalize_aggregate(aggstate, peragg, pergroupstate,
-						   &aggvalues[aggno], &aggnulls[aggno]);
+		if (aggstate->finalizeAggs)
+			finalize_aggregate(aggstate, peragg, pergroupstate,
+							   &aggvalues[aggno], &aggnulls[aggno]);
+
+		/*
+		 * serialfn_oid will be set if we must serialize the input state
+		 * before calling the combine function on the state.
+		 */
+		else if (OidIsValid(pertrans->serialfn_oid))
+		{
+			/* don't call a strict serial function with NULL input */
+			if (pertrans->serialfn.fn_strict &&
+				pergroupstate->transValueIsNull)
+				continue;
+			else
+			{
+				FunctionCallInfo fcinfo = &pertrans->serialfn_fcinfo;
+				fcinfo->arg[0] = pergroupstate->transValue;
+				fcinfo->argnull[0] = pergroupstate->transValueIsNull;
+
+				aggvalues[aggno] = FunctionCallInvoke(fcinfo);
+				aggnulls[aggno] = fcinfo->isnull;
+			}
+		}
+		else
+		{
+			aggvalues[aggno] = pergroupstate->transValue;
+			aggnulls[aggno] = pergroupstate->transValueIsNull;
+		}
 	}
 }
 
@@ -1811,7 +2053,10 @@ agg_retrieve_direct(AggState *aggstate)
 				 */
 				for (;;)
 				{
-					advance_aggregates(aggstate, pergroup);
+					if (!aggstate->combineStates)
+						advance_aggregates(aggstate, pergroup);
+					else
+						combine_aggregates(aggstate, pergroup);
 
 					/* Reset per-input-tuple context after each tuple */
 					ResetExprContext(tmpcontext);
@@ -1919,7 +2164,10 @@ agg_fill_hash_table(AggState *aggstate)
 		entry = lookup_hash_entry(aggstate, outerslot);
 
 		/* Advance the aggregates */
-		advance_aggregates(aggstate, entry->pergroup);
+		if (!aggstate->combineStates)
+			advance_aggregates(aggstate, entry->pergroup);
+		else
+			combine_aggregates(aggstate, entry->pergroup);
 
 		/* Reset per-input-tuple context after each tuple */
 		ResetExprContext(tmpcontext);
@@ -2051,6 +2299,9 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 	aggstate->pertrans = NULL;
 	aggstate->curpertrans = NULL;
 	aggstate->agg_done = false;
+	aggstate->combineStates = node->combineStates;
+	aggstate->finalizeAggs = node->finalizeAggs;
+	aggstate->serialStates = node->serialStates;
 	aggstate->input_done = false;
 	aggstate->pergroup = NULL;
 	aggstate->grp_firstTuple = NULL;
@@ -2359,6 +2610,9 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 		AclResult	aclresult;
 		Oid			transfn_oid,
 					finalfn_oid;
+		Oid			serialtype_oid,
+					serialfn_oid,
+					deserialfn_oid;
 		Expr	   *finalfnexpr;
 		Oid			aggtranstype;
 		Datum		textInitVal;
@@ -2402,8 +2656,67 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 						   get_func_name(aggref->aggfnoid));
 		InvokeFunctionExecuteHook(aggref->aggfnoid);
 
-		transfn_oid = aggform->aggtransfn;
-		peragg->finalfn_oid = finalfn_oid = aggform->aggfinalfn;
+		/*
+		 * If this aggregation is performing state combines, then instead of
+		 * using the transition function, we'll use the combine function
+		 */
+		if (aggstate->combineStates)
+		{
+			transfn_oid = aggform->aggcombinefn;
+
+			/* If not set then the planner messed up */
+			if (!OidIsValid(transfn_oid))
+				elog(ERROR, "combinefn not set for aggregate function");
+		}
+		else
+			transfn_oid = aggform->aggtransfn;
+
+		/* Final function only required if we're finalizing the aggregates */
+		if (aggstate->finalizeAggs)
+			peragg->finalfn_oid = finalfn_oid = aggform->aggfinalfn;
+		else
+			peragg->finalfn_oid = finalfn_oid = InvalidOid;
+
+		serialtype_oid = InvalidOid;
+		serialfn_oid = InvalidOid;
+		deserialfn_oid = InvalidOid;
+
+		/*
+		 * Determine if we require serialization or deserialization of the
+		 * aggregate states. This is only required if the aggregate state is
+		 * internal.
+		 */
+		if (aggstate->serialStates && aggform->aggtranstype == INTERNALOID)
+		{
+			/*
+			 * The planner should only have generated an agg node with
+			 * serialStates if every aggregate with an INTERNAL state has a
+			 * serial type, serial function and deserial function. Let's ensure
+			 * it didn't mess that up.
+			 */
+			if (!OidIsValid(aggform->aggserialtype))
+				elog(ERROR, "serial type not set during serialStates aggregation step");
+
+			if (!OidIsValid(aggform->aggserialfn))
+				elog(ERROR, "serial func not set during serialStates aggregation step");
+
+			if (!OidIsValid(aggform->aggdeserialfn))
+				elog(ERROR, "deserial func not set during serialStates aggregation step");
+
+			/* serial func only required when not finalizing aggs */
+			if (!aggstate->finalizeAggs)
+			{
+				serialfn_oid = aggform->aggserialfn;
+				serialtype_oid = aggform->aggserialtype;
+			}
+
+			/* deserial func only required when combining states */
+			if (aggstate->combineStates)
+			{
+				deserialfn_oid = aggform->aggdeserialfn;
+				serialtype_oid = aggform->aggserialtype;
+			}
+		}
 
 		/* Check that aggregate owner has permission to call component fns */
 		{
@@ -2433,6 +2746,24 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 								   get_func_name(finalfn_oid));
 				InvokeFunctionExecuteHook(finalfn_oid);
 			}
+			if (OidIsValid(serialfn_oid))
+			{
+				aclresult = pg_proc_aclcheck(serialfn_oid, aggOwner,
+											 ACL_EXECUTE);
+				if (aclresult != ACLCHECK_OK)
+					aclcheck_error(aclresult, ACL_KIND_PROC,
+								   get_func_name(serialfn_oid));
+				InvokeFunctionExecuteHook(serialfn_oid);
+			}
+			if (OidIsValid(deserialfn_oid))
+			{
+				aclresult = pg_proc_aclcheck(deserialfn_oid, aggOwner,
+											 ACL_EXECUTE);
+				if (aclresult != ACLCHECK_OK)
+					aclcheck_error(aclresult, ACL_KIND_PROC,
+								   get_func_name(deserialfn_oid));
+				InvokeFunctionExecuteHook(deserialfn_oid);
+			}
 		}
 
 		/*
@@ -2459,7 +2790,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 
 		/*
 		 * build expression trees using actual argument & result types for the
-		 * finalfn, if it exists
+		 * finalfn, if it exists and is required.
 		 */
 		if (OidIsValid(finalfn_oid))
 		{
@@ -2474,10 +2805,11 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 			fmgr_info_set_expr((Node *) finalfnexpr, &peragg->finalfn);
 		}
 
-		/* get info about the result type's datatype */
-		get_typlenbyval(aggref->aggtype,
-						&peragg->resulttypeLen,
-						&peragg->resulttypeByVal);
+		/* when finalizing we get info about the final result's datatype */
+		if (aggstate->finalizeAggs)
+			get_typlenbyval(aggref->aggtype,
+							&peragg->resulttypeLen,
+							&peragg->resulttypeByVal);
 
 		/*
 		 * initval is potentially null, so don't try to access it as a struct
@@ -2501,7 +2833,8 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 		 */
 		existing_transno = find_compatible_pertrans(aggstate, aggref,
 													transfn_oid, aggtranstype,
-												  initValue, initValueIsNull,
+												  serialfn_oid, deserialfn_oid,
+													initValue, initValueIsNull,
 													same_input_transnos);
 		if (existing_transno != -1)
 		{
@@ -2517,8 +2850,10 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 			pertrans = &pertransstates[++transno];
 			build_pertrans_for_aggref(pertrans, aggstate, estate,
 									  aggref, transfn_oid, aggtranstype,
-									  initValue, initValueIsNull,
-									  inputTypes, numArguments);
+									  serialtype_oid, serialfn_oid,
+									  deserialfn_oid, initValue,
+									  initValueIsNull, inputTypes,
+									  numArguments);
 			peragg->transno = transno;
 		}
 		ReleaseSysCache(aggTuple);
@@ -2546,12 +2881,15 @@ static void
 build_pertrans_for_aggref(AggStatePerTrans pertrans,
 						  AggState *aggstate, EState *estate,
 						  Aggref *aggref,
-						  Oid aggtransfn, Oid aggtranstype,
+						  Oid aggtransfn, Oid aggtranstype, Oid aggserialtype,
+						  Oid aggserialfn, Oid aggdeserialfn,
 						  Datum initValue, bool initValueIsNull,
 						  Oid *inputTypes, int numArguments)
 {
 	int			numGroupingSets = Max(aggstate->maxsets, 1);
 	Expr	   *transfnexpr;
+	Expr	   *serialfnexpr = NULL;
+	Expr	   *deserialfnexpr = NULL;
 	ListCell   *lc;
 	int			numInputs;
 	int			numDirectArgs;
@@ -2565,6 +2903,8 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 	pertrans->aggref = aggref;
 	pertrans->aggCollation = aggref->inputcollid;
 	pertrans->transfn_oid = aggtransfn;
+	pertrans->serialfn_oid = aggserialfn;
+	pertrans->deserialfn_oid = aggdeserialfn;
 	pertrans->initValue = initValue;
 	pertrans->initValueIsNull = initValueIsNull;
 
@@ -2583,44 +2923,68 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 		pertrans->numTransInputs = numArguments;
 
 	/*
-	 * Set up infrastructure for calling the transfn
+	 * When combining states, we have no use at all for the aggregate
+	 * function's transfn. Instead we use the combinefn. However we do
+	 * reuse the transfnexpr for the combinefn, perhaps this should change
 	 */
-	build_aggregate_transfn_expr(inputTypes,
-								 numArguments,
-								 numDirectArgs,
-								 aggref->aggvariadic,
-								 aggtranstype,
-								 aggref->inputcollid,
-								 aggtransfn,
-								 InvalidOid,	/* invtrans is not needed here */
-								 &transfnexpr,
-								 NULL);
-	fmgr_info(aggtransfn, &pertrans->transfn);
-	fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
-
-	InitFunctionCallInfoData(pertrans->transfn_fcinfo,
-							 &pertrans->transfn,
-							 pertrans->numTransInputs + 1,
-							 pertrans->aggCollation,
-							 (void *) aggstate, NULL);
+	if (aggstate->combineStates)
+	{
+		build_aggregate_combinefn_expr(aggtranstype,
+									   aggref->inputcollid,
+									   aggtransfn,
+									   &transfnexpr);
+		fmgr_info(aggtransfn, &pertrans->transfn);
+		fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
+
+		InitFunctionCallInfoData(pertrans->transfn_fcinfo,
+								 &pertrans->transfn,
+								 2,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
 
-	/*
-	 * If the transfn is strict and the initval is NULL, make sure input type
-	 * and transtype are the same (or at least binary-compatible), so that
-	 * it's OK to use the first aggregated input value as the initial
-	 * transValue.  This should have been checked at agg definition time, but
-	 * we must check again in case the transfn's strictness property has been
-	 * changed.
-	 */
-	if (pertrans->transfn.fn_strict && pertrans->initValueIsNull)
+	}
+	else
 	{
-		if (numArguments <= numDirectArgs ||
-			!IsBinaryCoercible(inputTypes[numDirectArgs],
-							   aggtranstype))
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
-					 errmsg("aggregate %u needs to have compatible input type and transition type",
-							aggref->aggfnoid)));
+		/*
+		 * Set up infrastructure for calling the transfn
+		 */
+		build_aggregate_transfn_expr(inputTypes,
+									 numArguments,
+									 numDirectArgs,
+									 aggref->aggvariadic,
+									 aggtranstype,
+									 aggref->inputcollid,
+									 aggtransfn,
+									 InvalidOid,	/* invtrans is not needed here */
+									 &transfnexpr,
+									 NULL);
+		fmgr_info(aggtransfn, &pertrans->transfn);
+		fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
+
+		InitFunctionCallInfoData(pertrans->transfn_fcinfo,
+								 &pertrans->transfn,
+								 pertrans->numTransInputs + 1,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+
+		/*
+		 * If the transfn is strict and the initval is NULL, make sure input type
+		 * and transtype are the same (or at least binary-compatible), so that
+		 * it's OK to use the first aggregated input value as the initial
+		 * transValue.  This should have been checked at agg definition time, but
+		 * we must check again in case the transfn's strictness property has been
+		 * changed.
+		 */
+		if (pertrans->transfn.fn_strict && pertrans->initValueIsNull)
+		{
+			if (numArguments <= numDirectArgs ||
+				!IsBinaryCoercible(inputTypes[numDirectArgs],
+								   aggtranstype))
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						 errmsg("aggregate %u needs to have compatible input type and transition type",
+								aggref->aggfnoid)));
+		}
 	}
 
 	/* get info about the state value's datatype */
@@ -2628,6 +2992,41 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 					&pertrans->transtypeLen,
 					&pertrans->transtypeByVal);
 
+	if (OidIsValid(aggserialfn))
+	{
+		build_aggregate_serialfn_expr(aggtranstype,
+									  aggserialtype,
+									  aggref->inputcollid,
+									  aggserialfn,
+									  &serialfnexpr);
+		fmgr_info(aggserialfn, &pertrans->serialfn);
+		fmgr_info_set_expr((Node *) serialfnexpr, &pertrans->serialfn);
+
+		InitFunctionCallInfoData(pertrans->serialfn_fcinfo,
+								 &pertrans->serialfn,
+								 1,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+	}
+
+	if (OidIsValid(aggdeserialfn))
+	{
+		build_aggregate_serialfn_expr(aggtranstype,
+									  aggserialtype,
+									  aggref->inputcollid,
+									  aggdeserialfn,
+									  &deserialfnexpr);
+		fmgr_info(aggdeserialfn, &pertrans->deserialfn);
+		fmgr_info_set_expr((Node *) deserialfnexpr, &pertrans->deserialfn);
+
+		InitFunctionCallInfoData(pertrans->deserialfn_fcinfo,
+								 &pertrans->deserialfn,
+								 1,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+
+	}
+
 	/*
 	 * Get a tupledesc corresponding to the aggregated inputs (including sort
 	 * expressions) of the agg.
@@ -2874,6 +3273,7 @@ find_compatible_peragg(Aggref *newagg, AggState *aggstate,
 static int
 find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 						 Oid aggtransfn, Oid aggtranstype,
+						 Oid aggserialfn, Oid aggdeserialfn,
 						 Datum initValue, bool initValueIsNull,
 						 List *transnos)
 {
@@ -2892,6 +3292,14 @@ find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 			aggtranstype != pertrans->aggtranstype)
 			continue;
 
+		/*
+		 * serial and deserial functions must match, if present. Remember that
+		 * these will be InvalidOid if they're not required for this agg node
+		 */
+		if (aggserialfn != pertrans->serialfn_oid ||
+			aggdeserialfn != pertrans->deserialfn_oid)
+			continue;
+
 		/* Check that the initial condition matches, too. */
 		if (initValueIsNull && pertrans->initValueIsNull)
 			return transno;
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index f47e0da..7e880fc 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -865,6 +865,9 @@ _copyAgg(const Agg *from)
 
 	COPY_SCALAR_FIELD(aggstrategy);
 	COPY_SCALAR_FIELD(numCols);
+	COPY_SCALAR_FIELD(combineStates);
+	COPY_SCALAR_FIELD(finalizeAggs);
+	COPY_SCALAR_FIELD(serialStates);
 	if (from->numCols > 0)
 	{
 		COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index d95e151..4cb78fa 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -695,6 +695,10 @@ _outAgg(StringInfo str, const Agg *node)
 	for (i = 0; i < node->numCols; i++)
 		appendStringInfo(str, " %d", node->grpColIdx[i]);
 
+	WRITE_BOOL_FIELD(combineStates);
+	WRITE_BOOL_FIELD(finalizeAggs);
+	WRITE_BOOL_FIELD(serialStates);
+
 	appendStringInfoString(str, " :grpOperators");
 	for (i = 0; i < node->numCols; i++)
 		appendStringInfo(str, " %u", node->grpOperators[i]);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 719a52c..d85f6db 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1989,6 +1989,9 @@ _readAgg(void)
 	READ_ENUM_FIELD(aggstrategy, AggStrategy);
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
+	READ_BOOL_FIELD(combineStates);
+	READ_BOOL_FIELD(finalizeAggs);
+	READ_BOOL_FIELD(serialStates);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 	READ_NODE_FIELD(groupingSets);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 953aa62..896a888 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -1054,6 +1054,9 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path)
 								 groupOperators,
 								 NIL,
 								 numGroups,
+								 false,
+								 true,
+								 false,
 								 subplan);
 	}
 	else
@@ -4557,9 +4560,8 @@ Agg *
 make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
 		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
-		 List *groupingSets,
-		 long numGroups,
-		 Plan *lefttree)
+		 List *groupingSets, long numGroups, bool combineStates,
+		 bool finalizeAggs, bool serialStates, Plan *lefttree)
 {
 	Agg		   *node = makeNode(Agg);
 	Plan	   *plan = &node->plan;
@@ -4568,6 +4570,9 @@ make_agg(PlannerInfo *root, List *tlist, List *qual,
 
 	node->aggstrategy = aggstrategy;
 	node->numCols = numGroupCols;
+	node->combineStates = combineStates;
+	node->finalizeAggs = finalizeAggs;
+	node->serialStates = serialStates;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
 	node->numGroups = numGroups;
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 131dc8a..ad99690 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -2005,6 +2005,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 									extract_grouping_ops(parse->groupClause),
 												NIL,
 												numGroups,
+												false,
+												true,
+												false,
 												result_plan);
 				/* Hashed aggregation produces randomly-ordered results */
 				current_pathkeys = NIL;
@@ -2312,6 +2315,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 								 extract_grouping_ops(parse->distinctClause),
 											NIL,
 											numDistinctRows,
+											false,
+											true,
+											false,
 											result_plan);
 			/* Hashed aggregation produces randomly-ordered results */
 			current_pathkeys = NIL;
@@ -2549,6 +2555,9 @@ build_grouping_chain(PlannerInfo *root,
 										 extract_grouping_ops(groupClause),
 										 gsets,
 										 numGroups,
+										 false,
+										 true,
+										 false,
 										 sort_plan);
 
 			/*
@@ -2588,6 +2597,9 @@ build_grouping_chain(PlannerInfo *root,
 										extract_grouping_ops(groupClause),
 										gsets,
 										numGroups,
+										false,
+										true,
+										false,
 										result_plan);
 
 		((Agg *) result_plan)->chain = chain;
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 615f3a2..007fc0f 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -15,7 +15,9 @@
  */
 #include "postgres.h"
 
+#include "access/htup_details.h"
 #include "access/transam.h"
+#include "catalog/pg_aggregate.h"
 #include "catalog/pg_type.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
@@ -139,6 +141,18 @@ static List *set_returning_clause_references(PlannerInfo *root,
 static bool fix_opfuncids_walker(Node *node, void *context);
 static bool extract_query_dependencies_walker(Node *node,
 								  PlannerInfo *context);
+static void set_combineagg_references(PlannerInfo *root, Plan *plan,
+									  int rtoffset);
+static Node *fix_combine_agg_expr(PlannerInfo *root,
+								  Node *node,
+								  indexed_tlist *subplan_itlist,
+								  Index newvarno,
+								  int rtoffset);
+static Node *fix_combine_agg_expr_mutator(Node *node,
+										  fix_upper_expr_context *context);
+static void set_partialagg_aggref_types(PlannerInfo *root, Plan *plan,
+										bool serializeStates);
+
 
 /*****************************************************************************
  *
@@ -668,8 +682,24 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 			}
 			break;
 		case T_Agg:
-			set_upper_references(root, plan, rtoffset);
-			break;
+			{
+				Agg *aggplan = (Agg *) plan;
+
+				/*
+				 * For partial aggregation we must adjust the return types of
+				 * the Aggrefs
+				 */
+				if (!aggplan->finalizeAggs)
+					set_partialagg_aggref_types(root, plan,
+												aggplan->serialStates);
+
+				if (aggplan->combineStates)
+					set_combineagg_references(root, plan, rtoffset);
+				else
+					set_upper_references(root, plan, rtoffset);
+
+				break;
+			}
 		case T_Group:
 			set_upper_references(root, plan, rtoffset);
 			break;
@@ -2432,3 +2462,199 @@ extract_query_dependencies_walker(Node *node, PlannerInfo *context)
 	return expression_tree_walker(node, extract_query_dependencies_walker,
 								  (void *) context);
 }
+
+static void
+set_combineagg_references(PlannerInfo *root, Plan *plan, int rtoffset)
+{
+	Plan	   *subplan = plan->lefttree;
+	indexed_tlist *subplan_itlist;
+	List	   *output_targetlist;
+	ListCell   *l;
+
+	Assert(IsA(plan, Agg));
+	Assert(((Agg *) plan)->combineStates);
+
+	subplan_itlist = build_tlist_index(subplan->targetlist);
+
+	output_targetlist = NIL;
+
+	foreach(l, plan->targetlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(l);
+		Node	   *newexpr;
+
+		/* If it's a non-Var sort/group item, first try to match by sortref */
+		if (tle->ressortgroupref != 0 && !IsA(tle->expr, Var))
+		{
+			newexpr = (Node *)
+				search_indexed_tlist_for_sortgroupref((Node *) tle->expr,
+														tle->ressortgroupref,
+														subplan_itlist,
+														OUTER_VAR);
+			if (!newexpr)
+				newexpr = fix_combine_agg_expr(root,
+												(Node *) tle->expr,
+												subplan_itlist,
+												OUTER_VAR,
+												rtoffset);
+		}
+		else
+			newexpr = fix_combine_agg_expr(root,
+											(Node *) tle->expr,
+											subplan_itlist,
+											OUTER_VAR,
+											rtoffset);
+		tle = flatCopyTargetEntry(tle);
+		tle->expr = (Expr *) newexpr;
+		output_targetlist = lappend(output_targetlist, tle);
+	}
+
+	plan->targetlist = output_targetlist;
+
+	plan->qual = (List *)
+		fix_upper_expr(root,
+					   (Node *) plan->qual,
+					   subplan_itlist,
+					   OUTER_VAR,
+					   rtoffset);
+
+	pfree(subplan_itlist);
+}
+
+
+/*
+ * Adjust the Aggref'a args to reference the correct Aggref target in the outer
+ * subplan.
+ */
+static Node *
+fix_combine_agg_expr(PlannerInfo *root,
+			   Node *node,
+			   indexed_tlist *subplan_itlist,
+			   Index newvarno,
+			   int rtoffset)
+{
+	fix_upper_expr_context context;
+
+	context.root = root;
+	context.subplan_itlist = subplan_itlist;
+	context.newvarno = newvarno;
+	context.rtoffset = rtoffset;
+	return fix_combine_agg_expr_mutator(node, &context);
+}
+
+static Node *
+fix_combine_agg_expr_mutator(Node *node, fix_upper_expr_context *context)
+{
+	Var		   *newvar;
+
+	if (node == NULL)
+		return NULL;
+	if (IsA(node, Var))
+	{
+		Var		   *var = (Var *) node;
+
+		newvar = search_indexed_tlist_for_var(var,
+											  context->subplan_itlist,
+											  context->newvarno,
+											  context->rtoffset);
+		if (!newvar)
+			elog(ERROR, "variable not found in subplan target list");
+		return (Node *) newvar;
+	}
+	if (IsA(node, Aggref))
+	{
+		TargetEntry *tle;
+		Aggref		*aggref = (Aggref*) node;
+
+		tle = tlist_member(node, context->subplan_itlist->tlist);
+		if (tle)
+		{
+			/* Found a matching subplan output expression */
+			Var		   *newvar;
+			TargetEntry *newtle;
+
+			newvar = makeVarFromTargetEntry(context->newvarno, tle);
+			newvar->varnoold = 0;	/* wasn't ever a plain Var */
+			newvar->varoattno = 0;
+
+			/* update the args in the aggref */
+
+			/* makeTargetEntry ,always set resno to one for finialize agg */
+			newtle = makeTargetEntry((Expr*) newvar, 1, NULL, false);
+
+			/*
+			 * Updated the args, let the newvar refer to the right position of
+			 * the agg function in the subplan
+			 */
+			aggref->args = list_make1(newtle);
+
+			return (Node *) aggref;
+		}
+		else
+			elog(ERROR, "aggref not found in subplan target list");
+	}
+	if (IsA(node, PlaceHolderVar))
+	{
+		PlaceHolderVar *phv = (PlaceHolderVar *) node;
+
+		/* See if the PlaceHolderVar has bubbled up from a lower plan node */
+		if (context->subplan_itlist->has_ph_vars)
+		{
+			newvar = search_indexed_tlist_for_non_var((Node *) phv,
+													  context->subplan_itlist,
+													  context->newvarno);
+			if (newvar)
+				return (Node *) newvar;
+		}
+		/* If not supplied by input plan, evaluate the contained expr */
+		return fix_upper_expr_mutator((Node *) phv->phexpr, context);
+	}
+	if (IsA(node, Param))
+		return fix_param_node(context->root, (Param *) node);
+
+	fix_expr_common(context->root, node);
+	return expression_tree_mutator(node,
+								   fix_combine_agg_expr_mutator,
+								   (void *) context);
+}
+
+/* XXX is this really the best place and way to do this? */
+static void
+set_partialagg_aggref_types(PlannerInfo *root, Plan *plan, bool serializeStates)
+{
+	ListCell *l;
+
+	foreach(l, plan->targetlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(l);
+
+		if (IsA(tle->expr, Aggref))
+		{
+			Aggref *aggref = (Aggref *) tle->expr;
+			HeapTuple	aggTuple;
+			Form_pg_aggregate aggform;
+
+			aggTuple = SearchSysCache1(AGGFNOID,
+									   ObjectIdGetDatum(aggref->aggfnoid));
+			if (!HeapTupleIsValid(aggTuple))
+				elog(ERROR, "cache lookup failed for aggregate %u",
+					 aggref->aggfnoid);
+			aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
+
+			/*
+			 * For partial aggregate nodes the return type of the Aggref
+			 * depends on if we're performing a serialization of the partially
+			 * aggregated states or not. If we are then the return type should
+			 * be the serial type rather than the trans type. We only require
+			 * this behavior for aggregates with INTERNAL trans types.
+			 */
+			if (serializeStates && OidIsValid(aggform->aggserialtype) &&
+				aggform->aggtranstype == INTERNALOID)
+				aggref->aggtype = aggform->aggserialtype;
+			else
+				aggref->aggtype = aggform->aggtranstype;
+
+			ReleaseSysCache(aggTuple);
+		}
+	}
+}
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 694e9ed..ab2f1a8 100644
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -775,6 +775,9 @@ make_union_unique(SetOperationStmt *op, Plan *plan,
 								 extract_grouping_ops(groupList),
 								 NIL,
 								 numGroups,
+								 false,
+								 true,
+								 false,
 								 plan);
 		/* Hashed aggregation produces randomly-ordered results */
 		*sortClauses = NIL;
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index ace8b38..a9012b6 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -52,6 +52,10 @@
 #include "utils/syscache.h"
 #include "utils/typcache.h"
 
+typedef struct
+{
+	PartialAggType allowedtype;
+} partial_agg_context;
 
 typedef struct
 {
@@ -93,6 +97,7 @@ typedef struct
 	bool		allow_restricted;
 } has_parallel_hazard_arg;
 
+static bool partial_aggregate_walker(Node *node, void *context);
 static bool contain_agg_clause_walker(Node *node, void *context);
 static bool count_agg_clauses_walker(Node *node,
 						 count_agg_clauses_context *context);
@@ -400,6 +405,89 @@ make_ands_implicit(Expr *clause)
  *****************************************************************************/
 
 /*
+ * aggregates_allow_partial
+ *		Recursively search for Aggref clauses and determine the maximum
+ *		'degree' of partial aggregation which can be supported. Partial
+ *		aggregation requires that each aggregate does not have a DISTINCT or
+ *		ORDER BY clause, and that it also has a combine function set. For
+ *		aggregates with an INTERNAL trans type we only can support all types of
+ *		partial aggregation when the aggregate has a serial and deserial
+ *		function set. If this is not present then we can only support, at most
+ *		partial aggregation in the context of a single backend process, as
+ *		internal state pointers cannot be dereferenced from another backend
+ *		process.
+ */
+PartialAggType
+aggregates_allow_partial(Node *clause)
+{
+	partial_agg_context context;
+
+	/* initially any type is ok, until we find Aggrefs which say otherwise */
+	context.allowedtype = PAT_ANY;
+
+	if (!partial_aggregate_walker(clause, &context))
+		return context.allowedtype;
+	return context.allowedtype;
+}
+
+static bool
+partial_aggregate_walker(Node *node, partial_agg_context *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Aggref))
+	{
+		Aggref	   *aggref = (Aggref *) node;
+		HeapTuple	aggTuple;
+		Form_pg_aggregate aggform;
+
+		Assert(aggref->agglevelsup == 0);
+
+		/*
+		 * We can't perform partial aggregation with Aggrefs containing a
+		 * DISTINCT or ORDER BY clause.
+		 */
+		if (aggref->aggdistinct || aggref->aggorder)
+		{
+			context->allowedtype = PAT_DISABLED;
+			return true;	/* abort search */
+		}
+		aggTuple = SearchSysCache1(AGGFNOID,
+								   ObjectIdGetDatum(aggref->aggfnoid));
+		if (!HeapTupleIsValid(aggTuple))
+			elog(ERROR, "cache lookup failed for aggregate %u",
+				 aggref->aggfnoid);
+		aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
+
+		/*
+		 * If there is no combine func, then partial aggregation is not
+		 * possible.
+		 */
+		if (!OidIsValid(aggform->aggcombinefn))
+		{
+			ReleaseSysCache(aggTuple);
+			context->allowedtype = PAT_DISABLED;
+			return true;	/* abort search */
+		}
+
+		/*
+		 * Any aggs with an internal transtype must have a serial type, serial
+		 * func and deserial func, otherwise we can only support internal mode.
+		 */
+		if (aggform->aggtranstype == INTERNALOID &&
+			(!OidIsValid(aggform->aggserialtype) ||
+			 !OidIsValid(aggform->aggserialfn) ||
+			 !OidIsValid(aggform->aggdeserialfn)))
+			context->allowedtype = PAT_INTERNAL_ONLY;
+
+		ReleaseSysCache(aggTuple);
+		return false; /* continue searching */
+	}
+	return expression_tree_walker(node, partial_aggregate_walker,
+								  (void *) context);
+}
+
+/*
  * contain_agg_clause
  *	  Recursively search for Aggref/GroupingFunc nodes within a clause.
  *
diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c
index b718169..ca3823a 100644
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -1929,6 +1929,116 @@ build_aggregate_transfn_expr(Oid *agg_input_types,
 
 /*
  * Like build_aggregate_transfn_expr, but creates an expression tree for the
+ * combine function of an aggregate, rather than the transition function.
+ */
+void
+build_aggregate_combinefn_expr(Oid agg_state_type,
+							   Oid agg_input_collation,
+							   Oid combinefn_oid,
+							   Expr **combinefnexpr)
+{
+	Param	   *argp;
+	List	   *args;
+	FuncExpr   *fexpr;
+
+	/* Build arg list to use in the combinefn FuncExpr node. */
+	argp = makeNode(Param);
+	argp->paramkind = PARAM_EXEC;
+	argp->paramid = -1;
+	argp->paramtype = agg_state_type;
+	argp->paramtypmod = -1;
+	argp->paramcollid = agg_input_collation;
+	argp->location = -1;
+
+	/* transition state type is arg 1 and 2 */
+	args = list_make2(argp, argp);
+
+	fexpr = makeFuncExpr(combinefn_oid,
+						 agg_state_type,
+						 args,
+						 InvalidOid,
+						 agg_input_collation,
+						 COERCE_EXPLICIT_CALL);
+	fexpr->funcvariadic = false;
+	*combinefnexpr = (Expr *) fexpr;
+}
+
+/*
+ * Like build_aggregate_transfn_expr, but creates an expression tree for the
+ * serial function of an aggregate, rather than the transition function.
+ */
+void
+build_aggregate_serialfn_expr(Oid agg_state_type,
+							  Oid agg_serial_type,
+							  Oid agg_input_collation,
+							  Oid serialfn_oid,
+							  Expr **serialfnexpr)
+{
+	Param	   *argp;
+	List	   *args;
+	FuncExpr   *fexpr;
+
+	/* Build arg list to use in the serialfn FuncExpr node. */
+	argp = makeNode(Param);
+	argp->paramkind = PARAM_EXEC;
+	argp->paramid = -1;
+	argp->paramtype = agg_state_type;
+	argp->paramtypmod = -1;
+	argp->paramcollid = agg_input_collation;
+	argp->location = -1;
+
+	/* takes a single arg of the transition state type */
+	args = list_make1(argp);
+
+	fexpr = makeFuncExpr(serialfn_oid,
+						 agg_serial_type,
+						 args,
+						 InvalidOid,
+						 agg_input_collation,
+						 COERCE_EXPLICIT_CALL);
+	fexpr->funcvariadic = false;
+	*serialfnexpr = (Expr *) fexpr;
+}
+
+/*
+ * Like build_aggregate_transfn_expr, but creates an expression tree for the
+ * deserial function of an aggregate, rather than the transition function.
+ */
+void
+build_aggregate_deserialfn_expr(Oid agg_state_type,
+								Oid agg_serial_type,
+								Oid agg_input_collation,
+								Oid deserialfn_oid,
+								Expr **deserialfnexpr)
+{
+	Param	   *argp;
+	List	   *args;
+	FuncExpr   *fexpr;
+
+	/* Build arg list to use in the serialfn FuncExpr node. */
+	argp = makeNode(Param);
+	argp->paramkind = PARAM_EXEC;
+	argp->paramid = -1;
+	argp->paramtype = agg_serial_type;
+	argp->paramtypmod = -1;
+	argp->paramcollid = agg_input_collation;
+	argp->location = -1;
+
+	/* takes a single arg of the serial type */
+	args = list_make1(argp);
+
+	fexpr = makeFuncExpr(deserialfn_oid,
+						 agg_state_type,
+						 args,
+						 InvalidOid,
+						 agg_input_collation,
+						 COERCE_EXPLICIT_CALL);
+	fexpr->funcvariadic = false;
+	*deserialfnexpr = (Expr *) fexpr;
+}
+
+/*
+ * Like build_aggregate_transfn_expr, but creates an expression tree for the
  * final function of an aggregate, rather than the transition function.
  */
 void
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index 07b2645..3947cba 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -3369,6 +3369,175 @@ numeric_avg_accum(PG_FUNCTION_ARGS)
 }
 
 /*
+ * Generic combine function for numeric aggregates without requirement for X^2
+ */
+Datum
+numeric_avg_combine(PG_FUNCTION_ARGS)
+{
+	NumericAggState *state1;
+	NumericAggState *state2;
+
+	state1 = PG_ARGISNULL(0) ? NULL : (NumericAggState *) PG_GETARG_POINTER(0);
+	state2 = PG_ARGISNULL(1) ? NULL : (NumericAggState *) PG_GETARG_POINTER(1);
+
+	if (state2 == NULL)
+		PG_RETURN_POINTER(state1);
+
+	/* manually copy all fields from state2 to state1 */
+	if (state1 == NULL)
+	{
+		MemoryContext old_context;
+
+		state1 = makeNumericAggState(fcinfo, false);
+		state1->N = state2->N;
+		state1->NaNcount = state2->NaNcount;
+		state1->maxScale = state2->maxScale;
+		state1->maxScaleCount = state2->maxScaleCount;
+
+		old_context = MemoryContextSwitchTo(state1->agg_context);
+
+		init_var(&state1->sumX);
+		set_var_from_var(&state2->sumX, &state1->sumX);
+
+		MemoryContextSwitchTo(old_context);
+
+		PG_RETURN_POINTER(state1);
+	}
+
+	if (state2->N > 0)
+	{
+		MemoryContext old_context;
+
+		state1->N += state2->N;
+		state1->NaNcount += state2->NaNcount;
+
+		/*
+		 * XXX do we care about these? They're really only needed for moving
+		 * aggregates.
+		 */
+		if (state2->maxScale > state1->maxScale)
+			state1->maxScale = state2->maxScale;
+		else if (state2->maxScale == state1->maxScale)
+			state1->maxScale += state2->maxScale;
+
+		/* The rest of this needs to work in the aggregate context */
+		old_context = MemoryContextSwitchTo(state1->agg_context);
+
+		/* Accumulate sums */
+		add_var(&(state1->sumX), &(state2->sumX), &(state1->sumX));
+
+		if (state1->calcSumX2)
+			add_var(&(state1->sumX2), &(state2->sumX2), &(state1->sumX2));
+
+		MemoryContextSwitchTo(old_context);
+	}
+	PG_RETURN_POINTER(state1);
+}
+
+/*
+ * numeric_avg_serialize
+ *		Serialize NumericAggState into text.
+ *		numeric_avg_deserialize(numeric_avg_serialize(state)) must result in
+ *		a state which matches the original input state.
+ */
+Datum
+numeric_avg_serialize(PG_FUNCTION_ARGS)
+{
+	NumericAggState *state;
+	StringInfoData string;
+	MemoryContext agg_context;
+	MemoryContext old_context;
+	text	   *result;
+
+	/* Ensure we disallow calling when not in aggregate context */
+	if (!AggCheckCallContext(fcinfo, &agg_context))
+		elog(ERROR, "aggregate function called in non-aggregate context");
+
+	state = (NumericAggState *) PG_GETARG_POINTER(0);
+
+	initStringInfo(&string);
+
+	/*
+	 * Transform the NumericAggState into a string with the following format:
+	 * "N sumX maxScale maxScaleCount NaNcount"
+	 * XXX perhaps we can come up with a more efficient format for this.
+	 */
+	appendStringInfo(&string, INT64_FORMAT " %s %d " INT64_FORMAT " " INT64_FORMAT,
+			state->N, get_str_from_var(&state->sumX), state->maxScale,
+			state->maxScaleCount, state->NaNcount);
+
+	old_context = MemoryContextSwitchTo(agg_context);
+
+	result = cstring_to_text_with_len(string.data, string.len);
+
+	MemoryContextSwitchTo(old_context);
+
+	PG_RETURN_TEXT_P(result);
+}
+
+/*
+ * numeric_avg_deserialize
+ *		deserialize Text into NumericAggState
+ *		numeric_avg_serialize(numeric_avg_deserialize(text)) must result in
+ *		text which matches the original input text.
+ */
+Datum
+numeric_avg_deserialize(PG_FUNCTION_ARGS)
+{
+	NumericAggState *result;
+	MemoryContext agg_context;
+	MemoryContext old_context;
+	Numeric		tmp;
+	text	   *sstate;
+	char	   *state;
+	char	   *token[5];
+	int			i;
+
+	if (!AggCheckCallContext(fcinfo, &agg_context))
+		elog(ERROR, "aggregate function called in non-aggregate context");
+
+	sstate = PG_GETARG_TEXT_P(0);
+	state = text_to_cstring(sstate);
+
+	token[0] = strtok(state, " ");
+
+	if (!token[0])
+		elog(ERROR, "invalid serialization format");
+
+	for (i = 1; i < 5; i++)
+	{
+		token[i] = strtok(NULL, " ");
+		if (!token[i])
+			elog(ERROR, "invalid serialization format");
+	}
+
+	old_context = MemoryContextSwitchTo(agg_context);
+
+	/*
+	 * Transform string into a NumericAggState. The string is in the format:
+	 * "N sumX maxScale maxScaleCount NaNcount"
+	 */
+	result = makeNumericAggState(fcinfo, false);
+
+	scanint8(token[0], false, &result->N);
+
+	tmp = DatumGetNumeric(DirectFunctionCall3(numeric_in,
+						  CStringGetDatum(token[1]),
+						  ObjectIdGetDatum(0),
+						  Int32GetDatum(-1)));
+	init_var_from_num(tmp, &result->sumX);
+
+	result->maxScale = pg_atoi(token[2], sizeof(int32), 0);
+	scanint8(token[3], false, &result->maxScaleCount);
+	scanint8(token[4], false, &result->NaNcount);
+
+	MemoryContextSwitchTo(old_context);
+
+	pfree(state);
+	PG_RETURN_POINTER(result);
+}
+
+/*
  * Generic inverse transition function for numeric aggregates
  * (with or without requirement for X^2).
  */
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 9196cf4..d2cfdd8 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -12386,6 +12386,9 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	PGresult   *res;
 	int			i_aggtransfn;
 	int			i_aggfinalfn;
+	int			i_aggcombinefn;
+	int			i_aggserialfn;
+	int			i_aggdeserialfn;
 	int			i_aggmtransfn;
 	int			i_aggminvtransfn;
 	int			i_aggmfinalfn;
@@ -12394,6 +12397,7 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	int			i_aggsortop;
 	int			i_hypothetical;
 	int			i_aggtranstype;
+	int			i_aggserialtype;
 	int			i_aggtransspace;
 	int			i_aggmtranstype;
 	int			i_aggmtransspace;
@@ -12402,6 +12406,9 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	int			i_convertok;
 	const char *aggtransfn;
 	const char *aggfinalfn;
+	const char *aggcombinefn;
+	const char *aggserialfn;
+	const char *aggdeserialfn;
 	const char *aggmtransfn;
 	const char *aggminvtransfn;
 	const char *aggmfinalfn;
@@ -12411,6 +12418,7 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	char	   *aggsortconvop;
 	bool		hypothetical;
 	const char *aggtranstype;
+	const char *aggserialtype;
 	const char *aggtransspace;
 	const char *aggmtranstype;
 	const char *aggmtransspace;
@@ -12432,7 +12440,27 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	selectSourceSchema(fout, agginfo->aggfn.dobj.namespace->dobj.name);
 
 	/* Get aggregate-specific details */
-	if (fout->remoteVersion >= 90400)
+	if (fout->remoteVersion >= 90600)
+	{
+		appendPQExpBuffer(query, "SELECT aggtransfn, "
+			"aggfinalfn, aggtranstype::pg_catalog.regtype, "
+			"aggcombinefn, aggserialfn, aggdeserialfn, aggmtransfn, "
+			"aggminvtransfn, aggmfinalfn, aggmtranstype::pg_catalog.regtype, "
+			"aggfinalextra, aggmfinalextra, "
+			"aggsortop::pg_catalog.regoperator, "
+			"aggserialtype::pg_catalog.regtype, "
+			"(aggkind = 'h') AS hypothetical, "
+			"aggtransspace, agginitval, "
+			"aggmtransspace, aggminitval, "
+			"true AS convertok, "
+			"pg_catalog.pg_get_function_arguments(p.oid) AS funcargs, "
+			"pg_catalog.pg_get_function_identity_arguments(p.oid) AS funciargs "
+			"FROM pg_catalog.pg_aggregate a, pg_catalog.pg_proc p "
+			"WHERE a.aggfnoid = p.oid "
+			"AND p.oid = '%u'::pg_catalog.oid",
+			agginfo->aggfn.dobj.catId.oid);
+	}
+	else if (fout->remoteVersion >= 90400)
 	{
 		appendPQExpBuffer(query, "SELECT aggtransfn, "
 						  "aggfinalfn, aggtranstype::pg_catalog.regtype, "
@@ -12542,12 +12570,16 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 
 	i_aggtransfn = PQfnumber(res, "aggtransfn");
 	i_aggfinalfn = PQfnumber(res, "aggfinalfn");
+	i_aggcombinefn = PQfnumber(res, "aggcombinefn");
+	i_aggserialfn = PQfnumber(res, "aggserialfn");
+	i_aggdeserialfn = PQfnumber(res, "aggdeserialfn");
 	i_aggmtransfn = PQfnumber(res, "aggmtransfn");
 	i_aggminvtransfn = PQfnumber(res, "aggminvtransfn");
 	i_aggmfinalfn = PQfnumber(res, "aggmfinalfn");
 	i_aggfinalextra = PQfnumber(res, "aggfinalextra");
 	i_aggmfinalextra = PQfnumber(res, "aggmfinalextra");
 	i_aggsortop = PQfnumber(res, "aggsortop");
+	i_aggserialtype = PQfnumber(res, "aggserialtype");
 	i_hypothetical = PQfnumber(res, "hypothetical");
 	i_aggtranstype = PQfnumber(res, "aggtranstype");
 	i_aggtransspace = PQfnumber(res, "aggtransspace");
@@ -12559,6 +12591,9 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 
 	aggtransfn = PQgetvalue(res, 0, i_aggtransfn);
 	aggfinalfn = PQgetvalue(res, 0, i_aggfinalfn);
+	aggcombinefn = PQgetvalue(res, 0, i_aggcombinefn);
+	aggserialfn = PQgetvalue(res, 0, i_aggserialfn);
+	aggdeserialfn = PQgetvalue(res, 0, i_aggdeserialfn);
 	aggmtransfn = PQgetvalue(res, 0, i_aggmtransfn);
 	aggminvtransfn = PQgetvalue(res, 0, i_aggminvtransfn);
 	aggmfinalfn = PQgetvalue(res, 0, i_aggmfinalfn);
@@ -12567,6 +12602,7 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	aggsortop = PQgetvalue(res, 0, i_aggsortop);
 	hypothetical = (PQgetvalue(res, 0, i_hypothetical)[0] == 't');
 	aggtranstype = PQgetvalue(res, 0, i_aggtranstype);
+	aggserialtype = PQgetvalue(res, 0, i_aggserialtype);
 	aggtransspace = PQgetvalue(res, 0, i_aggtransspace);
 	aggmtranstype = PQgetvalue(res, 0, i_aggmtranstype);
 	aggmtransspace = PQgetvalue(res, 0, i_aggmtransspace);
@@ -12647,6 +12683,18 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 			appendPQExpBufferStr(details, ",\n    FINALFUNC_EXTRA");
 	}
 
+	if (strcmp(aggcombinefn, "-") != 0)
+	{
+		appendPQExpBuffer(details, ",\n    COMBINEFUNC = %s",	aggcombinefn);
+	}
+
+	if (strcmp(aggserialfn, "-") != 0)
+	{
+		appendPQExpBuffer(details, ",\n    SERIALFUNC = %s",	aggserialfn);
+		appendPQExpBuffer(details, ",\n    DESERIALFUNC = %s",	aggdeserialfn);
+		appendPQExpBuffer(details, ",\n    SERIALTYPE = %s",	aggserialtype);
+	}
+
 	if (strcmp(aggmtransfn, "-") != 0)
 	{
 		appendPQExpBuffer(details, ",\n    MSFUNC = %s,\n    MINVFUNC = %s,\n    MSTYPE = %s",
diff --git a/src/include/catalog/pg_aggregate.h b/src/include/catalog/pg_aggregate.h
index 28b0669..ed2ee92 100644
--- a/src/include/catalog/pg_aggregate.h
+++ b/src/include/catalog/pg_aggregate.h
@@ -33,6 +33,9 @@
  *	aggnumdirectargs	number of arguments that are "direct" arguments
  *	aggtransfn			transition function
  *	aggfinalfn			final function (0 if none)
+ *	aggcombinefn		combine function (0 if none)
+ *	aggserialfn			function to convert transtype into serialtype
+ *	aggdeserialfn		function to convert serialtype into transtype
  *	aggmtransfn			forward function for moving-aggregate mode (0 if none)
  *	aggminvtransfn		inverse function for moving-aggregate mode (0 if none)
  *	aggmfinalfn			final function for moving-aggregate mode (0 if none)
@@ -42,6 +45,7 @@
  *	aggtranstype		type of aggregate's transition (state) data
  *	aggtransspace		estimated size of state data (0 for default estimate)
  *	aggmtranstype		type of moving-aggregate state data (0 if none)
+ *	aggserialtype		datatype to serialize state to. (0 if none)
  *	aggmtransspace		estimated size of moving-agg state (0 for default est)
  *	agginitval			initial value for transition state (can be NULL)
  *	aggminitval			initial value for moving-agg state (can be NULL)
@@ -56,6 +60,9 @@ CATALOG(pg_aggregate,2600) BKI_WITHOUT_OIDS
 	int16		aggnumdirectargs;
 	regproc		aggtransfn;
 	regproc		aggfinalfn;
+	regproc		aggcombinefn;
+	regproc		aggserialfn;
+	regproc		aggdeserialfn;
 	regproc		aggmtransfn;
 	regproc		aggminvtransfn;
 	regproc		aggmfinalfn;
@@ -63,6 +70,7 @@ CATALOG(pg_aggregate,2600) BKI_WITHOUT_OIDS
 	bool		aggmfinalextra;
 	Oid			aggsortop;
 	Oid			aggtranstype;
+	Oid			aggserialtype;
 	int32		aggtransspace;
 	Oid			aggmtranstype;
 	int32		aggmtransspace;
@@ -85,24 +93,28 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  * ----------------
  */
 
-#define Natts_pg_aggregate					17
+#define Natts_pg_aggregate					21
 #define Anum_pg_aggregate_aggfnoid			1
 #define Anum_pg_aggregate_aggkind			2
 #define Anum_pg_aggregate_aggnumdirectargs	3
 #define Anum_pg_aggregate_aggtransfn		4
 #define Anum_pg_aggregate_aggfinalfn		5
-#define Anum_pg_aggregate_aggmtransfn		6
-#define Anum_pg_aggregate_aggminvtransfn	7
-#define Anum_pg_aggregate_aggmfinalfn		8
-#define Anum_pg_aggregate_aggfinalextra		9
-#define Anum_pg_aggregate_aggmfinalextra	10
-#define Anum_pg_aggregate_aggsortop			11
-#define Anum_pg_aggregate_aggtranstype		12
-#define Anum_pg_aggregate_aggtransspace		13
-#define Anum_pg_aggregate_aggmtranstype		14
-#define Anum_pg_aggregate_aggmtransspace	15
-#define Anum_pg_aggregate_agginitval		16
-#define Anum_pg_aggregate_aggminitval		17
+#define Anum_pg_aggregate_aggcombinefn		6
+#define Anum_pg_aggregate_aggserialfn		7
+#define Anum_pg_aggregate_aggdeserialfn		8
+#define Anum_pg_aggregate_aggmtransfn		9
+#define Anum_pg_aggregate_aggminvtransfn	10
+#define Anum_pg_aggregate_aggmfinalfn		11
+#define Anum_pg_aggregate_aggfinalextra		12
+#define Anum_pg_aggregate_aggmfinalextra	13
+#define Anum_pg_aggregate_aggsortop			14
+#define Anum_pg_aggregate_aggtranstype		15
+#define Anum_pg_aggregate_aggserialtype		16
+#define Anum_pg_aggregate_aggtransspace		17
+#define Anum_pg_aggregate_aggmtranstype		18
+#define Anum_pg_aggregate_aggmtransspace	19
+#define Anum_pg_aggregate_agginitval		20
+#define Anum_pg_aggregate_aggminitval		21
 
 /*
  * Symbolic values for aggkind column.  We distinguish normal aggregates
@@ -126,184 +138,184 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  */
 
 /* avg */
-DATA(insert ( 2100	n 0 int8_avg_accum	numeric_poly_avg		int8_avg_accum	int8_avg_accum_inv	numeric_poly_avg	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg		int4_avg_accum	int4_avg_accum_inv	int8_avg					f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg		int2_avg_accum	int2_avg_accum_inv	int8_avg					f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg	numeric_avg_accum numeric_accum_inv numeric_avg					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2104	n 0 float4_accum	float8_avg		-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2105	n 0 float8_accum	float8_avg		-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2106	n 0 interval_accum	interval_avg	interval_accum	interval_accum_inv interval_avg					f f 0	1187	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
+DATA(insert ( 2100	n 0 int8_avg_accum	numeric_poly_avg	-					-	-	int8_avg_accum	int8_avg_accum_inv	numeric_poly_avg	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg			-					-	-	int4_avg_accum	int4_avg_accum_inv	int8_avg			f f 0	1016	0	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg			-					-	-	int2_avg_accum	int2_avg_accum_inv	int8_avg			f f 0	1016	0	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg		numeric_avg_combine	numeric_avg_serialize	numeric_avg_deserialize	numeric_avg_accum numeric_accum_inv numeric_avg			f f 0	2281	25	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2104	n 0 float4_accum	float8_avg			-					-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2105	n 0 float8_accum	float8_avg			-					-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2106	n 0 interval_accum	interval_avg		-					-	-	interval_accum	interval_accum_inv interval_avg			f f 0	1187	0	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
 
 /* sum */
-DATA(insert ( 2107	n 0 int8_avg_accum	numeric_poly_sum		int8_avg_accum	int8_avg_accum_inv numeric_poly_sum f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2108	n 0 int4_sum		-				int4_avg_accum	int4_avg_accum_inv int2int4_sum					f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2109	n 0 int2_sum		-				int2_avg_accum	int2_avg_accum_inv int2int4_sum					f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2110	n 0 float4pl		-				-				-				-								f f 0	700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2111	n 0 float8pl		-				-				-				-								f f 0	701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2112	n 0 cash_pl			-				cash_pl			cash_mi			-								f f 0	790		0	790		0	_null_ _null_ ));
-DATA(insert ( 2113	n 0 interval_pl		-				interval_pl		interval_mi		-								f f 0	1186	0	1186	0	_null_ _null_ ));
-DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum numeric_avg_accum numeric_accum_inv numeric_sum					f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2107	n 0 int8_avg_accum	numeric_poly_sum	-					-	-	int8_avg_accum	int8_avg_accum_inv	numeric_poly_sum	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2108	n 0 int4_sum		-					int8pl				-	-	int4_avg_accum	int4_avg_accum_inv	int2int4_sum		f f 0	20		0	0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2109	n 0 int2_sum		-					int8pl				-	-	int2_avg_accum	int2_avg_accum_inv	int2int4_sum		f f 0	20		0	0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2110	n 0 float4pl		-					float4pl			-	-	-				-					-					f f 0	700		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2111	n 0 float8pl		-					float8pl			-	-	-				-					-					f f 0	701		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2112	n 0 cash_pl			-					cash_pl				-	-	cash_pl			cash_mi				-					f f 0	790		0	0	790		0	_null_ _null_ ));
+DATA(insert ( 2113	n 0 interval_pl		-					interval_pl			-	-	interval_pl		interval_mi			-					f f 0	1186	0	0	1186	0	_null_ _null_ ));
+DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum		numeric_avg_combine	numeric_avg_serialize	numeric_avg_deserialize	numeric_avg_accum	numeric_accum_inv	numeric_sum		f f 0	2281	25	128 2281	128 _null_ _null_ ));
 
 /* max */
-DATA(insert ( 2115	n 0 int8larger		-				-				-				-				f f 413		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2116	n 0 int4larger		-				-				-				-				f f 521		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2117	n 0 int2larger		-				-				-				-				f f 520		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2118	n 0 oidlarger		-				-				-				-				f f 610		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2119	n 0 float4larger	-				-				-				-				f f 623		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2120	n 0 float8larger	-				-				-				-				f f 674		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2121	n 0 int4larger		-				-				-				-				f f 563		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2122	n 0 date_larger		-				-				-				-				f f 1097	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2123	n 0 time_larger		-				-				-				-				f f 1112	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2124	n 0 timetz_larger	-				-				-				-				f f 1554	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2125	n 0 cashlarger		-				-				-				-				f f 903		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2126	n 0 timestamp_larger	-			-				-				-				f f 2064	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2127	n 0 timestamptz_larger	-			-				-				-				f f 1324	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2128	n 0 interval_larger -				-				-				-				f f 1334	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2129	n 0 text_larger		-				-				-				-				f f 666		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2130	n 0 numeric_larger	-				-				-				-				f f 1756	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2050	n 0 array_larger	-				-				-				-				f f 1073	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2244	n 0 bpchar_larger	-				-				-				-				f f 1060	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2797	n 0 tidlarger		-				-				-				-				f f 2800	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3526	n 0 enum_larger		-				-				-				-				f f 3519	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3564	n 0 network_larger	-				-				-				-				f f 1205	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2115	n 0 int8larger		-				int8larger			-	-	-				-				-				f f 413		20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2116	n 0 int4larger		-				int4larger			-	-	-				-				-				f f 521		23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2117	n 0 int2larger		-				int2larger			-	-	-				-				-				f f 520		21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2118	n 0 oidlarger		-				oidlarger			-	-	-				-				-				f f 610		26		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2119	n 0 float4larger	-				float4larger		-	-	-				-				-				f f 623		700		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2120	n 0 float8larger	-				float8larger		-	-	-				-				-				f f 674		701		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2121	n 0 int4larger		-				int4larger			-	-	-				-				-				f f 563		702		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2122	n 0 date_larger		-				date_larger			-	-	-				-				-				f f 1097	1082	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2123	n 0 time_larger		-				time_larger			-	-	-				-				-				f f 1112	1083	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2124	n 0 timetz_larger	-				timetz_larger		-	-	-				-				-				f f 1554	1266	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2125	n 0 cashlarger		-				cashlarger			-	-	-				-				-				f f 903		790		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2126	n 0 timestamp_larger	-			timestamp_larger	-	-	-				-				-				f f 2064	1114	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2127	n 0 timestamptz_larger	-			timestamptz_larger	-	-	-				-				-				f f 1324	1184	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2128	n 0 interval_larger -				interval_larger		-	-	-				-				-				f f 1334	1186	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2129	n 0 text_larger		-				text_larger			-	-	-				-				-				f f 666		25		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2130	n 0 numeric_larger	-				numeric_larger		-	-	-				-				-				f f 1756	1700	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2050	n 0 array_larger	-				array_larger		-	-	-				-				-				f f 1073	2277	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2244	n 0 bpchar_larger	-				bpchar_larger		-	-	-				-				-				f f 1060	1042	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2797	n 0 tidlarger		-				tidlarger			-	-	-				-				-				f f 2800	27		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3526	n 0 enum_larger		-				enum_larger			-	-	-				-				-				f f 3519	3500	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3564	n 0 network_larger	-				network_larger		-	-	-				-				-				f f 1205	869		0	0	0		0	_null_ _null_ ));
 
 /* min */
-DATA(insert ( 2131	n 0 int8smaller		-				-				-				-				f f 412		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2132	n 0 int4smaller		-				-				-				-				f f 97		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2133	n 0 int2smaller		-				-				-				-				f f 95		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2134	n 0 oidsmaller		-				-				-				-				f f 609		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2135	n 0 float4smaller	-				-				-				-				f f 622		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2136	n 0 float8smaller	-				-				-				-				f f 672		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2137	n 0 int4smaller		-				-				-				-				f f 562		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2138	n 0 date_smaller	-				-				-				-				f f 1095	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2139	n 0 time_smaller	-				-				-				-				f f 1110	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2140	n 0 timetz_smaller	-				-				-				-				f f 1552	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2141	n 0 cashsmaller		-				-				-				-				f f 902		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2142	n 0 timestamp_smaller	-			-				-				-				f f 2062	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2143	n 0 timestamptz_smaller -			-				-				-				f f 1322	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2144	n 0 interval_smaller	-			-				-				-				f f 1332	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2145	n 0 text_smaller	-				-				-				-				f f 664		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2146	n 0 numeric_smaller -				-				-				-				f f 1754	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2051	n 0 array_smaller	-				-				-				-				f f 1072	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2245	n 0 bpchar_smaller	-				-				-				-				f f 1058	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2798	n 0 tidsmaller		-				-				-				-				f f 2799	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3527	n 0 enum_smaller	-				-				-				-				f f 3518	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3565	n 0 network_smaller -				-				-				-				f f 1203	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2131	n 0 int8smaller		-				int8smaller			-	-	-				-				-				f f 412		20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2132	n 0 int4smaller		-				int4smaller			-	-	-				-				-				f f 97		23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2133	n 0 int2smaller		-				int2smaller			-	-	-				-				-				f f 95		21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2134	n 0 oidsmaller		-				oidsmaller			-	-	-				-				-				f f 609		26		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2135	n 0 float4smaller	-				float4smaller		-	-	-				-				-				f f 622		700		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2136	n 0 float8smaller	-				float8smaller		-	-	-				-				-				f f 672		701		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2137	n 0 int4smaller		-				int4smaller			-	-	-				-				-				f f 562		702		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2138	n 0 date_smaller	-				date_smaller		-	-	-				-				-				f f 1095	1082	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2139	n 0 time_smaller	-				time_smaller		-	-	-				-				-				f f 1110	1083	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2140	n 0 timetz_smaller	-				timetz_smaller		-	-	-				-				-				f f 1552	1266	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2141	n 0 cashsmaller		-				cashsmaller			-	-	-				-				-				f f 902		790		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2142	n 0 timestamp_smaller	-			timestamp_smaller	-	-	-				-				-				f f 2062	1114	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2143	n 0 timestamptz_smaller -			timestamptz_smaller	-	-	-				-				-				f f 1322	1184	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2144	n 0 interval_smaller	-			interval_smaller	-	-	-				-				-				f f 1332	1186	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2145	n 0 text_smaller	-				text_smaller		-	-	-				-				-				f f 664		25		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2146	n 0 numeric_smaller -				numeric_smaller		-	-	-				-				-				f f 1754	1700	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2051	n 0 array_smaller	-				array_smaller		-	-	-				-				-				f f 1072	2277	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2245	n 0 bpchar_smaller	-				bpchar_smaller		-	-	-				-				-				f f 1058	1042	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2798	n 0 tidsmaller		-				tidsmaller			-	-	-				-				-				f f 2799	27		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3527	n 0 enum_smaller	-				enum_smaller		-	-	-				-				-				f f 3518	3500	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3565	n 0 network_smaller -				network_smaller		-	-	-				-				-				f f 1203	869		0	0	0		0	_null_ _null_ ));
 
 /* count */
-DATA(insert ( 2147	n 0 int8inc_any		-				int8inc_any		int8dec_any		-				f f 0		20		0	20		0	"0" "0" ));
-DATA(insert ( 2803	n 0 int8inc			-				int8inc			int8dec			-				f f 0		20		0	20		0	"0" "0" ));
+DATA(insert ( 2147	n 0 int8inc_any		-				int8pl	-	-	int8inc_any		int8dec_any		-				f f 0		20		0	0	20		0	"0" "0" ));
+DATA(insert ( 2803	n 0 int8inc			-				int8pl	-	-	int8inc			int8dec			-				f f 0		20		0	0	20		0	"0" "0" ));
 
 /* var_pop */
-DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop		int8_accum		int8_accum_inv	numeric_var_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2719	n 0 int4_accum	numeric_poly_var_pop		int4_accum		int4_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2720	n 0 int2_accum	numeric_poly_var_pop		int2_accum		int2_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2721	n 0 float4_accum	float8_var_pop	-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2722	n 0 float8_accum	float8_var_pop	-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop numeric_accum numeric_accum_inv numeric_var_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop			-	-	-	int8_accum		int8_accum_inv	numeric_var_pop			f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2719	n 0 int4_accum	numeric_poly_var_pop	-	-	-	int4_accum		int4_accum_inv	numeric_poly_var_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2720	n 0 int2_accum	numeric_poly_var_pop	-	-	-	int2_accum		int2_accum_inv	numeric_poly_var_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2721	n 0 float4_accum	float8_var_pop		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2722	n 0 float8_accum	float8_var_pop		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop		-	-	-	numeric_accum numeric_accum_inv numeric_var_pop			f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* var_samp */
-DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp	int8_accum		int8_accum_inv	numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2642	n 0 int4_accum	numeric_poly_var_samp		int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2643	n 0 int2_accum	numeric_poly_var_samp		int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2644	n 0 float4_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2645	n 0 float8_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp numeric_accum numeric_accum_inv numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp		-	-	-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2642	n 0 int4_accum	numeric_poly_var_samp	-	-	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2643	n 0 int2_accum	numeric_poly_var_samp	-	-	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2644	n 0 float4_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2645	n 0 float8_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp	-	-	-	numeric_accum	numeric_accum_inv numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* variance: historical Postgres syntax for var_samp */
-DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp	int8_accum		int8_accum_inv	numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2149	n 0 int4_accum	numeric_poly_var_samp		int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2150	n 0 int2_accum	numeric_poly_var_samp		int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2151	n 0 float4_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2152	n 0 float8_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp numeric_accum numeric_accum_inv numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp		-	-	-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2149	n 0 int4_accum	numeric_poly_var_samp	-	-	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2150	n 0 int2_accum	numeric_poly_var_samp	-	-	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2151	n 0 float4_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2152	n 0 float8_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp	-	-	-	numeric_accum numeric_accum_inv numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* stddev_pop */
-DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop	int8_accum	int8_accum_inv	numeric_stddev_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2725	n 0 int4_accum	numeric_poly_stddev_pop int4_accum	int4_accum_inv	numeric_poly_stddev_pop f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2726	n 0 int2_accum	numeric_poly_stddev_pop int2_accum	int2_accum_inv	numeric_poly_stddev_pop f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop numeric_accum numeric_accum_inv numeric_stddev_pop			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop		-	-	-	int8_accum	int8_accum_inv	numeric_stddev_pop		f f 0	2281	0	128	2281	128 _null_ _null_ ));
+DATA(insert ( 2725	n 0 int4_accum	numeric_poly_stddev_pop	-	-	-	int4_accum	int4_accum_inv	numeric_poly_stddev_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2726	n 0 int2_accum	numeric_poly_stddev_pop	-	-	-	int2_accum	int2_accum_inv	numeric_poly_stddev_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-	-	-	-				-				-					f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-	-	-	-				-				-					f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop	-	-	-	numeric_accum numeric_accum_inv numeric_stddev_pop	f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* stddev_samp */
-DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp		int8_accum	int8_accum_inv	numeric_stddev_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2713	n 0 int4_accum	numeric_poly_stddev_samp	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2714	n 0 int2_accum	numeric_poly_stddev_samp	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp numeric_accum numeric_accum_inv numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp			-	-	-	int8_accum	int8_accum_inv	numeric_stddev_samp			f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2713	n 0 int4_accum	numeric_poly_stddev_samp	-	-	-	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2714	n 0 int2_accum	numeric_poly_stddev_samp	-	-	-	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp		-	-	-	numeric_accum numeric_accum_inv numeric_stddev_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* stddev: historical Postgres syntax for stddev_samp */
-DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp		int8_accum	int8_accum_inv	numeric_stddev_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2155	n 0 int4_accum	numeric_poly_stddev_samp	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2156	n 0 int2_accum	numeric_poly_stddev_samp	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp numeric_accum numeric_accum_inv numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp			-	-	-	int8_accum		int8_accum_inv	numeric_stddev_samp			f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2155	n 0 int4_accum	numeric_poly_stddev_samp	-	-	-	int4_accum		int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2156	n 0 int2_accum	numeric_poly_stddev_samp	-	-	-	int2_accum		int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp		-	-	-	-				-				-							f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp		-	-	-	-				-				-							f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp		-	-	-	numeric_accum	numeric_accum_inv numeric_stddev_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* SQL2003 binary regression aggregates */
-DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-				-				-				f f 0	20		0	0		0	"0" _null_ ));
-DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-	-	-	-				-				-			f f 0	20		0	0	0		0	"0" _null_ ));
+DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
 
 /* boolean-and and boolean-or */
-DATA(insert ( 2517	n 0 booland_statefunc	-			bool_accum		bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2518	n 0 boolor_statefunc	-			bool_accum		bool_accum_inv	bool_anytrue	f f 59	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2519	n 0 booland_statefunc	-			bool_accum		bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2517	n 0 booland_statefunc	-	-	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16	0		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2518	n 0 boolor_statefunc	-	-	-	-	bool_accum	bool_accum_inv	bool_anytrue	f f 59	16	0		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2519	n 0 booland_statefunc	-	-	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16	0		0	2281	16	_null_ _null_ ));
 
 /* bitwise integer */
-DATA(insert ( 2236	n 0 int2and		-					-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2237	n 0 int2or		-					-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2238	n 0 int4and		-					-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2239	n 0 int4or		-					-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2240	n 0 int8and		-					-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2241	n 0 int8or		-					-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2242	n 0 bitand		-					-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
-DATA(insert ( 2243	n 0 bitor		-					-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
+DATA(insert ( 2236	n 0 int2and		-				int2and	-	-	-				-				-				f f 0	21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2237	n 0 int2or		-				int2or	-	-	-				-				-				f f 0	21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2238	n 0 int4and		-				int4and	-	-	-				-				-				f f 0	23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2239	n 0 int4or		-				int4or	-	-	-				-				-				f f 0	23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2240	n 0 int8and		-				int8and	-	-	-				-				-				f f 0	20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2241	n 0 int8or		-				int8or	-	-	-				-				-				f f 0	20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2242	n 0 bitand		-				bitand	-	-	-				-				-				f f 0	1560	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2243	n 0 bitor		-				bitor	-	-	-				-				-				f f 0	1560	0	0	0		0	_null_ _null_ ));
 
 /* xml */
-DATA(insert ( 2901	n 0 xmlconcat2	-					-				-				-				f f 0	142		0	0		0	_null_ _null_ ));
+DATA(insert ( 2901	n 0 xmlconcat2	-				-		-	-	-				-				-				f f 0	142		0	0	0		0	_null_ _null_ ));
 
 /* array */
-DATA(insert ( 2335	n 0 array_agg_transfn	array_agg_finalfn	-				-				-				t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn -		-				-				t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 2335	n 0 array_agg_transfn		array_agg_finalfn		-	-	-	-		-				-				t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn	-	-	-	-		-				-				t f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* text */
-DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-	-	-	-				-				-				f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* bytea */
-DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-				-				-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-	-	-	-				-				-		f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* json */
-DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-	-	-	-				-				-				f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -	-	-	-				-				-				f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* jsonb */
-DATA(insert ( 3267	n 0 jsonb_agg_transfn	jsonb_agg_finalfn			-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3270	n 0 jsonb_object_agg_transfn jsonb_object_agg_finalfn -				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3267	n 0 jsonb_agg_transfn	jsonb_agg_finalfn				-	-	-	-				-				-			f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3270	n 0 jsonb_object_agg_transfn jsonb_object_agg_finalfn	-	-	-	-				-				-			f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* ordered-set and hypothetical-set aggregates */
-DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
 
 
 /*
@@ -322,6 +334,9 @@ extern ObjectAddress AggregateCreate(const char *aggName,
 				Oid variadicArgType,
 				List *aggtransfnName,
 				List *aggfinalfnName,
+				List *aggcombinefnName,
+				List *aggserialfnName,
+				List *aggdeserialfnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
@@ -329,6 +344,7 @@ extern ObjectAddress AggregateCreate(const char *aggName,
 				bool mfinalfnExtraArgs,
 				List *aggsortopName,
 				Oid aggTransType,
+				Oid aggSerialType,
 				int32 aggTransSpace,
 				Oid aggmTransType,
 				int32 aggmTransSpace,
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index f58672e..5f4d37e 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -2517,6 +2517,12 @@ DESCR("aggregate final function");
 DATA(insert OID = 1833 (  numeric_accum    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_accum _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
 DATA(insert OID = 2858 (  numeric_avg_accum    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_avg_accum _null_ _null_ _null_ ));
+DESCR("aggregate combine function");
+DATA(insert OID = 3318 (  numeric_avg_combine    PGNSP PGUID 12 1 0 0 0 f f f f t f i s 2 0 2281 "2281 2281" _null_ _null_ _null_ _null_ _null_ numeric_avg_combine _null_ _null_ _null_ ));
+DESCR("aggregate serial function");
+DATA(insert OID = 3319 (  numeric_avg_serialize    PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 25 "2281" _null_ _null_ _null_ _null_ _null_ numeric_avg_serialize _null_ _null_ _null_ ));
+DESCR("aggregate deserial function");
+DATA(insert OID = 3320 (  numeric_avg_deserialize    PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 2281 "25" _null_ _null_ _null_ _null_ _null_ numeric_avg_deserialize _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
 DATA(insert OID = 3548 (  numeric_accum_inv    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_accum_inv _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index bfa5125..69a1dad 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1851,6 +1851,9 @@ typedef struct AggState
 	AggStatePerTrans curpertrans;	/* currently active trans state */
 	bool		input_done;		/* indicates end of input */
 	bool		agg_done;		/* indicates completion of Agg scan */
+	bool		combineStates;	/* input tuples contain transition states */
+	bool		finalizeAggs;	/* should we call the finalfn on agg states? */
+	bool		serialStates;	/* should partial states be serialized? */
 	int			projected_set;	/* The last projected grouping set */
 	int			current_set;	/* The current grouping set being evaluated */
 	Bitmapset  *grouped_cols;	/* grouped cols in current projection */
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index c92579b..b5d0e56 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -726,6 +726,9 @@ typedef struct Agg
 	AggStrategy aggstrategy;
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
+	bool		combineStates;	/* input tuples contain transition states */
+	bool		finalizeAggs;	/* should we call the finalfn on agg states? */
+	bool		serialStates;	/* should partial states be serialized? */
 	Oid		   *grpOperators;	/* equality operators to compare with */
 	long		numGroups;		/* estimated number of groups in input */
 	List	   *groupingSets;	/* grouping sets to use */
diff --git a/src/include/optimizer/clauses.h b/src/include/optimizer/clauses.h
index 3b3fd0f..d381ff0 100644
--- a/src/include/optimizer/clauses.h
+++ b/src/include/optimizer/clauses.h
@@ -27,6 +27,25 @@ typedef struct
 	List	  **windowFuncs;	/* lists of WindowFuncs for each winref */
 } WindowFuncLists;
 
+/*
+ * PartialAggType
+ *	PartialAggType stores whether partial aggregation is allowed and
+ *	which context it is allowed in. We require three states here as there are
+ *	two different contexts in which partial aggregation is safe. For aggregates
+ *	which have an 'stype' of INTERNAL, within a single backend process it is
+ *	okay to pass a pointer to the aggregate state, as the memory to which the
+ *	pointer points to will belong to the same process. In cases where the
+ *	aggregate state must be passed between different processes, for example
+ *	during parallel aggregation, passing the pointer is not okay due to the
+ *	fact that the memory being referenced won't be accessible from another
+ *	process.
+ */
+typedef enum
+{
+	PAT_ANY = 0,		/* Any type of partial aggregation is ok. */
+	PAT_INTERNAL_ONLY,	/* Some aggregates support only internal mode. */
+	PAT_DISABLED		/* Some aggregates don't support partial mode at all */
+} PartialAggType;
 
 extern Expr *make_opclause(Oid opno, Oid opresulttype, bool opretset,
 			  Expr *leftop, Expr *rightop,
@@ -47,6 +66,7 @@ extern Node *make_and_qual(Node *qual1, Node *qual2);
 extern Expr *make_ands_explicit(List *andclauses);
 extern List *make_ands_implicit(Expr *clause);
 
+extern PartialAggType aggregates_allow_partial(Node *clause);
 extern bool contain_agg_clause(Node *clause);
 extern void count_agg_clauses(PlannerInfo *root, Node *clause,
 				  AggClauseCosts *costs);
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index 275054f..c1819f6 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -60,9 +60,8 @@ extern Sort *make_sort_from_groupcols(PlannerInfo *root, List *groupcls,
 extern Agg *make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
 		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
-		 List *groupingSets,
-		 long numGroups,
-		 Plan *lefttree);
+		 List *groupingSets, long numGroups, bool combineStates,
+		 bool finalizeAggs, bool serialStates, Plan *lefttree);
 extern WindowAgg *make_windowagg(PlannerInfo *root, List *tlist,
 			   List *windowFuncs, Index winref,
 			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
diff --git a/src/include/parser/parse_agg.h b/src/include/parser/parse_agg.h
index 3e336b9..43be714 100644
--- a/src/include/parser/parse_agg.h
+++ b/src/include/parser/parse_agg.h
@@ -46,6 +46,23 @@ extern void build_aggregate_transfn_expr(Oid *agg_input_types,
 						Expr **transfnexpr,
 						Expr **invtransfnexpr);
 
+extern void build_aggregate_combinefn_expr(Oid agg_state_type,
+										   Oid agg_input_collation,
+										   Oid combinefn_oid,
+										   Expr **combinefnexpr);
+
+extern void build_aggregate_serialfn_expr(Oid agg_state_type,
+										  Oid agg_serial_type,
+										  Oid agg_input_collation,
+										  Oid serialfn_oid,
+										  Expr **serialfnexpr);
+
+extern void build_aggregate_deserialfn_expr(Oid agg_state_type,
+											Oid agg_serial_type,
+											Oid agg_input_collation,
+											Oid deserialfn_oid,
+											Expr **deserialfnexpr);
+
 extern void build_aggregate_finalfn_expr(Oid *agg_input_types,
 						int num_finalfn_inputs,
 						Oid agg_state_type,
diff --git a/src/test/regress/expected/create_aggregate.out b/src/test/regress/expected/create_aggregate.out
index 82a34fb..14f73c4 100644
--- a/src/test/regress/expected/create_aggregate.out
+++ b/src/test/regress/expected/create_aggregate.out
@@ -101,6 +101,93 @@ CREATE AGGREGATE sumdouble (float8)
     msfunc = float8pl,
     minvfunc = float8mi
 );
+-- aggregate combine and serialization functions
+-- Ensure stype and serialtype can't be the same
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = internal
+);
+ERROR:  aggregate serial data type cannot be "internal"
+-- if serialtype is specified we need a serialfunc and deserialfunc
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text
+);
+ERROR:  aggregate serialfunc must be specified when serialtype is specified
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize
+);
+ERROR:  aggregate deserialfunc must be specified when serialtype is specified
+-- serialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_deserialize,
+	deserialfunc = numeric_avg_deserialize
+);
+ERROR:  function numeric_avg_deserialize(internal) does not exist
+-- deserialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_serialize
+);
+ERROR:  function numeric_avg_serialize(text) does not exist
+-- ensure return type of serialfunc is checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = bytea,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize
+);
+ERROR:  return type of serial function numeric_avg_serialize is not bytea
+-- ensure combine function parameters are checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = int4larger
+);
+ERROR:  function int4larger(internal, internal) does not exist
+-- ensure create aggregate works.
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	finalfunc = numeric_avg,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = numeric_avg_combine
+);
+-- Ensure all these functions made it into the catalog
+SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype,aggserialfn,aggdeserialfn,aggserialtype
+FROM pg_aggregate
+WHERE aggfnoid = 'myavg'::REGPROC;
+ aggfnoid |    aggtransfn     |    aggcombinefn     | aggtranstype |      aggserialfn      |      aggdeserialfn      | aggserialtype 
+----------+-------------------+---------------------+--------------+-----------------------+-------------------------+---------------
+ myavg    | numeric_avg_accum | numeric_avg_combine |         2281 | numeric_avg_serialize | numeric_avg_deserialize |            25
+(1 row)
+
+DROP AGGREGATE myavg (numeric);
 -- invalid: nonstrict inverse with strict forward function
 CREATE FUNCTION float8mi_n(float8, float8) RETURNS float8 AS
 $$ SELECT $1 - $2; $$
diff --git a/src/test/regress/sql/create_aggregate.sql b/src/test/regress/sql/create_aggregate.sql
index 0ec1572..8395e5d 100644
--- a/src/test/regress/sql/create_aggregate.sql
+++ b/src/test/regress/sql/create_aggregate.sql
@@ -115,6 +115,92 @@ CREATE AGGREGATE sumdouble (float8)
     minvfunc = float8mi
 );
 
+-- aggregate combine and serialization functions
+
+-- Ensure stype and serialtype can't be the same
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = internal
+);
+
+-- if serialtype is specified we need a serialfunc and deserialfunc
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text
+);
+
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize
+);
+
+-- serialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_deserialize,
+	deserialfunc = numeric_avg_deserialize
+);
+
+-- deserialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_serialize
+);
+
+-- ensure return type of serialfunc is checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = bytea,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize
+);
+
+-- ensure combine function parameters are checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = int4larger
+);
+
+-- ensure create aggregate works.
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	finalfunc = numeric_avg,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = numeric_avg_combine
+);
+
+-- Ensure all these functions made it into the catalog
+SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype,aggserialfn,aggdeserialfn,aggserialtype
+FROM pg_aggregate
+WHERE aggfnoid = 'myavg'::REGPROC;
+
+DROP AGGREGATE myavg (numeric);
+
 -- invalid: nonstrict inverse with strict forward function
 
 CREATE FUNCTION float8mi_n(float8, float8) RETURNS float8 AS

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index ad99690..aa8719e 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -134,7 +134,104 @@ static Plan *build_grouping_chain(PlannerInfo *root,
 					 AttrNumber *groupColIdx,
 					 AggClauseCosts *agg_costs,
 					 long numGroups,
-					 Plan *result_plan);
+					 Plan *result_plan,
+					 PartialAggType partialaggtype);
+
+static List *
+make_aggregate_tlist(PlannerInfo *root,
+					 List *tlist,
+					 AttrNumber **groupColIdx)
+{
+	Query	   *parse = root->parse;
+	List	   *sub_tlist;
+	List	   *non_group_cols;
+	List	   *non_group_vars;
+	int			numCols;
+	ListCell   *tl;
+
+	*groupColIdx = NULL;
+
+	/*
+	 * Otherwise, we must build a tlist containing all grouping columns, plus
+	 * any other Vars mentioned in the targetlist and HAVING qual.
+	 */
+	sub_tlist = NIL;
+	non_group_cols = NIL;
+
+	numCols = list_length(parse->groupClause);
+	if (numCols > 0)
+	{
+		/*
+		 * If grouping, create sub_tlist entries for all GROUP BY columns, and
+		 * make an array showing where the group columns are in the sub_tlist.
+		 *
+		 * Note: with this implementation, the array entries will always be
+		 * 1..N, but we don't want callers to assume that.
+		 */
+		AttrNumber *grpColIdx;
+
+		grpColIdx = (AttrNumber *) palloc0(sizeof(AttrNumber) * numCols);
+		*groupColIdx = grpColIdx;
+
+		foreach(tl, tlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(tl);
+			int			colno;
+
+			colno = get_grouping_column_index(parse, tle);
+			if (colno >= 0)
+			{
+				/*
+				 * It's a grouping column, so add it to the result tlist and
+				 * remember its resno in grpColIdx[].
+				 */
+				TargetEntry *newtle;
+
+				newtle = makeTargetEntry((Expr *) copyObject(tle->expr),
+										 list_length(sub_tlist) + 1,
+										 NULL,
+										 tle->resjunk);
+				newtle->ressortgroupref = tle->ressortgroupref;
+				sub_tlist = lappend(sub_tlist, newtle);
+
+				Assert(grpColIdx[colno] == 0);	/* no dups expected */
+				grpColIdx[colno] = newtle->resno;
+			}
+			else
+			{
+				non_group_cols = lappend(non_group_cols, tle->expr);
+			}
+		}
+	}
+	else
+	{
+		foreach(tl, tlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(tl);
+			non_group_cols = lappend(non_group_cols, tle->expr);
+		}
+	}
+
+	/*
+	 * If there's a HAVING clause, we'll need need to ensure all Aggrefs from
+	 * there are also in the targetlist
+	 */
+	if (parse->havingQual)
+		non_group_cols = lappend(non_group_cols, parse->havingQual);
+
+
+	non_group_vars = pull_var_clause((Node *) non_group_cols,
+									 PVC_INCLUDE_AGGREGATES,
+									 PVC_INCLUDE_PLACEHOLDERS);
+
+	sub_tlist = add_to_flat_tlist(sub_tlist, non_group_vars);
+
+	/* clean up cruft */
+	list_free(non_group_vars);
+	list_free(non_group_cols);
+
+	return sub_tlist;
+}
 
 /*****************************************************************************
  *
@@ -1896,6 +1993,19 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			AttrNumber *groupColIdx = NULL;
 			bool		need_tlist_eval = true;
 			bool		need_sort_for_grouping = false;
+			PartialAggType partialaggtype;
+
+			/* Determine the level of partial aggregation we can use */
+			if (parse->groupingSets)
+				partialaggtype = PAT_DISABLED;
+			else
+			{
+				partialaggtype = aggregates_allow_partial((Node *) tlist);
+
+				if (partialaggtype != PAT_DISABLED)
+					partialaggtype = Min(partialaggtype,
+							aggregates_allow_partial(root->parse->havingQual));
+			}
 
 			result_plan = create_plan(root, best_path);
 			current_pathkeys = best_path->pathkeys;
@@ -1913,6 +2023,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 											   &groupColIdx,
 											   &need_tlist_eval);
 
+			if (partialaggtype != PAT_DISABLED)
+				need_tlist_eval = true;
+
 			/*
 			 * create_plan returns a plan with just a "flat" tlist of required
 			 * Vars.  Usually we need to insert the sub_tlist as the tlist of
@@ -1994,21 +2107,74 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			 */
 			if (use_hashed_grouping)
 			{
-				/* Hashed aggregate plan --- no sort needed */
-				result_plan = (Plan *) make_agg(root,
-												tlist,
-												(List *) parse->havingQual,
-												AGG_HASHED,
-												&agg_costs,
-												numGroupCols,
-												groupColIdx,
-									extract_grouping_ops(parse->groupClause),
-												NIL,
-												numGroups,
-												false,
-												true,
-												false,
-												result_plan);
+				if (partialaggtype != PAT_DISABLED)
+				{
+					AttrNumber *groupColIdx;
+					List *aggtlist;
+
+					aggtlist = make_aggregate_tlist(root, tlist, &groupColIdx);
+
+					/* Hashed aggregate plan --- no sort needed */
+					result_plan = (Plan *) make_agg(root,
+													aggtlist,
+													NIL,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													false,
+													false,
+													true,
+													result_plan);
+
+					result_plan->targetlist = aggtlist;
+
+					/*
+					 * Also, account for the cost of evaluation of the sub_tlist.
+					 * See comments for add_tlist_costs_to_plan() for more info.
+					 */
+					add_tlist_costs_to_plan(root, result_plan, aggtlist);
+
+					aggtlist  = make_aggregate_tlist(root, tlist, &groupColIdx);
+
+					result_plan = (Plan *) make_agg(root,
+													aggtlist,
+													(List *) parse->havingQual,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													true,
+													true,
+													true,
+													result_plan);
+					result_plan->targetlist = tlist;
+
+				}
+				else
+				{
+					/* Hashed aggregate plan --- no sort needed */
+					result_plan = (Plan *) make_agg(root,
+													tlist,
+													(List *) parse->havingQual,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													false,
+													true,
+													false,
+													result_plan);
+				}
 				/* Hashed aggregation produces randomly-ordered results */
 				current_pathkeys = NIL;
 			}
@@ -2037,7 +2203,8 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 												   groupColIdx,
 												   &agg_costs,
 												   numGroups,
-												   result_plan);
+												   result_plan,
+												   partialaggtype);
 			}
 			else if (parse->groupClause)
 			{
@@ -2483,7 +2650,8 @@ build_grouping_chain(PlannerInfo *root,
 					 AttrNumber *groupColIdx,
 					 AggClauseCosts *agg_costs,
 					 long numGroups,
-					 Plan *result_plan)
+					 Plan *result_plan,
+					 PartialAggType partialaggtype)
 {
 	AttrNumber *top_grpColIdx = groupColIdx;
 	List	   *chain = NIL;
@@ -2587,21 +2755,70 @@ build_grouping_chain(PlannerInfo *root,
 		else
 			numGroupCols = list_length(parse->groupClause);
 
-		result_plan = (Plan *) make_agg(root,
-										tlist,
-										(List *) parse->havingQual,
-								 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
-										agg_costs,
-										numGroupCols,
-										top_grpColIdx,
-										extract_grouping_ops(groupClause),
-										gsets,
-										numGroups,
-										false,
-										true,
-										false,
-										result_plan);
+		if (partialaggtype != PAT_DISABLED)
+		{
+			AttrNumber *groupColIdx;
+			List *aggtlist;
+
+			aggtlist = make_aggregate_tlist(root, tlist, &groupColIdx);
+
+			result_plan = (Plan *) make_agg(root,
+											aggtlist,
+											NIL,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											groupColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											false,
+											false,
+											true,
+											result_plan);
+			result_plan->targetlist = aggtlist;
+
+			/*
+			 * Also, account for the cost of evaluation of the sub_tlist.
+			 * See comments for add_tlist_costs_to_plan() for more info.
+			 */
+			add_tlist_costs_to_plan(root, result_plan, aggtlist);
+
+			aggtlist  = make_aggregate_tlist(root, tlist, &groupColIdx);
 
+			result_plan = (Plan *) make_agg(root,
+											aggtlist,
+											(List *) parse->havingQual,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											groupColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											true,
+											true,
+											true,
+											result_plan);
+			result_plan->targetlist = tlist;
+		}
+		else
+		{
+			result_plan = (Plan *) make_agg(root,
+											tlist,
+											(List *) parse->havingQual,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											top_grpColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											false,
+											true,
+											false,
+											result_plan);
+		}
 		((Agg *) result_plan)->chain = chain;
 
 		/*

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index ad99690..aa8719e 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -134,7 +134,104 @@ static Plan *build_grouping_chain(PlannerInfo *root,
 					 AttrNumber *groupColIdx,
 					 AggClauseCosts *agg_costs,
 					 long numGroups,
-					 Plan *result_plan);
+					 Plan *result_plan,
+					 PartialAggType partialaggtype);
+
+static List *
+make_aggregate_tlist(PlannerInfo *root,
+					 List *tlist,
+					 AttrNumber **groupColIdx)
+{
+	Query	   *parse = root->parse;
+	List	   *sub_tlist;
+	List	   *non_group_cols;
+	List	   *non_group_vars;
+	int			numCols;
+	ListCell   *tl;
+
+	*groupColIdx = NULL;
+
+	/*
+	 * Otherwise, we must build a tlist containing all grouping columns, plus
+	 * any other Vars mentioned in the targetlist and HAVING qual.
+	 */
+	sub_tlist = NIL;
+	non_group_cols = NIL;
+
+	numCols = list_length(parse->groupClause);
+	if (numCols > 0)
+	{
+		/*
+		 * If grouping, create sub_tlist entries for all GROUP BY columns, and
+		 * make an array showing where the group columns are in the sub_tlist.
+		 *
+		 * Note: with this implementation, the array entries will always be
+		 * 1..N, but we don't want callers to assume that.
+		 */
+		AttrNumber *grpColIdx;
+
+		grpColIdx = (AttrNumber *) palloc0(sizeof(AttrNumber) * numCols);
+		*groupColIdx = grpColIdx;
+
+		foreach(tl, tlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(tl);
+			int			colno;
+
+			colno = get_grouping_column_index(parse, tle);
+			if (colno >= 0)
+			{
+				/*
+				 * It's a grouping column, so add it to the result tlist and
+				 * remember its resno in grpColIdx[].
+				 */
+				TargetEntry *newtle;
+
+				newtle = makeTargetEntry((Expr *) copyObject(tle->expr),
+										 list_length(sub_tlist) + 1,
+										 NULL,
+										 tle->resjunk);
+				newtle->ressortgroupref = tle->ressortgroupref;
+				sub_tlist = lappend(sub_tlist, newtle);
+
+				Assert(grpColIdx[colno] == 0);	/* no dups expected */
+				grpColIdx[colno] = newtle->resno;
+			}
+			else
+			{
+				non_group_cols = lappend(non_group_cols, tle->expr);
+			}
+		}
+	}
+	else
+	{
+		foreach(tl, tlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(tl);
+			non_group_cols = lappend(non_group_cols, tle->expr);
+		}
+	}
+
+	/*
+	 * If there's a HAVING clause, we'll need need to ensure all Aggrefs from
+	 * there are also in the targetlist
+	 */
+	if (parse->havingQual)
+		non_group_cols = lappend(non_group_cols, parse->havingQual);
+
+
+	non_group_vars = pull_var_clause((Node *) non_group_cols,
+									 PVC_INCLUDE_AGGREGATES,
+									 PVC_INCLUDE_PLACEHOLDERS);
+
+	sub_tlist = add_to_flat_tlist(sub_tlist, non_group_vars);
+
+	/* clean up cruft */
+	list_free(non_group_vars);
+	list_free(non_group_cols);
+
+	return sub_tlist;
+}
 
 /*****************************************************************************
  *
@@ -1896,6 +1993,19 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			AttrNumber *groupColIdx = NULL;
 			bool		need_tlist_eval = true;
 			bool		need_sort_for_grouping = false;
+			PartialAggType partialaggtype;
+
+			/* Determine the level of partial aggregation we can use */
+			if (parse->groupingSets)
+				partialaggtype = PAT_DISABLED;
+			else
+			{
+				partialaggtype = aggregates_allow_partial((Node *) tlist);
+
+				if (partialaggtype != PAT_DISABLED)
+					partialaggtype = Min(partialaggtype,
+							aggregates_allow_partial(root->parse->havingQual));
+			}
 
 			result_plan = create_plan(root, best_path);
 			current_pathkeys = best_path->pathkeys;
@@ -1913,6 +2023,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 											   &groupColIdx,
 											   &need_tlist_eval);
 
+			if (partialaggtype != PAT_DISABLED)
+				need_tlist_eval = true;
+
 			/*
 			 * create_plan returns a plan with just a "flat" tlist of required
 			 * Vars.  Usually we need to insert the sub_tlist as the tlist of
@@ -1994,21 +2107,74 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			 */
 			if (use_hashed_grouping)
 			{
-				/* Hashed aggregate plan --- no sort needed */
-				result_plan = (Plan *) make_agg(root,
-												tlist,
-												(List *) parse->havingQual,
-												AGG_HASHED,
-												&agg_costs,
-												numGroupCols,
-												groupColIdx,
-									extract_grouping_ops(parse->groupClause),
-												NIL,
-												numGroups,
-												false,
-												true,
-												false,
-												result_plan);
+				if (partialaggtype != PAT_DISABLED)
+				{
+					AttrNumber *groupColIdx;
+					List *aggtlist;
+
+					aggtlist = make_aggregate_tlist(root, tlist, &groupColIdx);
+
+					/* Hashed aggregate plan --- no sort needed */
+					result_plan = (Plan *) make_agg(root,
+													aggtlist,
+													NIL,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													false,
+													false,
+													true,
+													result_plan);
+
+					result_plan->targetlist = aggtlist;
+
+					/*
+					 * Also, account for the cost of evaluation of the sub_tlist.
+					 * See comments for add_tlist_costs_to_plan() for more info.
+					 */
+					add_tlist_costs_to_plan(root, result_plan, aggtlist);
+
+					aggtlist  = make_aggregate_tlist(root, tlist, &groupColIdx);
+
+					result_plan = (Plan *) make_agg(root,
+													aggtlist,
+													(List *) parse->havingQual,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													true,
+													true,
+													true,
+													result_plan);
+					result_plan->targetlist = tlist;
+
+				}
+				else
+				{
+					/* Hashed aggregate plan --- no sort needed */
+					result_plan = (Plan *) make_agg(root,
+													tlist,
+													(List *) parse->havingQual,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													false,
+													true,
+													false,
+													result_plan);
+				}
 				/* Hashed aggregation produces randomly-ordered results */
 				current_pathkeys = NIL;
 			}
@@ -2037,7 +2203,8 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 												   groupColIdx,
 												   &agg_costs,
 												   numGroups,
-												   result_plan);
+												   result_plan,
+												   partialaggtype);
 			}
 			else if (parse->groupClause)
 			{
@@ -2483,7 +2650,8 @@ build_grouping_chain(PlannerInfo *root,
 					 AttrNumber *groupColIdx,
 					 AggClauseCosts *agg_costs,
 					 long numGroups,
-					 Plan *result_plan)
+					 Plan *result_plan,
+					 PartialAggType partialaggtype)
 {
 	AttrNumber *top_grpColIdx = groupColIdx;
 	List	   *chain = NIL;
@@ -2587,21 +2755,70 @@ build_grouping_chain(PlannerInfo *root,
 		else
 			numGroupCols = list_length(parse->groupClause);
 
-		result_plan = (Plan *) make_agg(root,
-										tlist,
-										(List *) parse->havingQual,
-								 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
-										agg_costs,
-										numGroupCols,
-										top_grpColIdx,
-										extract_grouping_ops(groupClause),
-										gsets,
-										numGroups,
-										false,
-										true,
-										false,
-										result_plan);
+		if (partialaggtype != PAT_DISABLED)
+		{
+			AttrNumber *groupColIdx;
+			List *aggtlist;
+
+			aggtlist = make_aggregate_tlist(root, tlist, &groupColIdx);
+
+			result_plan = (Plan *) make_agg(root,
+											aggtlist,
+											NIL,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											groupColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											false,
+											false,
+											true,
+											result_plan);
+			result_plan->targetlist = aggtlist;
+
+			/*
+			 * Also, account for the cost of evaluation of the sub_tlist.
+			 * See comments for add_tlist_costs_to_plan() for more info.
+			 */
+			add_tlist_costs_to_plan(root, result_plan, aggtlist);
+
+			aggtlist  = make_aggregate_tlist(root, tlist, &groupColIdx);
 
+			result_plan = (Plan *) make_agg(root,
+											aggtlist,
+											(List *) parse->havingQual,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											groupColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											true,
+											true,
+											true,
+											result_plan);
+			result_plan->targetlist = tlist;
+		}
+		else
+		{
+			result_plan = (Plan *) make_agg(root,
+											tlist,
+											(List *) parse->havingQual,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											top_grpColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											false,
+											true,
+											false,
+											result_plan);
+		}
 		((Agg *) result_plan)->chain = chain;
 
 		/*

diff --git a/doc/src/sgml/ref/create_aggregate.sgml b/doc/src/sgml/ref/create_aggregate.sgml
index eaa410b..bb62c96 100644
--- a/doc/src/sgml/ref/create_aggregate.sgml
+++ b/doc/src/sgml/ref/create_aggregate.sgml
@@ -27,6 +27,10 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ <replacea
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
+    [ , SERIALFUNC = <replaceable class="PARAMETER">serialfunc</replaceable> ]
+    [ , DESERIALFUNC = <replaceable class="PARAMETER">deserialfunc</replaceable> ]
+    [ , SERIALTYPE = <replaceable class="PARAMETER">serialtype</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -45,6 +49,10 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ [ <replac
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
+    [ , SERIALFUNC = <replaceable class="PARAMETER">serialfunc</replaceable> ]
+    [ , DESERIALFUNC = <replaceable class="PARAMETER">deserialfunc</replaceable> ]
+    [ , SERIALTYPE = <replaceable class="PARAMETER">serialtype</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , HYPOTHETICAL ]
 )
@@ -58,6 +66,10 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
+    [ , SERIALFUNC = <replaceable class="PARAMETER">serialfunc</replaceable> ]
+    [ , DESERIALFUNC = <replaceable class="PARAMETER">deserialfunc</replaceable> ]
+    [ , SERIALTYPE = <replaceable class="PARAMETER">serialtype</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -105,12 +117,23 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
    functions:
    a state transition function
    <replaceable class="PARAMETER">sfunc</replaceable>,
-   and an optional final calculation function
-   <replaceable class="PARAMETER">ffunc</replaceable>.
+   an optional final calculation function
+   <replaceable class="PARAMETER">ffunc</replaceable>,
+   an optional combine function
+   <replaceable class="PARAMETER">combinefunc</replaceable>,
+   an optional serialization function
+   <replaceable class="PARAMETER">serialfunc</replaceable>,
+   an optional deserialization function
+   <replaceable class="PARAMETER">deserialfunc</replaceable>,
+   and an optional serialization type
+   <replaceable class="PARAMETER">serialtype</replaceable>.
    These are used as follows:
 <programlisting>
 <replaceable class="PARAMETER">sfunc</replaceable>( internal-state, next-data-values ) ---> next-internal-state
 <replaceable class="PARAMETER">ffunc</replaceable>( internal-state ) ---> aggregate-value
+<replaceable class="PARAMETER">combinefunc</replaceable>( internal-state, internal-state ) ---> next-internal-state
+<replaceable class="PARAMETER">serialfunc</replaceable>( internal-state ) ---> serialized-state
+<replaceable class="PARAMETER">deserialfunc</replaceable>( serialized-state ) ---> internal-state
 </programlisting>
   </para>
 
@@ -128,6 +151,27 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
   </para>
 
   <para>
+   An aggregate function may also supply a combining function, which allows
+   the aggregation process to be broken down into multiple steps.  This
+   facilitates query optimization techniques such as parallel query.
+  </para>
+
+  <para>
+  A serialization and deserialization function may also be supplied. These
+  functions are required in order to allow parallel aggregation for aggregates
+  with an <replaceable class="PARAMETER">stype</replaceable> of <literal>
+  INTERNAL</>. The <replaceable class="PARAMETER">serialfunc</replaceable>, if
+  present must transform the aggregate state into a value of
+  <replaceable class="PARAMETER">serialtype</replaceable>, whereas the 
+  <replaceable class="PARAMETER">deserialfunc</replaceable> performs the
+  opposite, transforming the aggregate state back into the
+  <replaceable class="PARAMETER">stype</replaceable>. This is required due to
+  the process model being unable to pass <literal>INTERNAL</literal> types
+  between different <productname>PostgreSQL</productname> processes. These
+  parameters are only valid when <replaceable class="PARAMETER">stype
+  </replaceable> is <literal>INTERNAL</>.
+
+  <para>
    An aggregate function can provide an initial condition,
    that is, an initial value for the internal state value.
    This is specified and stored in the database as a value of type
diff --git a/src/backend/catalog/pg_aggregate.c b/src/backend/catalog/pg_aggregate.c
index 1d845ec..d971109 100644
--- a/src/backend/catalog/pg_aggregate.c
+++ b/src/backend/catalog/pg_aggregate.c
@@ -57,6 +57,9 @@ AggregateCreate(const char *aggName,
 				Oid variadicArgType,
 				List *aggtransfnName,
 				List *aggfinalfnName,
+				List *aggcombinefnName,
+				List *aggserialfnName,
+				List *aggdeserialfnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
@@ -64,6 +67,7 @@ AggregateCreate(const char *aggName,
 				bool mfinalfnExtraArgs,
 				List *aggsortopName,
 				Oid aggTransType,
+				Oid aggSerialType,
 				int32 aggTransSpace,
 				Oid aggmTransType,
 				int32 aggmTransSpace,
@@ -77,6 +81,9 @@ AggregateCreate(const char *aggName,
 	Form_pg_proc proc;
 	Oid			transfn;
 	Oid			finalfn = InvalidOid;	/* can be omitted */
+	Oid			combinefn = InvalidOid;	/* can be omitted */
+	Oid			serialfn = InvalidOid;	/* can be omitted */
+	Oid			deserialfn = InvalidOid;	/* can be omitted */
 	Oid			mtransfn = InvalidOid;	/* can be omitted */
 	Oid			minvtransfn = InvalidOid;		/* can be omitted */
 	Oid			mfinalfn = InvalidOid;	/* can be omitted */
@@ -396,6 +403,83 @@ AggregateCreate(const char *aggName,
 	}
 	Assert(OidIsValid(finaltype));
 
+	/* handle the combinefn, if supplied */
+	if (aggcombinefnName)
+	{
+		Oid combineType;
+
+		/*
+		 * Combine function must have 2 argument, each of which is the
+		 * trans type
+		 */
+		fnArgs[0] = aggTransType;
+		fnArgs[1] = aggTransType;
+
+		combinefn = lookup_agg_function(aggcombinefnName, 2, fnArgs,
+										variadicArgType, &combineType);
+
+		/* Ensure the return type matches the aggregates trans type */
+		if (combineType != aggTransType)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+			errmsg("return type of combine function %s is not %s",
+				   NameListToString(aggcombinefnName),
+				   format_type_be(aggTransType))));
+	}
+
+	/*
+	 * Validate the serial function, if present. We must ensure that the return
+	 * type of this function is the same as the specified serialType, and that
+	 * indeed a serialType was actually also specified.
+	 */
+	if (aggserialfnName)
+	{
+		/* check that we also got a serial type */
+		if (!OidIsValid(aggSerialType))
+			ereport(ERROR,
+				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+				 errmsg("must specify serialtype when specifying serialfunc")));
+
+		fnArgs[0] = aggTransType;
+
+		serialfn = lookup_agg_function(aggserialfnName, 1,
+									   fnArgs, variadicArgType,
+									   &rettype);
+
+		if (rettype != aggSerialType)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("return type of serial function %s is not %s",
+							NameListToString(aggserialfnName),
+							format_type_be(aggSerialType))));
+	}
+
+	/*
+	 * Validate the deserial function, if present. We must ensure that the
+	 * return type of this function is the same as the transType.
+	 */
+	if (aggdeserialfnName)
+	{
+		/* check that we also got a serial type */
+		if (!OidIsValid(aggSerialType))
+			ereport(ERROR,
+				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+				 errmsg("must specify serialtype when specifying deserialfunc")));
+
+		fnArgs[0] = aggSerialType;
+
+		deserialfn = lookup_agg_function(aggdeserialfnName, 1,
+										 fnArgs, variadicArgType,
+										 &rettype);
+
+		if (rettype != aggTransType)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("return type of deserial function %s is not %s",
+							NameListToString(aggdeserialfnName),
+							format_type_be(aggTransType))));
+	}
+
 	/*
 	 * If finaltype (i.e. aggregate return type) is polymorphic, inputs must
 	 * be polymorphic also, else parser will fail to deduce result type.
@@ -567,6 +651,9 @@ AggregateCreate(const char *aggName,
 	values[Anum_pg_aggregate_aggnumdirectargs - 1] = Int16GetDatum(numDirectArgs);
 	values[Anum_pg_aggregate_aggtransfn - 1] = ObjectIdGetDatum(transfn);
 	values[Anum_pg_aggregate_aggfinalfn - 1] = ObjectIdGetDatum(finalfn);
+	values[Anum_pg_aggregate_aggcombinefn - 1] = ObjectIdGetDatum(combinefn);
+	values[Anum_pg_aggregate_aggserialfn - 1] = ObjectIdGetDatum(serialfn);
+	values[Anum_pg_aggregate_aggdeserialfn - 1] = ObjectIdGetDatum(deserialfn);
 	values[Anum_pg_aggregate_aggmtransfn - 1] = ObjectIdGetDatum(mtransfn);
 	values[Anum_pg_aggregate_aggminvtransfn - 1] = ObjectIdGetDatum(minvtransfn);
 	values[Anum_pg_aggregate_aggmfinalfn - 1] = ObjectIdGetDatum(mfinalfn);
@@ -574,6 +661,7 @@ AggregateCreate(const char *aggName,
 	values[Anum_pg_aggregate_aggmfinalextra - 1] = BoolGetDatum(mfinalfnExtraArgs);
 	values[Anum_pg_aggregate_aggsortop - 1] = ObjectIdGetDatum(sortop);
 	values[Anum_pg_aggregate_aggtranstype - 1] = ObjectIdGetDatum(aggTransType);
+	values[Anum_pg_aggregate_aggserialtype - 1] = ObjectIdGetDatum(aggSerialType);
 	values[Anum_pg_aggregate_aggtransspace - 1] = Int32GetDatum(aggTransSpace);
 	values[Anum_pg_aggregate_aggmtranstype - 1] = ObjectIdGetDatum(aggmTransType);
 	values[Anum_pg_aggregate_aggmtransspace - 1] = Int32GetDatum(aggmTransSpace);
@@ -600,7 +688,8 @@ AggregateCreate(const char *aggName,
 	 * Create dependencies for the aggregate (above and beyond those already
 	 * made by ProcedureCreate).  Note: we don't need an explicit dependency
 	 * on aggTransType since we depend on it indirectly through transfn.
-	 * Likewise for aggmTransType if any.
+	 * Likewise for aggmTransType using the mtransfunc, and also for
+	 * aggSerialType using the serialfn, if they exist.
 	 */
 
 	/* Depends on transition function */
@@ -618,6 +707,33 @@ AggregateCreate(const char *aggName,
 		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
 	}
 
+	/* Depends on combine function, if any */
+	if (OidIsValid(combinefn))
+	{
+		referenced.classId = ProcedureRelationId;
+		referenced.objectId = combinefn;
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
+	/* Depends on serial function, if any */
+	if (OidIsValid(serialfn))
+	{
+		referenced.classId = ProcedureRelationId;
+		referenced.objectId = serialfn;
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
+	/* Depends on deserial function, if any */
+	if (OidIsValid(deserialfn))
+	{
+		referenced.classId = ProcedureRelationId;
+		referenced.objectId = deserialfn;
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
 	/* Depends on forward transition function, if any */
 	if (OidIsValid(mtransfn))
 	{
diff --git a/src/backend/commands/aggregatecmds.c b/src/backend/commands/aggregatecmds.c
index 441b3aa..4fa2920 100644
--- a/src/backend/commands/aggregatecmds.c
+++ b/src/backend/commands/aggregatecmds.c
@@ -61,6 +61,9 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	char		aggKind = AGGKIND_NORMAL;
 	List	   *transfuncName = NIL;
 	List	   *finalfuncName = NIL;
+	List	   *combinefuncName = NIL;
+	List	   *serialfuncName = NIL;
+	List	   *deserialfuncName = NIL;
 	List	   *mtransfuncName = NIL;
 	List	   *minvtransfuncName = NIL;
 	List	   *mfinalfuncName = NIL;
@@ -69,6 +72,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	List	   *sortoperatorName = NIL;
 	TypeName   *baseType = NULL;
 	TypeName   *transType = NULL;
+	TypeName   *serialType = NULL;
 	TypeName   *mtransType = NULL;
 	int32		transSpace = 0;
 	int32		mtransSpace = 0;
@@ -83,6 +87,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	List	   *parameterDefaults;
 	Oid			variadicArgType;
 	Oid			transTypeId;
+	Oid			serialTypeId = InvalidOid;
 	Oid			mtransTypeId = InvalidOid;
 	char		transTypeType;
 	char		mtransTypeType = 0;
@@ -124,6 +129,12 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 			transfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "finalfunc") == 0)
 			finalfuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "combinefunc") == 0)
+			combinefuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "serialfunc") == 0)
+			serialfuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "deserialfunc") == 0)
+			deserialfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "msfunc") == 0)
 			mtransfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "minvfunc") == 0)
@@ -151,6 +162,8 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 		}
 		else if (pg_strcasecmp(defel->defname, "stype") == 0)
 			transType = defGetTypeName(defel);
+		else if (pg_strcasecmp(defel->defname, "serialtype") == 0)
+			serialType = defGetTypeName(defel);
 		else if (pg_strcasecmp(defel->defname, "stype1") == 0)
 			transType = defGetTypeName(defel);
 		else if (pg_strcasecmp(defel->defname, "sspace") == 0)
@@ -316,6 +329,50 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 							format_type_be(transTypeId))));
 	}
 
+	if (serialType)
+	{
+		/*
+		 * There's little point in having a serial/deserial function on
+		 * aggregates that don't have an internal state, so let's just disallow
+		 * this as it may help clear up any confusion or needless authoring of
+		 * these functions.
+		 */
+		if (transTypeId != INTERNALOID)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("a serialtype must only be specified when stype is \"%s\"",
+						 format_type_be(INTERNALOID))));
+
+		serialTypeId = typenameTypeId(NULL, serialType);
+
+		/*
+		 * We disallow INTERNAL serialType as the whole point of the
+		 * serialzed types is to allow the aggregate state to be output,
+		 * and we cannot output INTERNAL. This check, combined with the one
+		 * above ensures that the trans type and serial type are not the same.
+		 */
+		if (serialTypeId == INTERNALOID)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						errmsg("aggregate serial data type cannot be \"%s\"",
+							format_type_be(serialTypeId))));
+
+		/*
+		 * If serialType is specified then serialfuncName and deserialfuncName
+		 * must be present; if not, then none of the serialization options
+		 * should have been specified.
+		 */
+		if (serialfuncName == NIL)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("aggregate serialfunc must be specified when serialtype is specified")));
+
+		if (deserialfuncName == NIL)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("aggregate deserialfunc must be specified when serialtype is specified")));
+	}
+
 	/*
 	 * If a moving-aggregate transtype is specified, look that up.  Same
 	 * restrictions as for transtype.
@@ -383,6 +440,9 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 						   variadicArgType,
 						   transfuncName,		/* step function name */
 						   finalfuncName,		/* final function name */
+						   combinefuncName,		/* combine function name */
+						   serialfuncName,		/* serial function name */
+						   deserialfuncName,	/* deserial function name */
 						   mtransfuncName,		/* fwd trans function name */
 						   minvtransfuncName,	/* inv trans function name */
 						   mfinalfuncName,		/* final function name */
@@ -390,6 +450,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 						   mfinalfuncExtraArgs,
 						   sortoperatorName,	/* sort operator name */
 						   transTypeId, /* transition data type */
+						   serialTypeId, /* serial data type */
 						   transSpace,	/* transition space */
 						   mtransTypeId,		/* transition data type */
 						   mtransSpace, /* transition space */
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 9827c39..58b5012 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -908,25 +908,38 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			pname = sname = "Group";
 			break;
 		case T_Agg:
-			sname = "Aggregate";
-			switch (((Agg *) plan)->aggstrategy)
 			{
-				case AGG_PLAIN:
-					pname = "Aggregate";
-					strategy = "Plain";
-					break;
-				case AGG_SORTED:
-					pname = "GroupAggregate";
-					strategy = "Sorted";
-					break;
-				case AGG_HASHED:
-					pname = "HashAggregate";
-					strategy = "Hashed";
-					break;
-				default:
-					pname = "Aggregate ???";
-					strategy = "???";
-					break;
+				char	   *modifier;
+				Agg		   *agg = (Agg *) plan;
+
+				sname = "Aggregate";
+
+				if (agg->finalizeAggs == false)
+					modifier = "Partial ";
+				else if (agg->combineStates == true)
+					modifier = "Finalize ";
+				else
+					modifier = "";
+
+				switch (agg->aggstrategy)
+				{
+					case AGG_PLAIN:
+						pname = psprintf("%sAggregate", modifier);
+						strategy = "Plain";
+						break;
+					case AGG_SORTED:
+						pname = psprintf("%sGroupAggregate", modifier);
+						strategy = "Sorted";
+						break;
+					case AGG_HASHED:
+						pname = psprintf("%sHashAggregate", modifier);
+						strategy = "Hashed";
+						break;
+					default:
+						pname = "Aggregate ???";
+						strategy = "???";
+						break;
+				}
 			}
 			break;
 		case T_WindowAgg:
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index f49114a..d0cc643 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -3,15 +3,57 @@
  * nodeAgg.c
  *	  Routines to handle aggregate nodes.
  *
- *	  ExecAgg evaluates each aggregate in the following steps:
+ *	  ExecAgg normally evaluates each aggregate in the following steps:
  *
  *		 transvalue = initcond
  *		 foreach input_tuple do
  *			transvalue = transfunc(transvalue, input_value(s))
  *		 result = finalfunc(transvalue, direct_argument(s))
  *
- *	  If a finalfunc is not supplied then the result is just the ending
- *	  value of transvalue.
+ *	  If a finalfunc is not supplied or finalizeAggs is false, then the result
+ *	  is just the ending value of transvalue.
+ *
+ *	  Other behavior is also supported and is controlled by the 'combineStates',
+ *	  'finalizeAggs' and 'serialStates' parameters. 'combineStates' controls
+ *	  whether the trans func or the combine func is used during aggregation.
+ *	  When 'combineStates' is true we expect other (previously) aggregated
+ *	  states as input rather than input tuples. This mode facilitates multiple
+ *	  aggregate stages which allows us to support pushing aggregation down
+ *	  deeper into the plan rather than leaving it for the final stage. For
+ *	  example with a query such as:
+ *
+ *	  SELECT count(*) FROM (SELECT * FROM a UNION ALL SELECT * FROM b);
+ *
+ *	  with this functionality the planner has the flexibility to generate a
+ *	  plan which performs count(*) on table a and table b separately and then
+ *	  add a combine phase to combine both results. In this case the combine
+ *	  function would simply add both counts together.
+ *
+ *	  When multiple aggregate stages exist the planner should have set the
+ *	  'finalizeAggs' to true only for the final aggregtion state, and each
+ *	  stage, apart from the very first one should have 'combineStates' set to
+ *	  true. This permits plans such as:
+ *
+ *		Finalize Aggregate
+ *			->  Partial Aggregate
+ *				->  Partial Aggregate
+ *
+ *	  Combine functions which use pass-by-ref states should be careful to
+ *	  always update the 1st state parameter by adding the 2nd parameter to it,
+ *	  rather than the other way around. If the 1st state is NULL, then it's not
+ *	  sufficient to simply return the 2nd state, as the memory context is
+ *	  incorrect. Instead a new state should be created in the correct aggregate
+ *	  memory context and the 2nd state should be copied over.
+ *
+ *	  The 'serialStates' option can be used to allow multi-stage aggregation
+ *	  for aggregates with an INTERNAL state type. When this mode is disabled
+ *	  only a pointer to the INTERNAL aggregate states are passed around the
+ *	  executor. This behaviour does not suit a parallel environment where the
+ *	  process is unable to dereference pointers for memory which belongs to a
+ *	  worker process. Enabling this mode causes the INTERNAL states to be
+ *	  serialized and deserialized as and when required, which of course
+ *	  requires that the aggregate function also have a 'serialfunc' and
+ *	  'deserialfunc' function specified.
  *
  *	  If a normal aggregate call specifies DISTINCT or ORDER BY, we sort the
  *	  input tuples and eliminate duplicates (if required) before performing
@@ -134,6 +176,7 @@
 #include "catalog/objectaccess.h"
 #include "catalog/pg_aggregate.h"
 #include "catalog/pg_proc.h"
+#include "catalog/pg_type.h"
 #include "executor/executor.h"
 #include "executor/nodeAgg.h"
 #include "miscadmin.h"
@@ -197,9 +240,15 @@ typedef struct AggStatePerTransData
 	 */
 	int			numTransInputs;
 
-	/* Oid of the state transition function */
+	/* Oid of the state transition or combine function */
 	Oid			transfn_oid;
 
+	/* Oid of the serial function or InvalidOid */
+	Oid			serialfn_oid;
+
+	/* Oid of the deserial function or InvalidOid */
+	Oid			deserialfn_oid;
+
 	/* Oid of state value's datatype */
 	Oid			aggtranstype;
 
@@ -209,11 +258,17 @@ typedef struct AggStatePerTransData
 	List	   *aggdirectargs;	/* states of direct-argument expressions */
 
 	/*
-	 * fmgr lookup data for transition function.  Note in particular that the
-	 * fn_strict flag is kept here.
+	 * fmgr lookup data for transition function or combination function.  Note
+	 * in particular that the fn_strict flag is kept here.
 	 */
 	FmgrInfo	transfn;
 
+	/* fmgr lookup data for serial function */
+	FmgrInfo	serialfn;
+
+	/* fmgr lookup data for deserial function */
+	FmgrInfo	deserialfn;
+
 	/* Input collation derived for aggregate */
 	Oid			aggCollation;
 
@@ -294,6 +349,11 @@ typedef struct AggStatePerTransData
 	 * worth the extra space consumption.
 	 */
 	FunctionCallInfoData transfn_fcinfo;
+
+	/* Likewise for serial and deserial functions */
+	FunctionCallInfoData serialfn_fcinfo;
+
+	FunctionCallInfoData deserialfn_fcinfo;
 }	AggStatePerTransData;
 
 /*
@@ -421,6 +481,10 @@ static void advance_transition_function(AggState *aggstate,
 							AggStatePerTrans pertrans,
 							AggStatePerGroup pergroupstate);
 static void advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup);
+static void advance_combination_function(AggState *aggstate,
+							AggStatePerTrans pertrans,
+							AggStatePerGroup pergroupstate);
+static void combine_aggregates(AggState *aggstate, AggStatePerGroup pergroup);
 static void process_ordered_aggregate_single(AggState *aggstate,
 								 AggStatePerTrans pertrans,
 								 AggStatePerGroup pergroupstate);
@@ -451,14 +515,17 @@ static Datum GetAggInitVal(Datum textInitVal, Oid transtype);
 static void build_pertrans_for_aggref(AggStatePerTrans pertrans,
 						  AggState *aggsate, EState *estate,
 						  Aggref *aggref, Oid aggtransfn, Oid aggtranstype,
-						  Datum initValue, bool initValueIsNull,
-						  Oid *inputTypes, int numArguments);
+						  Oid aggserialtype, Oid aggserialfn,
+						  Oid aggdeserialfn, Datum initValue,
+						  bool initValueIsNull, Oid *inputTypes,
+						  int numArguments);
 static int find_compatible_peragg(Aggref *newagg, AggState *aggstate,
 					   int lastaggno, List **same_input_transnos);
 static int find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 						 Oid aggtransfn, Oid aggtranstype,
+						 Oid aggserialfn, Oid aggdeserialfn,
 						 Datum initValue, bool initValueIsNull,
-						 List *possible_matches);
+						 List *transnos);
 
 
 /*
@@ -796,6 +863,8 @@ advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
 	int			numGroupingSets = Max(aggstate->phase->numsets, 1);
 	int			numTrans = aggstate->numtrans;
 
+	Assert(!aggstate->combineStates);
+
 	for (transno = 0; transno < numTrans; transno++)
 	{
 		AggStatePerTrans pertrans = &aggstate->pertrans[transno];
@@ -879,6 +948,152 @@ advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
 	}
 }
 
+/*
+ * combine_aggregates is used when running in 'combineState' mode. This
+ * advances each aggregate transition state by adding another transition state
+ * to it.
+ */
+static void
+combine_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
+{
+	int			transno;
+	int			numTrans = aggstate->numtrans;
+
+	/* combine not supported with grouping sets */
+	Assert(aggstate->phase->numsets == 0);
+	Assert(aggstate->combineStates);
+
+	for (transno = 0; transno < numTrans; transno++)
+	{
+		AggStatePerTrans pertrans = &aggstate->pertrans[transno];
+		TupleTableSlot *slot;
+		FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
+		AggStatePerGroup pergroupstate = &pergroup[transno];
+
+		/* Evaluate the current input expressions for this aggregate */
+		slot = ExecProject(pertrans->evalproj, NULL);
+		Assert(slot->tts_nvalid >= 1);
+
+		/*
+		 * deserialfn_oid will be set if we must deserialize the input state
+		 * before calling the combine function
+		 */
+		if (OidIsValid(pertrans->deserialfn_oid))
+		{
+			/* don't call a strict deserial function with NULL input */
+			if (pertrans->deserialfn.fn_strict && slot->tts_isnull[0] == true)
+				continue;
+			else
+			{
+				FunctionCallInfo dsinfo = &pertrans->deserialfn_fcinfo;
+				dsinfo->arg[0] = slot->tts_values[0];
+				dsinfo->argnull[0] = slot->tts_isnull[0];
+
+				fcinfo->arg[1] = FunctionCallInvoke(dsinfo);
+				fcinfo->argnull[1] = dsinfo->isnull;
+			}
+		}
+		else
+		{
+			fcinfo->arg[1] = slot->tts_values[0];
+			fcinfo->argnull[1] = slot->tts_isnull[0];
+		}
+
+		advance_combination_function(aggstate, pertrans, pergroupstate);
+	}
+}
+
+/*
+ * Perform combination of states between 2 aggregate states. Effectively this
+ * 'adds' two states together by whichever logic is defined in the aggregate
+ * function's combine function.
+ *
+ * Note that in this case transfn is set to the combination function. This
+ * perhaps should be changed to avoid confusion, but one field is ok for now
+ * as they'll never be needed at the same time.
+ */
+static void
+advance_combination_function(AggState *aggstate,
+							 AggStatePerTrans pertrans,
+							 AggStatePerGroup pergroupstate)
+{
+	FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
+	MemoryContext oldContext;
+	Datum		newVal;
+
+	if (pertrans->transfn.fn_strict)
+	{
+		/* if we're asked to merge to a NULL state, then do nothing */
+		if (fcinfo->argnull[1])
+			return;
+
+		if (pergroupstate->noTransValue)
+		{
+			/*
+			 * transValue has not yet been initialized.  If pass-by-ref
+			 * datatype we must copy the combining state value into aggcontext.
+			 */
+			if (!pertrans->transtypeByVal)
+			{
+				oldContext = MemoryContextSwitchTo(
+					aggstate->aggcontexts[aggstate->current_set]->ecxt_per_tuple_memory);
+				pergroupstate->transValue = datumCopy(fcinfo->arg[1],
+													  pertrans->transtypeByVal,
+													  pertrans->transtypeLen);
+				MemoryContextSwitchTo(oldContext);
+			}
+			else
+				pergroupstate->transValue = fcinfo->arg[1];
+
+			pergroupstate->transValueIsNull = false;
+			pergroupstate->noTransValue = false;
+			return;
+		}
+	}
+
+	/* We run the combine functions in per-input-tuple memory context */
+	oldContext = MemoryContextSwitchTo(aggstate->tmpcontext->ecxt_per_tuple_memory);
+
+	/* set up aggstate->curpertrans for AggGetAggref() */
+	aggstate->curpertrans = pertrans;
+
+	/*
+	 * OK to call the combine function
+	 */
+	fcinfo->arg[0] = pergroupstate->transValue;
+	fcinfo->argnull[0] = pergroupstate->transValueIsNull;
+	fcinfo->isnull = false;		/* just in case combine func doesn't set it */
+
+	newVal = FunctionCallInvoke(fcinfo);
+
+	aggstate->curpertrans = NULL;
+
+	/*
+	 * If pass-by-ref datatype, must copy the new value into aggcontext and
+	 * pfree the prior transValue.  But if the combine function returned a
+	 * pointer to its first input, we don't need to do anything.
+	 */
+	if (!pertrans->transtypeByVal &&
+		DatumGetPointer(newVal) != DatumGetPointer(pergroupstate->transValue))
+	{
+		if (!fcinfo->isnull)
+		{
+			MemoryContextSwitchTo(aggstate->aggcontexts[aggstate->current_set]->ecxt_per_tuple_memory);
+			newVal = datumCopy(newVal,
+							   pertrans->transtypeByVal,
+							   pertrans->transtypeLen);
+		}
+		if (!pergroupstate->transValueIsNull)
+			pfree(DatumGetPointer(pergroupstate->transValue));
+	}
+
+	pergroupstate->transValue = newVal;
+	pergroupstate->transValueIsNull = fcinfo->isnull;
+
+	MemoryContextSwitchTo(oldContext);
+
+}
+
 
 /*
  * Run the transition function for a DISTINCT or ORDER BY aggregate
@@ -1278,8 +1493,35 @@ finalize_aggregates(AggState *aggstate,
 												pergroupstate);
 		}
 
-		finalize_aggregate(aggstate, peragg, pergroupstate,
-						   &aggvalues[aggno], &aggnulls[aggno]);
+		if (aggstate->finalizeAggs)
+			finalize_aggregate(aggstate, peragg, pergroupstate,
+							   &aggvalues[aggno], &aggnulls[aggno]);
+
+		/*
+		 * serialfn_oid will be set if we must serialize the input state
+		 * before calling the combine function on the state.
+		 */
+		else if (OidIsValid(pertrans->serialfn_oid))
+		{
+			/* don't call a strict serial function with NULL input */
+			if (pertrans->serialfn.fn_strict &&
+				pergroupstate->transValueIsNull)
+				continue;
+			else
+			{
+				FunctionCallInfo fcinfo = &pertrans->serialfn_fcinfo;
+				fcinfo->arg[0] = pergroupstate->transValue;
+				fcinfo->argnull[0] = pergroupstate->transValueIsNull;
+
+				aggvalues[aggno] = FunctionCallInvoke(fcinfo);
+				aggnulls[aggno] = fcinfo->isnull;
+			}
+		}
+		else
+		{
+			aggvalues[aggno] = pergroupstate->transValue;
+			aggnulls[aggno] = pergroupstate->transValueIsNull;
+		}
 	}
 }
 
@@ -1811,7 +2053,10 @@ agg_retrieve_direct(AggState *aggstate)
 				 */
 				for (;;)
 				{
-					advance_aggregates(aggstate, pergroup);
+					if (!aggstate->combineStates)
+						advance_aggregates(aggstate, pergroup);
+					else
+						combine_aggregates(aggstate, pergroup);
 
 					/* Reset per-input-tuple context after each tuple */
 					ResetExprContext(tmpcontext);
@@ -1919,7 +2164,10 @@ agg_fill_hash_table(AggState *aggstate)
 		entry = lookup_hash_entry(aggstate, outerslot);
 
 		/* Advance the aggregates */
-		advance_aggregates(aggstate, entry->pergroup);
+		if (!aggstate->combineStates)
+			advance_aggregates(aggstate, entry->pergroup);
+		else
+			combine_aggregates(aggstate, entry->pergroup);
 
 		/* Reset per-input-tuple context after each tuple */
 		ResetExprContext(tmpcontext);
@@ -2051,6 +2299,9 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 	aggstate->pertrans = NULL;
 	aggstate->curpertrans = NULL;
 	aggstate->agg_done = false;
+	aggstate->combineStates = node->combineStates;
+	aggstate->finalizeAggs = node->finalizeAggs;
+	aggstate->serialStates = node->serialStates;
 	aggstate->input_done = false;
 	aggstate->pergroup = NULL;
 	aggstate->grp_firstTuple = NULL;
@@ -2359,6 +2610,9 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 		AclResult	aclresult;
 		Oid			transfn_oid,
 					finalfn_oid;
+		Oid			serialtype_oid,
+					serialfn_oid,
+					deserialfn_oid;
 		Expr	   *finalfnexpr;
 		Oid			aggtranstype;
 		Datum		textInitVal;
@@ -2402,8 +2656,67 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 						   get_func_name(aggref->aggfnoid));
 		InvokeFunctionExecuteHook(aggref->aggfnoid);
 
-		transfn_oid = aggform->aggtransfn;
-		peragg->finalfn_oid = finalfn_oid = aggform->aggfinalfn;
+		/*
+		 * If this aggregation is performing state combines, then instead of
+		 * using the transition function, we'll use the combine function
+		 */
+		if (aggstate->combineStates)
+		{
+			transfn_oid = aggform->aggcombinefn;
+
+			/* If not set then the planner messed up */
+			if (!OidIsValid(transfn_oid))
+				elog(ERROR, "combinefn not set for aggregate function");
+		}
+		else
+			transfn_oid = aggform->aggtransfn;
+
+		/* Final function only required if we're finalizing the aggregates */
+		if (aggstate->finalizeAggs)
+			peragg->finalfn_oid = finalfn_oid = aggform->aggfinalfn;
+		else
+			peragg->finalfn_oid = finalfn_oid = InvalidOid;
+
+		serialtype_oid = InvalidOid;
+		serialfn_oid = InvalidOid;
+		deserialfn_oid = InvalidOid;
+
+		/*
+		 * Determine if we require serialization or deserialization of the
+		 * aggregate states. This is only required if the aggregate state is
+		 * internal.
+		 */
+		if (aggstate->serialStates && aggform->aggtranstype == INTERNALOID)
+		{
+			/*
+			 * The planner should only have generated an agg node with
+			 * serialStates if every aggregate with an INTERNAL state has a
+			 * serial type, serial function and deserial function. Let's ensure
+			 * it didn't mess that up.
+			 */
+			if (!OidIsValid(aggform->aggserialtype))
+				elog(ERROR, "serial type not set during serialStates aggregation step");
+
+			if (!OidIsValid(aggform->aggserialfn))
+				elog(ERROR, "serial func not set during serialStates aggregation step");
+
+			if (!OidIsValid(aggform->aggdeserialfn))
+				elog(ERROR, "deserial func not set during serialStates aggregation step");
+
+			/* serial func only required when not finalizing aggs */
+			if (!aggstate->finalizeAggs)
+			{
+				serialfn_oid = aggform->aggserialfn;
+				serialtype_oid = aggform->aggserialtype;
+			}
+
+			/* deserial func only required when combining states */
+			if (aggstate->combineStates)
+			{
+				deserialfn_oid = aggform->aggdeserialfn;
+				serialtype_oid = aggform->aggserialtype;
+			}
+		}
 
 		/* Check that aggregate owner has permission to call component fns */
 		{
@@ -2433,6 +2746,24 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 								   get_func_name(finalfn_oid));
 				InvokeFunctionExecuteHook(finalfn_oid);
 			}
+			if (OidIsValid(serialfn_oid))
+			{
+				aclresult = pg_proc_aclcheck(serialfn_oid, aggOwner,
+											 ACL_EXECUTE);
+				if (aclresult != ACLCHECK_OK)
+					aclcheck_error(aclresult, ACL_KIND_PROC,
+								   get_func_name(serialfn_oid));
+				InvokeFunctionExecuteHook(serialfn_oid);
+			}
+			if (OidIsValid(deserialfn_oid))
+			{
+				aclresult = pg_proc_aclcheck(deserialfn_oid, aggOwner,
+											 ACL_EXECUTE);
+				if (aclresult != ACLCHECK_OK)
+					aclcheck_error(aclresult, ACL_KIND_PROC,
+								   get_func_name(deserialfn_oid));
+				InvokeFunctionExecuteHook(deserialfn_oid);
+			}
 		}
 
 		/*
@@ -2459,7 +2790,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 
 		/*
 		 * build expression trees using actual argument & result types for the
-		 * finalfn, if it exists
+		 * finalfn, if it exists and is required.
 		 */
 		if (OidIsValid(finalfn_oid))
 		{
@@ -2474,10 +2805,11 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 			fmgr_info_set_expr((Node *) finalfnexpr, &peragg->finalfn);
 		}
 
-		/* get info about the result type's datatype */
-		get_typlenbyval(aggref->aggtype,
-						&peragg->resulttypeLen,
-						&peragg->resulttypeByVal);
+		/* when finalizing we get info about the final result's datatype */
+		if (aggstate->finalizeAggs)
+			get_typlenbyval(aggref->aggtype,
+							&peragg->resulttypeLen,
+							&peragg->resulttypeByVal);
 
 		/*
 		 * initval is potentially null, so don't try to access it as a struct
@@ -2501,7 +2833,8 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 		 */
 		existing_transno = find_compatible_pertrans(aggstate, aggref,
 													transfn_oid, aggtranstype,
-												  initValue, initValueIsNull,
+												  serialfn_oid, deserialfn_oid,
+													initValue, initValueIsNull,
 													same_input_transnos);
 		if (existing_transno != -1)
 		{
@@ -2517,8 +2850,10 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 			pertrans = &pertransstates[++transno];
 			build_pertrans_for_aggref(pertrans, aggstate, estate,
 									  aggref, transfn_oid, aggtranstype,
-									  initValue, initValueIsNull,
-									  inputTypes, numArguments);
+									  serialtype_oid, serialfn_oid,
+									  deserialfn_oid, initValue,
+									  initValueIsNull, inputTypes,
+									  numArguments);
 			peragg->transno = transno;
 		}
 		ReleaseSysCache(aggTuple);
@@ -2546,12 +2881,15 @@ static void
 build_pertrans_for_aggref(AggStatePerTrans pertrans,
 						  AggState *aggstate, EState *estate,
 						  Aggref *aggref,
-						  Oid aggtransfn, Oid aggtranstype,
+						  Oid aggtransfn, Oid aggtranstype, Oid aggserialtype,
+						  Oid aggserialfn, Oid aggdeserialfn,
 						  Datum initValue, bool initValueIsNull,
 						  Oid *inputTypes, int numArguments)
 {
 	int			numGroupingSets = Max(aggstate->maxsets, 1);
 	Expr	   *transfnexpr;
+	Expr	   *serialfnexpr = NULL;
+	Expr	   *deserialfnexpr = NULL;
 	ListCell   *lc;
 	int			numInputs;
 	int			numDirectArgs;
@@ -2565,6 +2903,8 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 	pertrans->aggref = aggref;
 	pertrans->aggCollation = aggref->inputcollid;
 	pertrans->transfn_oid = aggtransfn;
+	pertrans->serialfn_oid = aggserialfn;
+	pertrans->deserialfn_oid = aggdeserialfn;
 	pertrans->initValue = initValue;
 	pertrans->initValueIsNull = initValueIsNull;
 
@@ -2583,44 +2923,68 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 		pertrans->numTransInputs = numArguments;
 
 	/*
-	 * Set up infrastructure for calling the transfn
+	 * When combining states, we have no use at all for the aggregate
+	 * function's transfn. Instead we use the combinefn. However we do
+	 * reuse the transfnexpr for the combinefn, perhaps this should change
 	 */
-	build_aggregate_transfn_expr(inputTypes,
-								 numArguments,
-								 numDirectArgs,
-								 aggref->aggvariadic,
-								 aggtranstype,
-								 aggref->inputcollid,
-								 aggtransfn,
-								 InvalidOid,	/* invtrans is not needed here */
-								 &transfnexpr,
-								 NULL);
-	fmgr_info(aggtransfn, &pertrans->transfn);
-	fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
-
-	InitFunctionCallInfoData(pertrans->transfn_fcinfo,
-							 &pertrans->transfn,
-							 pertrans->numTransInputs + 1,
-							 pertrans->aggCollation,
-							 (void *) aggstate, NULL);
+	if (aggstate->combineStates)
+	{
+		build_aggregate_combinefn_expr(aggtranstype,
+									   aggref->inputcollid,
+									   aggtransfn,
+									   &transfnexpr);
+		fmgr_info(aggtransfn, &pertrans->transfn);
+		fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
+
+		InitFunctionCallInfoData(pertrans->transfn_fcinfo,
+								 &pertrans->transfn,
+								 2,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
 
-	/*
-	 * If the transfn is strict and the initval is NULL, make sure input type
-	 * and transtype are the same (or at least binary-compatible), so that
-	 * it's OK to use the first aggregated input value as the initial
-	 * transValue.  This should have been checked at agg definition time, but
-	 * we must check again in case the transfn's strictness property has been
-	 * changed.
-	 */
-	if (pertrans->transfn.fn_strict && pertrans->initValueIsNull)
+	}
+	else
 	{
-		if (numArguments <= numDirectArgs ||
-			!IsBinaryCoercible(inputTypes[numDirectArgs],
-							   aggtranstype))
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
-					 errmsg("aggregate %u needs to have compatible input type and transition type",
-							aggref->aggfnoid)));
+		/*
+		 * Set up infrastructure for calling the transfn
+		 */
+		build_aggregate_transfn_expr(inputTypes,
+									 numArguments,
+									 numDirectArgs,
+									 aggref->aggvariadic,
+									 aggtranstype,
+									 aggref->inputcollid,
+									 aggtransfn,
+									 InvalidOid,	/* invtrans is not needed here */
+									 &transfnexpr,
+									 NULL);
+		fmgr_info(aggtransfn, &pertrans->transfn);
+		fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
+
+		InitFunctionCallInfoData(pertrans->transfn_fcinfo,
+								 &pertrans->transfn,
+								 pertrans->numTransInputs + 1,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+
+		/*
+		 * If the transfn is strict and the initval is NULL, make sure input type
+		 * and transtype are the same (or at least binary-compatible), so that
+		 * it's OK to use the first aggregated input value as the initial
+		 * transValue.  This should have been checked at agg definition time, but
+		 * we must check again in case the transfn's strictness property has been
+		 * changed.
+		 */
+		if (pertrans->transfn.fn_strict && pertrans->initValueIsNull)
+		{
+			if (numArguments <= numDirectArgs ||
+				!IsBinaryCoercible(inputTypes[numDirectArgs],
+								   aggtranstype))
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						 errmsg("aggregate %u needs to have compatible input type and transition type",
+								aggref->aggfnoid)));
+		}
 	}
 
 	/* get info about the state value's datatype */
@@ -2628,6 +2992,41 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 					&pertrans->transtypeLen,
 					&pertrans->transtypeByVal);
 
+	if (OidIsValid(aggserialfn))
+	{
+		build_aggregate_serialfn_expr(aggtranstype,
+									  aggserialtype,
+									  aggref->inputcollid,
+									  aggserialfn,
+									  &serialfnexpr);
+		fmgr_info(aggserialfn, &pertrans->serialfn);
+		fmgr_info_set_expr((Node *) serialfnexpr, &pertrans->serialfn);
+
+		InitFunctionCallInfoData(pertrans->serialfn_fcinfo,
+								 &pertrans->serialfn,
+								 1,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+	}
+
+	if (OidIsValid(aggdeserialfn))
+	{
+		build_aggregate_serialfn_expr(aggtranstype,
+									  aggserialtype,
+									  aggref->inputcollid,
+									  aggdeserialfn,
+									  &deserialfnexpr);
+		fmgr_info(aggdeserialfn, &pertrans->deserialfn);
+		fmgr_info_set_expr((Node *) deserialfnexpr, &pertrans->deserialfn);
+
+		InitFunctionCallInfoData(pertrans->deserialfn_fcinfo,
+								 &pertrans->deserialfn,
+								 1,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+
+	}
+
 	/*
 	 * Get a tupledesc corresponding to the aggregated inputs (including sort
 	 * expressions) of the agg.
@@ -2874,6 +3273,7 @@ find_compatible_peragg(Aggref *newagg, AggState *aggstate,
 static int
 find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 						 Oid aggtransfn, Oid aggtranstype,
+						 Oid aggserialfn, Oid aggdeserialfn,
 						 Datum initValue, bool initValueIsNull,
 						 List *transnos)
 {
@@ -2892,6 +3292,14 @@ find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 			aggtranstype != pertrans->aggtranstype)
 			continue;
 
+		/*
+		 * serial and deserial functions must match, if present. Remember that
+		 * these will be InvalidOid if they're not required for this agg node
+		 */
+		if (aggserialfn != pertrans->serialfn_oid ||
+			aggdeserialfn != pertrans->deserialfn_oid)
+			continue;
+
 		/* Check that the initial condition matches, too. */
 		if (initValueIsNull && pertrans->initValueIsNull)
 			return transno;
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index f47e0da..7e880fc 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -865,6 +865,9 @@ _copyAgg(const Agg *from)
 
 	COPY_SCALAR_FIELD(aggstrategy);
 	COPY_SCALAR_FIELD(numCols);
+	COPY_SCALAR_FIELD(combineStates);
+	COPY_SCALAR_FIELD(finalizeAggs);
+	COPY_SCALAR_FIELD(serialStates);
 	if (from->numCols > 0)
 	{
 		COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index d95e151..4cb78fa 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -695,6 +695,10 @@ _outAgg(StringInfo str, const Agg *node)
 	for (i = 0; i < node->numCols; i++)
 		appendStringInfo(str, " %d", node->grpColIdx[i]);
 
+	WRITE_BOOL_FIELD(combineStates);
+	WRITE_BOOL_FIELD(finalizeAggs);
+	WRITE_BOOL_FIELD(serialStates);
+
 	appendStringInfoString(str, " :grpOperators");
 	for (i = 0; i < node->numCols; i++)
 		appendStringInfo(str, " %u", node->grpOperators[i]);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 719a52c..d85f6db 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1989,6 +1989,9 @@ _readAgg(void)
 	READ_ENUM_FIELD(aggstrategy, AggStrategy);
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
+	READ_BOOL_FIELD(combineStates);
+	READ_BOOL_FIELD(finalizeAggs);
+	READ_BOOL_FIELD(serialStates);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 	READ_NODE_FIELD(groupingSets);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 953aa62..896a888 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -1054,6 +1054,9 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path)
 								 groupOperators,
 								 NIL,
 								 numGroups,
+								 false,
+								 true,
+								 false,
 								 subplan);
 	}
 	else
@@ -4557,9 +4560,8 @@ Agg *
 make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
 		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
-		 List *groupingSets,
-		 long numGroups,
-		 Plan *lefttree)
+		 List *groupingSets, long numGroups, bool combineStates,
+		 bool finalizeAggs, bool serialStates, Plan *lefttree)
 {
 	Agg		   *node = makeNode(Agg);
 	Plan	   *plan = &node->plan;
@@ -4568,6 +4570,9 @@ make_agg(PlannerInfo *root, List *tlist, List *qual,
 
 	node->aggstrategy = aggstrategy;
 	node->numCols = numGroupCols;
+	node->combineStates = combineStates;
+	node->finalizeAggs = finalizeAggs;
+	node->serialStates = serialStates;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
 	node->numGroups = numGroups;
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 131dc8a..ad99690 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -2005,6 +2005,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 									extract_grouping_ops(parse->groupClause),
 												NIL,
 												numGroups,
+												false,
+												true,
+												false,
 												result_plan);
 				/* Hashed aggregation produces randomly-ordered results */
 				current_pathkeys = NIL;
@@ -2312,6 +2315,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 								 extract_grouping_ops(parse->distinctClause),
 											NIL,
 											numDistinctRows,
+											false,
+											true,
+											false,
 											result_plan);
 			/* Hashed aggregation produces randomly-ordered results */
 			current_pathkeys = NIL;
@@ -2549,6 +2555,9 @@ build_grouping_chain(PlannerInfo *root,
 										 extract_grouping_ops(groupClause),
 										 gsets,
 										 numGroups,
+										 false,
+										 true,
+										 false,
 										 sort_plan);
 
 			/*
@@ -2588,6 +2597,9 @@ build_grouping_chain(PlannerInfo *root,
 										extract_grouping_ops(groupClause),
 										gsets,
 										numGroups,
+										false,
+										true,
+										false,
 										result_plan);
 
 		((Agg *) result_plan)->chain = chain;
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 615f3a2..007fc0f 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -15,7 +15,9 @@
  */
 #include "postgres.h"
 
+#include "access/htup_details.h"
 #include "access/transam.h"
+#include "catalog/pg_aggregate.h"
 #include "catalog/pg_type.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
@@ -139,6 +141,18 @@ static List *set_returning_clause_references(PlannerInfo *root,
 static bool fix_opfuncids_walker(Node *node, void *context);
 static bool extract_query_dependencies_walker(Node *node,
 								  PlannerInfo *context);
+static void set_combineagg_references(PlannerInfo *root, Plan *plan,
+									  int rtoffset);
+static Node *fix_combine_agg_expr(PlannerInfo *root,
+								  Node *node,
+								  indexed_tlist *subplan_itlist,
+								  Index newvarno,
+								  int rtoffset);
+static Node *fix_combine_agg_expr_mutator(Node *node,
+										  fix_upper_expr_context *context);
+static void set_partialagg_aggref_types(PlannerInfo *root, Plan *plan,
+										bool serializeStates);
+
 
 /*****************************************************************************
  *
@@ -668,8 +682,24 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 			}
 			break;
 		case T_Agg:
-			set_upper_references(root, plan, rtoffset);
-			break;
+			{
+				Agg *aggplan = (Agg *) plan;
+
+				/*
+				 * For partial aggregation we must adjust the return types of
+				 * the Aggrefs
+				 */
+				if (!aggplan->finalizeAggs)
+					set_partialagg_aggref_types(root, plan,
+												aggplan->serialStates);
+
+				if (aggplan->combineStates)
+					set_combineagg_references(root, plan, rtoffset);
+				else
+					set_upper_references(root, plan, rtoffset);
+
+				break;
+			}
 		case T_Group:
 			set_upper_references(root, plan, rtoffset);
 			break;
@@ -2432,3 +2462,199 @@ extract_query_dependencies_walker(Node *node, PlannerInfo *context)
 	return expression_tree_walker(node, extract_query_dependencies_walker,
 								  (void *) context);
 }
+
+static void
+set_combineagg_references(PlannerInfo *root, Plan *plan, int rtoffset)
+{
+	Plan	   *subplan = plan->lefttree;
+	indexed_tlist *subplan_itlist;
+	List	   *output_targetlist;
+	ListCell   *l;
+
+	Assert(IsA(plan, Agg));
+	Assert(((Agg *) plan)->combineStates);
+
+	subplan_itlist = build_tlist_index(subplan->targetlist);
+
+	output_targetlist = NIL;
+
+	foreach(l, plan->targetlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(l);
+		Node	   *newexpr;
+
+		/* If it's a non-Var sort/group item, first try to match by sortref */
+		if (tle->ressortgroupref != 0 && !IsA(tle->expr, Var))
+		{
+			newexpr = (Node *)
+				search_indexed_tlist_for_sortgroupref((Node *) tle->expr,
+														tle->ressortgroupref,
+														subplan_itlist,
+														OUTER_VAR);
+			if (!newexpr)
+				newexpr = fix_combine_agg_expr(root,
+												(Node *) tle->expr,
+												subplan_itlist,
+												OUTER_VAR,
+												rtoffset);
+		}
+		else
+			newexpr = fix_combine_agg_expr(root,
+											(Node *) tle->expr,
+											subplan_itlist,
+											OUTER_VAR,
+											rtoffset);
+		tle = flatCopyTargetEntry(tle);
+		tle->expr = (Expr *) newexpr;
+		output_targetlist = lappend(output_targetlist, tle);
+	}
+
+	plan->targetlist = output_targetlist;
+
+	plan->qual = (List *)
+		fix_upper_expr(root,
+					   (Node *) plan->qual,
+					   subplan_itlist,
+					   OUTER_VAR,
+					   rtoffset);
+
+	pfree(subplan_itlist);
+}
+
+
+/*
+ * Adjust the Aggref'a args to reference the correct Aggref target in the outer
+ * subplan.
+ */
+static Node *
+fix_combine_agg_expr(PlannerInfo *root,
+			   Node *node,
+			   indexed_tlist *subplan_itlist,
+			   Index newvarno,
+			   int rtoffset)
+{
+	fix_upper_expr_context context;
+
+	context.root = root;
+	context.subplan_itlist = subplan_itlist;
+	context.newvarno = newvarno;
+	context.rtoffset = rtoffset;
+	return fix_combine_agg_expr_mutator(node, &context);
+}
+
+static Node *
+fix_combine_agg_expr_mutator(Node *node, fix_upper_expr_context *context)
+{
+	Var		   *newvar;
+
+	if (node == NULL)
+		return NULL;
+	if (IsA(node, Var))
+	{
+		Var		   *var = (Var *) node;
+
+		newvar = search_indexed_tlist_for_var(var,
+											  context->subplan_itlist,
+											  context->newvarno,
+											  context->rtoffset);
+		if (!newvar)
+			elog(ERROR, "variable not found in subplan target list");
+		return (Node *) newvar;
+	}
+	if (IsA(node, Aggref))
+	{
+		TargetEntry *tle;
+		Aggref		*aggref = (Aggref*) node;
+
+		tle = tlist_member(node, context->subplan_itlist->tlist);
+		if (tle)
+		{
+			/* Found a matching subplan output expression */
+			Var		   *newvar;
+			TargetEntry *newtle;
+
+			newvar = makeVarFromTargetEntry(context->newvarno, tle);
+			newvar->varnoold = 0;	/* wasn't ever a plain Var */
+			newvar->varoattno = 0;
+
+			/* update the args in the aggref */
+
+			/* makeTargetEntry ,always set resno to one for finialize agg */
+			newtle = makeTargetEntry((Expr*) newvar, 1, NULL, false);
+
+			/*
+			 * Updated the args, let the newvar refer to the right position of
+			 * the agg function in the subplan
+			 */
+			aggref->args = list_make1(newtle);
+
+			return (Node *) aggref;
+		}
+		else
+			elog(ERROR, "aggref not found in subplan target list");
+	}
+	if (IsA(node, PlaceHolderVar))
+	{
+		PlaceHolderVar *phv = (PlaceHolderVar *) node;
+
+		/* See if the PlaceHolderVar has bubbled up from a lower plan node */
+		if (context->subplan_itlist->has_ph_vars)
+		{
+			newvar = search_indexed_tlist_for_non_var((Node *) phv,
+													  context->subplan_itlist,
+													  context->newvarno);
+			if (newvar)
+				return (Node *) newvar;
+		}
+		/* If not supplied by input plan, evaluate the contained expr */
+		return fix_upper_expr_mutator((Node *) phv->phexpr, context);
+	}
+	if (IsA(node, Param))
+		return fix_param_node(context->root, (Param *) node);
+
+	fix_expr_common(context->root, node);
+	return expression_tree_mutator(node,
+								   fix_combine_agg_expr_mutator,
+								   (void *) context);
+}
+
+/* XXX is this really the best place and way to do this? */
+static void
+set_partialagg_aggref_types(PlannerInfo *root, Plan *plan, bool serializeStates)
+{
+	ListCell *l;
+
+	foreach(l, plan->targetlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(l);
+
+		if (IsA(tle->expr, Aggref))
+		{
+			Aggref *aggref = (Aggref *) tle->expr;
+			HeapTuple	aggTuple;
+			Form_pg_aggregate aggform;
+
+			aggTuple = SearchSysCache1(AGGFNOID,
+									   ObjectIdGetDatum(aggref->aggfnoid));
+			if (!HeapTupleIsValid(aggTuple))
+				elog(ERROR, "cache lookup failed for aggregate %u",
+					 aggref->aggfnoid);
+			aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
+
+			/*
+			 * For partial aggregate nodes the return type of the Aggref
+			 * depends on if we're performing a serialization of the partially
+			 * aggregated states or not. If we are then the return type should
+			 * be the serial type rather than the trans type. We only require
+			 * this behavior for aggregates with INTERNAL trans types.
+			 */
+			if (serializeStates && OidIsValid(aggform->aggserialtype) &&
+				aggform->aggtranstype == INTERNALOID)
+				aggref->aggtype = aggform->aggserialtype;
+			else
+				aggref->aggtype = aggform->aggtranstype;
+
+			ReleaseSysCache(aggTuple);
+		}
+	}
+}
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 694e9ed..ab2f1a8 100644
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -775,6 +775,9 @@ make_union_unique(SetOperationStmt *op, Plan *plan,
 								 extract_grouping_ops(groupList),
 								 NIL,
 								 numGroups,
+								 false,
+								 true,
+								 false,
 								 plan);
 		/* Hashed aggregation produces randomly-ordered results */
 		*sortClauses = NIL;
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index ace8b38..b1eed99 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -52,6 +52,10 @@
 #include "utils/syscache.h"
 #include "utils/typcache.h"
 
+typedef struct
+{
+	PartialAggType allowedtype;
+} partial_agg_context;
 
 typedef struct
 {
@@ -93,6 +97,7 @@ typedef struct
 	bool		allow_restricted;
 } has_parallel_hazard_arg;
 
+static bool partial_aggregate_walker(Node *node, partial_agg_context *context);
 static bool contain_agg_clause_walker(Node *node, void *context);
 static bool count_agg_clauses_walker(Node *node,
 						 count_agg_clauses_context *context);
@@ -400,6 +405,89 @@ make_ands_implicit(Expr *clause)
  *****************************************************************************/
 
 /*
+ * aggregates_allow_partial
+ *		Recursively search for Aggref clauses and determine the maximum
+ *		'degree' of partial aggregation which can be supported. Partial
+ *		aggregation requires that each aggregate does not have a DISTINCT or
+ *		ORDER BY clause, and that it also has a combine function set. For
+ *		aggregates with an INTERNAL trans type we only can support all types of
+ *		partial aggregation when the aggregate has a serial and deserial
+ *		function set. If this is not present then we can only support, at most
+ *		partial aggregation in the context of a single backend process, as
+ *		internal state pointers cannot be dereferenced from another backend
+ *		process.
+ */
+PartialAggType
+aggregates_allow_partial(Node *clause)
+{
+	partial_agg_context context;
+
+	/* initially any type is ok, until we find Aggrefs which say otherwise */
+	context.allowedtype = PAT_ANY;
+
+	if (!partial_aggregate_walker(clause, &context))
+		return context.allowedtype;
+	return context.allowedtype;
+}
+
+static bool
+partial_aggregate_walker(Node *node, partial_agg_context *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Aggref))
+	{
+		Aggref	   *aggref = (Aggref *) node;
+		HeapTuple	aggTuple;
+		Form_pg_aggregate aggform;
+
+		Assert(aggref->agglevelsup == 0);
+
+		/*
+		 * We can't perform partial aggregation with Aggrefs containing a
+		 * DISTINCT or ORDER BY clause.
+		 */
+		if (aggref->aggdistinct || aggref->aggorder)
+		{
+			context->allowedtype = PAT_DISABLED;
+			return true;	/* abort search */
+		}
+		aggTuple = SearchSysCache1(AGGFNOID,
+								   ObjectIdGetDatum(aggref->aggfnoid));
+		if (!HeapTupleIsValid(aggTuple))
+			elog(ERROR, "cache lookup failed for aggregate %u",
+				 aggref->aggfnoid);
+		aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
+
+		/*
+		 * If there is no combine func, then partial aggregation is not
+		 * possible.
+		 */
+		if (!OidIsValid(aggform->aggcombinefn))
+		{
+			ReleaseSysCache(aggTuple);
+			context->allowedtype = PAT_DISABLED;
+			return true;	/* abort search */
+		}
+
+		/*
+		 * Any aggs with an internal transtype must have a serial type, serial
+		 * func and deserial func, otherwise we can only support internal mode.
+		 */
+		if (aggform->aggtranstype == INTERNALOID &&
+			(!OidIsValid(aggform->aggserialtype) ||
+			 !OidIsValid(aggform->aggserialfn) ||
+			 !OidIsValid(aggform->aggdeserialfn)))
+			context->allowedtype = PAT_INTERNAL_ONLY;
+
+		ReleaseSysCache(aggTuple);
+		return false; /* continue searching */
+	}
+	return expression_tree_walker(node, partial_aggregate_walker,
+								  (void *) context);
+}
+
+/*
  * contain_agg_clause
  *	  Recursively search for Aggref/GroupingFunc nodes within a clause.
  *
diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c
index b718169..ca3823a 100644
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -1929,6 +1929,116 @@ build_aggregate_transfn_expr(Oid *agg_input_types,
 
 /*
  * Like build_aggregate_transfn_expr, but creates an expression tree for the
+ * combine function of an aggregate, rather than the transition function.
+ */
+void
+build_aggregate_combinefn_expr(Oid agg_state_type,
+							   Oid agg_input_collation,
+							   Oid combinefn_oid,
+							   Expr **combinefnexpr)
+{
+	Param	   *argp;
+	List	   *args;
+	FuncExpr   *fexpr;
+
+	/* Build arg list to use in the combinefn FuncExpr node. */
+	argp = makeNode(Param);
+	argp->paramkind = PARAM_EXEC;
+	argp->paramid = -1;
+	argp->paramtype = agg_state_type;
+	argp->paramtypmod = -1;
+	argp->paramcollid = agg_input_collation;
+	argp->location = -1;
+
+	/* transition state type is arg 1 and 2 */
+	args = list_make2(argp, argp);
+
+	fexpr = makeFuncExpr(combinefn_oid,
+						 agg_state_type,
+						 args,
+						 InvalidOid,
+						 agg_input_collation,
+						 COERCE_EXPLICIT_CALL);
+	fexpr->funcvariadic = false;
+	*combinefnexpr = (Expr *) fexpr;
+}
+
+/*
+ * Like build_aggregate_transfn_expr, but creates an expression tree for the
+ * serial function of an aggregate, rather than the transition function.
+ */
+void
+build_aggregate_serialfn_expr(Oid agg_state_type,
+							  Oid agg_serial_type,
+							  Oid agg_input_collation,
+							  Oid serialfn_oid,
+							  Expr **serialfnexpr)
+{
+	Param	   *argp;
+	List	   *args;
+	FuncExpr   *fexpr;
+
+	/* Build arg list to use in the serialfn FuncExpr node. */
+	argp = makeNode(Param);
+	argp->paramkind = PARAM_EXEC;
+	argp->paramid = -1;
+	argp->paramtype = agg_state_type;
+	argp->paramtypmod = -1;
+	argp->paramcollid = agg_input_collation;
+	argp->location = -1;
+
+	/* takes a single arg of the transition state type */
+	args = list_make1(argp);
+
+	fexpr = makeFuncExpr(serialfn_oid,
+						 agg_serial_type,
+						 args,
+						 InvalidOid,
+						 agg_input_collation,
+						 COERCE_EXPLICIT_CALL);
+	fexpr->funcvariadic = false;
+	*serialfnexpr = (Expr *) fexpr;
+}
+
+/*
+ * Like build_aggregate_transfn_expr, but creates an expression tree for the
+ * deserial function of an aggregate, rather than the transition function.
+ */
+void
+build_aggregate_deserialfn_expr(Oid agg_state_type,
+								Oid agg_serial_type,
+								Oid agg_input_collation,
+								Oid deserialfn_oid,
+								Expr **deserialfnexpr)
+{
+	Param	   *argp;
+	List	   *args;
+	FuncExpr   *fexpr;
+
+	/* Build arg list to use in the serialfn FuncExpr node. */
+	argp = makeNode(Param);
+	argp->paramkind = PARAM_EXEC;
+	argp->paramid = -1;
+	argp->paramtype = agg_serial_type;
+	argp->paramtypmod = -1;
+	argp->paramcollid = agg_input_collation;
+	argp->location = -1;
+
+	/* takes a single arg of the serial type */
+	args = list_make1(argp);
+
+	fexpr = makeFuncExpr(deserialfn_oid,
+						 agg_state_type,
+						 args,
+						 InvalidOid,
+						 agg_input_collation,
+						 COERCE_EXPLICIT_CALL);
+	fexpr->funcvariadic = false;
+	*deserialfnexpr = (Expr *) fexpr;
+}
+
+/*
+ * Like build_aggregate_transfn_expr, but creates an expression tree for the
  * final function of an aggregate, rather than the transition function.
  */
 void
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index 07b2645..3947cba 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -3369,6 +3369,175 @@ numeric_avg_accum(PG_FUNCTION_ARGS)
 }
 
 /*
+ * Generic combine function for numeric aggregates without requirement for X^2
+ */
+Datum
+numeric_avg_combine(PG_FUNCTION_ARGS)
+{
+	NumericAggState *state1;
+	NumericAggState *state2;
+
+	state1 = PG_ARGISNULL(0) ? NULL : (NumericAggState *) PG_GETARG_POINTER(0);
+	state2 = PG_ARGISNULL(1) ? NULL : (NumericAggState *) PG_GETARG_POINTER(1);
+
+	if (state2 == NULL)
+		PG_RETURN_POINTER(state1);
+
+	/* manually copy all fields from state2 to state1 */
+	if (state1 == NULL)
+	{
+		MemoryContext old_context;
+
+		state1 = makeNumericAggState(fcinfo, false);
+		state1->N = state2->N;
+		state1->NaNcount = state2->NaNcount;
+		state1->maxScale = state2->maxScale;
+		state1->maxScaleCount = state2->maxScaleCount;
+
+		old_context = MemoryContextSwitchTo(state1->agg_context);
+
+		init_var(&state1->sumX);
+		set_var_from_var(&state2->sumX, &state1->sumX);
+
+		MemoryContextSwitchTo(old_context);
+
+		PG_RETURN_POINTER(state1);
+	}
+
+	if (state2->N > 0)
+	{
+		MemoryContext old_context;
+
+		state1->N += state2->N;
+		state1->NaNcount += state2->NaNcount;
+
+		/*
+		 * XXX do we care about these? They're really only needed for moving
+		 * aggregates.
+		 */
+		if (state2->maxScale > state1->maxScale)
+			state1->maxScale = state2->maxScale;
+		else if (state2->maxScale == state1->maxScale)
+			state1->maxScale += state2->maxScale;
+
+		/* The rest of this needs to work in the aggregate context */
+		old_context = MemoryContextSwitchTo(state1->agg_context);
+
+		/* Accumulate sums */
+		add_var(&(state1->sumX), &(state2->sumX), &(state1->sumX));
+
+		if (state1->calcSumX2)
+			add_var(&(state1->sumX2), &(state2->sumX2), &(state1->sumX2));
+
+		MemoryContextSwitchTo(old_context);
+	}
+	PG_RETURN_POINTER(state1);
+}
+
+/*
+ * numeric_avg_serialize
+ *		Serialize NumericAggState into text.
+ *		numeric_avg_deserialize(numeric_avg_serialize(state)) must result in
+ *		a state which matches the original input state.
+ */
+Datum
+numeric_avg_serialize(PG_FUNCTION_ARGS)
+{
+	NumericAggState *state;
+	StringInfoData string;
+	MemoryContext agg_context;
+	MemoryContext old_context;
+	text	   *result;
+
+	/* Ensure we disallow calling when not in aggregate context */
+	if (!AggCheckCallContext(fcinfo, &agg_context))
+		elog(ERROR, "aggregate function called in non-aggregate context");
+
+	state = (NumericAggState *) PG_GETARG_POINTER(0);
+
+	initStringInfo(&string);
+
+	/*
+	 * Transform the NumericAggState into a string with the following format:
+	 * "N sumX maxScale maxScaleCount NaNcount"
+	 * XXX perhaps we can come up with a more efficient format for this.
+	 */
+	appendStringInfo(&string, INT64_FORMAT " %s %d " INT64_FORMAT " " INT64_FORMAT,
+			state->N, get_str_from_var(&state->sumX), state->maxScale,
+			state->maxScaleCount, state->NaNcount);
+
+	old_context = MemoryContextSwitchTo(agg_context);
+
+	result = cstring_to_text_with_len(string.data, string.len);
+
+	MemoryContextSwitchTo(old_context);
+
+	PG_RETURN_TEXT_P(result);
+}
+
+/*
+ * numeric_avg_deserialize
+ *		deserialize Text into NumericAggState
+ *		numeric_avg_serialize(numeric_avg_deserialize(text)) must result in
+ *		text which matches the original input text.
+ */
+Datum
+numeric_avg_deserialize(PG_FUNCTION_ARGS)
+{
+	NumericAggState *result;
+	MemoryContext agg_context;
+	MemoryContext old_context;
+	Numeric		tmp;
+	text	   *sstate;
+	char	   *state;
+	char	   *token[5];
+	int			i;
+
+	if (!AggCheckCallContext(fcinfo, &agg_context))
+		elog(ERROR, "aggregate function called in non-aggregate context");
+
+	sstate = PG_GETARG_TEXT_P(0);
+	state = text_to_cstring(sstate);
+
+	token[0] = strtok(state, " ");
+
+	if (!token[0])
+		elog(ERROR, "invalid serialization format");
+
+	for (i = 1; i < 5; i++)
+	{
+		token[i] = strtok(NULL, " ");
+		if (!token[i])
+			elog(ERROR, "invalid serialization format");
+	}
+
+	old_context = MemoryContextSwitchTo(agg_context);
+
+	/*
+	 * Transform string into a NumericAggState. The string is in the format:
+	 * "N sumX maxScale maxScaleCount NaNcount"
+	 */
+	result = makeNumericAggState(fcinfo, false);
+
+	scanint8(token[0], false, &result->N);
+
+	tmp = DatumGetNumeric(DirectFunctionCall3(numeric_in,
+						  CStringGetDatum(token[1]),
+						  ObjectIdGetDatum(0),
+						  Int32GetDatum(-1)));
+	init_var_from_num(tmp, &result->sumX);
+
+	result->maxScale = pg_atoi(token[2], sizeof(int32), 0);
+	scanint8(token[3], false, &result->maxScaleCount);
+	scanint8(token[4], false, &result->NaNcount);
+
+	MemoryContextSwitchTo(old_context);
+
+	pfree(state);
+	PG_RETURN_POINTER(result);
+}
+
+/*
  * Generic inverse transition function for numeric aggregates
  * (with or without requirement for X^2).
  */
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 9196cf4..d2cfdd8 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -12386,6 +12386,9 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	PGresult   *res;
 	int			i_aggtransfn;
 	int			i_aggfinalfn;
+	int			i_aggcombinefn;
+	int			i_aggserialfn;
+	int			i_aggdeserialfn;
 	int			i_aggmtransfn;
 	int			i_aggminvtransfn;
 	int			i_aggmfinalfn;
@@ -12394,6 +12397,7 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	int			i_aggsortop;
 	int			i_hypothetical;
 	int			i_aggtranstype;
+	int			i_aggserialtype;
 	int			i_aggtransspace;
 	int			i_aggmtranstype;
 	int			i_aggmtransspace;
@@ -12402,6 +12406,9 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	int			i_convertok;
 	const char *aggtransfn;
 	const char *aggfinalfn;
+	const char *aggcombinefn;
+	const char *aggserialfn;
+	const char *aggdeserialfn;
 	const char *aggmtransfn;
 	const char *aggminvtransfn;
 	const char *aggmfinalfn;
@@ -12411,6 +12418,7 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	char	   *aggsortconvop;
 	bool		hypothetical;
 	const char *aggtranstype;
+	const char *aggserialtype;
 	const char *aggtransspace;
 	const char *aggmtranstype;
 	const char *aggmtransspace;
@@ -12432,7 +12440,27 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	selectSourceSchema(fout, agginfo->aggfn.dobj.namespace->dobj.name);
 
 	/* Get aggregate-specific details */
-	if (fout->remoteVersion >= 90400)
+	if (fout->remoteVersion >= 90600)
+	{
+		appendPQExpBuffer(query, "SELECT aggtransfn, "
+			"aggfinalfn, aggtranstype::pg_catalog.regtype, "
+			"aggcombinefn, aggserialfn, aggdeserialfn, aggmtransfn, "
+			"aggminvtransfn, aggmfinalfn, aggmtranstype::pg_catalog.regtype, "
+			"aggfinalextra, aggmfinalextra, "
+			"aggsortop::pg_catalog.regoperator, "
+			"aggserialtype::pg_catalog.regtype, "
+			"(aggkind = 'h') AS hypothetical, "
+			"aggtransspace, agginitval, "
+			"aggmtransspace, aggminitval, "
+			"true AS convertok, "
+			"pg_catalog.pg_get_function_arguments(p.oid) AS funcargs, "
+			"pg_catalog.pg_get_function_identity_arguments(p.oid) AS funciargs "
+			"FROM pg_catalog.pg_aggregate a, pg_catalog.pg_proc p "
+			"WHERE a.aggfnoid = p.oid "
+			"AND p.oid = '%u'::pg_catalog.oid",
+			agginfo->aggfn.dobj.catId.oid);
+	}
+	else if (fout->remoteVersion >= 90400)
 	{
 		appendPQExpBuffer(query, "SELECT aggtransfn, "
 						  "aggfinalfn, aggtranstype::pg_catalog.regtype, "
@@ -12542,12 +12570,16 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 
 	i_aggtransfn = PQfnumber(res, "aggtransfn");
 	i_aggfinalfn = PQfnumber(res, "aggfinalfn");
+	i_aggcombinefn = PQfnumber(res, "aggcombinefn");
+	i_aggserialfn = PQfnumber(res, "aggserialfn");
+	i_aggdeserialfn = PQfnumber(res, "aggdeserialfn");
 	i_aggmtransfn = PQfnumber(res, "aggmtransfn");
 	i_aggminvtransfn = PQfnumber(res, "aggminvtransfn");
 	i_aggmfinalfn = PQfnumber(res, "aggmfinalfn");
 	i_aggfinalextra = PQfnumber(res, "aggfinalextra");
 	i_aggmfinalextra = PQfnumber(res, "aggmfinalextra");
 	i_aggsortop = PQfnumber(res, "aggsortop");
+	i_aggserialtype = PQfnumber(res, "aggserialtype");
 	i_hypothetical = PQfnumber(res, "hypothetical");
 	i_aggtranstype = PQfnumber(res, "aggtranstype");
 	i_aggtransspace = PQfnumber(res, "aggtransspace");
@@ -12559,6 +12591,9 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 
 	aggtransfn = PQgetvalue(res, 0, i_aggtransfn);
 	aggfinalfn = PQgetvalue(res, 0, i_aggfinalfn);
+	aggcombinefn = PQgetvalue(res, 0, i_aggcombinefn);
+	aggserialfn = PQgetvalue(res, 0, i_aggserialfn);
+	aggdeserialfn = PQgetvalue(res, 0, i_aggdeserialfn);
 	aggmtransfn = PQgetvalue(res, 0, i_aggmtransfn);
 	aggminvtransfn = PQgetvalue(res, 0, i_aggminvtransfn);
 	aggmfinalfn = PQgetvalue(res, 0, i_aggmfinalfn);
@@ -12567,6 +12602,7 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	aggsortop = PQgetvalue(res, 0, i_aggsortop);
 	hypothetical = (PQgetvalue(res, 0, i_hypothetical)[0] == 't');
 	aggtranstype = PQgetvalue(res, 0, i_aggtranstype);
+	aggserialtype = PQgetvalue(res, 0, i_aggserialtype);
 	aggtransspace = PQgetvalue(res, 0, i_aggtransspace);
 	aggmtranstype = PQgetvalue(res, 0, i_aggmtranstype);
 	aggmtransspace = PQgetvalue(res, 0, i_aggmtransspace);
@@ -12647,6 +12683,18 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 			appendPQExpBufferStr(details, ",\n    FINALFUNC_EXTRA");
 	}
 
+	if (strcmp(aggcombinefn, "-") != 0)
+	{
+		appendPQExpBuffer(details, ",\n    COMBINEFUNC = %s",	aggcombinefn);
+	}
+
+	if (strcmp(aggserialfn, "-") != 0)
+	{
+		appendPQExpBuffer(details, ",\n    SERIALFUNC = %s",	aggserialfn);
+		appendPQExpBuffer(details, ",\n    DESERIALFUNC = %s",	aggdeserialfn);
+		appendPQExpBuffer(details, ",\n    SERIALTYPE = %s",	aggserialtype);
+	}
+
 	if (strcmp(aggmtransfn, "-") != 0)
 	{
 		appendPQExpBuffer(details, ",\n    MSFUNC = %s,\n    MINVFUNC = %s,\n    MSTYPE = %s",
diff --git a/src/include/catalog/pg_aggregate.h b/src/include/catalog/pg_aggregate.h
index 28b0669..ed2ee92 100644
--- a/src/include/catalog/pg_aggregate.h
+++ b/src/include/catalog/pg_aggregate.h
@@ -33,6 +33,9 @@
  *	aggnumdirectargs	number of arguments that are "direct" arguments
  *	aggtransfn			transition function
  *	aggfinalfn			final function (0 if none)
+ *	aggcombinefn		combine function (0 if none)
+ *	aggserialfn			function to convert transtype into serialtype
+ *	aggdeserialfn		function to convert serialtype into transtype
  *	aggmtransfn			forward function for moving-aggregate mode (0 if none)
  *	aggminvtransfn		inverse function for moving-aggregate mode (0 if none)
  *	aggmfinalfn			final function for moving-aggregate mode (0 if none)
@@ -42,6 +45,7 @@
  *	aggtranstype		type of aggregate's transition (state) data
  *	aggtransspace		estimated size of state data (0 for default estimate)
  *	aggmtranstype		type of moving-aggregate state data (0 if none)
+ *	aggserialtype		datatype to serialize state to. (0 if none)
  *	aggmtransspace		estimated size of moving-agg state (0 for default est)
  *	agginitval			initial value for transition state (can be NULL)
  *	aggminitval			initial value for moving-agg state (can be NULL)
@@ -56,6 +60,9 @@ CATALOG(pg_aggregate,2600) BKI_WITHOUT_OIDS
 	int16		aggnumdirectargs;
 	regproc		aggtransfn;
 	regproc		aggfinalfn;
+	regproc		aggcombinefn;
+	regproc		aggserialfn;
+	regproc		aggdeserialfn;
 	regproc		aggmtransfn;
 	regproc		aggminvtransfn;
 	regproc		aggmfinalfn;
@@ -63,6 +70,7 @@ CATALOG(pg_aggregate,2600) BKI_WITHOUT_OIDS
 	bool		aggmfinalextra;
 	Oid			aggsortop;
 	Oid			aggtranstype;
+	Oid			aggserialtype;
 	int32		aggtransspace;
 	Oid			aggmtranstype;
 	int32		aggmtransspace;
@@ -85,24 +93,28 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  * ----------------
  */
 
-#define Natts_pg_aggregate					17
+#define Natts_pg_aggregate					21
 #define Anum_pg_aggregate_aggfnoid			1
 #define Anum_pg_aggregate_aggkind			2
 #define Anum_pg_aggregate_aggnumdirectargs	3
 #define Anum_pg_aggregate_aggtransfn		4
 #define Anum_pg_aggregate_aggfinalfn		5
-#define Anum_pg_aggregate_aggmtransfn		6
-#define Anum_pg_aggregate_aggminvtransfn	7
-#define Anum_pg_aggregate_aggmfinalfn		8
-#define Anum_pg_aggregate_aggfinalextra		9
-#define Anum_pg_aggregate_aggmfinalextra	10
-#define Anum_pg_aggregate_aggsortop			11
-#define Anum_pg_aggregate_aggtranstype		12
-#define Anum_pg_aggregate_aggtransspace		13
-#define Anum_pg_aggregate_aggmtranstype		14
-#define Anum_pg_aggregate_aggmtransspace	15
-#define Anum_pg_aggregate_agginitval		16
-#define Anum_pg_aggregate_aggminitval		17
+#define Anum_pg_aggregate_aggcombinefn		6
+#define Anum_pg_aggregate_aggserialfn		7
+#define Anum_pg_aggregate_aggdeserialfn		8
+#define Anum_pg_aggregate_aggmtransfn		9
+#define Anum_pg_aggregate_aggminvtransfn	10
+#define Anum_pg_aggregate_aggmfinalfn		11
+#define Anum_pg_aggregate_aggfinalextra		12
+#define Anum_pg_aggregate_aggmfinalextra	13
+#define Anum_pg_aggregate_aggsortop			14
+#define Anum_pg_aggregate_aggtranstype		15
+#define Anum_pg_aggregate_aggserialtype		16
+#define Anum_pg_aggregate_aggtransspace		17
+#define Anum_pg_aggregate_aggmtranstype		18
+#define Anum_pg_aggregate_aggmtransspace	19
+#define Anum_pg_aggregate_agginitval		20
+#define Anum_pg_aggregate_aggminitval		21
 
 /*
  * Symbolic values for aggkind column.  We distinguish normal aggregates
@@ -126,184 +138,184 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  */
 
 /* avg */
-DATA(insert ( 2100	n 0 int8_avg_accum	numeric_poly_avg		int8_avg_accum	int8_avg_accum_inv	numeric_poly_avg	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg		int4_avg_accum	int4_avg_accum_inv	int8_avg					f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg		int2_avg_accum	int2_avg_accum_inv	int8_avg					f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg	numeric_avg_accum numeric_accum_inv numeric_avg					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2104	n 0 float4_accum	float8_avg		-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2105	n 0 float8_accum	float8_avg		-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2106	n 0 interval_accum	interval_avg	interval_accum	interval_accum_inv interval_avg					f f 0	1187	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
+DATA(insert ( 2100	n 0 int8_avg_accum	numeric_poly_avg	-					-	-	int8_avg_accum	int8_avg_accum_inv	numeric_poly_avg	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg			-					-	-	int4_avg_accum	int4_avg_accum_inv	int8_avg			f f 0	1016	0	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg			-					-	-	int2_avg_accum	int2_avg_accum_inv	int8_avg			f f 0	1016	0	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg		numeric_avg_combine	numeric_avg_serialize	numeric_avg_deserialize	numeric_avg_accum numeric_accum_inv numeric_avg			f f 0	2281	25	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2104	n 0 float4_accum	float8_avg			-					-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2105	n 0 float8_accum	float8_avg			-					-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2106	n 0 interval_accum	interval_avg		-					-	-	interval_accum	interval_accum_inv interval_avg			f f 0	1187	0	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
 
 /* sum */
-DATA(insert ( 2107	n 0 int8_avg_accum	numeric_poly_sum		int8_avg_accum	int8_avg_accum_inv numeric_poly_sum f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2108	n 0 int4_sum		-				int4_avg_accum	int4_avg_accum_inv int2int4_sum					f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2109	n 0 int2_sum		-				int2_avg_accum	int2_avg_accum_inv int2int4_sum					f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2110	n 0 float4pl		-				-				-				-								f f 0	700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2111	n 0 float8pl		-				-				-				-								f f 0	701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2112	n 0 cash_pl			-				cash_pl			cash_mi			-								f f 0	790		0	790		0	_null_ _null_ ));
-DATA(insert ( 2113	n 0 interval_pl		-				interval_pl		interval_mi		-								f f 0	1186	0	1186	0	_null_ _null_ ));
-DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum numeric_avg_accum numeric_accum_inv numeric_sum					f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2107	n 0 int8_avg_accum	numeric_poly_sum	-					-	-	int8_avg_accum	int8_avg_accum_inv	numeric_poly_sum	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2108	n 0 int4_sum		-					int8pl				-	-	int4_avg_accum	int4_avg_accum_inv	int2int4_sum		f f 0	20		0	0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2109	n 0 int2_sum		-					int8pl				-	-	int2_avg_accum	int2_avg_accum_inv	int2int4_sum		f f 0	20		0	0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2110	n 0 float4pl		-					float4pl			-	-	-				-					-					f f 0	700		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2111	n 0 float8pl		-					float8pl			-	-	-				-					-					f f 0	701		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2112	n 0 cash_pl			-					cash_pl				-	-	cash_pl			cash_mi				-					f f 0	790		0	0	790		0	_null_ _null_ ));
+DATA(insert ( 2113	n 0 interval_pl		-					interval_pl			-	-	interval_pl		interval_mi			-					f f 0	1186	0	0	1186	0	_null_ _null_ ));
+DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum		numeric_avg_combine	numeric_avg_serialize	numeric_avg_deserialize	numeric_avg_accum	numeric_accum_inv	numeric_sum		f f 0	2281	25	128 2281	128 _null_ _null_ ));
 
 /* max */
-DATA(insert ( 2115	n 0 int8larger		-				-				-				-				f f 413		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2116	n 0 int4larger		-				-				-				-				f f 521		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2117	n 0 int2larger		-				-				-				-				f f 520		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2118	n 0 oidlarger		-				-				-				-				f f 610		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2119	n 0 float4larger	-				-				-				-				f f 623		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2120	n 0 float8larger	-				-				-				-				f f 674		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2121	n 0 int4larger		-				-				-				-				f f 563		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2122	n 0 date_larger		-				-				-				-				f f 1097	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2123	n 0 time_larger		-				-				-				-				f f 1112	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2124	n 0 timetz_larger	-				-				-				-				f f 1554	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2125	n 0 cashlarger		-				-				-				-				f f 903		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2126	n 0 timestamp_larger	-			-				-				-				f f 2064	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2127	n 0 timestamptz_larger	-			-				-				-				f f 1324	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2128	n 0 interval_larger -				-				-				-				f f 1334	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2129	n 0 text_larger		-				-				-				-				f f 666		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2130	n 0 numeric_larger	-				-				-				-				f f 1756	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2050	n 0 array_larger	-				-				-				-				f f 1073	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2244	n 0 bpchar_larger	-				-				-				-				f f 1060	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2797	n 0 tidlarger		-				-				-				-				f f 2800	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3526	n 0 enum_larger		-				-				-				-				f f 3519	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3564	n 0 network_larger	-				-				-				-				f f 1205	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2115	n 0 int8larger		-				int8larger			-	-	-				-				-				f f 413		20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2116	n 0 int4larger		-				int4larger			-	-	-				-				-				f f 521		23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2117	n 0 int2larger		-				int2larger			-	-	-				-				-				f f 520		21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2118	n 0 oidlarger		-				oidlarger			-	-	-				-				-				f f 610		26		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2119	n 0 float4larger	-				float4larger		-	-	-				-				-				f f 623		700		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2120	n 0 float8larger	-				float8larger		-	-	-				-				-				f f 674		701		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2121	n 0 int4larger		-				int4larger			-	-	-				-				-				f f 563		702		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2122	n 0 date_larger		-				date_larger			-	-	-				-				-				f f 1097	1082	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2123	n 0 time_larger		-				time_larger			-	-	-				-				-				f f 1112	1083	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2124	n 0 timetz_larger	-				timetz_larger		-	-	-				-				-				f f 1554	1266	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2125	n 0 cashlarger		-				cashlarger			-	-	-				-				-				f f 903		790		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2126	n 0 timestamp_larger	-			timestamp_larger	-	-	-				-				-				f f 2064	1114	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2127	n 0 timestamptz_larger	-			timestamptz_larger	-	-	-				-				-				f f 1324	1184	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2128	n 0 interval_larger -				interval_larger		-	-	-				-				-				f f 1334	1186	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2129	n 0 text_larger		-				text_larger			-	-	-				-				-				f f 666		25		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2130	n 0 numeric_larger	-				numeric_larger		-	-	-				-				-				f f 1756	1700	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2050	n 0 array_larger	-				array_larger		-	-	-				-				-				f f 1073	2277	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2244	n 0 bpchar_larger	-				bpchar_larger		-	-	-				-				-				f f 1060	1042	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2797	n 0 tidlarger		-				tidlarger			-	-	-				-				-				f f 2800	27		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3526	n 0 enum_larger		-				enum_larger			-	-	-				-				-				f f 3519	3500	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3564	n 0 network_larger	-				network_larger		-	-	-				-				-				f f 1205	869		0	0	0		0	_null_ _null_ ));
 
 /* min */
-DATA(insert ( 2131	n 0 int8smaller		-				-				-				-				f f 412		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2132	n 0 int4smaller		-				-				-				-				f f 97		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2133	n 0 int2smaller		-				-				-				-				f f 95		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2134	n 0 oidsmaller		-				-				-				-				f f 609		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2135	n 0 float4smaller	-				-				-				-				f f 622		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2136	n 0 float8smaller	-				-				-				-				f f 672		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2137	n 0 int4smaller		-				-				-				-				f f 562		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2138	n 0 date_smaller	-				-				-				-				f f 1095	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2139	n 0 time_smaller	-				-				-				-				f f 1110	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2140	n 0 timetz_smaller	-				-				-				-				f f 1552	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2141	n 0 cashsmaller		-				-				-				-				f f 902		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2142	n 0 timestamp_smaller	-			-				-				-				f f 2062	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2143	n 0 timestamptz_smaller -			-				-				-				f f 1322	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2144	n 0 interval_smaller	-			-				-				-				f f 1332	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2145	n 0 text_smaller	-				-				-				-				f f 664		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2146	n 0 numeric_smaller -				-				-				-				f f 1754	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2051	n 0 array_smaller	-				-				-				-				f f 1072	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2245	n 0 bpchar_smaller	-				-				-				-				f f 1058	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2798	n 0 tidsmaller		-				-				-				-				f f 2799	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3527	n 0 enum_smaller	-				-				-				-				f f 3518	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3565	n 0 network_smaller -				-				-				-				f f 1203	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2131	n 0 int8smaller		-				int8smaller			-	-	-				-				-				f f 412		20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2132	n 0 int4smaller		-				int4smaller			-	-	-				-				-				f f 97		23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2133	n 0 int2smaller		-				int2smaller			-	-	-				-				-				f f 95		21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2134	n 0 oidsmaller		-				oidsmaller			-	-	-				-				-				f f 609		26		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2135	n 0 float4smaller	-				float4smaller		-	-	-				-				-				f f 622		700		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2136	n 0 float8smaller	-				float8smaller		-	-	-				-				-				f f 672		701		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2137	n 0 int4smaller		-				int4smaller			-	-	-				-				-				f f 562		702		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2138	n 0 date_smaller	-				date_smaller		-	-	-				-				-				f f 1095	1082	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2139	n 0 time_smaller	-				time_smaller		-	-	-				-				-				f f 1110	1083	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2140	n 0 timetz_smaller	-				timetz_smaller		-	-	-				-				-				f f 1552	1266	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2141	n 0 cashsmaller		-				cashsmaller			-	-	-				-				-				f f 902		790		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2142	n 0 timestamp_smaller	-			timestamp_smaller	-	-	-				-				-				f f 2062	1114	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2143	n 0 timestamptz_smaller -			timestamptz_smaller	-	-	-				-				-				f f 1322	1184	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2144	n 0 interval_smaller	-			interval_smaller	-	-	-				-				-				f f 1332	1186	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2145	n 0 text_smaller	-				text_smaller		-	-	-				-				-				f f 664		25		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2146	n 0 numeric_smaller -				numeric_smaller		-	-	-				-				-				f f 1754	1700	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2051	n 0 array_smaller	-				array_smaller		-	-	-				-				-				f f 1072	2277	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2245	n 0 bpchar_smaller	-				bpchar_smaller		-	-	-				-				-				f f 1058	1042	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2798	n 0 tidsmaller		-				tidsmaller			-	-	-				-				-				f f 2799	27		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3527	n 0 enum_smaller	-				enum_smaller		-	-	-				-				-				f f 3518	3500	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3565	n 0 network_smaller -				network_smaller		-	-	-				-				-				f f 1203	869		0	0	0		0	_null_ _null_ ));
 
 /* count */
-DATA(insert ( 2147	n 0 int8inc_any		-				int8inc_any		int8dec_any		-				f f 0		20		0	20		0	"0" "0" ));
-DATA(insert ( 2803	n 0 int8inc			-				int8inc			int8dec			-				f f 0		20		0	20		0	"0" "0" ));
+DATA(insert ( 2147	n 0 int8inc_any		-				int8pl	-	-	int8inc_any		int8dec_any		-				f f 0		20		0	0	20		0	"0" "0" ));
+DATA(insert ( 2803	n 0 int8inc			-				int8pl	-	-	int8inc			int8dec			-				f f 0		20		0	0	20		0	"0" "0" ));
 
 /* var_pop */
-DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop		int8_accum		int8_accum_inv	numeric_var_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2719	n 0 int4_accum	numeric_poly_var_pop		int4_accum		int4_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2720	n 0 int2_accum	numeric_poly_var_pop		int2_accum		int2_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2721	n 0 float4_accum	float8_var_pop	-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2722	n 0 float8_accum	float8_var_pop	-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop numeric_accum numeric_accum_inv numeric_var_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop			-	-	-	int8_accum		int8_accum_inv	numeric_var_pop			f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2719	n 0 int4_accum	numeric_poly_var_pop	-	-	-	int4_accum		int4_accum_inv	numeric_poly_var_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2720	n 0 int2_accum	numeric_poly_var_pop	-	-	-	int2_accum		int2_accum_inv	numeric_poly_var_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2721	n 0 float4_accum	float8_var_pop		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2722	n 0 float8_accum	float8_var_pop		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop		-	-	-	numeric_accum numeric_accum_inv numeric_var_pop			f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* var_samp */
-DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp	int8_accum		int8_accum_inv	numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2642	n 0 int4_accum	numeric_poly_var_samp		int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2643	n 0 int2_accum	numeric_poly_var_samp		int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2644	n 0 float4_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2645	n 0 float8_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp numeric_accum numeric_accum_inv numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp		-	-	-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2642	n 0 int4_accum	numeric_poly_var_samp	-	-	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2643	n 0 int2_accum	numeric_poly_var_samp	-	-	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2644	n 0 float4_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2645	n 0 float8_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp	-	-	-	numeric_accum	numeric_accum_inv numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* variance: historical Postgres syntax for var_samp */
-DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp	int8_accum		int8_accum_inv	numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2149	n 0 int4_accum	numeric_poly_var_samp		int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2150	n 0 int2_accum	numeric_poly_var_samp		int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2151	n 0 float4_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2152	n 0 float8_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp numeric_accum numeric_accum_inv numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp		-	-	-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2149	n 0 int4_accum	numeric_poly_var_samp	-	-	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2150	n 0 int2_accum	numeric_poly_var_samp	-	-	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2151	n 0 float4_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2152	n 0 float8_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp	-	-	-	numeric_accum numeric_accum_inv numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* stddev_pop */
-DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop	int8_accum	int8_accum_inv	numeric_stddev_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2725	n 0 int4_accum	numeric_poly_stddev_pop int4_accum	int4_accum_inv	numeric_poly_stddev_pop f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2726	n 0 int2_accum	numeric_poly_stddev_pop int2_accum	int2_accum_inv	numeric_poly_stddev_pop f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop numeric_accum numeric_accum_inv numeric_stddev_pop			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop		-	-	-	int8_accum	int8_accum_inv	numeric_stddev_pop		f f 0	2281	0	128	2281	128 _null_ _null_ ));
+DATA(insert ( 2725	n 0 int4_accum	numeric_poly_stddev_pop	-	-	-	int4_accum	int4_accum_inv	numeric_poly_stddev_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2726	n 0 int2_accum	numeric_poly_stddev_pop	-	-	-	int2_accum	int2_accum_inv	numeric_poly_stddev_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-	-	-	-				-				-					f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-	-	-	-				-				-					f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop	-	-	-	numeric_accum numeric_accum_inv numeric_stddev_pop	f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* stddev_samp */
-DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp		int8_accum	int8_accum_inv	numeric_stddev_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2713	n 0 int4_accum	numeric_poly_stddev_samp	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2714	n 0 int2_accum	numeric_poly_stddev_samp	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp numeric_accum numeric_accum_inv numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp			-	-	-	int8_accum	int8_accum_inv	numeric_stddev_samp			f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2713	n 0 int4_accum	numeric_poly_stddev_samp	-	-	-	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2714	n 0 int2_accum	numeric_poly_stddev_samp	-	-	-	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp		-	-	-	numeric_accum numeric_accum_inv numeric_stddev_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* stddev: historical Postgres syntax for stddev_samp */
-DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp		int8_accum	int8_accum_inv	numeric_stddev_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2155	n 0 int4_accum	numeric_poly_stddev_samp	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2156	n 0 int2_accum	numeric_poly_stddev_samp	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp numeric_accum numeric_accum_inv numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp			-	-	-	int8_accum		int8_accum_inv	numeric_stddev_samp			f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2155	n 0 int4_accum	numeric_poly_stddev_samp	-	-	-	int4_accum		int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2156	n 0 int2_accum	numeric_poly_stddev_samp	-	-	-	int2_accum		int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp		-	-	-	-				-				-							f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp		-	-	-	-				-				-							f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp		-	-	-	numeric_accum	numeric_accum_inv numeric_stddev_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* SQL2003 binary regression aggregates */
-DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-				-				-				f f 0	20		0	0		0	"0" _null_ ));
-DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-	-	-	-				-				-			f f 0	20		0	0	0		0	"0" _null_ ));
+DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
 
 /* boolean-and and boolean-or */
-DATA(insert ( 2517	n 0 booland_statefunc	-			bool_accum		bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2518	n 0 boolor_statefunc	-			bool_accum		bool_accum_inv	bool_anytrue	f f 59	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2519	n 0 booland_statefunc	-			bool_accum		bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2517	n 0 booland_statefunc	-	-	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16	0		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2518	n 0 boolor_statefunc	-	-	-	-	bool_accum	bool_accum_inv	bool_anytrue	f f 59	16	0		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2519	n 0 booland_statefunc	-	-	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16	0		0	2281	16	_null_ _null_ ));
 
 /* bitwise integer */
-DATA(insert ( 2236	n 0 int2and		-					-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2237	n 0 int2or		-					-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2238	n 0 int4and		-					-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2239	n 0 int4or		-					-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2240	n 0 int8and		-					-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2241	n 0 int8or		-					-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2242	n 0 bitand		-					-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
-DATA(insert ( 2243	n 0 bitor		-					-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
+DATA(insert ( 2236	n 0 int2and		-				int2and	-	-	-				-				-				f f 0	21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2237	n 0 int2or		-				int2or	-	-	-				-				-				f f 0	21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2238	n 0 int4and		-				int4and	-	-	-				-				-				f f 0	23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2239	n 0 int4or		-				int4or	-	-	-				-				-				f f 0	23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2240	n 0 int8and		-				int8and	-	-	-				-				-				f f 0	20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2241	n 0 int8or		-				int8or	-	-	-				-				-				f f 0	20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2242	n 0 bitand		-				bitand	-	-	-				-				-				f f 0	1560	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2243	n 0 bitor		-				bitor	-	-	-				-				-				f f 0	1560	0	0	0		0	_null_ _null_ ));
 
 /* xml */
-DATA(insert ( 2901	n 0 xmlconcat2	-					-				-				-				f f 0	142		0	0		0	_null_ _null_ ));
+DATA(insert ( 2901	n 0 xmlconcat2	-				-		-	-	-				-				-				f f 0	142		0	0	0		0	_null_ _null_ ));
 
 /* array */
-DATA(insert ( 2335	n 0 array_agg_transfn	array_agg_finalfn	-				-				-				t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn -		-				-				t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 2335	n 0 array_agg_transfn		array_agg_finalfn		-	-	-	-		-				-				t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn	-	-	-	-		-				-				t f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* text */
-DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-	-	-	-				-				-				f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* bytea */
-DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-				-				-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-	-	-	-				-				-		f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* json */
-DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-	-	-	-				-				-				f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -	-	-	-				-				-				f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* jsonb */
-DATA(insert ( 3267	n 0 jsonb_agg_transfn	jsonb_agg_finalfn			-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3270	n 0 jsonb_object_agg_transfn jsonb_object_agg_finalfn -				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3267	n 0 jsonb_agg_transfn	jsonb_agg_finalfn				-	-	-	-				-				-			f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3270	n 0 jsonb_object_agg_transfn jsonb_object_agg_finalfn	-	-	-	-				-				-			f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* ordered-set and hypothetical-set aggregates */
-DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
 
 
 /*
@@ -322,6 +334,9 @@ extern ObjectAddress AggregateCreate(const char *aggName,
 				Oid variadicArgType,
 				List *aggtransfnName,
 				List *aggfinalfnName,
+				List *aggcombinefnName,
+				List *aggserialfnName,
+				List *aggdeserialfnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
@@ -329,6 +344,7 @@ extern ObjectAddress AggregateCreate(const char *aggName,
 				bool mfinalfnExtraArgs,
 				List *aggsortopName,
 				Oid aggTransType,
+				Oid aggSerialType,
 				int32 aggTransSpace,
 				Oid aggmTransType,
 				int32 aggmTransSpace,
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index f58672e..5f4d37e 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -2517,6 +2517,12 @@ DESCR("aggregate final function");
 DATA(insert OID = 1833 (  numeric_accum    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_accum _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
 DATA(insert OID = 2858 (  numeric_avg_accum    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_avg_accum _null_ _null_ _null_ ));
+DESCR("aggregate combine function");
+DATA(insert OID = 3318 (  numeric_avg_combine    PGNSP PGUID 12 1 0 0 0 f f f f t f i s 2 0 2281 "2281 2281" _null_ _null_ _null_ _null_ _null_ numeric_avg_combine _null_ _null_ _null_ ));
+DESCR("aggregate serial function");
+DATA(insert OID = 3319 (  numeric_avg_serialize    PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 25 "2281" _null_ _null_ _null_ _null_ _null_ numeric_avg_serialize _null_ _null_ _null_ ));
+DESCR("aggregate deserial function");
+DATA(insert OID = 3320 (  numeric_avg_deserialize    PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 2281 "25" _null_ _null_ _null_ _null_ _null_ numeric_avg_deserialize _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
 DATA(insert OID = 3548 (  numeric_accum_inv    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_accum_inv _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index bfa5125..69a1dad 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1851,6 +1851,9 @@ typedef struct AggState
 	AggStatePerTrans curpertrans;	/* currently active trans state */
 	bool		input_done;		/* indicates end of input */
 	bool		agg_done;		/* indicates completion of Agg scan */
+	bool		combineStates;	/* input tuples contain transition states */
+	bool		finalizeAggs;	/* should we call the finalfn on agg states? */
+	bool		serialStates;	/* should partial states be serialized? */
 	int			projected_set;	/* The last projected grouping set */
 	int			current_set;	/* The current grouping set being evaluated */
 	Bitmapset  *grouped_cols;	/* grouped cols in current projection */
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index c92579b..b5d0e56 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -726,6 +726,9 @@ typedef struct Agg
 	AggStrategy aggstrategy;
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
+	bool		combineStates;	/* input tuples contain transition states */
+	bool		finalizeAggs;	/* should we call the finalfn on agg states? */
+	bool		serialStates;	/* should partial states be serialized? */
 	Oid		   *grpOperators;	/* equality operators to compare with */
 	long		numGroups;		/* estimated number of groups in input */
 	List	   *groupingSets;	/* grouping sets to use */
diff --git a/src/include/optimizer/clauses.h b/src/include/optimizer/clauses.h
index 3b3fd0f..d381ff0 100644
--- a/src/include/optimizer/clauses.h
+++ b/src/include/optimizer/clauses.h
@@ -27,6 +27,25 @@ typedef struct
 	List	  **windowFuncs;	/* lists of WindowFuncs for each winref */
 } WindowFuncLists;
 
+/*
+ * PartialAggType
+ *	PartialAggType stores whether partial aggregation is allowed and
+ *	which context it is allowed in. We require three states here as there are
+ *	two different contexts in which partial aggregation is safe. For aggregates
+ *	which have an 'stype' of INTERNAL, within a single backend process it is
+ *	okay to pass a pointer to the aggregate state, as the memory to which the
+ *	pointer points to will belong to the same process. In cases where the
+ *	aggregate state must be passed between different processes, for example
+ *	during parallel aggregation, passing the pointer is not okay due to the
+ *	fact that the memory being referenced won't be accessible from another
+ *	process.
+ */
+typedef enum
+{
+	PAT_ANY = 0,		/* Any type of partial aggregation is ok. */
+	PAT_INTERNAL_ONLY,	/* Some aggregates support only internal mode. */
+	PAT_DISABLED		/* Some aggregates don't support partial mode at all */
+} PartialAggType;
 
 extern Expr *make_opclause(Oid opno, Oid opresulttype, bool opretset,
 			  Expr *leftop, Expr *rightop,
@@ -47,6 +66,7 @@ extern Node *make_and_qual(Node *qual1, Node *qual2);
 extern Expr *make_ands_explicit(List *andclauses);
 extern List *make_ands_implicit(Expr *clause);
 
+extern PartialAggType aggregates_allow_partial(Node *clause);
 extern bool contain_agg_clause(Node *clause);
 extern void count_agg_clauses(PlannerInfo *root, Node *clause,
 				  AggClauseCosts *costs);
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index 275054f..c1819f6 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -60,9 +60,8 @@ extern Sort *make_sort_from_groupcols(PlannerInfo *root, List *groupcls,
 extern Agg *make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
 		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
-		 List *groupingSets,
-		 long numGroups,
-		 Plan *lefttree);
+		 List *groupingSets, long numGroups, bool combineStates,
+		 bool finalizeAggs, bool serialStates, Plan *lefttree);
 extern WindowAgg *make_windowagg(PlannerInfo *root, List *tlist,
 			   List *windowFuncs, Index winref,
 			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
diff --git a/src/include/parser/parse_agg.h b/src/include/parser/parse_agg.h
index 3e336b9..43be714 100644
--- a/src/include/parser/parse_agg.h
+++ b/src/include/parser/parse_agg.h
@@ -46,6 +46,23 @@ extern void build_aggregate_transfn_expr(Oid *agg_input_types,
 						Expr **transfnexpr,
 						Expr **invtransfnexpr);
 
+extern void build_aggregate_combinefn_expr(Oid agg_state_type,
+										   Oid agg_input_collation,
+										   Oid combinefn_oid,
+										   Expr **combinefnexpr);
+
+extern void build_aggregate_serialfn_expr(Oid agg_state_type,
+										  Oid agg_serial_type,
+										  Oid agg_input_collation,
+										  Oid serialfn_oid,
+										  Expr **serialfnexpr);
+
+extern void build_aggregate_deserialfn_expr(Oid agg_state_type,
+											Oid agg_serial_type,
+											Oid agg_input_collation,
+											Oid deserialfn_oid,
+											Expr **deserialfnexpr);
+
 extern void build_aggregate_finalfn_expr(Oid *agg_input_types,
 						int num_finalfn_inputs,
 						Oid agg_state_type,
diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h
index b35d206..afb195e 100644
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@@ -1036,6 +1036,9 @@ extern Datum float4_numeric(PG_FUNCTION_ARGS);
 extern Datum numeric_float4(PG_FUNCTION_ARGS);
 extern Datum numeric_accum(PG_FUNCTION_ARGS);
 extern Datum numeric_avg_accum(PG_FUNCTION_ARGS);
+extern Datum numeric_avg_combine(PG_FUNCTION_ARGS);
+extern Datum numeric_avg_serialize(PG_FUNCTION_ARGS);
+extern Datum numeric_avg_deserialize(PG_FUNCTION_ARGS);
 extern Datum numeric_accum_inv(PG_FUNCTION_ARGS);
 extern Datum int2_accum(PG_FUNCTION_ARGS);
 extern Datum int4_accum(PG_FUNCTION_ARGS);
diff --git a/src/test/regress/expected/create_aggregate.out b/src/test/regress/expected/create_aggregate.out
index 82a34fb..14f73c4 100644
--- a/src/test/regress/expected/create_aggregate.out
+++ b/src/test/regress/expected/create_aggregate.out
@@ -101,6 +101,93 @@ CREATE AGGREGATE sumdouble (float8)
     msfunc = float8pl,
     minvfunc = float8mi
 );
+-- aggregate combine and serialization functions
+-- Ensure stype and serialtype can't be the same
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = internal
+);
+ERROR:  aggregate serial data type cannot be "internal"
+-- if serialtype is specified we need a serialfunc and deserialfunc
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text
+);
+ERROR:  aggregate serialfunc must be specified when serialtype is specified
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize
+);
+ERROR:  aggregate deserialfunc must be specified when serialtype is specified
+-- serialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_deserialize,
+	deserialfunc = numeric_avg_deserialize
+);
+ERROR:  function numeric_avg_deserialize(internal) does not exist
+-- deserialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_serialize
+);
+ERROR:  function numeric_avg_serialize(text) does not exist
+-- ensure return type of serialfunc is checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = bytea,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize
+);
+ERROR:  return type of serial function numeric_avg_serialize is not bytea
+-- ensure combine function parameters are checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = int4larger
+);
+ERROR:  function int4larger(internal, internal) does not exist
+-- ensure create aggregate works.
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	finalfunc = numeric_avg,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = numeric_avg_combine
+);
+-- Ensure all these functions made it into the catalog
+SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype,aggserialfn,aggdeserialfn,aggserialtype
+FROM pg_aggregate
+WHERE aggfnoid = 'myavg'::REGPROC;
+ aggfnoid |    aggtransfn     |    aggcombinefn     | aggtranstype |      aggserialfn      |      aggdeserialfn      | aggserialtype 
+----------+-------------------+---------------------+--------------+-----------------------+-------------------------+---------------
+ myavg    | numeric_avg_accum | numeric_avg_combine |         2281 | numeric_avg_serialize | numeric_avg_deserialize |            25
+(1 row)
+
+DROP AGGREGATE myavg (numeric);
 -- invalid: nonstrict inverse with strict forward function
 CREATE FUNCTION float8mi_n(float8, float8) RETURNS float8 AS
 $$ SELECT $1 - $2; $$
diff --git a/src/test/regress/sql/create_aggregate.sql b/src/test/regress/sql/create_aggregate.sql
index 0ec1572..8395e5d 100644
--- a/src/test/regress/sql/create_aggregate.sql
+++ b/src/test/regress/sql/create_aggregate.sql
@@ -115,6 +115,92 @@ CREATE AGGREGATE sumdouble (float8)
     minvfunc = float8mi
 );
 
+-- aggregate combine and serialization functions
+
+-- Ensure stype and serialtype can't be the same
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = internal
+);
+
+-- if serialtype is specified we need a serialfunc and deserialfunc
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text
+);
+
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize
+);
+
+-- serialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_deserialize,
+	deserialfunc = numeric_avg_deserialize
+);
+
+-- deserialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_serialize
+);
+
+-- ensure return type of serialfunc is checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = bytea,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize
+);
+
+-- ensure combine function parameters are checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = int4larger
+);
+
+-- ensure create aggregate works.
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	finalfunc = numeric_avg,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = numeric_avg_combine
+);
+
+-- Ensure all these functions made it into the catalog
+SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype,aggserialfn,aggdeserialfn,aggserialtype
+FROM pg_aggregate
+WHERE aggfnoid = 'myavg'::REGPROC;
+
+DROP AGGREGATE myavg (numeric);
+
 -- invalid: nonstrict inverse with strict forward function
 
 CREATE FUNCTION float8mi_n(float8, float8) RETURNS float8 AS

diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index f49114a..a2c29c4 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -756,11 +756,18 @@ advance_transition_function(AggState *aggstate,
 	aggstate->curpertrans = NULL;
 
 	/*
-	 * If pass-by-ref datatype, must copy the new value into aggcontext and
-	 * pfree the prior transValue.  But if transfn returned a pointer to its
-	 * first input, we don't need to do anything.
+	 * If we got a R/W pointer to an expanded object, we can just take over
+	 * control of the object.  Any other pass-by-ref value must be copied into
+	 * aggcontext and the prior value freed; with the exception that if transfn
+	 * returned a pointer to its first input, we don't need to do anything.
 	 */
-	if (!pertrans->transtypeByVal &&
+	if (DatumIsReadWriteExpandedObject(newVal, fcinfo->isnull,
+									   pertrans->transtypeLen))
+	{
+		newVal = TransferExpandedObject(newVal,
+		  aggstate->aggcontexts[aggstate->current_set]->ecxt_per_tuple_memory);
+	}
+	else if (!pertrans->transtypeByVal &&
 		DatumGetPointer(newVal) != DatumGetPointer(pergroupstate->transValue))
 	{
 		if (!fcinfo->isnull)
diff --git a/src/backend/utils/adt/Makefile b/src/backend/utils/adt/Makefile
index 2cb7bab..61c9359 100644
--- a/src/backend/utils/adt/Makefile
+++ b/src/backend/utils/adt/Makefile
@@ -12,7 +12,7 @@ include $(top_builddir)/src/Makefile.global
 OBJS = acl.o arrayfuncs.o array_expanded.o array_selfuncs.o \
 	array_typanalyze.o array_userfuncs.o arrayutils.o ascii.o \
 	bool.o cash.o char.o date.o datetime.o datum.o dbsize.o domains.o \
-	encode.o enum.o expandeddatum.o \
+	encode.o enum.o expandeddatum.o expandedstring.o \
 	float.o format_type.o formatting.o genfile.o \
 	geo_ops.o geo_selfuncs.o inet_cidr_ntop.o inet_net_pton.o int.o \
 	int8.o json.o jsonb.o jsonb_gin.o jsonb_op.o jsonb_util.o \
diff --git a/src/backend/utils/adt/expandedstring.c b/src/backend/utils/adt/expandedstring.c
new file mode 100644
index 0000000..4e279a3
--- /dev/null
+++ b/src/backend/utils/adt/expandedstring.c
@@ -0,0 +1,86 @@
+/*-------------------------------------------------------------------------
+ *
+ * expandedstring.c
+ *	  Expand a varlena into a StringInfo.
+ *
+ * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/adt/expandeddatum.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "fmgr.h"
+#include "utils/expandedstring.h"
+#include "utils/memutils.h"
+
+static Size ESI_get_flat_size(ExpandedObjectHeader *eohptr);
+static void ESI_flatten_into(ExpandedObjectHeader *eohptr,
+				 void *result, Size allocated_size);
+
+static const ExpandedObjectMethods ESI_methods =
+{
+	ESI_get_flat_size,
+	ESI_flatten_into
+};
+
+/*
+ * Construct an expanded datum consisting of an empty StringInfo.
+ *
+ * Caller must ensure that CurrentMemoryContext points to a context with
+ * a suitable lifetime.
+ */
+ExpandedStringInfoHeader *
+GetExpandedStringInfo(void)
+{
+	ExpandedStringInfoHeader *esih;
+	MemoryContext	objcxt;
+	MemoryContext	oldcxt;
+
+	objcxt = AllocSetContextCreate(CurrentMemoryContext,
+								   "stringinfo expanded object",
+								   ALLOCSET_SMALL_MINSIZE,
+								   ALLOCSET_SMALL_INITSIZE,
+								   ALLOCSET_DEFAULT_MAXSIZE);
+
+	oldcxt = MemoryContextSwitchTo(objcxt);	
+	esih = palloc(sizeof(ExpandedStringInfoHeader));
+	EOH_init_header(&esih->hdr, &ESI_methods, objcxt);
+	initStringInfo(&esih->buf);
+	MemoryContextSwitchTo(oldcxt);
+
+	return esih;
+}
+
+/*
+ * The space required to flatten a StringInfo back to a plain old varlena is
+ * just the number of bytes we have in the buffer, plus the size of a 4-byte
+ * header.  Even if the buffer is short, we can't flatten to a packed
+ * representation.
+ */
+static Size
+ESI_get_flat_size(ExpandedObjectHeader *eohptr)
+{
+	ExpandedStringInfoHeader *esih = (ExpandedStringInfoHeader *) eohptr;
+
+	return VARHDRSZ + esih->buf.len;
+}
+
+/*
+ * Flattening a StringInfo just involves copying the data into the allocated
+ * space.
+ */
+static void
+ESI_flatten_into(ExpandedObjectHeader *eohptr,
+				 void *result, Size allocated_size)
+{
+	ExpandedStringInfoHeader *esih = (ExpandedStringInfoHeader *) eohptr;
+
+	Assert(allocated_size == VARHDRSZ + esih->buf.len);
+	memcpy(VARDATA(result), esih->buf.data, esih->buf.len);
+	SET_VARSIZE(result, VARHDRSZ + esih->buf.len);
+}
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 8683188..09d7c7e 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -30,6 +30,7 @@
 #include "regex/regex.h"
 #include "utils/builtins.h"
 #include "utils/bytea.h"
+#include "utils/expandedstring.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
 #include "utils/pg_locale.h"
@@ -4357,16 +4358,6 @@ pg_column_size(PG_FUNCTION_ARGS)
 	PG_RETURN_INT32(result);
 }
 
-/*
- * string_agg - Concatenates values and returns string.
- *
- * Syntax: string_agg(value text, delimiter text) RETURNS text
- *
- * Note: Any NULL values are ignored. The first-call delimiter isn't
- * actually used at all, and on subsequent calls the delimiter precedes
- * the associated value.
- */
-
 /* subroutine to initialize state */
 static StringInfo
 makeStringAggState(FunctionCallInfo fcinfo)
@@ -4392,46 +4383,54 @@ makeStringAggState(FunctionCallInfo fcinfo)
 	return state;
 }
 
+/*
+ * string_agg - Concatenates values and returns string.
+ *
+ * Syntax: string_agg(value text, delimiter text) RETURNS text
+ *
+ * Note: Any NULL values are ignored. The first-call delimiter isn't
+ * actually used at all, and on subsequent calls the delimiter precedes
+ * the associated value.
+ */
 Datum
 string_agg_transfn(PG_FUNCTION_ARGS)
 {
-	StringInfo	state;
+	ExpandedStringInfoHeader *state;
 
-	state = PG_ARGISNULL(0) ? NULL : (StringInfo) PG_GETARG_POINTER(0);
-
-	/* Append the value unless null. */
-	if (!PG_ARGISNULL(1))
+	/* If the second argument is NULL, just return the first argument. */
+	if (PG_ARGISNULL(1))
 	{
-		/* On the first time through, we ignore the delimiter. */
-		if (state == NULL)
-			state = makeStringAggState(fcinfo);
-		else if (!PG_ARGISNULL(2))
-			appendStringInfoText(state, PG_GETARG_TEXT_PP(2));	/* delimiter */
-
-		appendStringInfoText(state, PG_GETARG_TEXT_PP(1));		/* value */
+		if (PG_ARGISNULL(0))
+			PG_RETURN_NULL();
+		PG_RETURN_DATUM(PG_GETARG_DATUM(0));
 	}
 
 	/*
-	 * The transition type for string_agg() is declared to be "internal",
-	 * which is a pass-by-value type the same size as a pointer.
+	 * Expand the first argument if needed; then, add any delimeter (unless
+	 * the first argument is NULL).
 	 */
-	PG_RETURN_POINTER(state);
-}
-
-Datum
-string_agg_finalfn(PG_FUNCTION_ARGS)
-{
-	StringInfo	state;
-
-	/* cannot be called directly because of internal-type argument */
-	Assert(AggCheckCallContext(fcinfo, NULL));
+	if (!PG_ARGISNULL(0) && VARATT_IS_EXTERNAL_EXPANDED_RW(PG_GETARG_DATUM(0)))
+	{
+        state = (ExpandedStringInfoHeader *) DatumGetEOHP(PG_GETARG_DATUM(0));
+		if (!PG_ARGISNULL(2))
+			appendStringInfoText(&state->buf, PG_GETARG_TEXT_PP(2));
+	}
+	else
+	{
+		state = GetExpandedStringInfo();
+		/* Note that if the transition state is NULL, we skip the delimiter. */
+		if (!PG_ARGISNULL(0))
+		{
+			appendStringInfoText(&state->buf, PG_GETARG_TEXT_PP(0));
+			if (!PG_ARGISNULL(2))
+				appendStringInfoText(&state->buf, PG_GETARG_TEXT_PP(2));
+		}
+	}
 
-	state = PG_ARGISNULL(0) ? NULL : (StringInfo) PG_GETARG_POINTER(0);
+	/* Append second argument to first. */
+	appendStringInfoText(&state->buf, PG_GETARG_TEXT_PP(1));
 
-	if (state != NULL)
-		PG_RETURN_TEXT_P(cstring_to_text_with_len(state->data, state->len));
-	else
-		PG_RETURN_NULL();
+	PG_RETURN_DATUM(EOHPGetRWDatum(&state->hdr));
 }
 
 /*
diff --git a/src/include/catalog/pg_aggregate.h b/src/include/catalog/pg_aggregate.h
index 28b0669..d8f9649 100644
--- a/src/include/catalog/pg_aggregate.h
+++ b/src/include/catalog/pg_aggregate.h
@@ -279,7 +279,7 @@ DATA(insert ( 2335	n 0 array_agg_transfn	array_agg_finalfn	-				-				-				t f 0
 DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn -		-				-				t f 0	2281	0	0		0	_null_ _null_ ));
 
 /* text */
-DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3538	n 0 string_agg_transfn	-		-				-				-				f f 0	25 0	0		0	_null_ _null_ ));
 
 /* bytea */
 DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-				-				-		f f 0	2281	0	0		0	_null_ _null_ ));
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index f58672e..6def62d 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -2612,10 +2612,8 @@ DESCR("aggregate final function");
 DATA(insert OID = 2817 (  float8_corr				PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 701 "1022" _null_ _null_ _null_ _null_ _null_ float8_corr _null_ _null_ _null_ ));
 DESCR("aggregate final function");
 
-DATA(insert OID = 3535 (  string_agg_transfn		PGNSP PGUID 12 1 0 0 0 f f f f f f i s 3 0 2281 "2281 25 25" _null_ _null_ _null_ _null_ _null_ string_agg_transfn _null_ _null_ _null_ ));
+DATA(insert OID = 3535 (  string_agg_transfn		PGNSP PGUID 12 1 0 0 0 f f f f f f i s 3 0 25 "25 25 25" _null_ _null_ _null_ _null_ _null_ string_agg_transfn _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
-DATA(insert OID = 3536 (  string_agg_finalfn		PGNSP PGUID 12 1 0 0 0 f f f f f f i s 1 0 25 "2281" _null_ _null_ _null_ _null_ _null_ string_agg_finalfn _null_ _null_ _null_ ));
-DESCR("aggregate final function");
 DATA(insert OID = 3538 (  string_agg				PGNSP PGUID 12 1 0 0 0 t f f f f f i s 2 0 25 "25 25" _null_ _null_ _null_ _null_ _null_ aggregate_dummy _null_ _null_ _null_ ));
 DESCR("concatenate aggregate input into a string");
 DATA(insert OID = 3543 (  bytea_string_agg_transfn	PGNSP PGUID 12 1 0 0 0 f f f f f f i s 3 0 2281 "2281 17 17" _null_ _null_ _null_ _null_ _null_ bytea_string_agg_transfn _null_ _null_ _null_ ));
diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h
index b35d206..4af77b9 100644
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@@ -841,7 +841,6 @@ extern Datum pg_column_size(PG_FUNCTION_ARGS);
 extern Datum bytea_string_agg_transfn(PG_FUNCTION_ARGS);
 extern Datum bytea_string_agg_finalfn(PG_FUNCTION_ARGS);
 extern Datum string_agg_transfn(PG_FUNCTION_ARGS);
-extern Datum string_agg_finalfn(PG_FUNCTION_ARGS);
 
 extern Datum text_concat(PG_FUNCTION_ARGS);
 extern Datum text_concat_ws(PG_FUNCTION_ARGS);
diff --git a/src/include/utils/expandedstring.h b/src/include/utils/expandedstring.h
new file mode 100644
index 0000000..bb03d89
--- /dev/null
+++ b/src/include/utils/expandedstring.h
@@ -0,0 +1,31 @@
+/*-------------------------------------------------------------------------
+ *
+ * expandedstring.h
+ *	  Expand a varlena into a StringInfo for faster in-memory manipulation.
+ *
+ * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/utils/expandedstring.h
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef EXPANDEDSTRING_H
+#define EXPANDEDSTRING_H
+
+#include "lib/stringinfo.h"
+#include "utils/expandeddatum.h"
+
+typedef struct ExpandedStringInfoHeader
+{
+	/* Standard header for expanded objects */
+	ExpandedObjectHeader hdr;
+
+	/* String info */
+	StringInfoData		buf;
+} ExpandedStringInfoHeader;
+
+extern ExpandedStringInfoHeader *GetExpandedStringInfo(void);
+
+#endif

diff --git a/src/backend/utils/mmgr/aset.c b/src/backend/utils/mmgr/aset.c
index d26991e..3730a21 100644
--- a/src/backend/utils/mmgr/aset.c
+++ b/src/backend/utils/mmgr/aset.c
@@ -164,6 +164,14 @@ typedef void *AllocPointer;
 /*
  * AllocSetContext is our standard implementation of MemoryContext.
  *
+ * Note: An AllocSetContext can include one or more "keeper" blocks which
+ * are not freed when the context is reset.  "keeper" should point to the
+ * first of these blocks.  Sometimes, there may be a block which shouldn't
+ * be freed even when the context is deleted (because that space isn't a
+ * separate allocation); if so, "stopper" can point to this block.  "keeper"
+ * must be set whenever "stopper" is set, and must point to the same block
+ * as "stopper" or an earlier one.
+ *
  * Note: header.isReset means there is nothing for AllocSetReset to do.
  * This is different from the aset being physically empty (empty blocks list)
  * because we may still have a keeper block.  It's also different from the set
@@ -181,7 +189,8 @@ typedef struct AllocSetContext
 	Size		maxBlockSize;	/* maximum block size */
 	Size		nextBlockSize;	/* next block size to allocate */
 	Size		allocChunkLimit;	/* effective chunk size limit */
-	AllocBlock	keeper;			/* if not NULL, keep this block over resets */
+	AllocBlock	keeper;		/* on reset, stop freeing when we reach this */
+	AllocBlock	stopper;	/* on delete, stop freeing when we reach this */
 } AllocSetContext;
 
 typedef AllocSetContext *AllocSet;
@@ -248,7 +257,6 @@ typedef struct AllocChunkData
 static void *AllocSetAlloc(MemoryContext context, Size size);
 static void AllocSetFree(MemoryContext context, void *pointer);
 static void *AllocSetRealloc(MemoryContext context, void *pointer, Size size);
-static void AllocSetInit(MemoryContext context);
 static void AllocSetReset(MemoryContext context);
 static void AllocSetDelete(MemoryContext context);
 static Size AllocSetGetChunkSpace(MemoryContext context, void *pointer);
@@ -267,7 +275,6 @@ static MemoryContextMethods AllocSetMethods = {
 	AllocSetAlloc,
 	AllocSetFree,
 	AllocSetRealloc,
-	AllocSetInit,
 	AllocSetReset,
 	AllocSetDelete,
 	AllocSetGetChunkSpace,
@@ -440,13 +447,45 @@ AllocSetContextCreate(MemoryContext parent,
 					  Size maxBlockSize)
 {
 	AllocSet	set;
+	Size		needed;
+	Size		request_size;
+
+	/*
+	 * We always allocate at least 1kB so that we can service a few small
+	 * allocations without needing to request more memory from the operating
+	 * system.  If the name is extremely long or a minimum context size is
+	 * specified, we might need to allocate more space.
+	 */
+	needed = MAXALIGN(sizeof(AllocSetContext) + strlen(name) + 1);
+	request_size = Max(MAXALIGN(needed) + minContextSize, 1024);
+
+	/* Get initial space */
+	if (TopMemoryContext != NULL)
+	{
+		/* Normal case: allocate from TopMemoryContext */
+		set = MemoryContextAlloc(TopMemoryContext, request_size);
+	}
+	else
+	{
+		/* Special case for startup: use good ol' malloc. */
+		set = malloc(request_size);
+		if (set == NULL)
+			elog(FATAL, "out of memory");
+	}
 
-	/* Do the type-independent part of context creation */
-	set = (AllocSet) MemoryContextCreate(T_AllocSetContext,
-										 sizeof(AllocSetContext),
-										 &AllocSetMethods,
-										 parent,
-										 name);
+	/*
+	 * Initialize the node.  Note that the name and the containing context
+	 * are both stored in the same allocation, so there are no steps that
+	 * can fail after we've allocated memory and before MemoryContextCreate
+	 * gets called.  That's good, because any such failure would leak
+	 * memory.
+	 */
+	MemSetAligned(set, 0, sizeof(AllocSetContext));
+	set->header.type = T_AllocSetContext;
+	set->header.methods = &AllocSetMethods;
+	set->header.name = ((char *) set) + sizeof(AllocSetContext);
+	strcpy(set->header.name, name);
+	MemoryContextCreate(&set->header, parent);
 
 	/*
 	 * Make sure alloc parameters are reasonable, and save them.
@@ -489,30 +528,20 @@ AllocSetContextCreate(MemoryContext parent,
 		set->allocChunkLimit >>= 1;
 
 	/*
-	 * Grab always-allocated space, if requested
+	 * Turn any remaining space into an allocation block that is never freed.
 	 */
-	if (minContextSize > ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ)
+	if (request_size > needed + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ)
 	{
-		Size		blksize = MAXALIGN(minContextSize);
-		AllocBlock	block;
+		AllocBlock	block = (AllocBlock) (((char *) set) + needed);
 
-		block = (AllocBlock) malloc(blksize);
-		if (block == NULL)
-		{
-			MemoryContextStats(TopMemoryContext);
-			ereport(ERROR,
-					(errcode(ERRCODE_OUT_OF_MEMORY),
-					 errmsg("out of memory"),
-					 errdetail("Failed while creating memory context \"%s\".",
-							   name)));
-		}
 		block->aset = set;
 		block->freeptr = ((char *) block) + ALLOC_BLOCKHDRSZ;
-		block->endptr = ((char *) block) + blksize;
+		block->endptr = ((char *) set) + request_size;
 		block->next = set->blocks;
 		set->blocks = block;
-		/* Mark block as not to be released at reset time */
+		/* Mark block as not to be released - ever */
 		set->keeper = block;
+		set->stopper = block;
 
 		/* Mark unallocated space NOACCESS; leave the block header alone. */
 		VALGRIND_MAKE_MEM_NOACCESS(block->freeptr,
@@ -523,27 +552,6 @@ AllocSetContextCreate(MemoryContext parent,
 }
 
 /*
- * AllocSetInit
- *		Context-type-specific initialization routine.
- *
- * This is called by MemoryContextCreate() after setting up the
- * generic MemoryContext fields and before linking the new context
- * into the context tree.  We must do whatever is needed to make the
- * new context minimally valid for deletion.  We must *not* risk
- * failure --- thus, for example, allocating more memory is not cool.
- * (AllocSetContextCreate can allocate memory when it gets control
- * back, however.)
- */
-static void
-AllocSetInit(MemoryContext context)
-{
-	/*
-	 * Since MemoryContextCreate already zeroed the context node, we don't
-	 * have to do anything here: it's already OK.
-	 */
-}
-
-/*
  * AllocSetReset
  *		Frees all memory which is allocated in the given set.
  *
@@ -634,7 +642,7 @@ AllocSetDelete(MemoryContext context)
 	set->blocks = NULL;
 	set->keeper = NULL;
 
-	while (block != NULL)
+	while (block != set->stopper)
 	{
 		AllocBlock	next = block->next;
 
@@ -644,6 +652,8 @@ AllocSetDelete(MemoryContext context)
 		free(block);
 		block = next;
 	}
+
+	pfree(context);
 }
 
 /*
diff --git a/src/backend/utils/mmgr/mcxt.c b/src/backend/utils/mmgr/mcxt.c
index 2bfd364..87cc0f2 100644
--- a/src/backend/utils/mmgr/mcxt.c
+++ b/src/backend/utils/mmgr/mcxt.c
@@ -194,10 +194,9 @@ MemoryContextResetChildren(MemoryContext context)
  *		Delete a context and its descendants, and release all space
  *		allocated therein.
  *
- * The type-specific delete routine removes all subsidiary storage
- * for the context, but we have to delete the context node itself,
- * as well as recurse to get the children.  We must also delink the
- * node from its parent, if it has one.
+ * The type-specific delete routine removes the context itself and all
+ * subsidiary storage, but we have to recurse to get the children.  We must
+ * also delink the node from its parent, if it has one.
  */
 void
 MemoryContextDelete(MemoryContext context)
@@ -227,7 +226,6 @@ MemoryContextDelete(MemoryContext context)
 
 	(*context->methods->delete_context) (context);
 	VALGRIND_DESTROY_MEMPOOL(context);
-	pfree(context);
 }
 
 /*
@@ -640,89 +638,25 @@ MemoryContextContains(MemoryContext context, void *pointer)
  * This is only intended to be called by context-type-specific
  * context creation routines, not by the unwashed masses.
  *
- * The context creation procedure is a little bit tricky because
- * we want to be sure that we don't leave the context tree invalid
- * in case of failure (such as insufficient memory to allocate the
- * context node itself).  The procedure goes like this:
- *	1.  Context-type-specific routine first calls MemoryContextCreate(),
- *		passing the appropriate tag/size/methods values (the methods
- *		pointer will ordinarily point to statically allocated data).
- *		The parent and name parameters usually come from the caller.
- *	2.  MemoryContextCreate() attempts to allocate the context node,
- *		plus space for the name.  If this fails we can ereport() with no
- *		damage done.
- *	3.  We fill in all of the type-independent MemoryContext fields.
- *	4.  We call the type-specific init routine (using the methods pointer).
- *		The init routine is required to make the node minimally valid
- *		with zero chance of failure --- it can't allocate more memory,
- *		for example.
- *	5.  Now we have a minimally valid node that can behave correctly
- *		when told to reset or delete itself.  We link the node to its
- *		parent (if any), making the node part of the context tree.
- *	6.  We return to the context-type-specific routine, which finishes
- *		up type-specific initialization.  This routine can now do things
- *		that might fail (like allocate more memory), so long as it's
- *		sure the node is left in a state that delete will handle.
- *
- * This protocol doesn't prevent us from leaking memory if step 6 fails
- * during creation of a top-level context, since there's no parent link
- * in that case.  However, if you run out of memory while you're building
- * a top-level context, you might as well go home anyway...
- *
- * Normally, the context node and the name are allocated from
- * TopMemoryContext (NOT from the parent context, since the node must
- * survive resets of its parent context!).  However, this routine is itself
- * used to create TopMemoryContext!  If we see that TopMemoryContext is NULL,
- * we assume we are creating TopMemoryContext and use malloc() to allocate
- * the node.
- *
- * Note that the name field of a MemoryContext does not point to
- * separately-allocated storage, so it should not be freed at context
- * deletion.
+ * The caller must initialize a minimally-valid MemoryContext - the name
+ * and methods pointers must be valid, in particular - before calling this
+ * function, being careful to do so in a way that does not risk leaking
+ * memory used for the context or name.  Then, it should call this function
+ * to link the new context into the context tree.  Finally, it can finish
+ * any initialization steps that might fail (like allocate more memory),
+ * so long as it's sure the node will be left in a state that delete will
+ * handle.
  *--------------------
  */
-MemoryContext
-MemoryContextCreate(NodeTag tag, Size size,
-					MemoryContextMethods *methods,
-					MemoryContext parent,
-					const char *name)
+void
+MemoryContextCreate(MemoryContext node, MemoryContext parent)
 {
-	MemoryContext node;
-	Size		needed = size + strlen(name) + 1;
-
 	/* creating new memory contexts is not allowed in a critical section */
 	Assert(CritSectionCount == 0);
 
-	/* Get space for node and name */
-	if (TopMemoryContext != NULL)
-	{
-		/* Normal case: allocate the node in TopMemoryContext */
-		node = (MemoryContext) MemoryContextAlloc(TopMemoryContext,
-												  needed);
-	}
-	else
-	{
-		/* Special case for startup: use good ol' malloc */
-		node = (MemoryContext) malloc(needed);
-		Assert(node != NULL);
-	}
-
-	/* Initialize the node as best we can */
-	MemSet(node, 0, size);
-	node->type = tag;
-	node->methods = methods;
-	node->parent = NULL;		/* for the moment */
-	node->firstchild = NULL;
-	node->prevchild = NULL;
-	node->nextchild = NULL;
 	node->isReset = true;
-	node->name = ((char *) node) + size;
-	strcpy(node->name, name);
-
-	/* Type-specific routine finishes any other essential initialization */
-	(*node->methods->init) (node);
 
-	/* OK to link node to parent (if any) */
+	/* link node to parent (if any) */
 	/* Could use MemoryContextSetParent here, but doesn't seem worthwhile */
 	if (parent)
 	{
@@ -736,9 +670,6 @@ MemoryContextCreate(NodeTag tag, Size size,
 	}
 
 	VALGRIND_CREATE_MEMPOOL(node, 0, false);
-
-	/* Return to type-specific creation routine to finish up */
-	return node;
 }
 
 /*
diff --git a/src/include/nodes/memnodes.h b/src/include/nodes/memnodes.h
index ba069cc..56ea445 100644
--- a/src/include/nodes/memnodes.h
+++ b/src/include/nodes/memnodes.h
@@ -57,7 +57,6 @@ typedef struct MemoryContextMethods
 	/* call this free_p in case someone #define's free() */
 	void		(*free_p) (MemoryContext context, void *pointer);
 	void	   *(*realloc) (MemoryContext context, void *pointer, Size size);
-	void		(*init) (MemoryContext context);
 	void		(*reset) (MemoryContext context);
 	void		(*delete_context) (MemoryContext context);
 	Size		(*get_chunk_space) (MemoryContext context, void *pointer);
diff --git a/src/include/utils/memutils.h b/src/include/utils/memutils.h
index ae07705..8e1f645 100644
--- a/src/include/utils/memutils.h
+++ b/src/include/utils/memutils.h
@@ -118,10 +118,7 @@ extern bool MemoryContextContains(MemoryContext context, void *pointer);
  * context creation.  It's intended to be called from context-type-
  * specific creation routines, and noplace else.
  */
-extern MemoryContext MemoryContextCreate(NodeTag tag, Size size,
-					MemoryContextMethods *methods,
-					MemoryContext parent,
-					const char *name);
+extern void MemoryContextCreate(MemoryContext node, MemoryContext parent);
 
 
 /*

diff --git a/doc/src/sgml/ref/create_aggregate.sgml b/doc/src/sgml/ref/create_aggregate.sgml
index eaa410b..4bda23a 100644
--- a/doc/src/sgml/ref/create_aggregate.sgml
+++ b/doc/src/sgml/ref/create_aggregate.sgml
@@ -27,6 +27,7 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ <replacea
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -45,6 +46,7 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ [ <replac
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , HYPOTHETICAL ]
 )
@@ -58,6 +60,7 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
     [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ]
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
+    [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -105,12 +108,15 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
    functions:
    a state transition function
    <replaceable class="PARAMETER">sfunc</replaceable>,
-   and an optional final calculation function
-   <replaceable class="PARAMETER">ffunc</replaceable>.
+   an optional final calculation function
+   <replaceable class="PARAMETER">ffunc</replaceable>,
+   and an optional combine function
+   <replaceable class="PARAMETER">combinefunc</replaceable>.
    These are used as follows:
 <programlisting>
 <replaceable class="PARAMETER">sfunc</replaceable>( internal-state, next-data-values ) ---> next-internal-state
 <replaceable class="PARAMETER">ffunc</replaceable>( internal-state ) ---> aggregate-value
+<replaceable class="PARAMETER">combinefunc</replaceable>( internal-state, internal-state ) ---> next-internal-state
 </programlisting>
   </para>
 
@@ -128,6 +134,12 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
   </para>
 
   <para>
+   An aggregate function may also supply a combining function, which allows
+   the aggregation process to be broken down into multiple steps.  This
+   facilitates query optimization techniques such as parallel query.
+  </para>
+
+  <para>
    An aggregate function can provide an initial condition,
    that is, an initial value for the internal state value.
    This is specified and stored in the database as a value of type
diff --git a/src/backend/catalog/pg_aggregate.c b/src/backend/catalog/pg_aggregate.c
index 1d845ec..f8dd244 100644
--- a/src/backend/catalog/pg_aggregate.c
+++ b/src/backend/catalog/pg_aggregate.c
@@ -57,6 +57,7 @@ AggregateCreate(const char *aggName,
 				Oid variadicArgType,
 				List *aggtransfnName,
 				List *aggfinalfnName,
+				List *aggcombinefnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
@@ -77,6 +78,7 @@ AggregateCreate(const char *aggName,
 	Form_pg_proc proc;
 	Oid			transfn;
 	Oid			finalfn = InvalidOid;	/* can be omitted */
+	Oid			combinefn = InvalidOid;	/* can be omitted */
 	Oid			mtransfn = InvalidOid;	/* can be omitted */
 	Oid			minvtransfn = InvalidOid;		/* can be omitted */
 	Oid			mfinalfn = InvalidOid;	/* can be omitted */
@@ -396,6 +398,30 @@ AggregateCreate(const char *aggName,
 	}
 	Assert(OidIsValid(finaltype));
 
+	/* handle the combinefn, if supplied */
+	if (aggcombinefnName)
+	{
+		Oid combineType;
+
+		/*
+		 * Combine function must have 2 argument, each of which is the
+		 * trans type
+		 */
+		fnArgs[0] = aggTransType;
+		fnArgs[1] = aggTransType;
+
+		combinefn = lookup_agg_function(aggcombinefnName, 2, fnArgs,
+										variadicArgType, &combineType);
+
+		/* Ensure the return type matches the aggregates trans type */
+		if (combineType != aggTransType)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+			errmsg("return type of combine function %s is not %s",
+				   NameListToString(aggcombinefnName),
+				   format_type_be(aggTransType))));
+	}
+
 	/*
 	 * If finaltype (i.e. aggregate return type) is polymorphic, inputs must
 	 * be polymorphic also, else parser will fail to deduce result type.
@@ -567,6 +593,7 @@ AggregateCreate(const char *aggName,
 	values[Anum_pg_aggregate_aggnumdirectargs - 1] = Int16GetDatum(numDirectArgs);
 	values[Anum_pg_aggregate_aggtransfn - 1] = ObjectIdGetDatum(transfn);
 	values[Anum_pg_aggregate_aggfinalfn - 1] = ObjectIdGetDatum(finalfn);
+	values[Anum_pg_aggregate_aggcombinefn - 1] = ObjectIdGetDatum(combinefn);
 	values[Anum_pg_aggregate_aggmtransfn - 1] = ObjectIdGetDatum(mtransfn);
 	values[Anum_pg_aggregate_aggminvtransfn - 1] = ObjectIdGetDatum(minvtransfn);
 	values[Anum_pg_aggregate_aggmfinalfn - 1] = ObjectIdGetDatum(mfinalfn);
@@ -618,6 +645,15 @@ AggregateCreate(const char *aggName,
 		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
 	}
 
+	/* Depends on combine function, if any */
+	if (OidIsValid(combinefn))
+	{
+		referenced.classId = ProcedureRelationId;
+		referenced.objectId = combinefn;
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
 	/* Depends on forward transition function, if any */
 	if (OidIsValid(mtransfn))
 	{
diff --git a/src/backend/commands/aggregatecmds.c b/src/backend/commands/aggregatecmds.c
index 441b3aa..59bc6e6 100644
--- a/src/backend/commands/aggregatecmds.c
+++ b/src/backend/commands/aggregatecmds.c
@@ -61,6 +61,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	char		aggKind = AGGKIND_NORMAL;
 	List	   *transfuncName = NIL;
 	List	   *finalfuncName = NIL;
+	List	   *combinefuncName = NIL;
 	List	   *mtransfuncName = NIL;
 	List	   *minvtransfuncName = NIL;
 	List	   *mfinalfuncName = NIL;
@@ -124,6 +125,8 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 			transfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "finalfunc") == 0)
 			finalfuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "combinefunc") == 0)
+			combinefuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "msfunc") == 0)
 			mtransfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "minvfunc") == 0)
@@ -383,6 +386,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 						   variadicArgType,
 						   transfuncName,		/* step function name */
 						   finalfuncName,		/* final function name */
+						   combinefuncName,		/* combine function name */
 						   mtransfuncName,		/* fwd trans function name */
 						   minvtransfuncName,	/* inv trans function name */
 						   mfinalfuncName,		/* final function name */
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 9827c39..58b5012 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -908,25 +908,38 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			pname = sname = "Group";
 			break;
 		case T_Agg:
-			sname = "Aggregate";
-			switch (((Agg *) plan)->aggstrategy)
 			{
-				case AGG_PLAIN:
-					pname = "Aggregate";
-					strategy = "Plain";
-					break;
-				case AGG_SORTED:
-					pname = "GroupAggregate";
-					strategy = "Sorted";
-					break;
-				case AGG_HASHED:
-					pname = "HashAggregate";
-					strategy = "Hashed";
-					break;
-				default:
-					pname = "Aggregate ???";
-					strategy = "???";
-					break;
+				char	   *modifier;
+				Agg		   *agg = (Agg *) plan;
+
+				sname = "Aggregate";
+
+				if (agg->finalizeAggs == false)
+					modifier = "Partial ";
+				else if (agg->combineStates == true)
+					modifier = "Finalize ";
+				else
+					modifier = "";
+
+				switch (agg->aggstrategy)
+				{
+					case AGG_PLAIN:
+						pname = psprintf("%sAggregate", modifier);
+						strategy = "Plain";
+						break;
+					case AGG_SORTED:
+						pname = psprintf("%sGroupAggregate", modifier);
+						strategy = "Sorted";
+						break;
+					case AGG_HASHED:
+						pname = psprintf("%sHashAggregate", modifier);
+						strategy = "Hashed";
+						break;
+					default:
+						pname = "Aggregate ???";
+						strategy = "???";
+						break;
+				}
 			}
 			break;
 		case T_WindowAgg:
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index f49114a..e0ef057 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -3,15 +3,46 @@
  * nodeAgg.c
  *	  Routines to handle aggregate nodes.
  *
- *	  ExecAgg evaluates each aggregate in the following steps:
+ *	  ExecAgg normally evaluates each aggregate in the following steps:
  *
  *		 transvalue = initcond
  *		 foreach input_tuple do
  *			transvalue = transfunc(transvalue, input_value(s))
  *		 result = finalfunc(transvalue, direct_argument(s))
  *
- *	  If a finalfunc is not supplied then the result is just the ending
- *	  value of transvalue.
+ *	  If a finalfunc is not supplied or finalizeAggs is false, then the result
+ *	  is just the ending value of transvalue.
+ *
+ *	  Other behavior is also supported and is controlled by the 'combineStates'
+ *	  and 'finalizeAggs'. 'combineStates' controls whether the trans func or
+ *	  the combine func is used during aggregation.  When 'combineStates' is
+ *	  true we expect other (previously) aggregated states as input rather than
+ *	  input tuples. This mode facilitates multiple aggregate stages which
+ *	  allows us to support pushing aggregation down deeper into the plan rather
+ *	  than leaving it for the final stage. For example with a query such as:
+ *
+ *	  SELECT count(*) FROM (SELECT * FROM a UNION ALL SELECT * FROM b);
+ *
+ *	  with this functionality the planner has the flexibility to generate a
+ *	  plan which performs count(*) on table a and table b separately and then
+ *	  add a combine phase to combine both results. In this case the combine
+ *	  function would simply add both counts together.
+ *
+ *	  When multiple aggregate stages exist the planner should have set the
+ *	  'finalizeAggs' to true only for the final aggregtion state, and each
+ *	  stage, apart from the very first one should have 'combineStates' set to
+ *	  true. This permits plans such as:
+ *
+ *		Finalize Aggregate
+ *			->  Partial Aggregate
+ *				->  Partial Aggregate
+ *
+ *	  Combine functions which use pass-by-ref states should be careful to
+ *	  always update the 1st state parameter by adding the 2nd parameter to it,
+ *	  rather than the other way around. If the 1st state is NULL, then it's not
+ *	  sufficient to simply return the 2nd state, as the memory context is
+ *	  incorrect. Instead a new state should be created in the correct aggregate
+ *	  memory context and the 2nd state should be copied over.
  *
  *	  If a normal aggregate call specifies DISTINCT or ORDER BY, we sort the
  *	  input tuples and eliminate duplicates (if required) before performing
@@ -134,6 +165,7 @@
 #include "catalog/objectaccess.h"
 #include "catalog/pg_aggregate.h"
 #include "catalog/pg_proc.h"
+#include "catalog/pg_type.h"
 #include "executor/executor.h"
 #include "executor/nodeAgg.h"
 #include "miscadmin.h"
@@ -197,7 +229,7 @@ typedef struct AggStatePerTransData
 	 */
 	int			numTransInputs;
 
-	/* Oid of the state transition function */
+	/* Oid of the state transition or combine function */
 	Oid			transfn_oid;
 
 	/* Oid of state value's datatype */
@@ -209,8 +241,8 @@ typedef struct AggStatePerTransData
 	List	   *aggdirectargs;	/* states of direct-argument expressions */
 
 	/*
-	 * fmgr lookup data for transition function.  Note in particular that the
-	 * fn_strict flag is kept here.
+	 * fmgr lookup data for transition function or combination function.  Note
+	 * in particular that the fn_strict flag is kept here.
 	 */
 	FmgrInfo	transfn;
 
@@ -421,6 +453,10 @@ static void advance_transition_function(AggState *aggstate,
 							AggStatePerTrans pertrans,
 							AggStatePerGroup pergroupstate);
 static void advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup);
+static void advance_combination_function(AggState *aggstate,
+							AggStatePerTrans pertrans,
+							AggStatePerGroup pergroupstate);
+static void combine_aggregates(AggState *aggstate, AggStatePerGroup pergroup);
 static void process_ordered_aggregate_single(AggState *aggstate,
 								 AggStatePerTrans pertrans,
 								 AggStatePerGroup pergroupstate);
@@ -458,7 +494,7 @@ static int find_compatible_peragg(Aggref *newagg, AggState *aggstate,
 static int find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 						 Oid aggtransfn, Oid aggtranstype,
 						 Datum initValue, bool initValueIsNull,
-						 List *possible_matches);
+						 List *transnos);
 
 
 /*
@@ -796,6 +832,8 @@ advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
 	int			numGroupingSets = Max(aggstate->phase->numsets, 1);
 	int			numTrans = aggstate->numtrans;
 
+	Assert(!aggstate->combineStates);
+
 	for (transno = 0; transno < numTrans; transno++)
 	{
 		AggStatePerTrans pertrans = &aggstate->pertrans[transno];
@@ -879,6 +917,130 @@ advance_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
 	}
 }
 
+/*
+ * combine_aggregates is used when running in 'combineState' mode. This
+ * advances each aggregate transition state by adding another transition state
+ * to it.
+ */
+static void
+combine_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
+{
+	int			transno;
+	int			numTrans = aggstate->numtrans;
+
+	/* combine not supported with grouping sets */
+	Assert(aggstate->phase->numsets == 0);
+	Assert(aggstate->combineStates);
+
+	for (transno = 0; transno < numTrans; transno++)
+	{
+		AggStatePerTrans pertrans = &aggstate->pertrans[transno];
+		TupleTableSlot *slot;
+		FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
+		AggStatePerGroup pergroupstate = &pergroup[transno];
+
+		/* Evaluate the current input expressions for this aggregate */
+		slot = ExecProject(pertrans->evalproj, NULL);
+		Assert(slot->tts_nvalid >= 1);
+
+		fcinfo->arg[1] = slot->tts_values[0];
+		fcinfo->argnull[1] = slot->tts_isnull[0];
+
+		advance_combination_function(aggstate, pertrans, pergroupstate);
+	}
+}
+
+/*
+ * Perform combination of states between 2 aggregate states. Effectively this
+ * 'adds' two states together by whichever logic is defined in the aggregate
+ * function's combine function.
+ *
+ * Note that in this case transfn is set to the combination function. This
+ * perhaps should be changed to avoid confusion, but one field is ok for now
+ * as they'll never be needed at the same time.
+ */
+static void
+advance_combination_function(AggState *aggstate,
+							 AggStatePerTrans pertrans,
+							 AggStatePerGroup pergroupstate)
+{
+	FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
+	MemoryContext oldContext;
+	Datum		newVal;
+
+	if (pertrans->transfn.fn_strict)
+	{
+		/* if we're asked to merge to a NULL state, then do nothing */
+		if (fcinfo->argnull[1])
+			return;
+
+		if (pergroupstate->noTransValue)
+		{
+			/*
+			 * transValue has not yet been initialized.  If pass-by-ref
+			 * datatype we must copy the combining state value into aggcontext.
+			 */
+			if (!pertrans->transtypeByVal)
+			{
+				oldContext = MemoryContextSwitchTo(
+					aggstate->aggcontexts[aggstate->current_set]->ecxt_per_tuple_memory);
+				pergroupstate->transValue = datumCopy(fcinfo->arg[1],
+													  pertrans->transtypeByVal,
+													  pertrans->transtypeLen);
+				MemoryContextSwitchTo(oldContext);
+			}
+			else
+				pergroupstate->transValue = fcinfo->arg[1];
+
+			pergroupstate->transValueIsNull = false;
+			pergroupstate->noTransValue = false;
+			return;
+		}
+	}
+
+	/* We run the combine functions in per-input-tuple memory context */
+	oldContext = MemoryContextSwitchTo(aggstate->tmpcontext->ecxt_per_tuple_memory);
+
+	/* set up aggstate->curpertrans for AggGetAggref() */
+	aggstate->curpertrans = pertrans;
+
+	/*
+	 * OK to call the combine function
+	 */
+	fcinfo->arg[0] = pergroupstate->transValue;
+	fcinfo->argnull[0] = pergroupstate->transValueIsNull;
+	fcinfo->isnull = false;		/* just in case combine func doesn't set it */
+
+	newVal = FunctionCallInvoke(fcinfo);
+
+	aggstate->curpertrans = NULL;
+
+	/*
+	 * If pass-by-ref datatype, must copy the new value into aggcontext and
+	 * pfree the prior transValue.  But if the combine function returned a
+	 * pointer to its first input, we don't need to do anything.
+	 */
+	if (!pertrans->transtypeByVal &&
+		DatumGetPointer(newVal) != DatumGetPointer(pergroupstate->transValue))
+	{
+		if (!fcinfo->isnull)
+		{
+			MemoryContextSwitchTo(aggstate->aggcontexts[aggstate->current_set]->ecxt_per_tuple_memory);
+			newVal = datumCopy(newVal,
+							   pertrans->transtypeByVal,
+							   pertrans->transtypeLen);
+		}
+		if (!pergroupstate->transValueIsNull)
+			pfree(DatumGetPointer(pergroupstate->transValue));
+	}
+
+	pergroupstate->transValue = newVal;
+	pergroupstate->transValueIsNull = fcinfo->isnull;
+
+	MemoryContextSwitchTo(oldContext);
+
+}
+
 
 /*
  * Run the transition function for a DISTINCT or ORDER BY aggregate
@@ -1278,8 +1440,14 @@ finalize_aggregates(AggState *aggstate,
 												pergroupstate);
 		}
 
-		finalize_aggregate(aggstate, peragg, pergroupstate,
-						   &aggvalues[aggno], &aggnulls[aggno]);
+		if (aggstate->finalizeAggs)
+			finalize_aggregate(aggstate, peragg, pergroupstate,
+							   &aggvalues[aggno], &aggnulls[aggno]);
+		else
+		{
+			aggvalues[aggno] = pergroupstate->transValue;
+			aggnulls[aggno] = pergroupstate->transValueIsNull;
+		}
 	}
 }
 
@@ -1811,7 +1979,10 @@ agg_retrieve_direct(AggState *aggstate)
 				 */
 				for (;;)
 				{
-					advance_aggregates(aggstate, pergroup);
+					if (!aggstate->combineStates)
+						advance_aggregates(aggstate, pergroup);
+					else
+						combine_aggregates(aggstate, pergroup);
 
 					/* Reset per-input-tuple context after each tuple */
 					ResetExprContext(tmpcontext);
@@ -1919,7 +2090,10 @@ agg_fill_hash_table(AggState *aggstate)
 		entry = lookup_hash_entry(aggstate, outerslot);
 
 		/* Advance the aggregates */
-		advance_aggregates(aggstate, entry->pergroup);
+		if (!aggstate->combineStates)
+			advance_aggregates(aggstate, entry->pergroup);
+		else
+			combine_aggregates(aggstate, entry->pergroup);
 
 		/* Reset per-input-tuple context after each tuple */
 		ResetExprContext(tmpcontext);
@@ -2051,6 +2225,8 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 	aggstate->pertrans = NULL;
 	aggstate->curpertrans = NULL;
 	aggstate->agg_done = false;
+	aggstate->combineStates = node->combineStates;
+	aggstate->finalizeAggs = node->finalizeAggs;
 	aggstate->input_done = false;
 	aggstate->pergroup = NULL;
 	aggstate->grp_firstTuple = NULL;
@@ -2402,8 +2578,26 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 						   get_func_name(aggref->aggfnoid));
 		InvokeFunctionExecuteHook(aggref->aggfnoid);
 
-		transfn_oid = aggform->aggtransfn;
-		peragg->finalfn_oid = finalfn_oid = aggform->aggfinalfn;
+		/*
+		 * If this aggregation is performing state combines, then instead of
+		 * using the transition function, we'll use the combine function
+		 */
+		if (aggstate->combineStates)
+		{
+			transfn_oid = aggform->aggcombinefn;
+
+			/* If not set then the planner messed up */
+			if (!OidIsValid(transfn_oid))
+				elog(ERROR, "combinefn not set for aggregate function");
+		}
+		else
+			transfn_oid = aggform->aggtransfn;
+
+		/* Final function only required if we're finalizing the aggregates */
+		if (aggstate->finalizeAggs)
+			peragg->finalfn_oid = finalfn_oid = aggform->aggfinalfn;
+		else
+			peragg->finalfn_oid = finalfn_oid = InvalidOid;
 
 		/* Check that aggregate owner has permission to call component fns */
 		{
@@ -2459,7 +2653,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 
 		/*
 		 * build expression trees using actual argument & result types for the
-		 * finalfn, if it exists
+		 * finalfn, if it exists and is required.
 		 */
 		if (OidIsValid(finalfn_oid))
 		{
@@ -2474,10 +2668,11 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 			fmgr_info_set_expr((Node *) finalfnexpr, &peragg->finalfn);
 		}
 
-		/* get info about the result type's datatype */
-		get_typlenbyval(aggref->aggtype,
-						&peragg->resulttypeLen,
-						&peragg->resulttypeByVal);
+		/* when finalizing we get info about the final result's datatype */
+		if (aggstate->finalizeAggs)
+			get_typlenbyval(aggref->aggtype,
+							&peragg->resulttypeLen,
+							&peragg->resulttypeByVal);
 
 		/*
 		 * initval is potentially null, so don't try to access it as a struct
@@ -2583,44 +2778,67 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 		pertrans->numTransInputs = numArguments;
 
 	/*
-	 * Set up infrastructure for calling the transfn
+	 * When combining states, we have no use at all for the aggregate
+	 * function's transfn. Instead we use the combinefn. However we do
+	 * reuse the transfnexpr for the combinefn, perhaps this should change
 	 */
-	build_aggregate_transfn_expr(inputTypes,
-								 numArguments,
-								 numDirectArgs,
-								 aggref->aggvariadic,
-								 aggtranstype,
-								 aggref->inputcollid,
-								 aggtransfn,
-								 InvalidOid,	/* invtrans is not needed here */
-								 &transfnexpr,
-								 NULL);
-	fmgr_info(aggtransfn, &pertrans->transfn);
-	fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
-
-	InitFunctionCallInfoData(pertrans->transfn_fcinfo,
-							 &pertrans->transfn,
-							 pertrans->numTransInputs + 1,
-							 pertrans->aggCollation,
-							 (void *) aggstate, NULL);
-
-	/*
-	 * If the transfn is strict and the initval is NULL, make sure input type
-	 * and transtype are the same (or at least binary-compatible), so that
-	 * it's OK to use the first aggregated input value as the initial
-	 * transValue.  This should have been checked at agg definition time, but
-	 * we must check again in case the transfn's strictness property has been
-	 * changed.
-	 */
-	if (pertrans->transfn.fn_strict && pertrans->initValueIsNull)
+	if (aggstate->combineStates)
 	{
-		if (numArguments <= numDirectArgs ||
-			!IsBinaryCoercible(inputTypes[numDirectArgs],
-							   aggtranstype))
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
-					 errmsg("aggregate %u needs to have compatible input type and transition type",
-							aggref->aggfnoid)));
+		build_aggregate_combinefn_expr(aggtranstype,
+									   aggref->inputcollid,
+									   aggtransfn,
+									   &transfnexpr);
+		fmgr_info(aggtransfn, &pertrans->transfn);
+		fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
+
+		InitFunctionCallInfoData(pertrans->transfn_fcinfo,
+								 &pertrans->transfn,
+								 2,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+	}
+	else
+	{
+		/*
+		 * Set up infrastructure for calling the transfn
+		 */
+		build_aggregate_transfn_expr(inputTypes,
+									 numArguments,
+									 numDirectArgs,
+									 aggref->aggvariadic,
+									 aggtranstype,
+									 aggref->inputcollid,
+									 aggtransfn,
+									 InvalidOid,	/* invtrans is not needed here */
+									 &transfnexpr,
+									 NULL);
+		fmgr_info(aggtransfn, &pertrans->transfn);
+		fmgr_info_set_expr((Node *) transfnexpr, &pertrans->transfn);
+
+		InitFunctionCallInfoData(pertrans->transfn_fcinfo,
+								 &pertrans->transfn,
+								 pertrans->numTransInputs + 1,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+
+		/*
+		 * If the transfn is strict and the initval is NULL, make sure input type
+		 * and transtype are the same (or at least binary-compatible), so that
+		 * it's OK to use the first aggregated input value as the initial
+		 * transValue.  This should have been checked at agg definition time, but
+		 * we must check again in case the transfn's strictness property has been
+		 * changed.
+		 */
+		if (pertrans->transfn.fn_strict && pertrans->initValueIsNull)
+		{
+			if (numArguments <= numDirectArgs ||
+				!IsBinaryCoercible(inputTypes[numDirectArgs],
+								   aggtranstype))
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						 errmsg("aggregate %u needs to have compatible input type and transition type",
+								aggref->aggfnoid)));
+		}
 	}
 
 	/* get info about the state value's datatype */
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index f47e0da..5877037 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -865,6 +865,8 @@ _copyAgg(const Agg *from)
 
 	COPY_SCALAR_FIELD(aggstrategy);
 	COPY_SCALAR_FIELD(numCols);
+	COPY_SCALAR_FIELD(combineStates);
+	COPY_SCALAR_FIELD(finalizeAggs);
 	if (from->numCols > 0)
 	{
 		COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index f1e22e5..8817b56 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -695,6 +695,9 @@ _outAgg(StringInfo str, const Agg *node)
 	for (i = 0; i < node->numCols; i++)
 		appendStringInfo(str, " %d", node->grpColIdx[i]);
 
+	WRITE_BOOL_FIELD(combineStates);
+	WRITE_BOOL_FIELD(finalizeAggs);
+
 	appendStringInfoString(str, " :grpOperators");
 	for (i = 0; i < node->numCols; i++)
 		appendStringInfo(str, " %u", node->grpOperators[i]);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 719a52c..a67b337 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1989,6 +1989,8 @@ _readAgg(void)
 	READ_ENUM_FIELD(aggstrategy, AggStrategy);
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
+	READ_BOOL_FIELD(combineStates);
+	READ_BOOL_FIELD(finalizeAggs);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 	READ_NODE_FIELD(groupingSets);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 953aa62..01bd7e7 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -1054,6 +1054,8 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path)
 								 groupOperators,
 								 NIL,
 								 numGroups,
+								 false,
+								 true,
 								 subplan);
 	}
 	else
@@ -4557,9 +4559,8 @@ Agg *
 make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
 		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
-		 List *groupingSets,
-		 long numGroups,
-		 Plan *lefttree)
+		 List *groupingSets, long numGroups, bool combineStates,
+		 bool finalizeAggs, Plan *lefttree)
 {
 	Agg		   *node = makeNode(Agg);
 	Plan	   *plan = &node->plan;
@@ -4568,6 +4569,8 @@ make_agg(PlannerInfo *root, List *tlist, List *qual,
 
 	node->aggstrategy = aggstrategy;
 	node->numCols = numGroupCols;
+	node->combineStates = combineStates;
+	node->finalizeAggs = finalizeAggs;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
 	node->numGroups = numGroups;
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 131dc8a..c0ec905 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -2005,6 +2005,8 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 									extract_grouping_ops(parse->groupClause),
 												NIL,
 												numGroups,
+												false,
+												true,
 												result_plan);
 				/* Hashed aggregation produces randomly-ordered results */
 				current_pathkeys = NIL;
@@ -2312,6 +2314,8 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 								 extract_grouping_ops(parse->distinctClause),
 											NIL,
 											numDistinctRows,
+											false,
+											true,
 											result_plan);
 			/* Hashed aggregation produces randomly-ordered results */
 			current_pathkeys = NIL;
@@ -2549,6 +2553,8 @@ build_grouping_chain(PlannerInfo *root,
 										 extract_grouping_ops(groupClause),
 										 gsets,
 										 numGroups,
+										 false,
+										 true,
 										 sort_plan);
 
 			/*
@@ -2588,6 +2594,8 @@ build_grouping_chain(PlannerInfo *root,
 										extract_grouping_ops(groupClause),
 										gsets,
 										numGroups,
+										false,
+										true,
 										result_plan);
 
 		((Agg *) result_plan)->chain = chain;
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 615f3a2..25c1401 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -15,7 +15,9 @@
  */
 #include "postgres.h"
 
+#include "access/htup_details.h"
 #include "access/transam.h"
+#include "catalog/pg_aggregate.h"
 #include "catalog/pg_type.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
@@ -139,6 +141,16 @@ static List *set_returning_clause_references(PlannerInfo *root,
 static bool fix_opfuncids_walker(Node *node, void *context);
 static bool extract_query_dependencies_walker(Node *node,
 								  PlannerInfo *context);
+static void set_combineagg_references(PlannerInfo *root, Plan *plan,
+									  int rtoffset);
+static Node *fix_combine_agg_expr(PlannerInfo *root,
+								  Node *node,
+								  indexed_tlist *subplan_itlist,
+								  Index newvarno,
+								  int rtoffset);
+static Node *fix_combine_agg_expr_mutator(Node *node,
+										  fix_upper_expr_context *context);
+static void set_partialagg_aggref_types(PlannerInfo *root, Plan *plan);
 
 /*****************************************************************************
  *
@@ -668,8 +680,23 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 			}
 			break;
 		case T_Agg:
-			set_upper_references(root, plan, rtoffset);
-			break;
+			{
+				Agg *aggplan = (Agg *) plan;
+
+				/*
+				 * For partial aggregation we must adjust the return types of
+				 * the Aggrefs
+				 */
+				if (!aggplan->finalizeAggs)
+					set_partialagg_aggref_types(root, plan);
+
+				if (aggplan->combineStates)
+					set_combineagg_references(root, plan, rtoffset);
+				else
+					set_upper_references(root, plan, rtoffset);
+
+				break;
+			}
 		case T_Group:
 			set_upper_references(root, plan, rtoffset);
 			break;
@@ -2432,3 +2459,188 @@ extract_query_dependencies_walker(Node *node, PlannerInfo *context)
 	return expression_tree_walker(node, extract_query_dependencies_walker,
 								  (void *) context);
 }
+
+static void
+set_combineagg_references(PlannerInfo *root, Plan *plan, int rtoffset)
+{
+	Plan	   *subplan = plan->lefttree;
+	indexed_tlist *subplan_itlist;
+	List	   *output_targetlist;
+	ListCell   *l;
+
+	Assert(IsA(plan, Agg));
+	Assert(((Agg *) plan)->combineStates);
+
+	subplan_itlist = build_tlist_index(subplan->targetlist);
+
+	output_targetlist = NIL;
+
+	foreach(l, plan->targetlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(l);
+		Node	   *newexpr;
+
+		/* If it's a non-Var sort/group item, first try to match by sortref */
+		if (tle->ressortgroupref != 0 && !IsA(tle->expr, Var))
+		{
+			newexpr = (Node *)
+				search_indexed_tlist_for_sortgroupref((Node *) tle->expr,
+														tle->ressortgroupref,
+														subplan_itlist,
+														OUTER_VAR);
+			if (!newexpr)
+				newexpr = fix_combine_agg_expr(root,
+												(Node *) tle->expr,
+												subplan_itlist,
+												OUTER_VAR,
+												rtoffset);
+		}
+		else
+			newexpr = fix_combine_agg_expr(root,
+											(Node *) tle->expr,
+											subplan_itlist,
+											OUTER_VAR,
+											rtoffset);
+		tle = flatCopyTargetEntry(tle);
+		tle->expr = (Expr *) newexpr;
+		output_targetlist = lappend(output_targetlist, tle);
+	}
+
+	plan->targetlist = output_targetlist;
+
+	plan->qual = (List *)
+		fix_upper_expr(root,
+					   (Node *) plan->qual,
+					   subplan_itlist,
+					   OUTER_VAR,
+					   rtoffset);
+
+	pfree(subplan_itlist);
+}
+
+
+/*
+ * Adjust the Aggref'a args to reference the correct Aggref target in the outer
+ * subplan.
+ */
+static Node *
+fix_combine_agg_expr(PlannerInfo *root,
+			   Node *node,
+			   indexed_tlist *subplan_itlist,
+			   Index newvarno,
+			   int rtoffset)
+{
+	fix_upper_expr_context context;
+
+	context.root = root;
+	context.subplan_itlist = subplan_itlist;
+	context.newvarno = newvarno;
+	context.rtoffset = rtoffset;
+	return fix_combine_agg_expr_mutator(node, &context);
+}
+
+static Node *
+fix_combine_agg_expr_mutator(Node *node, fix_upper_expr_context *context)
+{
+	Var		   *newvar;
+
+	if (node == NULL)
+		return NULL;
+	if (IsA(node, Var))
+	{
+		Var		   *var = (Var *) node;
+
+		newvar = search_indexed_tlist_for_var(var,
+											  context->subplan_itlist,
+											  context->newvarno,
+											  context->rtoffset);
+		if (!newvar)
+			elog(ERROR, "variable not found in subplan target list");
+		return (Node *) newvar;
+	}
+	if (IsA(node, Aggref))
+	{
+		TargetEntry *tle;
+		Aggref		*aggref = (Aggref*) node;
+
+		tle = tlist_member(node, context->subplan_itlist->tlist);
+		if (tle)
+		{
+			/* Found a matching subplan output expression */
+			Var		   *newvar;
+			TargetEntry *newtle;
+
+			newvar = makeVarFromTargetEntry(context->newvarno, tle);
+			newvar->varnoold = 0;	/* wasn't ever a plain Var */
+			newvar->varoattno = 0;
+
+			/* update the args in the aggref */
+
+			/* makeTargetEntry ,always set resno to one for finialize agg */
+			newtle = makeTargetEntry((Expr*) newvar, 1, NULL, false);
+
+			/*
+			 * Updated the args, let the newvar refer to the right position of
+			 * the agg function in the subplan
+			 */
+			aggref->args = list_make1(newtle);
+
+			return (Node *) aggref;
+		}
+		else
+			elog(ERROR, "aggref not found in subplan target list");
+	}
+	if (IsA(node, PlaceHolderVar))
+	{
+		PlaceHolderVar *phv = (PlaceHolderVar *) node;
+
+		/* See if the PlaceHolderVar has bubbled up from a lower plan node */
+		if (context->subplan_itlist->has_ph_vars)
+		{
+			newvar = search_indexed_tlist_for_non_var((Node *) phv,
+													  context->subplan_itlist,
+													  context->newvarno);
+			if (newvar)
+				return (Node *) newvar;
+		}
+		/* If not supplied by input plan, evaluate the contained expr */
+		return fix_upper_expr_mutator((Node *) phv->phexpr, context);
+	}
+	if (IsA(node, Param))
+		return fix_param_node(context->root, (Param *) node);
+
+	fix_expr_common(context->root, node);
+	return expression_tree_mutator(node,
+								   fix_combine_agg_expr_mutator,
+								   (void *) context);
+}
+
+/* XXX is this really the best place and way to do this? */
+static void
+set_partialagg_aggref_types(PlannerInfo *root, Plan *plan)
+{
+	ListCell *l;
+
+	foreach(l, plan->targetlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(l);
+
+		if (IsA(tle->expr, Aggref))
+		{
+			Aggref *aggref = (Aggref *) tle->expr;
+			HeapTuple	aggTuple;
+			Form_pg_aggregate aggform;
+
+			aggTuple = SearchSysCache1(AGGFNOID,
+									   ObjectIdGetDatum(aggref->aggfnoid));
+			if (!HeapTupleIsValid(aggTuple))
+				elog(ERROR, "cache lookup failed for aggregate %u",
+					 aggref->aggfnoid);
+			aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
+
+			aggref->aggtype = aggform->aggtranstype;
+
+			ReleaseSysCache(aggTuple);
+		}
+	}
+}
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 694e9ed..e509a1a 100644
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -775,6 +775,8 @@ make_union_unique(SetOperationStmt *op, Plan *plan,
 								 extract_grouping_ops(groupList),
 								 NIL,
 								 numGroups,
+								 false,
+								 true,
 								 plan);
 		/* Hashed aggregation produces randomly-ordered results */
 		*sortClauses = NIL;
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index ace8b38..2ce7c02 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -52,6 +52,10 @@
 #include "utils/syscache.h"
 #include "utils/typcache.h"
 
+typedef struct
+{
+	PartialAggType allowedtype;
+} partial_agg_context;
 
 typedef struct
 {
@@ -93,6 +97,7 @@ typedef struct
 	bool		allow_restricted;
 } has_parallel_hazard_arg;
 
+static bool partial_aggregate_walker(Node *node, partial_agg_context *context);
 static bool contain_agg_clause_walker(Node *node, void *context);
 static bool count_agg_clauses_walker(Node *node,
 						 count_agg_clauses_context *context);
@@ -400,6 +405,81 @@ make_ands_implicit(Expr *clause)
  *****************************************************************************/
 
 /*
+ * aggregates_allow_partial
+ *		Recursively search for Aggref clauses and determine the maximum
+ *		'degree' of partial aggregation which can be supported. Partial
+ *		aggregation requires that each aggregate does not have a DISTINCT or
+ *		ORDER BY clause, and that it also has a combine function set.
+ */
+PartialAggType
+aggregates_allow_partial(Node *clause)
+{
+	partial_agg_context context;
+
+	/* initially any type is ok, until we find Aggrefs which say otherwise */
+	context.allowedtype = PAT_ANY;
+
+	if (!partial_aggregate_walker(clause, &context))
+		return context.allowedtype;
+	return context.allowedtype;
+}
+
+static bool
+partial_aggregate_walker(Node *node, partial_agg_context *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Aggref))
+	{
+		Aggref	   *aggref = (Aggref *) node;
+		HeapTuple	aggTuple;
+		Form_pg_aggregate aggform;
+
+		Assert(aggref->agglevelsup == 0);
+
+		/*
+		 * We can't perform partial aggregation with Aggrefs containing a
+		 * DISTINCT or ORDER BY clause.
+		 */
+		if (aggref->aggdistinct || aggref->aggorder)
+		{
+			context->allowedtype = PAT_DISABLED;
+			return true;	/* abort search */
+		}
+		aggTuple = SearchSysCache1(AGGFNOID,
+								   ObjectIdGetDatum(aggref->aggfnoid));
+		if (!HeapTupleIsValid(aggTuple))
+			elog(ERROR, "cache lookup failed for aggregate %u",
+				 aggref->aggfnoid);
+		aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
+
+		/*
+		 * If there is no combine func, then partial aggregation is not
+		 * possible.
+		 */
+		if (!OidIsValid(aggform->aggcombinefn))
+		{
+			ReleaseSysCache(aggTuple);
+			context->allowedtype = PAT_DISABLED;
+			return true;	/* abort search */
+		}
+
+		/*
+		 * If we find any aggs with an internal transtype then we must ensure
+		 * that pointers to aggregate states are not passed to other processes,
+		 * therefore we set the maximum degree to PAT_INTERNAL_ONLY.
+		 */
+		if (aggform->aggtranstype == INTERNALOID)
+			context->allowedtype = PAT_INTERNAL_ONLY;
+
+		ReleaseSysCache(aggTuple);
+		return false; /* continue searching */
+	}
+	return expression_tree_walker(node, partial_aggregate_walker,
+								  (void *) context);
+}
+
+/*
  * contain_agg_clause
  *	  Recursively search for Aggref/GroupingFunc nodes within a clause.
  *
diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c
index b718169..b790bb2 100644
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -1929,6 +1929,42 @@ build_aggregate_transfn_expr(Oid *agg_input_types,
 
 /*
  * Like build_aggregate_transfn_expr, but creates an expression tree for the
+ * combine function of an aggregate, rather than the transition function.
+ */
+void
+build_aggregate_combinefn_expr(Oid agg_state_type,
+							   Oid agg_input_collation,
+							   Oid combinefn_oid,
+							   Expr **combinefnexpr)
+{
+	Param	   *argp;
+	List	   *args;
+	FuncExpr   *fexpr;
+
+	/* Build arg list to use in the combinefn FuncExpr node. */
+	argp = makeNode(Param);
+	argp->paramkind = PARAM_EXEC;
+	argp->paramid = -1;
+	argp->paramtype = agg_state_type;
+	argp->paramtypmod = -1;
+	argp->paramcollid = agg_input_collation;
+	argp->location = -1;
+
+	/* transition state type is arg 1 and 2 */
+	args = list_make2(argp, argp);
+
+	fexpr = makeFuncExpr(combinefn_oid,
+						 agg_state_type,
+						 args,
+						 InvalidOid,
+						 agg_input_collation,
+						 COERCE_EXPLICIT_CALL);
+	fexpr->funcvariadic = false;
+	*combinefnexpr = (Expr *) fexpr;
+}
+
+/*
+ * Like build_aggregate_transfn_expr, but creates an expression tree for the
  * final function of an aggregate, rather than the transition function.
  */
 void
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 59542aa..9c6f885 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -12383,6 +12383,7 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	PGresult   *res;
 	int			i_aggtransfn;
 	int			i_aggfinalfn;
+	int			i_aggcombinefn;
 	int			i_aggmtransfn;
 	int			i_aggminvtransfn;
 	int			i_aggmfinalfn;
@@ -12399,6 +12400,7 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	int			i_convertok;
 	const char *aggtransfn;
 	const char *aggfinalfn;
+	const char *aggcombinefn;
 	const char *aggmtransfn;
 	const char *aggminvtransfn;
 	const char *aggmfinalfn;
@@ -12429,7 +12431,26 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	selectSourceSchema(fout, agginfo->aggfn.dobj.namespace->dobj.name);
 
 	/* Get aggregate-specific details */
-	if (fout->remoteVersion >= 90400)
+	if (fout->remoteVersion >= 90600)
+	{
+		appendPQExpBuffer(query, "SELECT aggtransfn, "
+			"aggfinalfn, aggtranstype::pg_catalog.regtype, "
+			"aggcombinefn, aggmtransfn, "
+			"aggminvtransfn, aggmfinalfn, aggmtranstype::pg_catalog.regtype, "
+			"aggfinalextra, aggmfinalextra, "
+			"aggsortop::pg_catalog.regoperator, "
+			"(aggkind = 'h') AS hypothetical, "
+			"aggtransspace, agginitval, "
+			"aggmtransspace, aggminitval, "
+			"true AS convertok, "
+			"pg_catalog.pg_get_function_arguments(p.oid) AS funcargs, "
+			"pg_catalog.pg_get_function_identity_arguments(p.oid) AS funciargs "
+			"FROM pg_catalog.pg_aggregate a, pg_catalog.pg_proc p "
+			"WHERE a.aggfnoid = p.oid "
+			"AND p.oid = '%u'::pg_catalog.oid",
+			agginfo->aggfn.dobj.catId.oid);
+	}
+	else if (fout->remoteVersion >= 90400)
 	{
 		appendPQExpBuffer(query, "SELECT aggtransfn, "
 						  "aggfinalfn, aggtranstype::pg_catalog.regtype, "
@@ -12539,6 +12560,7 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 
 	i_aggtransfn = PQfnumber(res, "aggtransfn");
 	i_aggfinalfn = PQfnumber(res, "aggfinalfn");
+	i_aggcombinefn = PQfnumber(res, "aggcombinefn");
 	i_aggmtransfn = PQfnumber(res, "aggmtransfn");
 	i_aggminvtransfn = PQfnumber(res, "aggminvtransfn");
 	i_aggmfinalfn = PQfnumber(res, "aggmfinalfn");
@@ -12556,6 +12578,7 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 
 	aggtransfn = PQgetvalue(res, 0, i_aggtransfn);
 	aggfinalfn = PQgetvalue(res, 0, i_aggfinalfn);
+	aggcombinefn = PQgetvalue(res, 0, i_aggcombinefn);
 	aggmtransfn = PQgetvalue(res, 0, i_aggmtransfn);
 	aggminvtransfn = PQgetvalue(res, 0, i_aggminvtransfn);
 	aggmfinalfn = PQgetvalue(res, 0, i_aggmfinalfn);
@@ -12644,6 +12667,11 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 			appendPQExpBufferStr(details, ",\n    FINALFUNC_EXTRA");
 	}
 
+	if (strcmp(aggcombinefn, "-") != 0)
+	{
+		appendPQExpBuffer(details, ",\n    COMBINEFUNC = %s",	aggcombinefn);
+	}
+
 	if (strcmp(aggmtransfn, "-") != 0)
 	{
 		appendPQExpBuffer(details, ",\n    MSFUNC = %s,\n    MINVFUNC = %s,\n    MSTYPE = %s",
diff --git a/src/include/catalog/pg_aggregate.h b/src/include/catalog/pg_aggregate.h
index 28b0669..441db30 100644
--- a/src/include/catalog/pg_aggregate.h
+++ b/src/include/catalog/pg_aggregate.h
@@ -33,6 +33,7 @@
  *	aggnumdirectargs	number of arguments that are "direct" arguments
  *	aggtransfn			transition function
  *	aggfinalfn			final function (0 if none)
+ *	aggcombinefn		combine function (0 if none)
  *	aggmtransfn			forward function for moving-aggregate mode (0 if none)
  *	aggminvtransfn		inverse function for moving-aggregate mode (0 if none)
  *	aggmfinalfn			final function for moving-aggregate mode (0 if none)
@@ -56,6 +57,7 @@ CATALOG(pg_aggregate,2600) BKI_WITHOUT_OIDS
 	int16		aggnumdirectargs;
 	regproc		aggtransfn;
 	regproc		aggfinalfn;
+	regproc		aggcombinefn;
 	regproc		aggmtransfn;
 	regproc		aggminvtransfn;
 	regproc		aggmfinalfn;
@@ -85,24 +87,25 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  * ----------------
  */
 
-#define Natts_pg_aggregate					17
+#define Natts_pg_aggregate					18
 #define Anum_pg_aggregate_aggfnoid			1
 #define Anum_pg_aggregate_aggkind			2
 #define Anum_pg_aggregate_aggnumdirectargs	3
 #define Anum_pg_aggregate_aggtransfn		4
 #define Anum_pg_aggregate_aggfinalfn		5
-#define Anum_pg_aggregate_aggmtransfn		6
-#define Anum_pg_aggregate_aggminvtransfn	7
-#define Anum_pg_aggregate_aggmfinalfn		8
-#define Anum_pg_aggregate_aggfinalextra		9
-#define Anum_pg_aggregate_aggmfinalextra	10
-#define Anum_pg_aggregate_aggsortop			11
-#define Anum_pg_aggregate_aggtranstype		12
-#define Anum_pg_aggregate_aggtransspace		13
-#define Anum_pg_aggregate_aggmtranstype		14
-#define Anum_pg_aggregate_aggmtransspace	15
-#define Anum_pg_aggregate_agginitval		16
-#define Anum_pg_aggregate_aggminitval		17
+#define Anum_pg_aggregate_aggcombinefn		6
+#define Anum_pg_aggregate_aggmtransfn		7
+#define Anum_pg_aggregate_aggminvtransfn	8
+#define Anum_pg_aggregate_aggmfinalfn		9
+#define Anum_pg_aggregate_aggfinalextra		10
+#define Anum_pg_aggregate_aggmfinalextra	11
+#define Anum_pg_aggregate_aggsortop			12
+#define Anum_pg_aggregate_aggtranstype		13
+#define Anum_pg_aggregate_aggtransspace		14
+#define Anum_pg_aggregate_aggmtranstype		15
+#define Anum_pg_aggregate_aggmtransspace	16
+#define Anum_pg_aggregate_agginitval		17
+#define Anum_pg_aggregate_aggminitval		18
 
 /*
  * Symbolic values for aggkind column.  We distinguish normal aggregates
@@ -126,184 +129,184 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  */
 
 /* avg */
-DATA(insert ( 2100	n 0 int8_avg_accum	numeric_poly_avg		int8_avg_accum	int8_avg_accum_inv	numeric_poly_avg	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg		int4_avg_accum	int4_avg_accum_inv	int8_avg					f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg		int2_avg_accum	int2_avg_accum_inv	int8_avg					f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg	numeric_avg_accum numeric_accum_inv numeric_avg					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2104	n 0 float4_accum	float8_avg		-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2105	n 0 float8_accum	float8_avg		-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2106	n 0 interval_accum	interval_avg	interval_accum	interval_accum_inv interval_avg					f f 0	1187	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
+DATA(insert ( 2100	n 0 int8_avg_accum	numeric_poly_avg	-	int8_avg_accum	int8_avg_accum_inv	numeric_poly_avg	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg			-	int4_avg_accum	int4_avg_accum_inv	int8_avg			f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg			-	int2_avg_accum	int2_avg_accum_inv	int8_avg			f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg		-	numeric_avg_accum numeric_accum_inv numeric_avg			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2104	n 0 float4_accum	float8_avg			-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2105	n 0 float8_accum	float8_avg			-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2106	n 0 interval_accum	interval_avg		-	interval_accum	interval_accum_inv interval_avg			f f 0	1187	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
 
 /* sum */
-DATA(insert ( 2107	n 0 int8_avg_accum	numeric_poly_sum		int8_avg_accum	int8_avg_accum_inv numeric_poly_sum f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2108	n 0 int4_sum		-				int4_avg_accum	int4_avg_accum_inv int2int4_sum					f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2109	n 0 int2_sum		-				int2_avg_accum	int2_avg_accum_inv int2int4_sum					f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2110	n 0 float4pl		-				-				-				-								f f 0	700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2111	n 0 float8pl		-				-				-				-								f f 0	701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2112	n 0 cash_pl			-				cash_pl			cash_mi			-								f f 0	790		0	790		0	_null_ _null_ ));
-DATA(insert ( 2113	n 0 interval_pl		-				interval_pl		interval_mi		-								f f 0	1186	0	1186	0	_null_ _null_ ));
-DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum numeric_avg_accum numeric_accum_inv numeric_sum					f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2107	n 0 int8_avg_accum	numeric_poly_sum	-					int8_avg_accum	int8_avg_accum_inv	numeric_poly_sum	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2108	n 0 int4_sum		-					int8pl				int4_avg_accum	int4_avg_accum_inv	int2int4_sum		f f 0	20		0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2109	n 0 int2_sum		-					int8pl				int2_avg_accum	int2_avg_accum_inv	int2int4_sum		f f 0	20		0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2110	n 0 float4pl		-					float4pl			-				-					-					f f 0	700		0	0		0	_null_ _null_ ));
+DATA(insert ( 2111	n 0 float8pl		-					float8pl			-				-					-					f f 0	701		0	0		0	_null_ _null_ ));
+DATA(insert ( 2112	n 0 cash_pl			-					cash_pl				cash_pl			cash_mi				-					f f 0	790		0	790		0	_null_ _null_ ));
+DATA(insert ( 2113	n 0 interval_pl		-					interval_pl			interval_pl		interval_mi			-					f f 0	1186	0	1186	0	_null_ _null_ ));
+DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum		-					numeric_avg_accum	numeric_accum_inv	numeric_sum		f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* max */
-DATA(insert ( 2115	n 0 int8larger		-				-				-				-				f f 413		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2116	n 0 int4larger		-				-				-				-				f f 521		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2117	n 0 int2larger		-				-				-				-				f f 520		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2118	n 0 oidlarger		-				-				-				-				f f 610		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2119	n 0 float4larger	-				-				-				-				f f 623		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2120	n 0 float8larger	-				-				-				-				f f 674		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2121	n 0 int4larger		-				-				-				-				f f 563		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2122	n 0 date_larger		-				-				-				-				f f 1097	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2123	n 0 time_larger		-				-				-				-				f f 1112	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2124	n 0 timetz_larger	-				-				-				-				f f 1554	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2125	n 0 cashlarger		-				-				-				-				f f 903		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2126	n 0 timestamp_larger	-			-				-				-				f f 2064	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2127	n 0 timestamptz_larger	-			-				-				-				f f 1324	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2128	n 0 interval_larger -				-				-				-				f f 1334	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2129	n 0 text_larger		-				-				-				-				f f 666		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2130	n 0 numeric_larger	-				-				-				-				f f 1756	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2050	n 0 array_larger	-				-				-				-				f f 1073	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2244	n 0 bpchar_larger	-				-				-				-				f f 1060	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2797	n 0 tidlarger		-				-				-				-				f f 2800	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3526	n 0 enum_larger		-				-				-				-				f f 3519	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3564	n 0 network_larger	-				-				-				-				f f 1205	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2115	n 0 int8larger		-				int8larger			-				-				-				f f 413		20		0	0		0	_null_ _null_ ));
+DATA(insert ( 2116	n 0 int4larger		-				int4larger			-				-				-				f f 521		23		0	0		0	_null_ _null_ ));
+DATA(insert ( 2117	n 0 int2larger		-				int2larger			-				-				-				f f 520		21		0	0		0	_null_ _null_ ));
+DATA(insert ( 2118	n 0 oidlarger		-				oidlarger			-				-				-				f f 610		26		0	0		0	_null_ _null_ ));
+DATA(insert ( 2119	n 0 float4larger	-				float4larger		-				-				-				f f 623		700		0	0		0	_null_ _null_ ));
+DATA(insert ( 2120	n 0 float8larger	-				float8larger		-				-				-				f f 674		701		0	0		0	_null_ _null_ ));
+DATA(insert ( 2121	n 0 int4larger		-				int4larger			-				-				-				f f 563		702		0	0		0	_null_ _null_ ));
+DATA(insert ( 2122	n 0 date_larger		-				date_larger			-				-				-				f f 1097	1082	0	0		0	_null_ _null_ ));
+DATA(insert ( 2123	n 0 time_larger		-				time_larger			-				-				-				f f 1112	1083	0	0		0	_null_ _null_ ));
+DATA(insert ( 2124	n 0 timetz_larger	-				timetz_larger		-				-				-				f f 1554	1266	0	0		0	_null_ _null_ ));
+DATA(insert ( 2125	n 0 cashlarger		-				cashlarger			-				-				-				f f 903		790		0	0		0	_null_ _null_ ));
+DATA(insert ( 2126	n 0 timestamp_larger	-			timestamp_larger	-				-				-				f f 2064	1114	0	0		0	_null_ _null_ ));
+DATA(insert ( 2127	n 0 timestamptz_larger	-			timestamptz_larger	-				-				-				f f 1324	1184	0	0		0	_null_ _null_ ));
+DATA(insert ( 2128	n 0 interval_larger -				interval_larger		-				-				-				f f 1334	1186	0	0		0	_null_ _null_ ));
+DATA(insert ( 2129	n 0 text_larger		-				text_larger			-				-				-				f f 666		25		0	0		0	_null_ _null_ ));
+DATA(insert ( 2130	n 0 numeric_larger	-				numeric_larger		-				-				-				f f 1756	1700	0	0		0	_null_ _null_ ));
+DATA(insert ( 2050	n 0 array_larger	-				array_larger		-				-				-				f f 1073	2277	0	0		0	_null_ _null_ ));
+DATA(insert ( 2244	n 0 bpchar_larger	-				bpchar_larger		-				-				-				f f 1060	1042	0	0		0	_null_ _null_ ));
+DATA(insert ( 2797	n 0 tidlarger		-				tidlarger			-				-				-				f f 2800	27		0	0		0	_null_ _null_ ));
+DATA(insert ( 3526	n 0 enum_larger		-				enum_larger			-				-				-				f f 3519	3500	0	0		0	_null_ _null_ ));
+DATA(insert ( 3564	n 0 network_larger	-				network_larger		-				-				-				f f 1205	869		0	0		0	_null_ _null_ ));
 
 /* min */
-DATA(insert ( 2131	n 0 int8smaller		-				-				-				-				f f 412		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2132	n 0 int4smaller		-				-				-				-				f f 97		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2133	n 0 int2smaller		-				-				-				-				f f 95		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2134	n 0 oidsmaller		-				-				-				-				f f 609		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2135	n 0 float4smaller	-				-				-				-				f f 622		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2136	n 0 float8smaller	-				-				-				-				f f 672		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2137	n 0 int4smaller		-				-				-				-				f f 562		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2138	n 0 date_smaller	-				-				-				-				f f 1095	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2139	n 0 time_smaller	-				-				-				-				f f 1110	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2140	n 0 timetz_smaller	-				-				-				-				f f 1552	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2141	n 0 cashsmaller		-				-				-				-				f f 902		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2142	n 0 timestamp_smaller	-			-				-				-				f f 2062	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2143	n 0 timestamptz_smaller -			-				-				-				f f 1322	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2144	n 0 interval_smaller	-			-				-				-				f f 1332	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2145	n 0 text_smaller	-				-				-				-				f f 664		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2146	n 0 numeric_smaller -				-				-				-				f f 1754	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2051	n 0 array_smaller	-				-				-				-				f f 1072	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2245	n 0 bpchar_smaller	-				-				-				-				f f 1058	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2798	n 0 tidsmaller		-				-				-				-				f f 2799	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3527	n 0 enum_smaller	-				-				-				-				f f 3518	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3565	n 0 network_smaller -				-				-				-				f f 1203	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2131	n 0 int8smaller		-				int8smaller			-				-				-				f f 412		20		0	0		0	_null_ _null_ ));
+DATA(insert ( 2132	n 0 int4smaller		-				int4smaller			-				-				-				f f 97		23		0	0		0	_null_ _null_ ));
+DATA(insert ( 2133	n 0 int2smaller		-				int2smaller			-				-				-				f f 95		21		0	0		0	_null_ _null_ ));
+DATA(insert ( 2134	n 0 oidsmaller		-				oidsmaller			-				-				-				f f 609		26		0	0		0	_null_ _null_ ));
+DATA(insert ( 2135	n 0 float4smaller	-				float4smaller		-				-				-				f f 622		700		0	0		0	_null_ _null_ ));
+DATA(insert ( 2136	n 0 float8smaller	-				float8smaller		-				-				-				f f 672		701		0	0		0	_null_ _null_ ));
+DATA(insert ( 2137	n 0 int4smaller		-				int4smaller			-				-				-				f f 562		702		0	0		0	_null_ _null_ ));
+DATA(insert ( 2138	n 0 date_smaller	-				date_smaller		-				-				-				f f 1095	1082	0	0		0	_null_ _null_ ));
+DATA(insert ( 2139	n 0 time_smaller	-				time_smaller		-				-				-				f f 1110	1083	0	0		0	_null_ _null_ ));
+DATA(insert ( 2140	n 0 timetz_smaller	-				timetz_smaller		-				-				-				f f 1552	1266	0	0		0	_null_ _null_ ));
+DATA(insert ( 2141	n 0 cashsmaller		-				cashsmaller			-				-				-				f f 902		790		0	0		0	_null_ _null_ ));
+DATA(insert ( 2142	n 0 timestamp_smaller	-			timestamp_smaller	-				-				-				f f 2062	1114	0	0		0	_null_ _null_ ));
+DATA(insert ( 2143	n 0 timestamptz_smaller -			timestamptz_smaller	-				-				-				f f 1322	1184	0	0		0	_null_ _null_ ));
+DATA(insert ( 2144	n 0 interval_smaller	-			interval_smaller	-				-				-				f f 1332	1186	0	0		0	_null_ _null_ ));
+DATA(insert ( 2145	n 0 text_smaller	-				text_smaller		-				-				-				f f 664		25		0	0		0	_null_ _null_ ));
+DATA(insert ( 2146	n 0 numeric_smaller -				numeric_smaller		-				-				-				f f 1754	1700	0	0		0	_null_ _null_ ));
+DATA(insert ( 2051	n 0 array_smaller	-				array_smaller		-				-				-				f f 1072	2277	0	0		0	_null_ _null_ ));
+DATA(insert ( 2245	n 0 bpchar_smaller	-				bpchar_smaller		-				-				-				f f 1058	1042	0	0		0	_null_ _null_ ));
+DATA(insert ( 2798	n 0 tidsmaller		-				tidsmaller			-				-				-				f f 2799	27		0	0		0	_null_ _null_ ));
+DATA(insert ( 3527	n 0 enum_smaller	-				enum_smaller		-				-				-				f f 3518	3500	0	0		0	_null_ _null_ ));
+DATA(insert ( 3565	n 0 network_smaller -				network_smaller		-				-				-				f f 1203	869		0	0		0	_null_ _null_ ));
 
 /* count */
-DATA(insert ( 2147	n 0 int8inc_any		-				int8inc_any		int8dec_any		-				f f 0		20		0	20		0	"0" "0" ));
-DATA(insert ( 2803	n 0 int8inc			-				int8inc			int8dec			-				f f 0		20		0	20		0	"0" "0" ));
+DATA(insert ( 2147	n 0 int8inc_any		-				int8pl	int8inc_any		int8dec_any		-				f f 0		20		0	20		0	"0" "0" ));
+DATA(insert ( 2803	n 0 int8inc			-				int8pl	int8inc			int8dec			-				f f 0		20		0	20		0	"0" "0" ));
 
 /* var_pop */
-DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop		int8_accum		int8_accum_inv	numeric_var_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2719	n 0 int4_accum	numeric_poly_var_pop		int4_accum		int4_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2720	n 0 int2_accum	numeric_poly_var_pop		int2_accum		int2_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2721	n 0 float4_accum	float8_var_pop	-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2722	n 0 float8_accum	float8_var_pop	-				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop numeric_accum numeric_accum_inv numeric_var_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop			-	int8_accum		int8_accum_inv	numeric_var_pop			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2719	n 0 int4_accum	numeric_poly_var_pop	-	int4_accum		int4_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2720	n 0 int2_accum	numeric_poly_var_pop	-	int2_accum		int2_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2721	n 0 float4_accum	float8_var_pop		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2722	n 0 float8_accum	float8_var_pop		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop		-	numeric_accum numeric_accum_inv numeric_var_pop			f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* var_samp */
-DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp	int8_accum		int8_accum_inv	numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2642	n 0 int4_accum	numeric_poly_var_samp		int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2643	n 0 int2_accum	numeric_poly_var_samp		int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2644	n 0 float4_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2645	n 0 float8_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp numeric_accum numeric_accum_inv numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp		-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2642	n 0 int4_accum	numeric_poly_var_samp	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2643	n 0 int2_accum	numeric_poly_var_samp	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2644	n 0 float4_accum	float8_var_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2645	n 0 float8_accum	float8_var_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp	-	numeric_accum	numeric_accum_inv numeric_var_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* variance: historical Postgres syntax for var_samp */
-DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp	int8_accum		int8_accum_inv	numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2149	n 0 int4_accum	numeric_poly_var_samp		int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2150	n 0 int2_accum	numeric_poly_var_samp		int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2151	n 0 float4_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2152	n 0 float8_accum	float8_var_samp -				-				-								f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp numeric_accum numeric_accum_inv numeric_var_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp		-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2149	n 0 int4_accum	numeric_poly_var_samp	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2150	n 0 int2_accum	numeric_poly_var_samp	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2151	n 0 float4_accum	float8_var_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2152	n 0 float8_accum	float8_var_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp	-	numeric_accum numeric_accum_inv numeric_var_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* stddev_pop */
-DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop	int8_accum	int8_accum_inv	numeric_stddev_pop					f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2725	n 0 int4_accum	numeric_poly_stddev_pop int4_accum	int4_accum_inv	numeric_poly_stddev_pop f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2726	n 0 int2_accum	numeric_poly_stddev_pop int2_accum	int2_accum_inv	numeric_poly_stddev_pop f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop numeric_accum numeric_accum_inv numeric_stddev_pop			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop		-	int8_accum	int8_accum_inv	numeric_stddev_pop		f f 0	2281	128	2281	128 _null_ _null_ ));
+DATA(insert ( 2725	n 0 int4_accum	numeric_poly_stddev_pop	-	int4_accum	int4_accum_inv	numeric_poly_stddev_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2726	n 0 int2_accum	numeric_poly_stddev_pop	-	int2_accum	int2_accum_inv	numeric_poly_stddev_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-	-				-				-					f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-	-				-				-					f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop	-	numeric_accum numeric_accum_inv numeric_stddev_pop	f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* stddev_samp */
-DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp		int8_accum	int8_accum_inv	numeric_stddev_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2713	n 0 int4_accum	numeric_poly_stddev_samp	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2714	n 0 int2_accum	numeric_poly_stddev_samp	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp numeric_accum numeric_accum_inv numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp			-	int8_accum	int8_accum_inv	numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2713	n 0 int4_accum	numeric_poly_stddev_samp	-	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2714	n 0 int2_accum	numeric_poly_stddev_samp	-	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp		-	numeric_accum numeric_accum_inv numeric_stddev_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* stddev: historical Postgres syntax for stddev_samp */
-DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp		int8_accum	int8_accum_inv	numeric_stddev_samp				f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2155	n 0 int4_accum	numeric_poly_stddev_samp	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2156	n 0 int2_accum	numeric_poly_stddev_samp	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp numeric_accum numeric_accum_inv numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp			-	int8_accum		int8_accum_inv	numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2155	n 0 int4_accum	numeric_poly_stddev_samp	-	int4_accum		int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2156	n 0 int2_accum	numeric_poly_stddev_samp	-	int2_accum		int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp		-	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp		-	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp		-	numeric_accum	numeric_accum_inv numeric_stddev_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
 
 /* SQL2003 binary regression aggregates */
-DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-				-				-				f f 0	20		0	0		0	"0" _null_ ));
-DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-				-				-				f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-	-				-				-			f f 0	20		0	0		0	"0" _null_ ));
+DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
 
 /* boolean-and and boolean-or */
-DATA(insert ( 2517	n 0 booland_statefunc	-			bool_accum		bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2518	n 0 boolor_statefunc	-			bool_accum		bool_accum_inv	bool_anytrue	f f 59	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2519	n 0 booland_statefunc	-			bool_accum		bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2517	n 0 booland_statefunc	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2518	n 0 boolor_statefunc	-	-	bool_accum	bool_accum_inv	bool_anytrue	f f 59	16		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2519	n 0 booland_statefunc	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
 
 /* bitwise integer */
-DATA(insert ( 2236	n 0 int2and		-					-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2237	n 0 int2or		-					-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2238	n 0 int4and		-					-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2239	n 0 int4or		-					-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2240	n 0 int8and		-					-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2241	n 0 int8or		-					-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2242	n 0 bitand		-					-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
-DATA(insert ( 2243	n 0 bitor		-					-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
+DATA(insert ( 2236	n 0 int2and		-				int2and	-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
+DATA(insert ( 2237	n 0 int2or		-				int2or	-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
+DATA(insert ( 2238	n 0 int4and		-				int4and	-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
+DATA(insert ( 2239	n 0 int4or		-				int4or	-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
+DATA(insert ( 2240	n 0 int8and		-				int8and	-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
+DATA(insert ( 2241	n 0 int8or		-				int8or	-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
+DATA(insert ( 2242	n 0 bitand		-				bitand	-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
+DATA(insert ( 2243	n 0 bitor		-				bitor	-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
 
 /* xml */
-DATA(insert ( 2901	n 0 xmlconcat2	-					-				-				-				f f 0	142		0	0		0	_null_ _null_ ));
+DATA(insert ( 2901	n 0 xmlconcat2	-				-		-				-				-				f f 0	142		0	0		0	_null_ _null_ ));
 
 /* array */
-DATA(insert ( 2335	n 0 array_agg_transfn	array_agg_finalfn	-				-				-				t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn -		-				-				t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 2335	n 0 array_agg_transfn		array_agg_finalfn		-	-		-				-				t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn	-	-		-				-				t f 0	2281	0	0		0	_null_ _null_ ));
 
 /* text */
-DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
 
 /* bytea */
-DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-				-				-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-	-				-				-		f f 0	2281	0	0		0	_null_ _null_ ));
 
 /* json */
-DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
 
 /* jsonb */
-DATA(insert ( 3267	n 0 jsonb_agg_transfn	jsonb_agg_finalfn			-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3270	n 0 jsonb_object_agg_transfn jsonb_object_agg_finalfn -				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3267	n 0 jsonb_agg_transfn	jsonb_agg_finalfn				-	-				-				-			f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3270	n 0 jsonb_object_agg_transfn jsonb_object_agg_finalfn	-	-				-				-			f f 0	2281	0	0		0	_null_ _null_ ));
 
 /* ordered-set and hypothetical-set aggregates */
-DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
 
 
 /*
@@ -322,6 +325,7 @@ extern ObjectAddress AggregateCreate(const char *aggName,
 				Oid variadicArgType,
 				List *aggtransfnName,
 				List *aggfinalfnName,
+				List *aggcombinefnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index bfa5125..07cd20a 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1851,6 +1851,8 @@ typedef struct AggState
 	AggStatePerTrans curpertrans;	/* currently active trans state */
 	bool		input_done;		/* indicates end of input */
 	bool		agg_done;		/* indicates completion of Agg scan */
+	bool		combineStates;	/* input tuples contain transition states */
+	bool		finalizeAggs;	/* should we call the finalfn on agg states? */
 	int			projected_set;	/* The last projected grouping set */
 	int			current_set;	/* The current grouping set being evaluated */
 	Bitmapset  *grouped_cols;	/* grouped cols in current projection */
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index c92579b..e823c83 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -726,6 +726,8 @@ typedef struct Agg
 	AggStrategy aggstrategy;
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
+	bool		combineStates;	/* input tuples contain transition states */
+	bool		finalizeAggs;	/* should we call the finalfn on agg states? */
 	Oid		   *grpOperators;	/* equality operators to compare with */
 	long		numGroups;		/* estimated number of groups in input */
 	List	   *groupingSets;	/* grouping sets to use */
diff --git a/src/include/optimizer/clauses.h b/src/include/optimizer/clauses.h
index 3b3fd0f..d381ff0 100644
--- a/src/include/optimizer/clauses.h
+++ b/src/include/optimizer/clauses.h
@@ -27,6 +27,25 @@ typedef struct
 	List	  **windowFuncs;	/* lists of WindowFuncs for each winref */
 } WindowFuncLists;
 
+/*
+ * PartialAggType
+ *	PartialAggType stores whether partial aggregation is allowed and
+ *	which context it is allowed in. We require three states here as there are
+ *	two different contexts in which partial aggregation is safe. For aggregates
+ *	which have an 'stype' of INTERNAL, within a single backend process it is
+ *	okay to pass a pointer to the aggregate state, as the memory to which the
+ *	pointer points to will belong to the same process. In cases where the
+ *	aggregate state must be passed between different processes, for example
+ *	during parallel aggregation, passing the pointer is not okay due to the
+ *	fact that the memory being referenced won't be accessible from another
+ *	process.
+ */
+typedef enum
+{
+	PAT_ANY = 0,		/* Any type of partial aggregation is ok. */
+	PAT_INTERNAL_ONLY,	/* Some aggregates support only internal mode. */
+	PAT_DISABLED		/* Some aggregates don't support partial mode at all */
+} PartialAggType;
 
 extern Expr *make_opclause(Oid opno, Oid opresulttype, bool opretset,
 			  Expr *leftop, Expr *rightop,
@@ -47,6 +66,7 @@ extern Node *make_and_qual(Node *qual1, Node *qual2);
 extern Expr *make_ands_explicit(List *andclauses);
 extern List *make_ands_implicit(Expr *clause);
 
+extern PartialAggType aggregates_allow_partial(Node *clause);
 extern bool contain_agg_clause(Node *clause);
 extern void count_agg_clauses(PlannerInfo *root, Node *clause,
 				  AggClauseCosts *costs);
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index 275054f..7ae7367 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -60,9 +60,8 @@ extern Sort *make_sort_from_groupcols(PlannerInfo *root, List *groupcls,
 extern Agg *make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
 		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
-		 List *groupingSets,
-		 long numGroups,
-		 Plan *lefttree);
+		 List *groupingSets, long numGroups, bool combineStates,
+		 bool finalizeAggs, Plan *lefttree);
 extern WindowAgg *make_windowagg(PlannerInfo *root, List *tlist,
 			   List *windowFuncs, Index winref,
 			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
diff --git a/src/include/parser/parse_agg.h b/src/include/parser/parse_agg.h
index 3e336b9..699b61c 100644
--- a/src/include/parser/parse_agg.h
+++ b/src/include/parser/parse_agg.h
@@ -46,6 +46,11 @@ extern void build_aggregate_transfn_expr(Oid *agg_input_types,
 						Expr **transfnexpr,
 						Expr **invtransfnexpr);
 
+extern void build_aggregate_combinefn_expr(Oid agg_state_type,
+										   Oid agg_input_collation,
+										   Oid combinefn_oid,
+										   Expr **combinefnexpr);
+
 extern void build_aggregate_finalfn_expr(Oid *agg_input_types,
 						int num_finalfn_inputs,
 						Oid agg_state_type,
diff --git a/src/test/regress/expected/create_aggregate.out b/src/test/regress/expected/create_aggregate.out
index 82a34fb..66e073d 100644
--- a/src/test/regress/expected/create_aggregate.out
+++ b/src/test/regress/expected/create_aggregate.out
@@ -101,6 +101,24 @@ CREATE AGGREGATE sumdouble (float8)
     msfunc = float8pl,
     minvfunc = float8mi
 );
+-- Test aggregate combine function
+-- ensure create aggregate works.
+CREATE AGGREGATE mysum (int)
+(
+	stype = int,
+	sfunc = int4pl,
+	combinefunc = int4pl
+);
+-- Ensure all these functions made it into the catalog
+SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype
+FROM pg_aggregate
+WHERE aggfnoid = 'mysum'::REGPROC;
+ aggfnoid | aggtransfn | aggcombinefn | aggtranstype 
+----------+------------+--------------+--------------
+ mysum    | int4pl     | int4pl       |           23
+(1 row)
+
+DROP AGGREGATE mysum (int);
 -- invalid: nonstrict inverse with strict forward function
 CREATE FUNCTION float8mi_n(float8, float8) RETURNS float8 AS
 $$ SELECT $1 - $2; $$
diff --git a/src/test/regress/sql/create_aggregate.sql b/src/test/regress/sql/create_aggregate.sql
index 0ec1572..dfcbc5a 100644
--- a/src/test/regress/sql/create_aggregate.sql
+++ b/src/test/regress/sql/create_aggregate.sql
@@ -115,6 +115,23 @@ CREATE AGGREGATE sumdouble (float8)
     minvfunc = float8mi
 );
 
+-- Test aggregate combine function
+
+-- ensure create aggregate works.
+CREATE AGGREGATE mysum (int)
+(
+	stype = int,
+	sfunc = int4pl,
+	combinefunc = int4pl
+);
+
+-- Ensure all these functions made it into the catalog
+SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype
+FROM pg_aggregate
+WHERE aggfnoid = 'mysum'::REGPROC;
+
+DROP AGGREGATE mysum (int);
+
 -- invalid: nonstrict inverse with strict forward function
 
 CREATE FUNCTION float8mi_n(float8, float8) RETURNS float8 AS

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index c0ec905..87e4ca2 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -134,7 +134,104 @@ static Plan *build_grouping_chain(PlannerInfo *root,
 					 AttrNumber *groupColIdx,
 					 AggClauseCosts *agg_costs,
 					 long numGroups,
-					 Plan *result_plan);
+					 Plan *result_plan,
+					 PartialAggType partialaggtype);
+
+static List *
+make_aggregate_tlist(PlannerInfo *root,
+					 List *tlist,
+					 AttrNumber **groupColIdx)
+{
+	Query	   *parse = root->parse;
+	List	   *sub_tlist;
+	List	   *non_group_cols;
+	List	   *non_group_vars;
+	int			numCols;
+	ListCell   *tl;
+
+	*groupColIdx = NULL;
+
+	/*
+	 * Otherwise, we must build a tlist containing all grouping columns, plus
+	 * any other Vars mentioned in the targetlist and HAVING qual.
+	 */
+	sub_tlist = NIL;
+	non_group_cols = NIL;
+
+	numCols = list_length(parse->groupClause);
+	if (numCols > 0)
+	{
+		/*
+		 * If grouping, create sub_tlist entries for all GROUP BY columns, and
+		 * make an array showing where the group columns are in the sub_tlist.
+		 *
+		 * Note: with this implementation, the array entries will always be
+		 * 1..N, but we don't want callers to assume that.
+		 */
+		AttrNumber *grpColIdx;
+
+		grpColIdx = (AttrNumber *) palloc0(sizeof(AttrNumber) * numCols);
+		*groupColIdx = grpColIdx;
+
+		foreach(tl, tlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(tl);
+			int			colno;
+
+			colno = get_grouping_column_index(parse, tle);
+			if (colno >= 0)
+			{
+				/*
+				 * It's a grouping column, so add it to the result tlist and
+				 * remember its resno in grpColIdx[].
+				 */
+				TargetEntry *newtle;
+
+				newtle = makeTargetEntry((Expr *) copyObject(tle->expr),
+										 list_length(sub_tlist) + 1,
+										 NULL,
+										 tle->resjunk);
+				newtle->ressortgroupref = tle->ressortgroupref;
+				sub_tlist = lappend(sub_tlist, newtle);
+
+				Assert(grpColIdx[colno] == 0);	/* no dups expected */
+				grpColIdx[colno] = newtle->resno;
+			}
+			else
+			{
+				non_group_cols = lappend(non_group_cols, tle->expr);
+			}
+		}
+	}
+	else
+	{
+		foreach(tl, tlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(tl);
+			non_group_cols = lappend(non_group_cols, tle->expr);
+		}
+	}
+
+	/*
+	 * If there's a HAVING clause, we'll need need to ensure all Aggrefs from
+	 * there are also in the targetlist
+	 */
+	if (parse->havingQual)
+		non_group_cols = lappend(non_group_cols, parse->havingQual);
+
+
+	non_group_vars = pull_var_clause((Node *) non_group_cols,
+									 PVC_INCLUDE_AGGREGATES,
+									 PVC_INCLUDE_PLACEHOLDERS);
+
+	sub_tlist = add_to_flat_tlist(sub_tlist, non_group_vars);
+
+	/* clean up cruft */
+	list_free(non_group_vars);
+	list_free(non_group_cols);
+
+	return sub_tlist;
+}
 
 /*****************************************************************************
  *
@@ -1896,6 +1993,19 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			AttrNumber *groupColIdx = NULL;
 			bool		need_tlist_eval = true;
 			bool		need_sort_for_grouping = false;
+			PartialAggType partialaggtype;
+
+			/* Determine the level of partial aggregation we can use */
+			if (parse->groupingSets)
+				partialaggtype = PAT_DISABLED;
+			else
+			{
+				partialaggtype = aggregates_allow_partial((Node *) tlist);
+
+				if (partialaggtype != PAT_DISABLED)
+					partialaggtype = Min(partialaggtype,
+							aggregates_allow_partial(root->parse->havingQual));
+			}
 
 			result_plan = create_plan(root, best_path);
 			current_pathkeys = best_path->pathkeys;
@@ -1913,6 +2023,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 											   &groupColIdx,
 											   &need_tlist_eval);
 
+			if (partialaggtype != PAT_DISABLED)
+				need_tlist_eval = true;
+
 			/*
 			 * create_plan returns a plan with just a "flat" tlist of required
 			 * Vars.  Usually we need to insert the sub_tlist as the tlist of
@@ -1994,20 +2107,71 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			 */
 			if (use_hashed_grouping)
 			{
-				/* Hashed aggregate plan --- no sort needed */
-				result_plan = (Plan *) make_agg(root,
-												tlist,
-												(List *) parse->havingQual,
-												AGG_HASHED,
-												&agg_costs,
-												numGroupCols,
-												groupColIdx,
-									extract_grouping_ops(parse->groupClause),
-												NIL,
-												numGroups,
-												false,
-												true,
-												result_plan);
+				if (partialaggtype != PAT_DISABLED)
+				{
+					AttrNumber *groupColIdx;
+					List *aggtlist;
+
+					aggtlist = make_aggregate_tlist(root, tlist, &groupColIdx);
+
+					/* Hashed aggregate plan --- no sort needed */
+					result_plan = (Plan *) make_agg(root,
+													aggtlist,
+													NIL,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													false,
+													false,
+													result_plan);
+
+					result_plan->targetlist = aggtlist;
+
+					/*
+					 * Also, account for the cost of evaluation of the sub_tlist.
+					 * See comments for add_tlist_costs_to_plan() for more info.
+					 */
+					add_tlist_costs_to_plan(root, result_plan, aggtlist);
+
+					aggtlist  = make_aggregate_tlist(root, tlist, &groupColIdx);
+
+					result_plan = (Plan *) make_agg(root,
+													aggtlist,
+													(List *) parse->havingQual,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													true,
+													true,
+													result_plan);
+					result_plan->targetlist = tlist;
+
+				}
+				else
+				{
+					/* Hashed aggregate plan --- no sort needed */
+					result_plan = (Plan *) make_agg(root,
+													tlist,
+													(List *) parse->havingQual,
+													AGG_HASHED,
+													&agg_costs,
+													numGroupCols,
+													groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+													NIL,
+													numGroups,
+													false,
+													true,
+													result_plan);
+				}
 				/* Hashed aggregation produces randomly-ordered results */
 				current_pathkeys = NIL;
 			}
@@ -2036,7 +2200,8 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 												   groupColIdx,
 												   &agg_costs,
 												   numGroups,
-												   result_plan);
+												   result_plan,
+												   partialaggtype);
 			}
 			else if (parse->groupClause)
 			{
@@ -2481,7 +2646,8 @@ build_grouping_chain(PlannerInfo *root,
 					 AttrNumber *groupColIdx,
 					 AggClauseCosts *agg_costs,
 					 long numGroups,
-					 Plan *result_plan)
+					 Plan *result_plan,
+					 PartialAggType partialaggtype)
 {
 	AttrNumber *top_grpColIdx = groupColIdx;
 	List	   *chain = NIL;
@@ -2584,20 +2750,67 @@ build_grouping_chain(PlannerInfo *root,
 		else
 			numGroupCols = list_length(parse->groupClause);
 
-		result_plan = (Plan *) make_agg(root,
-										tlist,
-										(List *) parse->havingQual,
-								 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
-										agg_costs,
-										numGroupCols,
-										top_grpColIdx,
-										extract_grouping_ops(groupClause),
-										gsets,
-										numGroups,
-										false,
-										true,
-										result_plan);
+		if (partialaggtype != PAT_DISABLED)
+		{
+			AttrNumber *groupColIdx;
+			List *aggtlist;
+
+			aggtlist = make_aggregate_tlist(root, tlist, &groupColIdx);
+
+			result_plan = (Plan *) make_agg(root,
+											aggtlist,
+											NIL,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											groupColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											false,
+											false,
+											result_plan);
+			result_plan->targetlist = aggtlist;
+
+			/*
+			 * Also, account for the cost of evaluation of the sub_tlist.
+			 * See comments for add_tlist_costs_to_plan() for more info.
+			 */
+			add_tlist_costs_to_plan(root, result_plan, aggtlist);
+
+			aggtlist  = make_aggregate_tlist(root, tlist, &groupColIdx);
 
+			result_plan = (Plan *) make_agg(root,
+											aggtlist,
+											(List *) parse->havingQual,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											groupColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											true,
+											true,
+											result_plan);
+			result_plan->targetlist = tlist;
+		}
+		else
+		{
+			result_plan = (Plan *) make_agg(root,
+											tlist,
+											(List *) parse->havingQual,
+									 (numGroupCols > 0) ? AGG_SORTED : AGG_PLAIN,
+											agg_costs,
+											numGroupCols,
+											top_grpColIdx,
+											extract_grouping_ops(groupClause),
+											gsets,
+											numGroups,
+											false,
+											true,
+											result_plan);
+		}
 		((Agg *) result_plan)->chain = chain;
 
 		/*

diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 5fc80e7..184e1e0 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -126,6 +126,7 @@ bool		enable_material = true;
 bool		enable_mergejoin = true;
 bool		enable_hashjoin = true;
 
+bool		enable_parallelagg = false;
 typedef struct
 {
 	PlannerInfo *root;
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index c0ec905..0ac84f7 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -49,6 +49,8 @@
 #include "utils/rel.h"
 #include "utils/selfuncs.h"
 
+#include "utils/syscache.h"
+#include "catalog/pg_aggregate.h"
 
 /* GUC parameter */
 double		cursor_tuple_fraction = DEFAULT_CURSOR_TUPLE_FRACTION;
@@ -77,6 +79,12 @@ typedef struct
 	List	   *groupClause;	/* overrides parse->groupClause */
 } standard_qp_extra;
 
+typedef struct
+{
+	AttrNumber 	resno;
+	List		*targetlist;
+} AddQualInTListExprContext;
+
 /* Local functions */
 static Node *preprocess_expression(PlannerInfo *root, Node *expr, int kind);
 static void preprocess_qual_conditions(PlannerInfo *root, Node *jtnode);
@@ -134,8 +142,35 @@ static Plan *build_grouping_chain(PlannerInfo *root,
 					 AttrNumber *groupColIdx,
 					 AggClauseCosts *agg_costs,
 					 long numGroups,
+					 bool combineStates,
+					 bool finalizeAggs,
+					 Plan *result_plan);
+static Plan *make_group_agg(PlannerInfo *root,
+					 Query *parse,
+					 List *tlist,
+					 bool need_sort_for_grouping,
+					 List *rollup_groupclauses,
+					 List *rollup_lists,
+					 AttrNumber *groupColIdx,
+					 AggClauseCosts *agg_costs,
+					 long numGroups,
+					 bool parallel_agg,
 					 Plan *result_plan);
 
+static AttrNumber*get_grpColIdx_from_subPlan(PlannerInfo *root, List *tlist);
+static List *make_partial_agg_tlist(List *tlist,List *groupClause);
+static List* add_qual_in_tlist(List *targetlist, List *qual);
+static bool add_qual_in_tlist_walker (Node *node,
+					 AddQualInTListExprContext *context);
+static Plan *make_hash_agg(PlannerInfo *root,
+						   Query *parse,
+						   List *tlist,
+						   AggClauseCosts *aggcosts,
+						   int numGroupCols,
+						   AttrNumber *grpColIdx,
+						   long numGroups,
+						   bool parallel_agg,
+						   Plan *lefttree);
 /*****************************************************************************
  *
  *	   Query optimizer entry point
@@ -1329,6 +1364,7 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 	double		dNumGroups = 0;
 	bool		use_hashed_distinct = false;
 	bool		tested_hashed_distinct = false;
+	bool		parallel_agg = false;
 
 	/* Tweak caller-supplied tuple_fraction if have LIMIT/OFFSET */
 	if (parse->limitCount || parse->limitOffset)
@@ -1411,6 +1447,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 	else
 	{
 		/* No set operations, do regular planning */
+		List	   *sub_tlist;
+		AttrNumber *groupColIdx = NULL;
+		bool		need_tlist_eval = true;
 		long		numGroups = 0;
 		AggClauseCosts agg_costs;
 		int			numGroupCols;
@@ -1425,8 +1464,8 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 		List	   *rollup_groupclauses = NIL;
 		standard_qp_extra qp_extra;
 		RelOptInfo *final_rel;
-		Path	   *cheapest_path;
-		Path	   *sorted_path;
+		Path	   *cheapest_path = NULL;
+		Path	   *sorted_path = NULL;
 		Path	   *best_path;
 
 		MemSet(&agg_costs, 0, sizeof(AggClauseCosts));
@@ -1752,22 +1791,54 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 		}
 
 		/*
-		 * Pick out the cheapest-total path as well as the cheapest presorted
-		 * path for the requested pathkeys (if there is one).  We should take
-		 * the tuple fraction into account when selecting the cheapest
-		 * presorted path, but not when selecting the cheapest-total path,
-		 * since if we have to sort then we'll have to fetch all the tuples.
-		 * (But there's a special case: if query_pathkeys is NIL, meaning
-		 * order doesn't matter, then the "cheapest presorted" path will be
-		 * the cheapest overall for the tuple fraction.)
+		 * Prepare a gather path on the partial path, in case if it satisfies
+		 * parallel aggregate plan.
 		 */
-		cheapest_path = final_rel->cheapest_total_path;
+		if (enable_parallelagg
+				&& final_rel->partial_pathlist
+				&& (dNumGroups < (path_rows / 4)))
+		{
+			/*
+			 * check for parallel aggregate eligibility by referring all aggregate
+			 * functions in both qualification and targetlist.
+			 */
+			if (aggregates_allow_partial((Node *)tlist)
+					&& aggregates_allow_partial(parse->havingQual))
+			{
+				Path	   *cheapest_partial_path;
+
+				cheapest_partial_path = linitial(final_rel->partial_pathlist);
+				cheapest_path = (Path *)
+						create_gather_path(root, final_rel, cheapest_partial_path, NULL);
+
+				sorted_path =
+					get_cheapest_fractional_path_for_pathkeys(final_rel->partial_pathlist,
+															  root->query_pathkeys,
+															  NULL,
+															  tuple_fraction);
+				parallel_agg = true;
+			}
+		}
+		else
+		{
+			/*
+			 * Pick out the cheapest-total path as well as the cheapest presorted
+			 * path for the requested pathkeys (if there is one).  We should take
+			 * the tuple fraction into account when selecting the cheapest
+			 * presorted path, but not when selecting the cheapest-total path,
+			 * since if we have to sort then we'll have to fetch all the tuples.
+			 * (But there's a special case: if query_pathkeys is NIL, meaning
+			 * order doesn't matter, then the "cheapest presorted" path will be
+			 * the cheapest overall for the tuple fraction.)
+			 */
+			cheapest_path = final_rel->cheapest_total_path;
 
-		sorted_path =
-			get_cheapest_fractional_path_for_pathkeys(final_rel->pathlist,
-													  root->query_pathkeys,
-													  NULL,
-													  tuple_fraction);
+			sorted_path =
+				get_cheapest_fractional_path_for_pathkeys(final_rel->pathlist,
+														  root->query_pathkeys,
+														  NULL,
+														  tuple_fraction);
+		}
 
 		/* Don't consider same path in both guises; just wastes effort */
 		if (sorted_path == cheapest_path)
@@ -1892,9 +1963,6 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			 * Normal case --- create a plan according to query_planner's
 			 * results.
 			 */
-			List	   *sub_tlist;
-			AttrNumber *groupColIdx = NULL;
-			bool		need_tlist_eval = true;
 			bool		need_sort_for_grouping = false;
 
 			result_plan = create_plan(root, best_path);
@@ -1903,15 +1971,22 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			/* Detect if we'll need an explicit sort for grouping */
 			if (parse->groupClause && !use_hashed_grouping &&
 			  !pathkeys_contained_in(root->group_pathkeys, current_pathkeys))
+			{
 				need_sort_for_grouping = true;
 
+				/*
+				 * Always override create_plan's tlist, so that we don't sort
+				 * useless data from a "physical" tlist.
+				 */
+				need_tlist_eval = true;
+			}
+
 			/*
-			 * Generate appropriate target list for scan/join subplan; may be
-			 * different from tlist if grouping or aggregation is needed.
+			 * Generate appropriate target list for subplan; may be different from
+			 * tlist if grouping or aggregation is needed.
 			 */
 			sub_tlist = make_subplanTargetList(root, tlist,
-											   &groupColIdx,
-											   &need_tlist_eval);
+											   &groupColIdx, &need_tlist_eval);
 
 			/*
 			 * create_plan returns a plan with just a "flat" tlist of required
@@ -1994,20 +2069,16 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			 */
 			if (use_hashed_grouping)
 			{
-				/* Hashed aggregate plan --- no sort needed */
-				result_plan = (Plan *) make_agg(root,
-												tlist,
-												(List *) parse->havingQual,
-												AGG_HASHED,
-												&agg_costs,
-												numGroupCols,
-												groupColIdx,
-									extract_grouping_ops(parse->groupClause),
-												NIL,
-												numGroups,
-												false,
-												true,
-												result_plan);
+				result_plan = make_hash_agg(root,
+											parse,
+											tlist,
+											&agg_costs,
+											numGroupCols,
+											groupColIdx,
+											numGroups,
+											parallel_agg,
+											result_plan);
+
 				/* Hashed aggregation produces randomly-ordered results */
 				current_pathkeys = NIL;
 			}
@@ -2027,16 +2098,24 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 				else
 					current_pathkeys = NIL;
 
-				result_plan = build_grouping_chain(root,
-												   parse,
-												   tlist,
-												   need_sort_for_grouping,
-												   rollup_groupclauses,
-												   rollup_lists,
-												   groupColIdx,
-												   &agg_costs,
-												   numGroups,
-												   result_plan);
+				result_plan = make_group_agg(root,
+										     parse,
+											 tlist,
+											 need_sort_for_grouping,
+											 rollup_groupclauses,
+											 rollup_lists,
+											 groupColIdx,
+											 &agg_costs,
+											 numGroups,
+											 parallel_agg,
+											 result_plan);
+
+				/*
+				 * these are destroyed by build_grouping_chain, so make sure
+				 * we don't try and touch them again
+				 */
+				rollup_groupclauses = NIL;
+				rollup_lists = NIL;
 			}
 			else if (parse->groupClause)
 			{
@@ -2481,6 +2560,8 @@ build_grouping_chain(PlannerInfo *root,
 					 AttrNumber *groupColIdx,
 					 AggClauseCosts *agg_costs,
 					 long numGroups,
+					 bool combineStates,
+					 bool finalizeAggs,
 					 Plan *result_plan)
 {
 	AttrNumber *top_grpColIdx = groupColIdx;
@@ -2553,8 +2634,8 @@ build_grouping_chain(PlannerInfo *root,
 										 extract_grouping_ops(groupClause),
 										 gsets,
 										 numGroups,
-										 false,
-										 true,
+									 combineStates,
+									 finalizeAggs,
 										 sort_plan);
 
 			/*
@@ -2594,8 +2675,8 @@ build_grouping_chain(PlannerInfo *root,
 										extract_grouping_ops(groupClause),
 										gsets,
 										numGroups,
-										false,
-										true,
+										combineStates,
+										finalizeAggs,
 										result_plan);
 
 		((Agg *) result_plan)->chain = chain;
@@ -4718,3 +4799,396 @@ plan_cluster_use_sort(Oid tableOid, Oid indexOid)
 
 	return (seqScanAndSortPath.total_cost < indexScanPath->path.total_cost);
 }
+
+/*
+ * This function build a hash parallelagg plan as result_plan as following :
+ * Finalize Hash Aggregate
+ *   -> Gather
+ *     -> Partial Hash Aggregate
+ *       -> Any partial plan
+ * The input result_plan will be
+ * Gather
+ *  -> Any partial plan
+ * So this function will do the following steps:
+ * 1. Make a PartialHashAgg and set Gather node as above node
+ * 2. Change the targetlist of Gather node
+ * 3. Make a FinalizeHashAgg as top node above the Gather node
+ */
+
+static Plan *
+make_hash_agg(PlannerInfo *root,
+			   Query *parse,
+			   List *tlist,
+			   AggClauseCosts *agg_costs,
+			   int numGroupCols,
+			   AttrNumber *groupColIdx,
+			   long numGroups,
+			   bool parallel_agg,
+			   Plan *lefttree)
+{
+	Plan *result_plan = NULL;
+	Plan *partial_agg_plan = NULL;
+	Plan *gather_plan = NULL;
+	List *partial_agg_tlist = NIL;
+	List *qual = (List*)parse->havingQual;
+	AttrNumber *topgroupColIdx = NULL;
+
+	if (!parallel_agg || nodeTag(lefttree) != T_Gather)
+	{
+		result_plan = (Plan *) make_agg(root,
+										tlist,
+										(List *) parse->havingQual,
+										AGG_HASHED,
+										agg_costs,
+										numGroupCols,
+										groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+										NIL,
+										numGroups,
+										false,
+										true,
+										lefttree);
+		return result_plan;
+	}
+
+	Assert(nodeTag(lefttree) == T_Gather);
+	gather_plan = lefttree;
+
+	/*
+	 * The underlying Agg targetlist should be a flat tlist of all Vars and Aggs
+	 * needed to evaluate the expressions and final values of aggregates present
+	 * in the main target list. The quals also should be included.
+	 */
+	partial_agg_tlist = make_partial_agg_tlist(add_qual_in_tlist(tlist, qual),
+												parse->groupClause);
+
+	/* Make PartialHashAgg plan node */
+	partial_agg_plan = (Plan *) make_agg(root,
+									partial_agg_tlist,
+									NULL,
+									AGG_HASHED,
+									agg_costs,
+									numGroupCols,
+									groupColIdx,
+									extract_grouping_ops(parse->groupClause),
+									NIL,
+									numGroups,
+									false,
+									false,
+									gather_plan->lefttree);
+
+	gather_plan->lefttree = partial_agg_plan;
+	gather_plan->targetlist = partial_agg_plan->targetlist;
+
+	/*
+	 * Get the sortIndex according the subplan
+	 */
+	topgroupColIdx = get_grpColIdx_from_subPlan(root, partial_agg_tlist);
+
+	/* Make FinalizeHashAgg plan node */
+	result_plan = (Plan *) make_agg(root,
+									tlist,
+									(List *) parse->havingQual,
+									AGG_HASHED,
+									agg_costs,
+									numGroupCols,
+									topgroupColIdx,
+									extract_grouping_ops(parse->groupClause),
+									NIL,
+									numGroups,
+									true,
+									true,
+									gather_plan);
+
+	return result_plan;
+}
+
+/*
+ * This function build a group parallelagg plan as result_plan as following :
+ * Finalize Group Aggregate
+ *   ->  Sort
+ * 	   -> Gather
+ * 	     -> Partial Group Aggregate
+ * 	       -> Sort
+ * 	         -> Any partial plan
+ * The input result_plan will be
+ * Gather
+ *  -> Any partial plan
+ * So this function will do the following steps:
+ * 1. Move up the Gather node and change its targetlist
+ * 2. Change the Group Aggregate to be Partial Group Aggregate
+ * 3. Add Finalize Group Aggregate and Sort node
+ */
+static Plan *
+make_group_agg(PlannerInfo *root,
+			   Query *parse,
+			   List *tlist,
+			   bool need_sort_for_grouping,
+			   List *rollup_groupclauses,
+			   List *rollup_lists,
+			   AttrNumber *groupColIdx,
+			   AggClauseCosts *agg_costs,
+			   long numGroups,
+			   bool parallel_agg,
+			   Plan *result_plan)
+{
+	Plan *partial_agg = NULL;
+	Plan *gather_plan = NULL;
+	List *qual = (List*)parse->havingQual;
+	List *partial_agg_tlist = NULL;
+	AttrNumber *topgroupColIdx = NULL;
+
+	if (!parallel_agg || nodeTag(result_plan) != T_Gather)
+	{
+		result_plan = build_grouping_chain(root,
+										   parse,
+										   tlist,
+										   need_sort_for_grouping,
+										   rollup_groupclauses,
+										   rollup_lists,
+										   groupColIdx,
+										   &agg_costs,
+										   numGroups,
+										   false,
+										   true,
+										   result_plan);
+		return result_plan;
+	}
+
+	Assert(nodeTag(result_plan) == T_Gather);
+	gather_plan = result_plan;
+
+	/*
+	 * The underlying Agg targetlist should be a flat tlist of all Vars and Aggs
+	 * needed to evaluate the expressions and final values of aggregates present
+	 * in the main target list. The quals also should be included.
+	 */
+	partial_agg_tlist = make_partial_agg_tlist(add_qual_in_tlist(tlist, qual),
+												llast(rollup_groupclauses));
+
+	/* Add PartialAgg and Sort node */
+	partial_agg = build_grouping_chain(root,
+								   parse,
+								   partial_agg_tlist,
+								   need_sort_for_grouping,
+								   rollup_groupclauses,
+								   rollup_lists,
+								   groupColIdx,
+								   agg_costs,
+								   numGroups,
+								   false,
+								   false,
+								   gather_plan->lefttree);
+
+
+
+	/* Let the Gather node as upper node of partial_agg node */
+	gather_plan->targetlist = partial_agg->targetlist;
+	gather_plan->lefttree = partial_agg;
+
+	/*
+	 * Get the sortIndex according the subplan
+	 */
+	topgroupColIdx = get_grpColIdx_from_subPlan(root, partial_agg_tlist);
+
+	 /* Make the Finalize Group Aggregate node */
+	result_plan = build_grouping_chain(root,
+								   parse,
+								   tlist,
+								   need_sort_for_grouping,
+								   rollup_groupclauses,
+								   rollup_lists,
+								   topgroupColIdx,
+								   agg_costs,
+								   numGroups,
+								   true,
+								   true,
+								   gather_plan);
+
+	return result_plan;
+}
+
+/* Function to get the grouping column index from the provided plan */
+static AttrNumber*
+get_grpColIdx_from_subPlan(PlannerInfo *root, List *tlist)
+{
+	Query	   *parse = root->parse;
+	int			numCols;
+
+	AttrNumber *grpColIdx = NULL;
+
+	numCols = list_length(parse->groupClause);
+	if (numCols > 0)
+	{
+		ListCell   *tl;
+
+		grpColIdx = (AttrNumber *) palloc0(sizeof(AttrNumber) * numCols);
+
+		foreach(tl, tlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(tl);
+			int			colno;
+
+			colno = get_grouping_column_index(parse, tle);
+			if (colno >= 0)
+			{
+				Assert(grpColIdx[colno] == 0);	/* no dups expected */
+				grpColIdx[colno] = tle->resno;
+			}
+		}
+	}
+
+	return grpColIdx;
+}
+
+/*
+ * make_partial_agg_tlist
+ *	  Generate appropriate Agg node target list for input to ParallelAgg nodes.
+ *
+ * The initial target list passed to ParallelAgg node from the parser contains
+ * aggregates and GROUP BY columns. For the underlying agg node, we want to
+ * generate a tlist containing bare aggregate references (Aggref) and GROUP BY
+ * expressions. So we flatten all expressions except GROUP BY items into their
+ * component variables.
+ * For example, given a query like
+ *		SELECT a+b, 2 * SUM(c+d) , AVG(d)+SUM(c+d) FROM table GROUP BY a+b;
+ * we want to pass this targetlist to the Agg plan:
+ *		a+b, SUM(c+d), AVG(d)
+ * where the a+b target will be used by the Sort/Group steps, and the
+ * other targets will be used for computing the final results.
+ * Note that we don't flatten Aggref's , since those are to be computed
+ * by the underlying Agg node, and they will be referenced like Vars above it.
+ *
+ * 'tlist' is the ParallelAgg's final target list.
+ *
+ * The result is the targetlist to be computed by the Agg node below the
+ * ParallelAgg node.
+ */
+static List *
+make_partial_agg_tlist(List *tlist,List *groupClause)
+{
+	Bitmapset  *sgrefs;
+	List	   *new_tlist;
+	List	   *flattenable_cols;
+	List	   *flattenable_vars;
+	ListCell   *lc;
+
+	/*
+	 * Collect the sortgroupref numbers of GROUP BY clauses
+	 * into a bitmapset for convenient reference below.
+	 */
+	sgrefs = NULL;
+
+	/* Add in sortgroupref numbers of GROUP BY clauses */
+	foreach(lc, groupClause)
+	{
+		SortGroupClause *grpcl = (SortGroupClause *) lfirst(lc);
+
+		sgrefs = bms_add_member(sgrefs, grpcl->tleSortGroupRef);
+	}
+
+	/*
+	 * Construct a tlist containing all the non-flattenable tlist items, and
+	 * save aside the others for a moment.
+	 */
+	new_tlist = NIL;
+	flattenable_cols = NIL;
+
+	foreach(lc, tlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(lc);
+
+		/* Don't want to deconstruct GROUP BY items. */
+		if (tle->ressortgroupref != 0 &&
+			bms_is_member(tle->ressortgroupref, sgrefs))
+		{
+			/* Don't want to deconstruct this value, so add to new_tlist */
+			TargetEntry *newtle;
+
+			newtle = makeTargetEntry(tle->expr,
+									 list_length(new_tlist) + 1,
+									 NULL,
+									 false);
+			/* Preserve its sortgroupref marking, in case it's volatile */
+			newtle->ressortgroupref = tle->ressortgroupref;
+			new_tlist = lappend(new_tlist, newtle);
+		}
+		else
+		{
+			/*
+			 * Column is to be flattened, so just remember the expression for
+			 * later call to pull_var_clause.  There's no need for
+			 * pull_var_clause to examine the TargetEntry node itself.
+			 */
+			flattenable_cols = lappend(flattenable_cols, tle->expr);
+		}
+	}
+
+	/*
+	 * Pull out all the Vars and Aggrefs mentioned in flattenable columns, and
+	 * add them to the result tlist if not already present.  (Some might be
+	 * there already because they're used directly as group clauses.)
+	 *
+	 * Note: it's essential to use PVC_INCLUDE_AGGREGATES here, so that the
+	 * Aggrefs are placed in the Agg node's tlist and not left to be computed
+	 * at higher levels.
+	 */
+	flattenable_vars = pull_var_clause((Node *) flattenable_cols,
+									   PVC_INCLUDE_AGGREGATES,
+									   PVC_INCLUDE_PLACEHOLDERS);
+	new_tlist = add_to_flat_tlist(new_tlist, flattenable_vars);
+
+	/* clean up cruft */
+	list_free(flattenable_vars);
+	list_free(flattenable_cols);
+
+	return new_tlist;
+}
+
+/*
+ * add_qual_in_tlist
+ *		Add the agg functions in qual into the target list used in agg plan
+ */
+static List*
+add_qual_in_tlist(List *targetlist, List *qual)
+{
+	AddQualInTListExprContext context;
+
+	if(qual == NULL)
+		return targetlist;
+
+	context.targetlist = copyObject(targetlist);
+	context.resno = list_length(context.targetlist) + 1;;
+
+	add_qual_in_tlist_walker((Node*)qual, &context);
+
+	return context.targetlist;
+}
+
+/*
+ * add_qual_in_tlist_walker
+ *		Go through the qual list to get the aggref and add it in targetlist
+ */
+static bool
+add_qual_in_tlist_walker (Node *node, AddQualInTListExprContext *context)
+{
+	if (node == NULL)
+		return false;
+
+	if (IsA(node, Aggref))
+	{
+		List *tlist = context->targetlist;
+		TargetEntry *te = makeNode(TargetEntry);
+
+		te = makeTargetEntry((Expr *) node,
+				  context->resno++,
+				  NULL,
+				  false);
+
+		tlist = lappend(tlist,te);
+	}
+	else
+		return expression_tree_walker(node, add_qual_in_tlist_walker, context);
+
+	return false;
+}
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 615f3a2..85b649e 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -15,7 +15,9 @@
  */
 #include "postgres.h"
 
+#include "access/htup_details.h"
 #include "access/transam.h"
+#include "catalog/pg_aggregate.h"
 #include "catalog/pg_type.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
@@ -65,6 +67,7 @@ typedef struct
 	indexed_tlist *subplan_itlist;
 	Index		newvarno;
 	int			rtoffset;
+	bool		partial_agg;
 } fix_upper_expr_context;
 
 /*
@@ -104,6 +107,8 @@ static Node *fix_scan_expr_mutator(Node *node, fix_scan_expr_context *context);
 static bool fix_scan_expr_walker(Node *node, fix_scan_expr_context *context);
 static void set_join_references(PlannerInfo *root, Join *join, int rtoffset);
 static void set_upper_references(PlannerInfo *root, Plan *plan, int rtoffset);
+static void set_agg_references(PlannerInfo *root, Plan *plan, int rtoffset);
+static void set_partialagg_aggref_types(PlannerInfo *root, Plan *plan);
 static void set_dummy_tlist_references(Plan *plan, int rtoffset);
 static indexed_tlist *build_tlist_index(List *tlist);
 static Var *search_indexed_tlist_for_var(Var *var,
@@ -128,7 +133,8 @@ static Node *fix_upper_expr(PlannerInfo *root,
 			   Node *node,
 			   indexed_tlist *subplan_itlist,
 			   Index newvarno,
-			   int rtoffset);
+			   int rtoffset,
+			   bool partial_agg);
 static Node *fix_upper_expr_mutator(Node *node,
 					   fix_upper_expr_context *context);
 static List *set_returning_clause_references(PlannerInfo *root,
@@ -140,6 +146,7 @@ static bool fix_opfuncids_walker(Node *node, void *context);
 static bool extract_query_dependencies_walker(Node *node,
 								  PlannerInfo *context);
 
+
 /*****************************************************************************
  *
  *		SUBPLAN REFERENCES
@@ -668,7 +675,7 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 			}
 			break;
 		case T_Agg:
-			set_upper_references(root, plan, rtoffset);
+			set_agg_references(root, plan, rtoffset);
 			break;
 		case T_Group:
 			set_upper_references(root, plan, rtoffset);
@@ -943,13 +950,15 @@ set_indexonlyscan_references(PlannerInfo *root,
 					   (Node *) plan->scan.plan.targetlist,
 					   index_itlist,
 					   INDEX_VAR,
-					   rtoffset);
+					   rtoffset,
+					   false);
 	plan->scan.plan.qual = (List *)
 		fix_upper_expr(root,
 					   (Node *) plan->scan.plan.qual,
 					   index_itlist,
 					   INDEX_VAR,
-					   rtoffset);
+					   rtoffset,
+					   false);
 	/* indexqual is already transformed to reference index columns */
 	plan->indexqual = fix_scan_list(root, plan->indexqual, rtoffset);
 	/* indexorderby is already transformed to reference index columns */
@@ -1116,25 +1125,29 @@ set_foreignscan_references(PlannerInfo *root,
 						   (Node *) fscan->scan.plan.targetlist,
 						   itlist,
 						   INDEX_VAR,
-						   rtoffset);
+						   rtoffset,
+						   false);
 		fscan->scan.plan.qual = (List *)
 			fix_upper_expr(root,
 						   (Node *) fscan->scan.plan.qual,
 						   itlist,
 						   INDEX_VAR,
-						   rtoffset);
+						   rtoffset,
+						   false);
 		fscan->fdw_exprs = (List *)
 			fix_upper_expr(root,
 						   (Node *) fscan->fdw_exprs,
 						   itlist,
 						   INDEX_VAR,
-						   rtoffset);
+						   rtoffset,
+						   false);
 		fscan->fdw_recheck_quals = (List *)
 			fix_upper_expr(root,
 						   (Node *) fscan->fdw_recheck_quals,
 						   itlist,
 						   INDEX_VAR,
-						   rtoffset);
+						   rtoffset,
+						   false);
 		pfree(itlist);
 		/* fdw_scan_tlist itself just needs fix_scan_list() adjustments */
 		fscan->fdw_scan_tlist =
@@ -1190,19 +1203,22 @@ set_customscan_references(PlannerInfo *root,
 						   (Node *) cscan->scan.plan.targetlist,
 						   itlist,
 						   INDEX_VAR,
-						   rtoffset);
+						   rtoffset,
+						   false);
 		cscan->scan.plan.qual = (List *)
 			fix_upper_expr(root,
 						   (Node *) cscan->scan.plan.qual,
 						   itlist,
 						   INDEX_VAR,
-						   rtoffset);
+						   rtoffset,
+						   false);
 		cscan->custom_exprs = (List *)
 			fix_upper_expr(root,
 						   (Node *) cscan->custom_exprs,
 						   itlist,
 						   INDEX_VAR,
-						   rtoffset);
+						   rtoffset,
+						   false);
 		pfree(itlist);
 		/* custom_scan_tlist itself just needs fix_scan_list() adjustments */
 		cscan->custom_scan_tlist =
@@ -1524,7 +1540,8 @@ set_join_references(PlannerInfo *root, Join *join, int rtoffset)
 												   (Node *) nlp->paramval,
 												   outer_itlist,
 												   OUTER_VAR,
-												   rtoffset);
+												   rtoffset,
+												   false);
 			/* Check we replaced any PlaceHolderVar with simple Var */
 			if (!(IsA(nlp->paramval, Var) &&
 				  nlp->paramval->varno == OUTER_VAR))
@@ -1648,14 +1665,16 @@ set_upper_references(PlannerInfo *root, Plan *plan, int rtoffset)
 										 (Node *) tle->expr,
 										 subplan_itlist,
 										 OUTER_VAR,
-										 rtoffset);
+										 rtoffset,
+										 false);
 		}
 		else
 			newexpr = fix_upper_expr(root,
 									 (Node *) tle->expr,
 									 subplan_itlist,
 									 OUTER_VAR,
-									 rtoffset);
+									 rtoffset,
+									 false);
 		tle = flatCopyTargetEntry(tle);
 		tle->expr = (Expr *) newexpr;
 		output_targetlist = lappend(output_targetlist, tle);
@@ -1667,7 +1686,8 @@ set_upper_references(PlannerInfo *root, Plan *plan, int rtoffset)
 					   (Node *) plan->qual,
 					   subplan_itlist,
 					   OUTER_VAR,
-					   rtoffset);
+					   rtoffset,
+					   false);
 
 	pfree(subplan_itlist);
 }
@@ -2121,7 +2141,8 @@ fix_upper_expr(PlannerInfo *root,
 			   Node *node,
 			   indexed_tlist *subplan_itlist,
 			   Index newvarno,
-			   int rtoffset)
+			   int rtoffset,
+			   bool partial_agg)
 {
 	fix_upper_expr_context context;
 
@@ -2129,6 +2150,7 @@ fix_upper_expr(PlannerInfo *root,
 	context.subplan_itlist = subplan_itlist;
 	context.newvarno = newvarno;
 	context.rtoffset = rtoffset;
+	context.partial_agg = partial_agg;
 	return fix_upper_expr_mutator(node, &context);
 }
 
@@ -2151,6 +2173,36 @@ fix_upper_expr_mutator(Node *node, fix_upper_expr_context *context)
 			elog(ERROR, "variable not found in subplan target list");
 		return (Node *) newvar;
 	}
+	if (IsA(node, Aggref) && context->partial_agg)
+	{
+		TargetEntry *tle;
+		Aggref		*aggref = (Aggref*)node;
+		List	    *args = NIL;
+
+		tle = tlist_member(node, context->subplan_itlist->tlist);
+		if (tle)
+		{
+			/* Found a matching subplan output expression */
+			Var		   *newvar;
+			TargetEntry *newtle;
+
+			newvar = makeVarFromTargetEntry(context->newvarno, tle);
+			newvar->varnoold = 0;	/* wasn't ever a plain Var */
+			newvar->varoattno = 0;
+
+			/* makeTargetEntry ,always set resno to one for finialize agg */
+			newtle = makeTargetEntry((Expr*)newvar,1,NULL,false);
+			args = lappend(args,newtle);
+
+			/*
+			 * Updated the args, let the newvar refer to the right position of
+			 * the agg function in the subplan
+			 */
+			aggref->args = args;
+
+			return (Node *) aggref;
+		}
+	}
 	if (IsA(node, PlaceHolderVar))
 	{
 		PlaceHolderVar *phv = (PlaceHolderVar *) node;
@@ -2432,3 +2484,123 @@ extract_query_dependencies_walker(Node *node, PlannerInfo *context)
 	return expression_tree_walker(node, extract_query_dependencies_walker,
 								  (void *) context);
 }
+
+/*
+ * set_agg_references
+ *	  Update the targetlist and quals of an upper-level plan node
+ *	  to refer to the tuples returned by its lefttree subplan.
+ *	  Also perform opcode lookup for these expressions, and
+ *	  add regclass OIDs to root->glob->relationOids.
+ *
+ * This is used for single-input plan types like Agg, Group, Result.
+ *
+ * In most cases, we have to match up individual Vars in the tlist and
+ * qual expressions with elements of the subplan's tlist (which was
+ * generated by flatten_tlist() from these selfsame expressions, so it
+ * should have all the required variables).  There is an important exception,
+ * however: GROUP BY and ORDER BY expressions will have been pushed into the
+ * subplan tlist unflattened.  If these values are also needed in the output
+ * then we want to reference the subplan tlist element rather than recomputing
+ * the expression.
+ */
+static void
+set_agg_references(PlannerInfo *root, Plan *plan, int rtoffset)
+{
+	Agg 	   *agg = (Agg*)plan;
+	Plan	   *subplan = plan->lefttree;
+	indexed_tlist *subplan_itlist;
+	List	   *output_targetlist;
+	ListCell   *l;
+
+	if (!agg->combineStates)
+		return set_upper_references(root, plan, rtoffset);
+
+	/*
+	 * For partial aggregation we must adjust the return types of
+	 * the Aggrefs
+	 */
+	if (!agg->finalizeAggs)
+		set_partialagg_aggref_types(root, plan);
+
+	subplan_itlist = build_tlist_index(subplan->targetlist);
+
+	output_targetlist = NIL;
+
+	if(agg->combineStates)
+	{
+		foreach(l, plan->targetlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(l);
+			Node	   *newexpr;
+
+			/* If it's a non-Var sort/group item, first try to match by sortref */
+			if (tle->ressortgroupref != 0 && !IsA(tle->expr, Var))
+			{
+				newexpr = (Node *)
+					search_indexed_tlist_for_sortgroupref((Node *) tle->expr,
+														  tle->ressortgroupref,
+														  subplan_itlist,
+														  OUTER_VAR);
+				if (!newexpr)
+					newexpr = fix_upper_expr(root,
+											 (Node *) tle->expr,
+											 subplan_itlist,
+											 OUTER_VAR,
+											 rtoffset,
+											 true);
+			}
+			else
+				newexpr = fix_upper_expr(root,
+										 (Node *) tle->expr,
+										 subplan_itlist,
+										 OUTER_VAR,
+										 rtoffset,
+										 true);
+			tle = flatCopyTargetEntry(tle);
+			tle->expr = (Expr *) newexpr;
+			output_targetlist = lappend(output_targetlist, tle);
+		}
+	}
+
+	plan->targetlist = output_targetlist;
+
+	plan->qual = (List *)
+		fix_upper_expr(root,
+					   (Node *) plan->qual,
+					   subplan_itlist,
+					   OUTER_VAR,
+					   rtoffset,
+					   false);
+
+	pfree(subplan_itlist);
+}
+
+/* XXX is this really the best place and way to do this? */
+static void
+set_partialagg_aggref_types(PlannerInfo *root, Plan *plan)
+{
+	ListCell *l;
+
+	foreach(l, plan->targetlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(l);
+
+		if (IsA(tle->expr, Aggref))
+		{
+			Aggref *aggref = (Aggref *) tle->expr;
+			HeapTuple	aggTuple;
+			Form_pg_aggregate aggform;
+
+			aggTuple = SearchSysCache1(AGGFNOID,
+									   ObjectIdGetDatum(aggref->aggfnoid));
+			if (!HeapTupleIsValid(aggTuple))
+				elog(ERROR, "cache lookup failed for aggregate %u",
+					 aggref->aggfnoid);
+			aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
+
+			aggref->aggtype = aggform->aggtranstype;
+
+			ReleaseSysCache(aggTuple);
+		}
+	}
+}
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index ace8b38..a00259b 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -93,6 +93,7 @@ typedef struct
 	bool		allow_restricted;
 } has_parallel_hazard_arg;
 
+static bool partial_aggregate_walker(Node *node, void *context);
 static bool contain_agg_clause_walker(Node *node, void *context);
 static bool count_agg_clauses_walker(Node *node,
 						 count_agg_clauses_context *context);
@@ -400,6 +401,64 @@ make_ands_implicit(Expr *clause)
  *****************************************************************************/
 
 /*
+ * aggregates_allow_partial
+ *		Recursively search for Aggref clauses and determine if each of them
+ *		support partial aggregation. Partial aggregation requires that the
+ *		aggregate does not have a DISTINCT or ORDER BY clause, and that it also
+ *		has a combine function set. Returns true if all found Aggrefs support
+ *		partial aggregation and false if any don't.
+ */
+bool
+aggregates_allow_partial(Node *clause)
+{
+	if (!partial_aggregate_walker(clause, NULL))
+		return true;
+	return false;
+}
+
+/*
+ * partial_aggregate_walker
+ *		Walker function for aggregates_allow_partial. Returns false if all
+ *		aggregates support partial aggregation and true if any don't.
+ */
+static bool
+partial_aggregate_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Aggref))
+	{
+		Aggref	   *aggref = (Aggref *) node;
+		HeapTuple	aggTuple;
+		Oid			aggcombinefn;
+		Form_pg_aggregate aggform;
+
+		Assert(aggref->agglevelsup == 0);
+
+		/* can't combine aggs with DISTINCT or ORDER BY */
+		if (aggref->aggdistinct || aggref->aggorder)
+			return true;	/* abort search */
+
+		aggTuple = SearchSysCache1(AGGFNOID,
+								   ObjectIdGetDatum(aggref->aggfnoid));
+		if (!HeapTupleIsValid(aggTuple))
+			elog(ERROR, "cache lookup failed for aggregate %u",
+				 aggref->aggfnoid);
+		aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
+		aggcombinefn = aggform->aggcombinefn;
+		ReleaseSysCache(aggTuple);
+
+		/* Do we have a combine function? */
+		if (!OidIsValid(aggcombinefn))
+			return true;	/* abort search */
+
+		return false; /* continue searching */
+	}
+	return expression_tree_walker(node, partial_aggregate_walker,
+								  (void *) context);
+}
+
+/*
  * contain_agg_clause
  *	  Recursively search for Aggref/GroupingFunc nodes within a clause.
  *
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 38ba82f..51400b2 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -828,6 +828,15 @@ static struct config_bool ConfigureNamesBool[] =
 		NULL, NULL, NULL
 	},
 	{
+		{"enable_parallelagg", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of parallel agg plans."),
+			NULL
+		},
+		&enable_parallelagg,
+		true,
+		NULL, NULL, NULL
+	},
+	{
 		{"enable_material", PGC_USERSET, QUERY_TUNING_METHOD,
 			gettext_noop("Enables the planner's use of materialization."),
 			NULL
diff --git a/src/include/optimizer/clauses.h b/src/include/optimizer/clauses.h
index 3b3fd0f..fc86b38 100644
--- a/src/include/optimizer/clauses.h
+++ b/src/include/optimizer/clauses.h
@@ -47,6 +47,7 @@ extern Node *make_and_qual(Node *qual1, Node *qual2);
 extern Expr *make_ands_explicit(List *andclauses);
 extern List *make_ands_implicit(Expr *clause);
 
+extern bool aggregates_allow_partial(Node *clause);
 extern bool contain_agg_clause(Node *clause);
 extern void count_agg_clauses(PlannerInfo *root, Node *clause,
 				  AggClauseCosts *costs);
diff --git a/src/include/optimizer/cost.h b/src/include/optimizer/cost.h
index 78c7cae..0ab043a 100644
--- a/src/include/optimizer/cost.h
+++ b/src/include/optimizer/cost.h
@@ -62,6 +62,7 @@ extern bool enable_bitmapscan;
 extern bool enable_tidscan;
 extern bool enable_sort;
 extern bool enable_hashagg;
+extern bool enable_parallelagg;
 extern bool enable_nestloop;
 extern bool enable_material;
 extern bool enable_mergejoin;

diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 5fc80e7..184e1e0 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -126,6 +126,7 @@ bool		enable_material = true;
 bool		enable_mergejoin = true;
 bool		enable_hashjoin = true;
 
+bool		enable_parallelagg = false;
 typedef struct
 {
 	PlannerInfo *root;
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index c0ec905..950984e 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -49,6 +49,8 @@
 #include "utils/rel.h"
 #include "utils/selfuncs.h"
 
+#include "utils/syscache.h"
+#include "catalog/pg_aggregate.h"
 
 /* GUC parameter */
 double		cursor_tuple_fraction = DEFAULT_CURSOR_TUPLE_FRACTION;
@@ -77,6 +79,12 @@ typedef struct
 	List	   *groupClause;	/* overrides parse->groupClause */
 } standard_qp_extra;
 
+typedef struct
+{
+	AttrNumber 	resno;
+	List		*targetlist;
+} AddQualInTListExprContext;
+
 /* Local functions */
 static Node *preprocess_expression(PlannerInfo *root, Node *expr, int kind);
 static void preprocess_qual_conditions(PlannerInfo *root, Node *jtnode);
@@ -134,8 +142,35 @@ static Plan *build_grouping_chain(PlannerInfo *root,
 					 AttrNumber *groupColIdx,
 					 AggClauseCosts *agg_costs,
 					 long numGroups,
+					 bool combineStates,
+					 bool finalizeAggs,
+					 Plan *result_plan);
+static Plan *make_group_agg(PlannerInfo *root,
+					 Query *parse,
+					 List *tlist,
+					 bool need_sort_for_grouping,
+					 List *rollup_groupclauses,
+					 List *rollup_lists,
+					 AttrNumber *groupColIdx,
+					 AggClauseCosts *agg_costs,
+					 long numGroups,
+					 bool parallel_agg,
 					 Plan *result_plan);
 
+static AttrNumber*get_grpColIdx_from_subPlan(PlannerInfo *root, List *tlist);
+static List *make_partial_agg_tlist(List *tlist,List *groupClause);
+static List* add_qual_in_tlist(List *targetlist, List *qual);
+static bool add_qual_in_tlist_walker (Node *node,
+					 AddQualInTListExprContext *context);
+static Plan *make_hash_agg(PlannerInfo *root,
+						   Query *parse,
+						   List *tlist,
+						   AggClauseCosts *aggcosts,
+						   int numGroupCols,
+						   AttrNumber *grpColIdx,
+						   long numGroups,
+						   bool parallel_agg,
+						   Plan *lefttree);
 /*****************************************************************************
  *
  *	   Query optimizer entry point
@@ -1329,6 +1364,7 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 	double		dNumGroups = 0;
 	bool		use_hashed_distinct = false;
 	bool		tested_hashed_distinct = false;
+	bool		parallel_agg = false;
 
 	/* Tweak caller-supplied tuple_fraction if have LIMIT/OFFSET */
 	if (parse->limitCount || parse->limitOffset)
@@ -1411,6 +1447,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 	else
 	{
 		/* No set operations, do regular planning */
+		List	   *sub_tlist;
+		AttrNumber *groupColIdx = NULL;
+		bool		need_tlist_eval = true;
 		long		numGroups = 0;
 		AggClauseCosts agg_costs;
 		int			numGroupCols;
@@ -1425,8 +1464,8 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 		List	   *rollup_groupclauses = NIL;
 		standard_qp_extra qp_extra;
 		RelOptInfo *final_rel;
-		Path	   *cheapest_path;
-		Path	   *sorted_path;
+		Path	   *cheapest_path = NULL;
+		Path	   *sorted_path = NULL;
 		Path	   *best_path;
 
 		MemSet(&agg_costs, 0, sizeof(AggClauseCosts));
@@ -1752,22 +1791,54 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 		}
 
 		/*
-		 * Pick out the cheapest-total path as well as the cheapest presorted
-		 * path for the requested pathkeys (if there is one).  We should take
-		 * the tuple fraction into account when selecting the cheapest
-		 * presorted path, but not when selecting the cheapest-total path,
-		 * since if we have to sort then we'll have to fetch all the tuples.
-		 * (But there's a special case: if query_pathkeys is NIL, meaning
-		 * order doesn't matter, then the "cheapest presorted" path will be
-		 * the cheapest overall for the tuple fraction.)
+		 * Prepare a gather path on the partial path, in case if it satisfies
+		 * parallel aggregate plan.
 		 */
-		cheapest_path = final_rel->cheapest_total_path;
+		if (enable_parallelagg
+				&& final_rel->partial_pathlist
+				&& (dNumGroups < (path_rows / 4)))
+		{
+			/*
+			 * check for parallel aggregate eligibility by referring all aggregate
+			 * functions in both qualification and targetlist.
+			 */
+			if (aggregates_allow_partial((Node *)tlist)
+					&& aggregates_allow_partial(parse->havingQual))
+			{
+				Path	   *cheapest_partial_path;
+
+				cheapest_partial_path = linitial(final_rel->partial_pathlist);
+				cheapest_path = (Path *)
+						create_gather_path(root, final_rel, cheapest_partial_path, NULL);
+
+				sorted_path =
+					get_cheapest_fractional_path_for_pathkeys(final_rel->partial_pathlist,
+															  root->query_pathkeys,
+															  NULL,
+															  tuple_fraction);
+				parallel_agg = true;
+			}
+		}
+		else
+		{
+			/*
+			 * Pick out the cheapest-total path as well as the cheapest presorted
+			 * path for the requested pathkeys (if there is one).  We should take
+			 * the tuple fraction into account when selecting the cheapest
+			 * presorted path, but not when selecting the cheapest-total path,
+			 * since if we have to sort then we'll have to fetch all the tuples.
+			 * (But there's a special case: if query_pathkeys is NIL, meaning
+			 * order doesn't matter, then the "cheapest presorted" path will be
+			 * the cheapest overall for the tuple fraction.)
+			 */
+			cheapest_path = final_rel->cheapest_total_path;
 
-		sorted_path =
-			get_cheapest_fractional_path_for_pathkeys(final_rel->pathlist,
-													  root->query_pathkeys,
-													  NULL,
-													  tuple_fraction);
+			sorted_path =
+				get_cheapest_fractional_path_for_pathkeys(final_rel->pathlist,
+														  root->query_pathkeys,
+														  NULL,
+														  tuple_fraction);
+		}
 
 		/* Don't consider same path in both guises; just wastes effort */
 		if (sorted_path == cheapest_path)
@@ -1892,9 +1963,6 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			 * Normal case --- create a plan according to query_planner's
 			 * results.
 			 */
-			List	   *sub_tlist;
-			AttrNumber *groupColIdx = NULL;
-			bool		need_tlist_eval = true;
 			bool		need_sort_for_grouping = false;
 
 			result_plan = create_plan(root, best_path);
@@ -1903,15 +1971,22 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			/* Detect if we'll need an explicit sort for grouping */
 			if (parse->groupClause && !use_hashed_grouping &&
 			  !pathkeys_contained_in(root->group_pathkeys, current_pathkeys))
+			{
 				need_sort_for_grouping = true;
 
+				/*
+				 * Always override create_plan's tlist, so that we don't sort
+				 * useless data from a "physical" tlist.
+				 */
+				need_tlist_eval = true;
+			}
+
 			/*
-			 * Generate appropriate target list for scan/join subplan; may be
-			 * different from tlist if grouping or aggregation is needed.
+			 * Generate appropriate target list for subplan; may be different from
+			 * tlist if grouping or aggregation is needed.
 			 */
 			sub_tlist = make_subplanTargetList(root, tlist,
-											   &groupColIdx,
-											   &need_tlist_eval);
+											   &groupColIdx, &need_tlist_eval);
 
 			/*
 			 * create_plan returns a plan with just a "flat" tlist of required
@@ -1994,20 +2069,16 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			 */
 			if (use_hashed_grouping)
 			{
-				/* Hashed aggregate plan --- no sort needed */
-				result_plan = (Plan *) make_agg(root,
-												tlist,
-												(List *) parse->havingQual,
-												AGG_HASHED,
-												&agg_costs,
-												numGroupCols,
-												groupColIdx,
-									extract_grouping_ops(parse->groupClause),
-												NIL,
-												numGroups,
-												false,
-												true,
-												result_plan);
+				result_plan = make_hash_agg(root,
+											parse,
+											tlist,
+											&agg_costs,
+											numGroupCols,
+											groupColIdx,
+											numGroups,
+											parallel_agg,
+											result_plan);
+
 				/* Hashed aggregation produces randomly-ordered results */
 				current_pathkeys = NIL;
 			}
@@ -2027,16 +2098,24 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 				else
 					current_pathkeys = NIL;
 
-				result_plan = build_grouping_chain(root,
-												   parse,
-												   tlist,
-												   need_sort_for_grouping,
-												   rollup_groupclauses,
-												   rollup_lists,
-												   groupColIdx,
-												   &agg_costs,
-												   numGroups,
-												   result_plan);
+				result_plan = make_group_agg(root,
+										     parse,
+											 tlist,
+											 need_sort_for_grouping,
+											 rollup_groupclauses,
+											 rollup_lists,
+											 groupColIdx,
+											 &agg_costs,
+											 numGroups,
+											 parallel_agg,
+											 result_plan);
+
+				/*
+				 * these are destroyed by build_grouping_chain, so make sure
+				 * we don't try and touch them again
+				 */
+				rollup_groupclauses = NIL;
+				rollup_lists = NIL;
 			}
 			else if (parse->groupClause)
 			{
@@ -2481,6 +2560,8 @@ build_grouping_chain(PlannerInfo *root,
 					 AttrNumber *groupColIdx,
 					 AggClauseCosts *agg_costs,
 					 long numGroups,
+					 bool combineStates,
+					 bool finalizeAggs,
 					 Plan *result_plan)
 {
 	AttrNumber *top_grpColIdx = groupColIdx;
@@ -2553,8 +2634,8 @@ build_grouping_chain(PlannerInfo *root,
 										 extract_grouping_ops(groupClause),
 										 gsets,
 										 numGroups,
-										 false,
-										 true,
+									 combineStates,
+									 finalizeAggs,
 										 sort_plan);
 
 			/*
@@ -2594,8 +2675,8 @@ build_grouping_chain(PlannerInfo *root,
 										extract_grouping_ops(groupClause),
 										gsets,
 										numGroups,
-										false,
-										true,
+										combineStates,
+										finalizeAggs,
 										result_plan);
 
 		((Agg *) result_plan)->chain = chain;
@@ -4718,3 +4799,396 @@ plan_cluster_use_sort(Oid tableOid, Oid indexOid)
 
 	return (seqScanAndSortPath.total_cost < indexScanPath->path.total_cost);
 }
+
+/*
+ * This function build a hash parallelagg plan as result_plan as following :
+ * Finalize Hash Aggregate
+ *   -> Gather
+ *     -> Partial Hash Aggregate
+ *       -> Any partial plan
+ * The input result_plan will be
+ * Gather
+ *  -> Any partial plan
+ * So this function will do the following steps:
+ * 1. Make a PartialHashAgg and set Gather node as above node
+ * 2. Change the targetlist of Gather node
+ * 3. Make a FinalizeHashAgg as top node above the Gather node
+ */
+
+static Plan *
+make_hash_agg(PlannerInfo *root,
+			   Query *parse,
+			   List *tlist,
+			   AggClauseCosts *agg_costs,
+			   int numGroupCols,
+			   AttrNumber *groupColIdx,
+			   long numGroups,
+			   bool parallel_agg,
+			   Plan *lefttree)
+{
+	Plan *result_plan = NULL;
+	Plan *partial_agg_plan = NULL;
+	Plan *gather_plan = NULL;
+	List *partial_agg_tlist = NIL;
+	List *qual = (List*)parse->havingQual;
+	AttrNumber *topgroupColIdx = NULL;
+
+	if (!parallel_agg || nodeTag(lefttree) != T_Gather)
+	{
+		result_plan = (Plan *) make_agg(root,
+										tlist,
+										(List *) parse->havingQual,
+										AGG_HASHED,
+										agg_costs,
+										numGroupCols,
+										groupColIdx,
+										extract_grouping_ops(parse->groupClause),
+										NIL,
+										numGroups,
+										false,
+										true,
+										lefttree);
+		return result_plan;
+	}
+
+	Assert(nodeTag(lefttree) == T_Gather);
+	gather_plan = lefttree;
+
+	/*
+	 * The underlying Agg targetlist should be a flat tlist of all Vars and Aggs
+	 * needed to evaluate the expressions and final values of aggregates present
+	 * in the main target list. The quals also should be included.
+	 */
+	partial_agg_tlist = make_partial_agg_tlist(add_qual_in_tlist(tlist, qual),
+												parse->groupClause);
+
+	/* Make PartialHashAgg plan node */
+	partial_agg_plan = (Plan *) make_agg(root,
+									partial_agg_tlist,
+									NULL,
+									AGG_HASHED,
+									agg_costs,
+									numGroupCols,
+									groupColIdx,
+									extract_grouping_ops(parse->groupClause),
+									NIL,
+									numGroups,
+									false,
+									false,
+									gather_plan->lefttree);
+
+	gather_plan->lefttree = partial_agg_plan;
+	gather_plan->targetlist = partial_agg_plan->targetlist;
+
+	/*
+	 * Get the sortIndex according the subplan
+	 */
+	topgroupColIdx = get_grpColIdx_from_subPlan(root, partial_agg_tlist);
+
+	/* Make FinalizeHashAgg plan node */
+	result_plan = (Plan *) make_agg(root,
+									tlist,
+									(List *) parse->havingQual,
+									AGG_HASHED,
+									agg_costs,
+									numGroupCols,
+									topgroupColIdx,
+									extract_grouping_ops(parse->groupClause),
+									NIL,
+									numGroups,
+									true,
+									true,
+									gather_plan);
+
+	return result_plan;
+}
+
+/*
+ * This function build a group parallelagg plan as result_plan as following :
+ * Finalize Group Aggregate
+ *   ->  Sort
+ * 	   -> Gather
+ * 	     -> Partial Group Aggregate
+ * 	       -> Sort
+ * 	         -> Any partial plan
+ * The input result_plan will be
+ * Gather
+ *  -> Any partial plan
+ * So this function will do the following steps:
+ * 1. Move up the Gather node and change its targetlist
+ * 2. Change the Group Aggregate to be Partial Group Aggregate
+ * 3. Add Finalize Group Aggregate and Sort node
+ */
+static Plan *
+make_group_agg(PlannerInfo *root,
+			   Query *parse,
+			   List *tlist,
+			   bool need_sort_for_grouping,
+			   List *rollup_groupclauses,
+			   List *rollup_lists,
+			   AttrNumber *groupColIdx,
+			   AggClauseCosts *agg_costs,
+			   long numGroups,
+			   bool parallel_agg,
+			   Plan *result_plan)
+{
+	Plan *partial_agg = NULL;
+	Plan *gather_plan = NULL;
+	List *qual = (List*)parse->havingQual;
+	List *partial_agg_tlist = NULL;
+	AttrNumber *topgroupColIdx = NULL;
+
+	if (!parallel_agg || nodeTag(result_plan) != T_Gather)
+	{
+		result_plan = build_grouping_chain(root,
+										   parse,
+										   tlist,
+										   need_sort_for_grouping,
+										   rollup_groupclauses,
+										   rollup_lists,
+										   groupColIdx,
+										   agg_costs,
+										   numGroups,
+										   false,
+										   true,
+										   result_plan);
+		return result_plan;
+	}
+
+	Assert(nodeTag(result_plan) == T_Gather);
+	gather_plan = result_plan;
+
+	/*
+	 * The underlying Agg targetlist should be a flat tlist of all Vars and Aggs
+	 * needed to evaluate the expressions and final values of aggregates present
+	 * in the main target list. The quals also should be included.
+	 */
+	partial_agg_tlist = make_partial_agg_tlist(add_qual_in_tlist(tlist, qual),
+												llast(rollup_groupclauses));
+
+	/* Add PartialAgg and Sort node */
+	partial_agg = build_grouping_chain(root,
+								   parse,
+								   partial_agg_tlist,
+								   need_sort_for_grouping,
+								   rollup_groupclauses,
+								   rollup_lists,
+								   groupColIdx,
+								   agg_costs,
+								   numGroups,
+								   false,
+								   false,
+								   gather_plan->lefttree);
+
+
+
+	/* Let the Gather node as upper node of partial_agg node */
+	gather_plan->targetlist = partial_agg->targetlist;
+	gather_plan->lefttree = partial_agg;
+
+	/*
+	 * Get the sortIndex according the subplan
+	 */
+	topgroupColIdx = get_grpColIdx_from_subPlan(root, partial_agg_tlist);
+
+	 /* Make the Finalize Group Aggregate node */
+	result_plan = build_grouping_chain(root,
+								   parse,
+								   tlist,
+								   need_sort_for_grouping,
+								   rollup_groupclauses,
+								   rollup_lists,
+								   topgroupColIdx,
+								   agg_costs,
+								   numGroups,
+								   true,
+								   true,
+								   gather_plan);
+
+	return result_plan;
+}
+
+/* Function to get the grouping column index from the provided plan */
+static AttrNumber*
+get_grpColIdx_from_subPlan(PlannerInfo *root, List *tlist)
+{
+	Query	   *parse = root->parse;
+	int			numCols;
+
+	AttrNumber *grpColIdx = NULL;
+
+	numCols = list_length(parse->groupClause);
+	if (numCols > 0)
+	{
+		ListCell   *tl;
+
+		grpColIdx = (AttrNumber *) palloc0(sizeof(AttrNumber) * numCols);
+
+		foreach(tl, tlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(tl);
+			int			colno;
+
+			colno = get_grouping_column_index(parse, tle);
+			if (colno >= 0)
+			{
+				Assert(grpColIdx[colno] == 0);	/* no dups expected */
+				grpColIdx[colno] = tle->resno;
+			}
+		}
+	}
+
+	return grpColIdx;
+}
+
+/*
+ * make_partial_agg_tlist
+ *	  Generate appropriate Agg node target list for input to ParallelAgg nodes.
+ *
+ * The initial target list passed to ParallelAgg node from the parser contains
+ * aggregates and GROUP BY columns. For the underlying agg node, we want to
+ * generate a tlist containing bare aggregate references (Aggref) and GROUP BY
+ * expressions. So we flatten all expressions except GROUP BY items into their
+ * component variables.
+ * For example, given a query like
+ *		SELECT a+b, 2 * SUM(c+d) , AVG(d)+SUM(c+d) FROM table GROUP BY a+b;
+ * we want to pass this targetlist to the Agg plan:
+ *		a+b, SUM(c+d), AVG(d)
+ * where the a+b target will be used by the Sort/Group steps, and the
+ * other targets will be used for computing the final results.
+ * Note that we don't flatten Aggref's , since those are to be computed
+ * by the underlying Agg node, and they will be referenced like Vars above it.
+ *
+ * 'tlist' is the ParallelAgg's final target list.
+ *
+ * The result is the targetlist to be computed by the Agg node below the
+ * ParallelAgg node.
+ */
+static List *
+make_partial_agg_tlist(List *tlist,List *groupClause)
+{
+	Bitmapset  *sgrefs;
+	List	   *new_tlist;
+	List	   *flattenable_cols;
+	List	   *flattenable_vars;
+	ListCell   *lc;
+
+	/*
+	 * Collect the sortgroupref numbers of GROUP BY clauses
+	 * into a bitmapset for convenient reference below.
+	 */
+	sgrefs = NULL;
+
+	/* Add in sortgroupref numbers of GROUP BY clauses */
+	foreach(lc, groupClause)
+	{
+		SortGroupClause *grpcl = (SortGroupClause *) lfirst(lc);
+
+		sgrefs = bms_add_member(sgrefs, grpcl->tleSortGroupRef);
+	}
+
+	/*
+	 * Construct a tlist containing all the non-flattenable tlist items, and
+	 * save aside the others for a moment.
+	 */
+	new_tlist = NIL;
+	flattenable_cols = NIL;
+
+	foreach(lc, tlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(lc);
+
+		/* Don't want to deconstruct GROUP BY items. */
+		if (tle->ressortgroupref != 0 &&
+			bms_is_member(tle->ressortgroupref, sgrefs))
+		{
+			/* Don't want to deconstruct this value, so add to new_tlist */
+			TargetEntry *newtle;
+
+			newtle = makeTargetEntry(tle->expr,
+									 list_length(new_tlist) + 1,
+									 NULL,
+									 false);
+			/* Preserve its sortgroupref marking, in case it's volatile */
+			newtle->ressortgroupref = tle->ressortgroupref;
+			new_tlist = lappend(new_tlist, newtle);
+		}
+		else
+		{
+			/*
+			 * Column is to be flattened, so just remember the expression for
+			 * later call to pull_var_clause.  There's no need for
+			 * pull_var_clause to examine the TargetEntry node itself.
+			 */
+			flattenable_cols = lappend(flattenable_cols, tle->expr);
+		}
+	}
+
+	/*
+	 * Pull out all the Vars and Aggrefs mentioned in flattenable columns, and
+	 * add them to the result tlist if not already present.  (Some might be
+	 * there already because they're used directly as group clauses.)
+	 *
+	 * Note: it's essential to use PVC_INCLUDE_AGGREGATES here, so that the
+	 * Aggrefs are placed in the Agg node's tlist and not left to be computed
+	 * at higher levels.
+	 */
+	flattenable_vars = pull_var_clause((Node *) flattenable_cols,
+									   PVC_INCLUDE_AGGREGATES,
+									   PVC_INCLUDE_PLACEHOLDERS);
+	new_tlist = add_to_flat_tlist(new_tlist, flattenable_vars);
+
+	/* clean up cruft */
+	list_free(flattenable_vars);
+	list_free(flattenable_cols);
+
+	return new_tlist;
+}
+
+/*
+ * add_qual_in_tlist
+ *		Add the agg functions in qual into the target list used in agg plan
+ */
+static List*
+add_qual_in_tlist(List *targetlist, List *qual)
+{
+	AddQualInTListExprContext context;
+
+	if(qual == NULL)
+		return targetlist;
+
+	context.targetlist = copyObject(targetlist);
+	context.resno = list_length(context.targetlist) + 1;;
+
+	add_qual_in_tlist_walker((Node*)qual, &context);
+
+	return context.targetlist;
+}
+
+/*
+ * add_qual_in_tlist_walker
+ *		Go through the qual list to get the aggref and add it in targetlist
+ */
+static bool
+add_qual_in_tlist_walker (Node *node, AddQualInTListExprContext *context)
+{
+	if (node == NULL)
+		return false;
+
+	if (IsA(node, Aggref))
+	{
+		List *tlist = context->targetlist;
+		TargetEntry *te = makeNode(TargetEntry);
+
+		te = makeTargetEntry((Expr *) node,
+				  context->resno++,
+				  NULL,
+				  false);
+
+		tlist = lappend(tlist,te);
+	}
+	else
+		return expression_tree_walker(node, add_qual_in_tlist_walker, context);
+
+	return false;
+}
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 615f3a2..85b649e 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -15,7 +15,9 @@
  */
 #include "postgres.h"
 
+#include "access/htup_details.h"
 #include "access/transam.h"
+#include "catalog/pg_aggregate.h"
 #include "catalog/pg_type.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
@@ -65,6 +67,7 @@ typedef struct
 	indexed_tlist *subplan_itlist;
 	Index		newvarno;
 	int			rtoffset;
+	bool		partial_agg;
 } fix_upper_expr_context;
 
 /*
@@ -104,6 +107,8 @@ static Node *fix_scan_expr_mutator(Node *node, fix_scan_expr_context *context);
 static bool fix_scan_expr_walker(Node *node, fix_scan_expr_context *context);
 static void set_join_references(PlannerInfo *root, Join *join, int rtoffset);
 static void set_upper_references(PlannerInfo *root, Plan *plan, int rtoffset);
+static void set_agg_references(PlannerInfo *root, Plan *plan, int rtoffset);
+static void set_partialagg_aggref_types(PlannerInfo *root, Plan *plan);
 static void set_dummy_tlist_references(Plan *plan, int rtoffset);
 static indexed_tlist *build_tlist_index(List *tlist);
 static Var *search_indexed_tlist_for_var(Var *var,
@@ -128,7 +133,8 @@ static Node *fix_upper_expr(PlannerInfo *root,
 			   Node *node,
 			   indexed_tlist *subplan_itlist,
 			   Index newvarno,
-			   int rtoffset);
+			   int rtoffset,
+			   bool partial_agg);
 static Node *fix_upper_expr_mutator(Node *node,
 					   fix_upper_expr_context *context);
 static List *set_returning_clause_references(PlannerInfo *root,
@@ -140,6 +146,7 @@ static bool fix_opfuncids_walker(Node *node, void *context);
 static bool extract_query_dependencies_walker(Node *node,
 								  PlannerInfo *context);
 
+
 /*****************************************************************************
  *
  *		SUBPLAN REFERENCES
@@ -668,7 +675,7 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 			}
 			break;
 		case T_Agg:
-			set_upper_references(root, plan, rtoffset);
+			set_agg_references(root, plan, rtoffset);
 			break;
 		case T_Group:
 			set_upper_references(root, plan, rtoffset);
@@ -943,13 +950,15 @@ set_indexonlyscan_references(PlannerInfo *root,
 					   (Node *) plan->scan.plan.targetlist,
 					   index_itlist,
 					   INDEX_VAR,
-					   rtoffset);
+					   rtoffset,
+					   false);
 	plan->scan.plan.qual = (List *)
 		fix_upper_expr(root,
 					   (Node *) plan->scan.plan.qual,
 					   index_itlist,
 					   INDEX_VAR,
-					   rtoffset);
+					   rtoffset,
+					   false);
 	/* indexqual is already transformed to reference index columns */
 	plan->indexqual = fix_scan_list(root, plan->indexqual, rtoffset);
 	/* indexorderby is already transformed to reference index columns */
@@ -1116,25 +1125,29 @@ set_foreignscan_references(PlannerInfo *root,
 						   (Node *) fscan->scan.plan.targetlist,
 						   itlist,
 						   INDEX_VAR,
-						   rtoffset);
+						   rtoffset,
+						   false);
 		fscan->scan.plan.qual = (List *)
 			fix_upper_expr(root,
 						   (Node *) fscan->scan.plan.qual,
 						   itlist,
 						   INDEX_VAR,
-						   rtoffset);
+						   rtoffset,
+						   false);
 		fscan->fdw_exprs = (List *)
 			fix_upper_expr(root,
 						   (Node *) fscan->fdw_exprs,
 						   itlist,
 						   INDEX_VAR,
-						   rtoffset);
+						   rtoffset,
+						   false);
 		fscan->fdw_recheck_quals = (List *)
 			fix_upper_expr(root,
 						   (Node *) fscan->fdw_recheck_quals,
 						   itlist,
 						   INDEX_VAR,
-						   rtoffset);
+						   rtoffset,
+						   false);
 		pfree(itlist);
 		/* fdw_scan_tlist itself just needs fix_scan_list() adjustments */
 		fscan->fdw_scan_tlist =
@@ -1190,19 +1203,22 @@ set_customscan_references(PlannerInfo *root,
 						   (Node *) cscan->scan.plan.targetlist,
 						   itlist,
 						   INDEX_VAR,
-						   rtoffset);
+						   rtoffset,
+						   false);
 		cscan->scan.plan.qual = (List *)
 			fix_upper_expr(root,
 						   (Node *) cscan->scan.plan.qual,
 						   itlist,
 						   INDEX_VAR,
-						   rtoffset);
+						   rtoffset,
+						   false);
 		cscan->custom_exprs = (List *)
 			fix_upper_expr(root,
 						   (Node *) cscan->custom_exprs,
 						   itlist,
 						   INDEX_VAR,
-						   rtoffset);
+						   rtoffset,
+						   false);
 		pfree(itlist);
 		/* custom_scan_tlist itself just needs fix_scan_list() adjustments */
 		cscan->custom_scan_tlist =
@@ -1524,7 +1540,8 @@ set_join_references(PlannerInfo *root, Join *join, int rtoffset)
 												   (Node *) nlp->paramval,
 												   outer_itlist,
 												   OUTER_VAR,
-												   rtoffset);
+												   rtoffset,
+												   false);
 			/* Check we replaced any PlaceHolderVar with simple Var */
 			if (!(IsA(nlp->paramval, Var) &&
 				  nlp->paramval->varno == OUTER_VAR))
@@ -1648,14 +1665,16 @@ set_upper_references(PlannerInfo *root, Plan *plan, int rtoffset)
 										 (Node *) tle->expr,
 										 subplan_itlist,
 										 OUTER_VAR,
-										 rtoffset);
+										 rtoffset,
+										 false);
 		}
 		else
 			newexpr = fix_upper_expr(root,
 									 (Node *) tle->expr,
 									 subplan_itlist,
 									 OUTER_VAR,
-									 rtoffset);
+									 rtoffset,
+									 false);
 		tle = flatCopyTargetEntry(tle);
 		tle->expr = (Expr *) newexpr;
 		output_targetlist = lappend(output_targetlist, tle);
@@ -1667,7 +1686,8 @@ set_upper_references(PlannerInfo *root, Plan *plan, int rtoffset)
 					   (Node *) plan->qual,
 					   subplan_itlist,
 					   OUTER_VAR,
-					   rtoffset);
+					   rtoffset,
+					   false);
 
 	pfree(subplan_itlist);
 }
@@ -2121,7 +2141,8 @@ fix_upper_expr(PlannerInfo *root,
 			   Node *node,
 			   indexed_tlist *subplan_itlist,
 			   Index newvarno,
-			   int rtoffset)
+			   int rtoffset,
+			   bool partial_agg)
 {
 	fix_upper_expr_context context;
 
@@ -2129,6 +2150,7 @@ fix_upper_expr(PlannerInfo *root,
 	context.subplan_itlist = subplan_itlist;
 	context.newvarno = newvarno;
 	context.rtoffset = rtoffset;
+	context.partial_agg = partial_agg;
 	return fix_upper_expr_mutator(node, &context);
 }
 
@@ -2151,6 +2173,36 @@ fix_upper_expr_mutator(Node *node, fix_upper_expr_context *context)
 			elog(ERROR, "variable not found in subplan target list");
 		return (Node *) newvar;
 	}
+	if (IsA(node, Aggref) && context->partial_agg)
+	{
+		TargetEntry *tle;
+		Aggref		*aggref = (Aggref*)node;
+		List	    *args = NIL;
+
+		tle = tlist_member(node, context->subplan_itlist->tlist);
+		if (tle)
+		{
+			/* Found a matching subplan output expression */
+			Var		   *newvar;
+			TargetEntry *newtle;
+
+			newvar = makeVarFromTargetEntry(context->newvarno, tle);
+			newvar->varnoold = 0;	/* wasn't ever a plain Var */
+			newvar->varoattno = 0;
+
+			/* makeTargetEntry ,always set resno to one for finialize agg */
+			newtle = makeTargetEntry((Expr*)newvar,1,NULL,false);
+			args = lappend(args,newtle);
+
+			/*
+			 * Updated the args, let the newvar refer to the right position of
+			 * the agg function in the subplan
+			 */
+			aggref->args = args;
+
+			return (Node *) aggref;
+		}
+	}
 	if (IsA(node, PlaceHolderVar))
 	{
 		PlaceHolderVar *phv = (PlaceHolderVar *) node;
@@ -2432,3 +2484,123 @@ extract_query_dependencies_walker(Node *node, PlannerInfo *context)
 	return expression_tree_walker(node, extract_query_dependencies_walker,
 								  (void *) context);
 }
+
+/*
+ * set_agg_references
+ *	  Update the targetlist and quals of an upper-level plan node
+ *	  to refer to the tuples returned by its lefttree subplan.
+ *	  Also perform opcode lookup for these expressions, and
+ *	  add regclass OIDs to root->glob->relationOids.
+ *
+ * This is used for single-input plan types like Agg, Group, Result.
+ *
+ * In most cases, we have to match up individual Vars in the tlist and
+ * qual expressions with elements of the subplan's tlist (which was
+ * generated by flatten_tlist() from these selfsame expressions, so it
+ * should have all the required variables).  There is an important exception,
+ * however: GROUP BY and ORDER BY expressions will have been pushed into the
+ * subplan tlist unflattened.  If these values are also needed in the output
+ * then we want to reference the subplan tlist element rather than recomputing
+ * the expression.
+ */
+static void
+set_agg_references(PlannerInfo *root, Plan *plan, int rtoffset)
+{
+	Agg 	   *agg = (Agg*)plan;
+	Plan	   *subplan = plan->lefttree;
+	indexed_tlist *subplan_itlist;
+	List	   *output_targetlist;
+	ListCell   *l;
+
+	if (!agg->combineStates)
+		return set_upper_references(root, plan, rtoffset);
+
+	/*
+	 * For partial aggregation we must adjust the return types of
+	 * the Aggrefs
+	 */
+	if (!agg->finalizeAggs)
+		set_partialagg_aggref_types(root, plan);
+
+	subplan_itlist = build_tlist_index(subplan->targetlist);
+
+	output_targetlist = NIL;
+
+	if(agg->combineStates)
+	{
+		foreach(l, plan->targetlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(l);
+			Node	   *newexpr;
+
+			/* If it's a non-Var sort/group item, first try to match by sortref */
+			if (tle->ressortgroupref != 0 && !IsA(tle->expr, Var))
+			{
+				newexpr = (Node *)
+					search_indexed_tlist_for_sortgroupref((Node *) tle->expr,
+														  tle->ressortgroupref,
+														  subplan_itlist,
+														  OUTER_VAR);
+				if (!newexpr)
+					newexpr = fix_upper_expr(root,
+											 (Node *) tle->expr,
+											 subplan_itlist,
+											 OUTER_VAR,
+											 rtoffset,
+											 true);
+			}
+			else
+				newexpr = fix_upper_expr(root,
+										 (Node *) tle->expr,
+										 subplan_itlist,
+										 OUTER_VAR,
+										 rtoffset,
+										 true);
+			tle = flatCopyTargetEntry(tle);
+			tle->expr = (Expr *) newexpr;
+			output_targetlist = lappend(output_targetlist, tle);
+		}
+	}
+
+	plan->targetlist = output_targetlist;
+
+	plan->qual = (List *)
+		fix_upper_expr(root,
+					   (Node *) plan->qual,
+					   subplan_itlist,
+					   OUTER_VAR,
+					   rtoffset,
+					   false);
+
+	pfree(subplan_itlist);
+}
+
+/* XXX is this really the best place and way to do this? */
+static void
+set_partialagg_aggref_types(PlannerInfo *root, Plan *plan)
+{
+	ListCell *l;
+
+	foreach(l, plan->targetlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(l);
+
+		if (IsA(tle->expr, Aggref))
+		{
+			Aggref *aggref = (Aggref *) tle->expr;
+			HeapTuple	aggTuple;
+			Form_pg_aggregate aggform;
+
+			aggTuple = SearchSysCache1(AGGFNOID,
+									   ObjectIdGetDatum(aggref->aggfnoid));
+			if (!HeapTupleIsValid(aggTuple))
+				elog(ERROR, "cache lookup failed for aggregate %u",
+					 aggref->aggfnoid);
+			aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
+
+			aggref->aggtype = aggform->aggtranstype;
+
+			ReleaseSysCache(aggTuple);
+		}
+	}
+}
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index ace8b38..a00259b 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -93,6 +93,7 @@ typedef struct
 	bool		allow_restricted;
 } has_parallel_hazard_arg;
 
+static bool partial_aggregate_walker(Node *node, void *context);
 static bool contain_agg_clause_walker(Node *node, void *context);
 static bool count_agg_clauses_walker(Node *node,
 						 count_agg_clauses_context *context);
@@ -400,6 +401,64 @@ make_ands_implicit(Expr *clause)
  *****************************************************************************/
 
 /*
+ * aggregates_allow_partial
+ *		Recursively search for Aggref clauses and determine if each of them
+ *		support partial aggregation. Partial aggregation requires that the
+ *		aggregate does not have a DISTINCT or ORDER BY clause, and that it also
+ *		has a combine function set. Returns true if all found Aggrefs support
+ *		partial aggregation and false if any don't.
+ */
+bool
+aggregates_allow_partial(Node *clause)
+{
+	if (!partial_aggregate_walker(clause, NULL))
+		return true;
+	return false;
+}
+
+/*
+ * partial_aggregate_walker
+ *		Walker function for aggregates_allow_partial. Returns false if all
+ *		aggregates support partial aggregation and true if any don't.
+ */
+static bool
+partial_aggregate_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Aggref))
+	{
+		Aggref	   *aggref = (Aggref *) node;
+		HeapTuple	aggTuple;
+		Oid			aggcombinefn;
+		Form_pg_aggregate aggform;
+
+		Assert(aggref->agglevelsup == 0);
+
+		/* can't combine aggs with DISTINCT or ORDER BY */
+		if (aggref->aggdistinct || aggref->aggorder)
+			return true;	/* abort search */
+
+		aggTuple = SearchSysCache1(AGGFNOID,
+								   ObjectIdGetDatum(aggref->aggfnoid));
+		if (!HeapTupleIsValid(aggTuple))
+			elog(ERROR, "cache lookup failed for aggregate %u",
+				 aggref->aggfnoid);
+		aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
+		aggcombinefn = aggform->aggcombinefn;
+		ReleaseSysCache(aggTuple);
+
+		/* Do we have a combine function? */
+		if (!OidIsValid(aggcombinefn))
+			return true;	/* abort search */
+
+		return false; /* continue searching */
+	}
+	return expression_tree_walker(node, partial_aggregate_walker,
+								  (void *) context);
+}
+
+/*
  * contain_agg_clause
  *	  Recursively search for Aggref/GroupingFunc nodes within a clause.
  *
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 38ba82f..51400b2 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -828,6 +828,15 @@ static struct config_bool ConfigureNamesBool[] =
 		NULL, NULL, NULL
 	},
 	{
+		{"enable_parallelagg", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of parallel agg plans."),
+			NULL
+		},
+		&enable_parallelagg,
+		true,
+		NULL, NULL, NULL
+	},
+	{
 		{"enable_material", PGC_USERSET, QUERY_TUNING_METHOD,
 			gettext_noop("Enables the planner's use of materialization."),
 			NULL
diff --git a/src/include/optimizer/clauses.h b/src/include/optimizer/clauses.h
index 3b3fd0f..fc86b38 100644
--- a/src/include/optimizer/clauses.h
+++ b/src/include/optimizer/clauses.h
@@ -47,6 +47,7 @@ extern Node *make_and_qual(Node *qual1, Node *qual2);
 extern Expr *make_ands_explicit(List *andclauses);
 extern List *make_ands_implicit(Expr *clause);
 
+extern bool aggregates_allow_partial(Node *clause);
 extern bool contain_agg_clause(Node *clause);
 extern void count_agg_clauses(PlannerInfo *root, Node *clause,
 				  AggClauseCosts *costs);
diff --git a/src/include/optimizer/cost.h b/src/include/optimizer/cost.h
index 78c7cae..0ab043a 100644
--- a/src/include/optimizer/cost.h
+++ b/src/include/optimizer/cost.h
@@ -62,6 +62,7 @@ extern bool enable_bitmapscan;
 extern bool enable_tidscan;
 extern bool enable_sort;
 extern bool enable_hashagg;
+extern bool enable_parallelagg;
 extern bool enable_nestloop;
 extern bool enable_material;
 extern bool enable_mergejoin;

diff --git a/doc/src/sgml/ref/create_aggregate.sgml b/doc/src/sgml/ref/create_aggregate.sgml
index 4bda23a..bb62c96 100644
--- a/doc/src/sgml/ref/create_aggregate.sgml
+++ b/doc/src/sgml/ref/create_aggregate.sgml
@@ -28,6 +28,9 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ <replacea
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
     [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
+    [ , SERIALFUNC = <replaceable class="PARAMETER">serialfunc</replaceable> ]
+    [ , DESERIALFUNC = <replaceable class="PARAMETER">deserialfunc</replaceable> ]
+    [ , SERIALTYPE = <replaceable class="PARAMETER">serialtype</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -47,6 +50,9 @@ CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ [ <replac
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
     [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
+    [ , SERIALFUNC = <replaceable class="PARAMETER">serialfunc</replaceable> ]
+    [ , DESERIALFUNC = <replaceable class="PARAMETER">deserialfunc</replaceable> ]
+    [ , SERIALTYPE = <replaceable class="PARAMETER">serialtype</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , HYPOTHETICAL ]
 )
@@ -61,6 +67,9 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
     [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
     [ , FINALFUNC_EXTRA ]
     [ , COMBINEFUNC = <replaceable class="PARAMETER">combinefunc</replaceable> ]
+    [ , SERIALFUNC = <replaceable class="PARAMETER">serialfunc</replaceable> ]
+    [ , DESERIALFUNC = <replaceable class="PARAMETER">deserialfunc</replaceable> ]
+    [ , SERIALTYPE = <replaceable class="PARAMETER">serialtype</replaceable> ]
     [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
     [ , MSFUNC = <replaceable class="PARAMETER">msfunc</replaceable> ]
     [ , MINVFUNC = <replaceable class="PARAMETER">minvfunc</replaceable> ]
@@ -110,13 +119,21 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
    <replaceable class="PARAMETER">sfunc</replaceable>,
    an optional final calculation function
    <replaceable class="PARAMETER">ffunc</replaceable>,
-   and an optional combine function
-   <replaceable class="PARAMETER">combinefunc</replaceable>.
+   an optional combine function
+   <replaceable class="PARAMETER">combinefunc</replaceable>,
+   an optional serialization function
+   <replaceable class="PARAMETER">serialfunc</replaceable>,
+   an optional deserialization function
+   <replaceable class="PARAMETER">deserialfunc</replaceable>,
+   and an optional serialization type
+   <replaceable class="PARAMETER">serialtype</replaceable>.
    These are used as follows:
 <programlisting>
 <replaceable class="PARAMETER">sfunc</replaceable>( internal-state, next-data-values ) ---> next-internal-state
 <replaceable class="PARAMETER">ffunc</replaceable>( internal-state ) ---> aggregate-value
 <replaceable class="PARAMETER">combinefunc</replaceable>( internal-state, internal-state ) ---> next-internal-state
+<replaceable class="PARAMETER">serialfunc</replaceable>( internal-state ) ---> serialized-state
+<replaceable class="PARAMETER">deserialfunc</replaceable>( serialized-state ) ---> internal-state
 </programlisting>
   </para>
 
@@ -140,6 +157,21 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
   </para>
 
   <para>
+  A serialization and deserialization function may also be supplied. These
+  functions are required in order to allow parallel aggregation for aggregates
+  with an <replaceable class="PARAMETER">stype</replaceable> of <literal>
+  INTERNAL</>. The <replaceable class="PARAMETER">serialfunc</replaceable>, if
+  present must transform the aggregate state into a value of
+  <replaceable class="PARAMETER">serialtype</replaceable>, whereas the 
+  <replaceable class="PARAMETER">deserialfunc</replaceable> performs the
+  opposite, transforming the aggregate state back into the
+  <replaceable class="PARAMETER">stype</replaceable>. This is required due to
+  the process model being unable to pass <literal>INTERNAL</literal> types
+  between different <productname>PostgreSQL</productname> processes. These
+  parameters are only valid when <replaceable class="PARAMETER">stype
+  </replaceable> is <literal>INTERNAL</>.
+
+  <para>
    An aggregate function can provide an initial condition,
    that is, an initial value for the internal state value.
    This is specified and stored in the database as a value of type
diff --git a/src/backend/catalog/pg_aggregate.c b/src/backend/catalog/pg_aggregate.c
index c612ab9..667a07a 100644
--- a/src/backend/catalog/pg_aggregate.c
+++ b/src/backend/catalog/pg_aggregate.c
@@ -58,6 +58,8 @@ AggregateCreate(const char *aggName,
 				List *aggtransfnName,
 				List *aggfinalfnName,
 				List *aggcombinefnName,
+				List *aggserialfnName,
+				List *aggdeserialfnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
@@ -65,6 +67,7 @@ AggregateCreate(const char *aggName,
 				bool mfinalfnExtraArgs,
 				List *aggsortopName,
 				Oid aggTransType,
+				Oid aggSerialType,
 				int32 aggTransSpace,
 				Oid aggmTransType,
 				int32 aggmTransSpace,
@@ -79,6 +82,8 @@ AggregateCreate(const char *aggName,
 	Oid			transfn;
 	Oid			finalfn = InvalidOid;	/* can be omitted */
 	Oid			combinefn = InvalidOid;	/* can be omitted */
+	Oid			serialfn = InvalidOid;	/* can be omitted */
+	Oid			deserialfn = InvalidOid;	/* can be omitted */
 	Oid			mtransfn = InvalidOid;	/* can be omitted */
 	Oid			minvtransfn = InvalidOid;		/* can be omitted */
 	Oid			mfinalfn = InvalidOid;	/* can be omitted */
@@ -423,6 +428,59 @@ AggregateCreate(const char *aggName,
 	}
 
 	/*
+	 * Validate the serial function, if present. We must ensure that the return
+	 * type of this function is the same as the specified serialType, and that
+	 * indeed a serialType was actually also specified.
+	 */
+	if (aggserialfnName)
+	{
+		/* check that we also got a serial type */
+		if (!OidIsValid(aggSerialType))
+			ereport(ERROR,
+				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+				 errmsg("must specify serialtype when specifying serialfunc")));
+
+		fnArgs[0] = aggTransType;
+
+		serialfn = lookup_agg_function(aggserialfnName, 1,
+									   fnArgs, variadicArgType,
+									   &rettype);
+
+		if (rettype != aggSerialType)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("return type of serial function %s is not %s",
+							NameListToString(aggserialfnName),
+							format_type_be(aggSerialType))));
+	}
+
+	/*
+	 * Validate the deserial function, if present. We must ensure that the
+	 * return type of this function is the same as the transType.
+	 */
+	if (aggdeserialfnName)
+	{
+		/* check that we also got a serial type */
+		if (!OidIsValid(aggSerialType))
+			ereport(ERROR,
+				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+				 errmsg("must specify serialtype when specifying deserialfunc")));
+
+		fnArgs[0] = aggSerialType;
+
+		deserialfn = lookup_agg_function(aggdeserialfnName, 1,
+										 fnArgs, variadicArgType,
+										 &rettype);
+
+		if (rettype != aggTransType)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("return type of deserial function %s is not %s",
+							NameListToString(aggdeserialfnName),
+							format_type_be(aggTransType))));
+	}
+
+	/*
 	 * If finaltype (i.e. aggregate return type) is polymorphic, inputs must
 	 * be polymorphic also, else parser will fail to deduce result type.
 	 * (Note: given the previous test on transtype and inputs, this cannot
@@ -594,6 +652,8 @@ AggregateCreate(const char *aggName,
 	values[Anum_pg_aggregate_aggtransfn - 1] = ObjectIdGetDatum(transfn);
 	values[Anum_pg_aggregate_aggfinalfn - 1] = ObjectIdGetDatum(finalfn);
 	values[Anum_pg_aggregate_aggcombinefn - 1] = ObjectIdGetDatum(combinefn);
+	values[Anum_pg_aggregate_aggserialfn - 1] = ObjectIdGetDatum(serialfn);
+	values[Anum_pg_aggregate_aggdeserialfn - 1] = ObjectIdGetDatum(deserialfn);
 	values[Anum_pg_aggregate_aggmtransfn - 1] = ObjectIdGetDatum(mtransfn);
 	values[Anum_pg_aggregate_aggminvtransfn - 1] = ObjectIdGetDatum(minvtransfn);
 	values[Anum_pg_aggregate_aggmfinalfn - 1] = ObjectIdGetDatum(mfinalfn);
@@ -601,6 +661,7 @@ AggregateCreate(const char *aggName,
 	values[Anum_pg_aggregate_aggmfinalextra - 1] = BoolGetDatum(mfinalfnExtraArgs);
 	values[Anum_pg_aggregate_aggsortop - 1] = ObjectIdGetDatum(sortop);
 	values[Anum_pg_aggregate_aggtranstype - 1] = ObjectIdGetDatum(aggTransType);
+	values[Anum_pg_aggregate_aggserialtype - 1] = ObjectIdGetDatum(aggSerialType);
 	values[Anum_pg_aggregate_aggtransspace - 1] = Int32GetDatum(aggTransSpace);
 	values[Anum_pg_aggregate_aggmtranstype - 1] = ObjectIdGetDatum(aggmTransType);
 	values[Anum_pg_aggregate_aggmtransspace - 1] = Int32GetDatum(aggmTransSpace);
@@ -627,7 +688,8 @@ AggregateCreate(const char *aggName,
 	 * Create dependencies for the aggregate (above and beyond those already
 	 * made by ProcedureCreate).  Note: we don't need an explicit dependency
 	 * on aggTransType since we depend on it indirectly through transfn.
-	 * Likewise for aggmTransType if any.
+	 * Likewise for aggmTransType using the mtransfunc, and also for
+	 * aggSerialType using the serialfn, if they exist.
 	 */
 
 	/* Depends on transition function */
@@ -654,6 +716,24 @@ AggregateCreate(const char *aggName,
 		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
 	}
 
+	/* Depends on serial function, if any */
+	if (OidIsValid(serialfn))
+	{
+		referenced.classId = ProcedureRelationId;
+		referenced.objectId = serialfn;
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
+	/* Depends on deserial function, if any */
+	if (OidIsValid(deserialfn))
+	{
+		referenced.classId = ProcedureRelationId;
+		referenced.objectId = deserialfn;
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
 	/* Depends on forward transition function, if any */
 	if (OidIsValid(mtransfn))
 	{
diff --git a/src/backend/commands/aggregatecmds.c b/src/backend/commands/aggregatecmds.c
index 59bc6e6..4fa2920 100644
--- a/src/backend/commands/aggregatecmds.c
+++ b/src/backend/commands/aggregatecmds.c
@@ -62,6 +62,8 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	List	   *transfuncName = NIL;
 	List	   *finalfuncName = NIL;
 	List	   *combinefuncName = NIL;
+	List	   *serialfuncName = NIL;
+	List	   *deserialfuncName = NIL;
 	List	   *mtransfuncName = NIL;
 	List	   *minvtransfuncName = NIL;
 	List	   *mfinalfuncName = NIL;
@@ -70,6 +72,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	List	   *sortoperatorName = NIL;
 	TypeName   *baseType = NULL;
 	TypeName   *transType = NULL;
+	TypeName   *serialType = NULL;
 	TypeName   *mtransType = NULL;
 	int32		transSpace = 0;
 	int32		mtransSpace = 0;
@@ -84,6 +87,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 	List	   *parameterDefaults;
 	Oid			variadicArgType;
 	Oid			transTypeId;
+	Oid			serialTypeId = InvalidOid;
 	Oid			mtransTypeId = InvalidOid;
 	char		transTypeType;
 	char		mtransTypeType = 0;
@@ -127,6 +131,10 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 			finalfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "combinefunc") == 0)
 			combinefuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "serialfunc") == 0)
+			serialfuncName = defGetQualifiedName(defel);
+		else if (pg_strcasecmp(defel->defname, "deserialfunc") == 0)
+			deserialfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "msfunc") == 0)
 			mtransfuncName = defGetQualifiedName(defel);
 		else if (pg_strcasecmp(defel->defname, "minvfunc") == 0)
@@ -154,6 +162,8 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 		}
 		else if (pg_strcasecmp(defel->defname, "stype") == 0)
 			transType = defGetTypeName(defel);
+		else if (pg_strcasecmp(defel->defname, "serialtype") == 0)
+			serialType = defGetTypeName(defel);
 		else if (pg_strcasecmp(defel->defname, "stype1") == 0)
 			transType = defGetTypeName(defel);
 		else if (pg_strcasecmp(defel->defname, "sspace") == 0)
@@ -319,6 +329,50 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 							format_type_be(transTypeId))));
 	}
 
+	if (serialType)
+	{
+		/*
+		 * There's little point in having a serial/deserial function on
+		 * aggregates that don't have an internal state, so let's just disallow
+		 * this as it may help clear up any confusion or needless authoring of
+		 * these functions.
+		 */
+		if (transTypeId != INTERNALOID)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("a serialtype must only be specified when stype is \"%s\"",
+						 format_type_be(INTERNALOID))));
+
+		serialTypeId = typenameTypeId(NULL, serialType);
+
+		/*
+		 * We disallow INTERNAL serialType as the whole point of the
+		 * serialzed types is to allow the aggregate state to be output,
+		 * and we cannot output INTERNAL. This check, combined with the one
+		 * above ensures that the trans type and serial type are not the same.
+		 */
+		if (serialTypeId == INTERNALOID)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						errmsg("aggregate serial data type cannot be \"%s\"",
+							format_type_be(serialTypeId))));
+
+		/*
+		 * If serialType is specified then serialfuncName and deserialfuncName
+		 * must be present; if not, then none of the serialization options
+		 * should have been specified.
+		 */
+		if (serialfuncName == NIL)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("aggregate serialfunc must be specified when serialtype is specified")));
+
+		if (deserialfuncName == NIL)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("aggregate deserialfunc must be specified when serialtype is specified")));
+	}
+
 	/*
 	 * If a moving-aggregate transtype is specified, look that up.  Same
 	 * restrictions as for transtype.
@@ -387,6 +441,8 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 						   transfuncName,		/* step function name */
 						   finalfuncName,		/* final function name */
 						   combinefuncName,		/* combine function name */
+						   serialfuncName,		/* serial function name */
+						   deserialfuncName,	/* deserial function name */
 						   mtransfuncName,		/* fwd trans function name */
 						   minvtransfuncName,	/* inv trans function name */
 						   mfinalfuncName,		/* final function name */
@@ -394,6 +450,7 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters,
 						   mfinalfuncExtraArgs,
 						   sortoperatorName,	/* sort operator name */
 						   transTypeId, /* transition data type */
+						   serialTypeId, /* serial data type */
 						   transSpace,	/* transition space */
 						   mtransTypeId,		/* transition data type */
 						   mtransSpace, /* transition space */
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index b5aac67..113d1d5 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -13,13 +13,14 @@
  *	  If a finalfunc is not supplied or finalizeAggs is false, then the result
  *	  is just the ending value of transvalue.
  *
- *	  Other behavior is also supported and is controlled by the 'combineStates'
- *	  and 'finalizeAggs'. 'combineStates' controls whether the trans func or
- *	  the combine func is used during aggregation.  When 'combineStates' is
- *	  true we expect other (previously) aggregated states as input rather than
- *	  input tuples. This mode facilitates multiple aggregate stages which
- *	  allows us to support pushing aggregation down deeper into the plan rather
- *	  than leaving it for the final stage. For example with a query such as:
+ *	  Other behavior is also supported and is controlled by the 'combineStates',
+ *	  'finalizeAggs' and 'serialStates' parameters. 'combineStates' controls
+ *	  whether the trans func or the combine func is used during aggregation.
+ *	  When 'combineStates' is true we expect other (previously) aggregated
+ *	  states as input rather than input tuples. This mode facilitates multiple
+ *	  aggregate stages which allows us to support pushing aggregation down
+ *	  deeper into the plan rather than leaving it for the final stage. For
+ *	  example with a query such as:
  *
  *	  SELECT count(*) FROM (SELECT * FROM a UNION ALL SELECT * FROM b);
  *
@@ -44,6 +45,16 @@
  *	  incorrect. Instead a new state should be created in the correct aggregate
  *	  memory context and the 2nd state should be copied over.
  *
+ *	  The 'serialStates' option can be used to allow multi-stage aggregation
+ *	  for aggregates with an INTERNAL state type. When this mode is disabled
+ *	  only a pointer to the INTERNAL aggregate states are passed around the
+ *	  executor. This behaviour does not suit a parallel environment where the
+ *	  process is unable to dereference pointers for memory which belongs to a
+ *	  worker process. Enabling this mode causes the INTERNAL states to be
+ *	  serialized and deserialized as and when required, which of course
+ *	  requires that the aggregate function also have a 'serialfunc' and
+ *	  'deserialfunc' function specified.
+ *
  *	  If a normal aggregate call specifies DISTINCT or ORDER BY, we sort the
  *	  input tuples and eliminate duplicates (if required) before performing
  *	  the above-depicted process.  (However, we don't do that for ordered-set
@@ -232,6 +243,12 @@ typedef struct AggStatePerTransData
 	/* Oid of the state transition or combine function */
 	Oid			transfn_oid;
 
+	/* Oid of the serial function or InvalidOid */
+	Oid			serialfn_oid;
+
+	/* Oid of the deserial function or InvalidOid */
+	Oid			deserialfn_oid;
+
 	/* Oid of state value's datatype */
 	Oid			aggtranstype;
 
@@ -246,6 +263,12 @@ typedef struct AggStatePerTransData
 	 */
 	FmgrInfo	transfn;
 
+	/* fmgr lookup data for serial function */
+	FmgrInfo	serialfn;
+
+	/* fmgr lookup data for deserial function */
+	FmgrInfo	deserialfn;
+
 	/* Input collation derived for aggregate */
 	Oid			aggCollation;
 
@@ -326,6 +349,11 @@ typedef struct AggStatePerTransData
 	 * worth the extra space consumption.
 	 */
 	FunctionCallInfoData transfn_fcinfo;
+
+	/* Likewise for serial and deserial functions */
+	FunctionCallInfoData serialfn_fcinfo;
+
+	FunctionCallInfoData deserialfn_fcinfo;
 }	AggStatePerTransData;
 
 /*
@@ -487,12 +515,15 @@ static Datum GetAggInitVal(Datum textInitVal, Oid transtype);
 static void build_pertrans_for_aggref(AggStatePerTrans pertrans,
 						  AggState *aggsate, EState *estate,
 						  Aggref *aggref, Oid aggtransfn, Oid aggtranstype,
-						  Datum initValue, bool initValueIsNull,
-						  Oid *inputTypes, int numArguments);
+						  Oid aggserialtype, Oid aggserialfn,
+						  Oid aggdeserialfn, Datum initValue,
+						  bool initValueIsNull, Oid *inputTypes,
+						  int numArguments);
 static int find_compatible_peragg(Aggref *newagg, AggState *aggstate,
 					   int lastaggno, List **same_input_transnos);
 static int find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 						 Oid aggtransfn, Oid aggtranstype,
+						 Oid aggserialfn, Oid aggdeserialfn,
 						 Datum initValue, bool initValueIsNull,
 						 List *transnos);
 
@@ -943,8 +974,30 @@ combine_aggregates(AggState *aggstate, AggStatePerGroup pergroup)
 		slot = ExecProject(pertrans->evalproj, NULL);
 		Assert(slot->tts_nvalid >= 1);
 
-		fcinfo->arg[1] = slot->tts_values[0];
-		fcinfo->argnull[1] = slot->tts_isnull[0];
+		/*
+		 * deserialfn_oid will be set if we must deserialize the input state
+		 * before calling the combine function
+		 */
+		if (OidIsValid(pertrans->deserialfn_oid))
+		{
+			/* don't call a strict deserial function with NULL input */
+			if (pertrans->deserialfn.fn_strict && slot->tts_isnull[0] == true)
+				continue;
+			else
+			{
+				FunctionCallInfo dsinfo = &pertrans->deserialfn_fcinfo;
+				dsinfo->arg[0] = slot->tts_values[0];
+				dsinfo->argnull[0] = slot->tts_isnull[0];
+
+				fcinfo->arg[1] = FunctionCallInvoke(dsinfo);
+				fcinfo->argnull[1] = dsinfo->isnull;
+			}
+		}
+		else
+		{
+			fcinfo->arg[1] = slot->tts_values[0];
+			fcinfo->argnull[1] = slot->tts_isnull[0];
+		}
 
 		advance_combine_function(aggstate, pertrans, pergroupstate);
 	}
@@ -1444,6 +1497,27 @@ finalize_aggregates(AggState *aggstate,
 		if (aggstate->finalizeAggs)
 			finalize_aggregate(aggstate, peragg, pergroupstate,
 							   &aggvalues[aggno], &aggnulls[aggno]);
+
+		/*
+		 * serialfn_oid will be set if we must serialize the input state
+		 * before calling the combine function on the state.
+		 */
+		else if (OidIsValid(pertrans->serialfn_oid))
+		{
+			/* don't call a strict serial function with NULL input */
+			if (pertrans->serialfn.fn_strict &&
+				pergroupstate->transValueIsNull)
+				continue;
+			else
+			{
+				FunctionCallInfo fcinfo = &pertrans->serialfn_fcinfo;
+				fcinfo->arg[0] = pergroupstate->transValue;
+				fcinfo->argnull[0] = pergroupstate->transValueIsNull;
+
+				aggvalues[aggno] = FunctionCallInvoke(fcinfo);
+				aggnulls[aggno] = fcinfo->isnull;
+			}
+		}
 		else
 		{
 			aggvalues[aggno] = pergroupstate->transValue;
@@ -2228,6 +2302,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 	aggstate->agg_done = false;
 	aggstate->combineStates = node->combineStates;
 	aggstate->finalizeAggs = node->finalizeAggs;
+	aggstate->serialStates = node->serialStates;
 	aggstate->input_done = false;
 	aggstate->pergroup = NULL;
 	aggstate->grp_firstTuple = NULL;
@@ -2536,6 +2611,9 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 		AclResult	aclresult;
 		Oid			transfn_oid,
 					finalfn_oid;
+		Oid			serialtype_oid,
+					serialfn_oid,
+					deserialfn_oid;
 		Expr	   *finalfnexpr;
 		Oid			aggtranstype;
 		Datum		textInitVal;
@@ -2600,6 +2678,47 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 		else
 			peragg->finalfn_oid = finalfn_oid = InvalidOid;
 
+		serialtype_oid = InvalidOid;
+		serialfn_oid = InvalidOid;
+		deserialfn_oid = InvalidOid;
+
+		/*
+		 * Determine if we require serialization or deserialization of the
+		 * aggregate states. This is only required if the aggregate state is
+		 * internal.
+		 */
+		if (aggstate->serialStates && aggform->aggtranstype == INTERNALOID)
+		{
+			/*
+			 * The planner should only have generated an agg node with
+			 * serialStates if every aggregate with an INTERNAL state has a
+			 * serial type, serial function and deserial function. Let's ensure
+			 * it didn't mess that up.
+			 */
+			if (!OidIsValid(aggform->aggserialtype))
+				elog(ERROR, "serial type not set during serialStates aggregation step");
+
+			if (!OidIsValid(aggform->aggserialfn))
+				elog(ERROR, "serial func not set during serialStates aggregation step");
+
+			if (!OidIsValid(aggform->aggdeserialfn))
+				elog(ERROR, "deserial func not set during serialStates aggregation step");
+
+			/* serial func only required when not finalizing aggs */
+			if (!aggstate->finalizeAggs)
+			{
+				serialfn_oid = aggform->aggserialfn;
+				serialtype_oid = aggform->aggserialtype;
+			}
+
+			/* deserial func only required when combining states */
+			if (aggstate->combineStates)
+			{
+				deserialfn_oid = aggform->aggdeserialfn;
+				serialtype_oid = aggform->aggserialtype;
+			}
+		}
+
 		/* Check that aggregate owner has permission to call component fns */
 		{
 			HeapTuple	procTuple;
@@ -2628,6 +2747,24 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 								   get_func_name(finalfn_oid));
 				InvokeFunctionExecuteHook(finalfn_oid);
 			}
+			if (OidIsValid(serialfn_oid))
+			{
+				aclresult = pg_proc_aclcheck(serialfn_oid, aggOwner,
+											 ACL_EXECUTE);
+				if (aclresult != ACLCHECK_OK)
+					aclcheck_error(aclresult, ACL_KIND_PROC,
+								   get_func_name(serialfn_oid));
+				InvokeFunctionExecuteHook(serialfn_oid);
+			}
+			if (OidIsValid(deserialfn_oid))
+			{
+				aclresult = pg_proc_aclcheck(deserialfn_oid, aggOwner,
+											 ACL_EXECUTE);
+				if (aclresult != ACLCHECK_OK)
+					aclcheck_error(aclresult, ACL_KIND_PROC,
+								   get_func_name(deserialfn_oid));
+				InvokeFunctionExecuteHook(deserialfn_oid);
+			}
 		}
 
 		/*
@@ -2697,7 +2834,8 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 		 */
 		existing_transno = find_compatible_pertrans(aggstate, aggref,
 													transfn_oid, aggtranstype,
-												  initValue, initValueIsNull,
+												  serialfn_oid, deserialfn_oid,
+													initValue, initValueIsNull,
 													same_input_transnos);
 		if (existing_transno != -1)
 		{
@@ -2713,8 +2851,10 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 			pertrans = &pertransstates[++transno];
 			build_pertrans_for_aggref(pertrans, aggstate, estate,
 									  aggref, transfn_oid, aggtranstype,
-									  initValue, initValueIsNull,
-									  inputTypes, numArguments);
+									  serialtype_oid, serialfn_oid,
+									  deserialfn_oid, initValue,
+									  initValueIsNull, inputTypes,
+									  numArguments);
 			peragg->transno = transno;
 		}
 		ReleaseSysCache(aggTuple);
@@ -2742,11 +2882,14 @@ static void
 build_pertrans_for_aggref(AggStatePerTrans pertrans,
 						  AggState *aggstate, EState *estate,
 						  Aggref *aggref,
-						  Oid aggtransfn, Oid aggtranstype,
+						  Oid aggtransfn, Oid aggtranstype, Oid aggserialtype,
+						  Oid aggserialfn, Oid aggdeserialfn,
 						  Datum initValue, bool initValueIsNull,
 						  Oid *inputTypes, int numArguments)
 {
 	int			numGroupingSets = Max(aggstate->maxsets, 1);
+	Expr	   *serialfnexpr = NULL;
+	Expr	   *deserialfnexpr = NULL;
 	ListCell   *lc;
 	int			numInputs;
 	int			numDirectArgs;
@@ -2760,6 +2903,8 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 	pertrans->aggref = aggref;
 	pertrans->aggCollation = aggref->inputcollid;
 	pertrans->transfn_oid = aggtransfn;
+	pertrans->serialfn_oid = aggserialfn;
+	pertrans->deserialfn_oid = aggdeserialfn;
 	pertrans->initValue = initValue;
 	pertrans->initValueIsNull = initValueIsNull;
 
@@ -2851,6 +2996,41 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 					&pertrans->transtypeLen,
 					&pertrans->transtypeByVal);
 
+	if (OidIsValid(aggserialfn))
+	{
+		build_aggregate_serialfn_expr(aggtranstype,
+									  aggserialtype,
+									  aggref->inputcollid,
+									  aggserialfn,
+									  &serialfnexpr);
+		fmgr_info(aggserialfn, &pertrans->serialfn);
+		fmgr_info_set_expr((Node *) serialfnexpr, &pertrans->serialfn);
+
+		InitFunctionCallInfoData(pertrans->serialfn_fcinfo,
+								 &pertrans->serialfn,
+								 1,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+	}
+
+	if (OidIsValid(aggdeserialfn))
+	{
+		build_aggregate_serialfn_expr(aggtranstype,
+									  aggserialtype,
+									  aggref->inputcollid,
+									  aggdeserialfn,
+									  &deserialfnexpr);
+		fmgr_info(aggdeserialfn, &pertrans->deserialfn);
+		fmgr_info_set_expr((Node *) deserialfnexpr, &pertrans->deserialfn);
+
+		InitFunctionCallInfoData(pertrans->deserialfn_fcinfo,
+								 &pertrans->deserialfn,
+								 1,
+								 pertrans->aggCollation,
+								 (void *) aggstate, NULL);
+
+	}
+
 	/*
 	 * Get a tupledesc corresponding to the aggregated inputs (including sort
 	 * expressions) of the agg.
@@ -3097,6 +3277,7 @@ find_compatible_peragg(Aggref *newagg, AggState *aggstate,
 static int
 find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 						 Oid aggtransfn, Oid aggtranstype,
+						 Oid aggserialfn, Oid aggdeserialfn,
 						 Datum initValue, bool initValueIsNull,
 						 List *transnos)
 {
@@ -3115,6 +3296,14 @@ find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 			aggtranstype != pertrans->aggtranstype)
 			continue;
 
+		/*
+		 * serial and deserial functions must match, if present. Remember that
+		 * these will be InvalidOid if they're not required for this agg node
+		 */
+		if (aggserialfn != pertrans->serialfn_oid ||
+			aggdeserialfn != pertrans->deserialfn_oid)
+			continue;
+
 		/* Check that the initial condition matches, too. */
 		if (initValueIsNull && pertrans->initValueIsNull)
 			return transno;
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 5877037..7e880fc 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -867,6 +867,7 @@ _copyAgg(const Agg *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_SCALAR_FIELD(combineStates);
 	COPY_SCALAR_FIELD(finalizeAggs);
+	COPY_SCALAR_FIELD(serialStates);
 	if (from->numCols > 0)
 	{
 		COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index b5e0b55..ffb29ca 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -697,6 +697,7 @@ _outAgg(StringInfo str, const Agg *node)
 
 	WRITE_BOOL_FIELD(combineStates);
 	WRITE_BOOL_FIELD(finalizeAggs);
+	WRITE_BOOL_FIELD(serialStates);
 
 	appendStringInfoString(str, " :grpOperators");
 	for (i = 0; i < node->numCols; i++)
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index a67b337..d85f6db 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1991,6 +1991,7 @@ _readAgg(void)
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
 	READ_BOOL_FIELD(combineStates);
 	READ_BOOL_FIELD(finalizeAggs);
+	READ_BOOL_FIELD(serialStates);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 	READ_NODE_FIELD(groupingSets);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index fda4df6..4616b90 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -1056,6 +1056,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path)
 								 numGroups,
 								 false,
 								 true,
+								 false,
 								 subplan);
 	}
 	else
@@ -4560,7 +4561,7 @@ make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
 		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
 		 List *groupingSets, long numGroups, bool combineStates,
-		 bool finalizeAggs, Plan *lefttree)
+		 bool finalizeAggs, bool serialStates, Plan *lefttree)
 {
 	Agg		   *node = makeNode(Agg);
 	Plan	   *plan = &node->plan;
@@ -4571,6 +4572,7 @@ make_agg(PlannerInfo *root, List *tlist, List *qual,
 	node->numCols = numGroupCols;
 	node->combineStates = combineStates;
 	node->finalizeAggs = finalizeAggs;
+	node->serialStates = serialStates;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
 	node->numGroups = numGroups;
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index c0ec905..ad99690 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -2007,6 +2007,7 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 												numGroups,
 												false,
 												true,
+												false,
 												result_plan);
 				/* Hashed aggregation produces randomly-ordered results */
 				current_pathkeys = NIL;
@@ -2316,6 +2317,7 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 											numDistinctRows,
 											false,
 											true,
+											false,
 											result_plan);
 			/* Hashed aggregation produces randomly-ordered results */
 			current_pathkeys = NIL;
@@ -2555,6 +2557,7 @@ build_grouping_chain(PlannerInfo *root,
 										 numGroups,
 										 false,
 										 true,
+										 false,
 										 sort_plan);
 
 			/*
@@ -2596,6 +2599,7 @@ build_grouping_chain(PlannerInfo *root,
 										numGroups,
 										false,
 										true,
+										false,
 										result_plan);
 
 		((Agg *) result_plan)->chain = chain;
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 615f3a2..007fc0f 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -15,7 +15,9 @@
  */
 #include "postgres.h"
 
+#include "access/htup_details.h"
 #include "access/transam.h"
+#include "catalog/pg_aggregate.h"
 #include "catalog/pg_type.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
@@ -139,6 +141,18 @@ static List *set_returning_clause_references(PlannerInfo *root,
 static bool fix_opfuncids_walker(Node *node, void *context);
 static bool extract_query_dependencies_walker(Node *node,
 								  PlannerInfo *context);
+static void set_combineagg_references(PlannerInfo *root, Plan *plan,
+									  int rtoffset);
+static Node *fix_combine_agg_expr(PlannerInfo *root,
+								  Node *node,
+								  indexed_tlist *subplan_itlist,
+								  Index newvarno,
+								  int rtoffset);
+static Node *fix_combine_agg_expr_mutator(Node *node,
+										  fix_upper_expr_context *context);
+static void set_partialagg_aggref_types(PlannerInfo *root, Plan *plan,
+										bool serializeStates);
+
 
 /*****************************************************************************
  *
@@ -668,8 +682,24 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 			}
 			break;
 		case T_Agg:
-			set_upper_references(root, plan, rtoffset);
-			break;
+			{
+				Agg *aggplan = (Agg *) plan;
+
+				/*
+				 * For partial aggregation we must adjust the return types of
+				 * the Aggrefs
+				 */
+				if (!aggplan->finalizeAggs)
+					set_partialagg_aggref_types(root, plan,
+												aggplan->serialStates);
+
+				if (aggplan->combineStates)
+					set_combineagg_references(root, plan, rtoffset);
+				else
+					set_upper_references(root, plan, rtoffset);
+
+				break;
+			}
 		case T_Group:
 			set_upper_references(root, plan, rtoffset);
 			break;
@@ -2432,3 +2462,199 @@ extract_query_dependencies_walker(Node *node, PlannerInfo *context)
 	return expression_tree_walker(node, extract_query_dependencies_walker,
 								  (void *) context);
 }
+
+static void
+set_combineagg_references(PlannerInfo *root, Plan *plan, int rtoffset)
+{
+	Plan	   *subplan = plan->lefttree;
+	indexed_tlist *subplan_itlist;
+	List	   *output_targetlist;
+	ListCell   *l;
+
+	Assert(IsA(plan, Agg));
+	Assert(((Agg *) plan)->combineStates);
+
+	subplan_itlist = build_tlist_index(subplan->targetlist);
+
+	output_targetlist = NIL;
+
+	foreach(l, plan->targetlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(l);
+		Node	   *newexpr;
+
+		/* If it's a non-Var sort/group item, first try to match by sortref */
+		if (tle->ressortgroupref != 0 && !IsA(tle->expr, Var))
+		{
+			newexpr = (Node *)
+				search_indexed_tlist_for_sortgroupref((Node *) tle->expr,
+														tle->ressortgroupref,
+														subplan_itlist,
+														OUTER_VAR);
+			if (!newexpr)
+				newexpr = fix_combine_agg_expr(root,
+												(Node *) tle->expr,
+												subplan_itlist,
+												OUTER_VAR,
+												rtoffset);
+		}
+		else
+			newexpr = fix_combine_agg_expr(root,
+											(Node *) tle->expr,
+											subplan_itlist,
+											OUTER_VAR,
+											rtoffset);
+		tle = flatCopyTargetEntry(tle);
+		tle->expr = (Expr *) newexpr;
+		output_targetlist = lappend(output_targetlist, tle);
+	}
+
+	plan->targetlist = output_targetlist;
+
+	plan->qual = (List *)
+		fix_upper_expr(root,
+					   (Node *) plan->qual,
+					   subplan_itlist,
+					   OUTER_VAR,
+					   rtoffset);
+
+	pfree(subplan_itlist);
+}
+
+
+/*
+ * Adjust the Aggref'a args to reference the correct Aggref target in the outer
+ * subplan.
+ */
+static Node *
+fix_combine_agg_expr(PlannerInfo *root,
+			   Node *node,
+			   indexed_tlist *subplan_itlist,
+			   Index newvarno,
+			   int rtoffset)
+{
+	fix_upper_expr_context context;
+
+	context.root = root;
+	context.subplan_itlist = subplan_itlist;
+	context.newvarno = newvarno;
+	context.rtoffset = rtoffset;
+	return fix_combine_agg_expr_mutator(node, &context);
+}
+
+static Node *
+fix_combine_agg_expr_mutator(Node *node, fix_upper_expr_context *context)
+{
+	Var		   *newvar;
+
+	if (node == NULL)
+		return NULL;
+	if (IsA(node, Var))
+	{
+		Var		   *var = (Var *) node;
+
+		newvar = search_indexed_tlist_for_var(var,
+											  context->subplan_itlist,
+											  context->newvarno,
+											  context->rtoffset);
+		if (!newvar)
+			elog(ERROR, "variable not found in subplan target list");
+		return (Node *) newvar;
+	}
+	if (IsA(node, Aggref))
+	{
+		TargetEntry *tle;
+		Aggref		*aggref = (Aggref*) node;
+
+		tle = tlist_member(node, context->subplan_itlist->tlist);
+		if (tle)
+		{
+			/* Found a matching subplan output expression */
+			Var		   *newvar;
+			TargetEntry *newtle;
+
+			newvar = makeVarFromTargetEntry(context->newvarno, tle);
+			newvar->varnoold = 0;	/* wasn't ever a plain Var */
+			newvar->varoattno = 0;
+
+			/* update the args in the aggref */
+
+			/* makeTargetEntry ,always set resno to one for finialize agg */
+			newtle = makeTargetEntry((Expr*) newvar, 1, NULL, false);
+
+			/*
+			 * Updated the args, let the newvar refer to the right position of
+			 * the agg function in the subplan
+			 */
+			aggref->args = list_make1(newtle);
+
+			return (Node *) aggref;
+		}
+		else
+			elog(ERROR, "aggref not found in subplan target list");
+	}
+	if (IsA(node, PlaceHolderVar))
+	{
+		PlaceHolderVar *phv = (PlaceHolderVar *) node;
+
+		/* See if the PlaceHolderVar has bubbled up from a lower plan node */
+		if (context->subplan_itlist->has_ph_vars)
+		{
+			newvar = search_indexed_tlist_for_non_var((Node *) phv,
+													  context->subplan_itlist,
+													  context->newvarno);
+			if (newvar)
+				return (Node *) newvar;
+		}
+		/* If not supplied by input plan, evaluate the contained expr */
+		return fix_upper_expr_mutator((Node *) phv->phexpr, context);
+	}
+	if (IsA(node, Param))
+		return fix_param_node(context->root, (Param *) node);
+
+	fix_expr_common(context->root, node);
+	return expression_tree_mutator(node,
+								   fix_combine_agg_expr_mutator,
+								   (void *) context);
+}
+
+/* XXX is this really the best place and way to do this? */
+static void
+set_partialagg_aggref_types(PlannerInfo *root, Plan *plan, bool serializeStates)
+{
+	ListCell *l;
+
+	foreach(l, plan->targetlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(l);
+
+		if (IsA(tle->expr, Aggref))
+		{
+			Aggref *aggref = (Aggref *) tle->expr;
+			HeapTuple	aggTuple;
+			Form_pg_aggregate aggform;
+
+			aggTuple = SearchSysCache1(AGGFNOID,
+									   ObjectIdGetDatum(aggref->aggfnoid));
+			if (!HeapTupleIsValid(aggTuple))
+				elog(ERROR, "cache lookup failed for aggregate %u",
+					 aggref->aggfnoid);
+			aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
+
+			/*
+			 * For partial aggregate nodes the return type of the Aggref
+			 * depends on if we're performing a serialization of the partially
+			 * aggregated states or not. If we are then the return type should
+			 * be the serial type rather than the trans type. We only require
+			 * this behavior for aggregates with INTERNAL trans types.
+			 */
+			if (serializeStates && OidIsValid(aggform->aggserialtype) &&
+				aggform->aggtranstype == INTERNALOID)
+				aggref->aggtype = aggform->aggserialtype;
+			else
+				aggref->aggtype = aggform->aggtranstype;
+
+			ReleaseSysCache(aggTuple);
+		}
+	}
+}
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index e509a1a..ab2f1a8 100644
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -777,6 +777,7 @@ make_union_unique(SetOperationStmt *op, Plan *plan,
 								 numGroups,
 								 false,
 								 true,
+								 false,
 								 plan);
 		/* Hashed aggregation produces randomly-ordered results */
 		*sortClauses = NIL;
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index ace8b38..b1eed99 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -52,6 +52,10 @@
 #include "utils/syscache.h"
 #include "utils/typcache.h"
 
+typedef struct
+{
+	PartialAggType allowedtype;
+} partial_agg_context;
 
 typedef struct
 {
@@ -93,6 +97,7 @@ typedef struct
 	bool		allow_restricted;
 } has_parallel_hazard_arg;
 
+static bool partial_aggregate_walker(Node *node, partial_agg_context *context);
 static bool contain_agg_clause_walker(Node *node, void *context);
 static bool count_agg_clauses_walker(Node *node,
 						 count_agg_clauses_context *context);
@@ -400,6 +405,89 @@ make_ands_implicit(Expr *clause)
  *****************************************************************************/
 
 /*
+ * aggregates_allow_partial
+ *		Recursively search for Aggref clauses and determine the maximum
+ *		'degree' of partial aggregation which can be supported. Partial
+ *		aggregation requires that each aggregate does not have a DISTINCT or
+ *		ORDER BY clause, and that it also has a combine function set. For
+ *		aggregates with an INTERNAL trans type we only can support all types of
+ *		partial aggregation when the aggregate has a serial and deserial
+ *		function set. If this is not present then we can only support, at most
+ *		partial aggregation in the context of a single backend process, as
+ *		internal state pointers cannot be dereferenced from another backend
+ *		process.
+ */
+PartialAggType
+aggregates_allow_partial(Node *clause)
+{
+	partial_agg_context context;
+
+	/* initially any type is ok, until we find Aggrefs which say otherwise */
+	context.allowedtype = PAT_ANY;
+
+	if (!partial_aggregate_walker(clause, &context))
+		return context.allowedtype;
+	return context.allowedtype;
+}
+
+static bool
+partial_aggregate_walker(Node *node, partial_agg_context *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Aggref))
+	{
+		Aggref	   *aggref = (Aggref *) node;
+		HeapTuple	aggTuple;
+		Form_pg_aggregate aggform;
+
+		Assert(aggref->agglevelsup == 0);
+
+		/*
+		 * We can't perform partial aggregation with Aggrefs containing a
+		 * DISTINCT or ORDER BY clause.
+		 */
+		if (aggref->aggdistinct || aggref->aggorder)
+		{
+			context->allowedtype = PAT_DISABLED;
+			return true;	/* abort search */
+		}
+		aggTuple = SearchSysCache1(AGGFNOID,
+								   ObjectIdGetDatum(aggref->aggfnoid));
+		if (!HeapTupleIsValid(aggTuple))
+			elog(ERROR, "cache lookup failed for aggregate %u",
+				 aggref->aggfnoid);
+		aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
+
+		/*
+		 * If there is no combine func, then partial aggregation is not
+		 * possible.
+		 */
+		if (!OidIsValid(aggform->aggcombinefn))
+		{
+			ReleaseSysCache(aggTuple);
+			context->allowedtype = PAT_DISABLED;
+			return true;	/* abort search */
+		}
+
+		/*
+		 * Any aggs with an internal transtype must have a serial type, serial
+		 * func and deserial func, otherwise we can only support internal mode.
+		 */
+		if (aggform->aggtranstype == INTERNALOID &&
+			(!OidIsValid(aggform->aggserialtype) ||
+			 !OidIsValid(aggform->aggserialfn) ||
+			 !OidIsValid(aggform->aggdeserialfn)))
+			context->allowedtype = PAT_INTERNAL_ONLY;
+
+		ReleaseSysCache(aggTuple);
+		return false; /* continue searching */
+	}
+	return expression_tree_walker(node, partial_aggregate_walker,
+								  (void *) context);
+}
+
+/*
  * contain_agg_clause
  *	  Recursively search for Aggref/GroupingFunc nodes within a clause.
  *
diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c
index b790bb2..ca3823a 100644
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -1965,6 +1965,80 @@ build_aggregate_combinefn_expr(Oid agg_state_type,
 
 /*
  * Like build_aggregate_transfn_expr, but creates an expression tree for the
+ * serial function of an aggregate, rather than the transition function.
+ */
+void
+build_aggregate_serialfn_expr(Oid agg_state_type,
+							  Oid agg_serial_type,
+							  Oid agg_input_collation,
+							  Oid serialfn_oid,
+							  Expr **serialfnexpr)
+{
+	Param	   *argp;
+	List	   *args;
+	FuncExpr   *fexpr;
+
+	/* Build arg list to use in the serialfn FuncExpr node. */
+	argp = makeNode(Param);
+	argp->paramkind = PARAM_EXEC;
+	argp->paramid = -1;
+	argp->paramtype = agg_state_type;
+	argp->paramtypmod = -1;
+	argp->paramcollid = agg_input_collation;
+	argp->location = -1;
+
+	/* takes a single arg of the transition state type */
+	args = list_make1(argp);
+
+	fexpr = makeFuncExpr(serialfn_oid,
+						 agg_serial_type,
+						 args,
+						 InvalidOid,
+						 agg_input_collation,
+						 COERCE_EXPLICIT_CALL);
+	fexpr->funcvariadic = false;
+	*serialfnexpr = (Expr *) fexpr;
+}
+
+/*
+ * Like build_aggregate_transfn_expr, but creates an expression tree for the
+ * deserial function of an aggregate, rather than the transition function.
+ */
+void
+build_aggregate_deserialfn_expr(Oid agg_state_type,
+								Oid agg_serial_type,
+								Oid agg_input_collation,
+								Oid deserialfn_oid,
+								Expr **deserialfnexpr)
+{
+	Param	   *argp;
+	List	   *args;
+	FuncExpr   *fexpr;
+
+	/* Build arg list to use in the serialfn FuncExpr node. */
+	argp = makeNode(Param);
+	argp->paramkind = PARAM_EXEC;
+	argp->paramid = -1;
+	argp->paramtype = agg_serial_type;
+	argp->paramtypmod = -1;
+	argp->paramcollid = agg_input_collation;
+	argp->location = -1;
+
+	/* takes a single arg of the serial type */
+	args = list_make1(argp);
+
+	fexpr = makeFuncExpr(deserialfn_oid,
+						 agg_state_type,
+						 args,
+						 InvalidOid,
+						 agg_input_collation,
+						 COERCE_EXPLICIT_CALL);
+	fexpr->funcvariadic = false;
+	*deserialfnexpr = (Expr *) fexpr;
+}
+
+/*
+ * Like build_aggregate_transfn_expr, but creates an expression tree for the
  * final function of an aggregate, rather than the transition function.
  */
 void
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index 07b2645..bd14b61 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -3369,6 +3369,178 @@ numeric_avg_accum(PG_FUNCTION_ARGS)
 }
 
 /*
+ * Generic combine function for numeric aggregates without requirement for X^2
+ */
+Datum
+numeric_avg_combine(PG_FUNCTION_ARGS)
+{
+	NumericAggState *state1;
+	NumericAggState *state2;
+
+	state1 = PG_ARGISNULL(0) ? NULL : (NumericAggState *) PG_GETARG_POINTER(0);
+	state2 = PG_ARGISNULL(1) ? NULL : (NumericAggState *) PG_GETARG_POINTER(1);
+
+	if (state2 == NULL)
+		PG_RETURN_POINTER(state1);
+
+	/* manually copy all fields from state2 to state1 */
+	if (state1 == NULL)
+	{
+		MemoryContext old_context;
+
+		state1 = makeNumericAggState(fcinfo, false);
+		state1->N = state2->N;
+		state1->NaNcount = state2->NaNcount;
+		state1->maxScale = state2->maxScale;
+		state1->maxScaleCount = state2->maxScaleCount;
+
+		old_context = MemoryContextSwitchTo(state1->agg_context);
+
+		init_var(&state1->sumX);
+		set_var_from_var(&state2->sumX, &state1->sumX);
+
+		MemoryContextSwitchTo(old_context);
+
+		PG_RETURN_POINTER(state1);
+	}
+
+	if (state2->N > 0)
+	{
+		MemoryContext old_context;
+
+		state1->N += state2->N;
+		state1->NaNcount += state2->NaNcount;
+
+		/*
+		 * XXX do we care about these? They're really only needed for moving
+		 * aggregates.
+		 */
+		if (state2->maxScale > state1->maxScale)
+		{
+			state1->maxScale = state2->maxScale;
+			state1->maxScaleCount = state2->maxScaleCount;
+		}
+		else if (state2->maxScale == state1->maxScale)
+			state1->maxScaleCount += state2->maxScaleCount;
+
+		/* The rest of this needs to work in the aggregate context */
+		old_context = MemoryContextSwitchTo(state1->agg_context);
+
+		/* Accumulate sums */
+		add_var(&(state1->sumX), &(state2->sumX), &(state1->sumX));
+
+		if (state1->calcSumX2)
+			add_var(&(state1->sumX2), &(state2->sumX2), &(state1->sumX2));
+
+		MemoryContextSwitchTo(old_context);
+	}
+	PG_RETURN_POINTER(state1);
+}
+
+/*
+ * numeric_avg_serialize
+ *		Serialize NumericAggState into text.
+ *		numeric_avg_deserialize(numeric_avg_serialize(state)) must result in
+ *		a state which matches the original input state.
+ */
+Datum
+numeric_avg_serialize(PG_FUNCTION_ARGS)
+{
+	NumericAggState *state;
+	StringInfoData string;
+	MemoryContext agg_context;
+	MemoryContext old_context;
+	text	   *result;
+
+	/* Ensure we disallow calling when not in aggregate context */
+	if (!AggCheckCallContext(fcinfo, &agg_context))
+		elog(ERROR, "aggregate function called in non-aggregate context");
+
+	state = (NumericAggState *) PG_GETARG_POINTER(0);
+
+	initStringInfo(&string);
+
+	/*
+	 * Transform the NumericAggState into a string with the following format:
+	 * "N sumX maxScale maxScaleCount NaNcount"
+	 * XXX perhaps we can come up with a more efficient format for this.
+	 */
+	appendStringInfo(&string, INT64_FORMAT " %s %d " INT64_FORMAT " " INT64_FORMAT,
+			state->N, get_str_from_var(&state->sumX), state->maxScale,
+			state->maxScaleCount, state->NaNcount);
+
+	old_context = MemoryContextSwitchTo(agg_context);
+
+	result = cstring_to_text_with_len(string.data, string.len);
+
+	MemoryContextSwitchTo(old_context);
+
+	PG_RETURN_TEXT_P(result);
+}
+
+/*
+ * numeric_avg_deserialize
+ *		deserialize Text into NumericAggState
+ *		numeric_avg_serialize(numeric_avg_deserialize(text)) must result in
+ *		text which matches the original input text.
+ */
+Datum
+numeric_avg_deserialize(PG_FUNCTION_ARGS)
+{
+	NumericAggState *result;
+	MemoryContext agg_context;
+	MemoryContext old_context;
+	Numeric		tmp;
+	text	   *sstate;
+	char	   *state;
+	char	   *token[5];
+	int			i;
+
+	if (!AggCheckCallContext(fcinfo, &agg_context))
+		elog(ERROR, "aggregate function called in non-aggregate context");
+
+	sstate = PG_GETARG_TEXT_P(0);
+	state = text_to_cstring(sstate);
+
+	token[0] = strtok(state, " ");
+
+	if (!token[0])
+		elog(ERROR, "invalid serialization format");
+
+	for (i = 1; i < 5; i++)
+	{
+		token[i] = strtok(NULL, " ");
+		if (!token[i])
+			elog(ERROR, "invalid serialization format");
+	}
+
+	old_context = MemoryContextSwitchTo(agg_context);
+
+	/*
+	 * Transform string into a NumericAggState. The string is in the format:
+	 * "N sumX maxScale maxScaleCount NaNcount"
+	 */
+	result = makeNumericAggState(fcinfo, false);
+
+	scanint8(token[0], false, &result->N);
+
+	tmp = DatumGetNumeric(DirectFunctionCall3(numeric_in,
+						  CStringGetDatum(token[1]),
+						  ObjectIdGetDatum(0),
+						  Int32GetDatum(-1)));
+	init_var_from_num(tmp, &result->sumX);
+
+	result->maxScale = pg_atoi(token[2], sizeof(int32), 0);
+	scanint8(token[3], false, &result->maxScaleCount);
+	scanint8(token[4], false, &result->NaNcount);
+
+	MemoryContextSwitchTo(old_context);
+
+	pfree(state);
+	PG_RETURN_POINTER(result);
+}
+
+/*
  * Generic inverse transition function for numeric aggregates
  * (with or without requirement for X^2).
  */
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 9c6f885..b9d0b53 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -12384,6 +12384,8 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	int			i_aggtransfn;
 	int			i_aggfinalfn;
 	int			i_aggcombinefn;
+	int			i_aggserialfn;
+	int			i_aggdeserialfn;
 	int			i_aggmtransfn;
 	int			i_aggminvtransfn;
 	int			i_aggmfinalfn;
@@ -12392,6 +12394,7 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	int			i_aggsortop;
 	int			i_hypothetical;
 	int			i_aggtranstype;
+	int			i_aggserialtype;
 	int			i_aggtransspace;
 	int			i_aggmtranstype;
 	int			i_aggmtransspace;
@@ -12401,6 +12404,8 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	const char *aggtransfn;
 	const char *aggfinalfn;
 	const char *aggcombinefn;
+	const char *aggserialfn;
+	const char *aggdeserialfn;
 	const char *aggmtransfn;
 	const char *aggminvtransfn;
 	const char *aggmfinalfn;
@@ -12410,6 +12415,7 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	char	   *aggsortconvop;
 	bool		hypothetical;
 	const char *aggtranstype;
+	const char *aggserialtype;
 	const char *aggtransspace;
 	const char *aggmtranstype;
 	const char *aggmtransspace;
@@ -12435,10 +12441,11 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	{
 		appendPQExpBuffer(query, "SELECT aggtransfn, "
 			"aggfinalfn, aggtranstype::pg_catalog.regtype, "
-			"aggcombinefn, aggmtransfn, "
+			"aggcombinefn, aggserialfn, aggdeserialfn, aggmtransfn, "
 			"aggminvtransfn, aggmfinalfn, aggmtranstype::pg_catalog.regtype, "
 			"aggfinalextra, aggmfinalextra, "
 			"aggsortop::pg_catalog.regoperator, "
+			"aggserialtype::pg_catalog.regtype, "
 			"(aggkind = 'h') AS hypothetical, "
 			"aggtransspace, agginitval, "
 			"aggmtransspace, aggminitval, "
@@ -12561,12 +12568,15 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	i_aggtransfn = PQfnumber(res, "aggtransfn");
 	i_aggfinalfn = PQfnumber(res, "aggfinalfn");
 	i_aggcombinefn = PQfnumber(res, "aggcombinefn");
+	i_aggserialfn = PQfnumber(res, "aggserialfn");
+	i_aggdeserialfn = PQfnumber(res, "aggdeserialfn");
 	i_aggmtransfn = PQfnumber(res, "aggmtransfn");
 	i_aggminvtransfn = PQfnumber(res, "aggminvtransfn");
 	i_aggmfinalfn = PQfnumber(res, "aggmfinalfn");
 	i_aggfinalextra = PQfnumber(res, "aggfinalextra");
 	i_aggmfinalextra = PQfnumber(res, "aggmfinalextra");
 	i_aggsortop = PQfnumber(res, "aggsortop");
+	i_aggserialtype = PQfnumber(res, "aggserialtype");
 	i_hypothetical = PQfnumber(res, "hypothetical");
 	i_aggtranstype = PQfnumber(res, "aggtranstype");
 	i_aggtransspace = PQfnumber(res, "aggtransspace");
@@ -12579,6 +12589,8 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	aggtransfn = PQgetvalue(res, 0, i_aggtransfn);
 	aggfinalfn = PQgetvalue(res, 0, i_aggfinalfn);
 	aggcombinefn = PQgetvalue(res, 0, i_aggcombinefn);
+	aggserialfn = PQgetvalue(res, 0, i_aggserialfn);
+	aggdeserialfn = PQgetvalue(res, 0, i_aggdeserialfn);
 	aggmtransfn = PQgetvalue(res, 0, i_aggmtransfn);
 	aggminvtransfn = PQgetvalue(res, 0, i_aggminvtransfn);
 	aggmfinalfn = PQgetvalue(res, 0, i_aggmfinalfn);
@@ -12587,6 +12599,7 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	aggsortop = PQgetvalue(res, 0, i_aggsortop);
 	hypothetical = (PQgetvalue(res, 0, i_hypothetical)[0] == 't');
 	aggtranstype = PQgetvalue(res, 0, i_aggtranstype);
+	aggserialtype = PQgetvalue(res, 0, i_aggserialtype);
 	aggtransspace = PQgetvalue(res, 0, i_aggtransspace);
 	aggmtranstype = PQgetvalue(res, 0, i_aggmtranstype);
 	aggmtransspace = PQgetvalue(res, 0, i_aggmtransspace);
@@ -12672,6 +12685,13 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 		appendPQExpBuffer(details, ",\n    COMBINEFUNC = %s",	aggcombinefn);
 	}
 
+	if (strcmp(aggserialfn, "-") != 0)
+	{
+		appendPQExpBuffer(details, ",\n    SERIALFUNC = %s",	aggserialfn);
+		appendPQExpBuffer(details, ",\n    DESERIALFUNC = %s",	aggdeserialfn);
+		appendPQExpBuffer(details, ",\n    SERIALTYPE = %s",	aggserialtype);
+	}
+
 	if (strcmp(aggmtransfn, "-") != 0)
 	{
 		appendPQExpBuffer(details, ",\n    MSFUNC = %s,\n    MINVFUNC = %s,\n    MSTYPE = %s",
diff --git a/src/include/catalog/pg_aggregate.h b/src/include/catalog/pg_aggregate.h
index 441db30..ed2ee92 100644
--- a/src/include/catalog/pg_aggregate.h
+++ b/src/include/catalog/pg_aggregate.h
@@ -34,6 +34,8 @@
  *	aggtransfn			transition function
  *	aggfinalfn			final function (0 if none)
  *	aggcombinefn		combine function (0 if none)
+ *	aggserialfn			function to convert transtype into serialtype
+ *	aggdeserialfn		function to convert serialtype into transtype
  *	aggmtransfn			forward function for moving-aggregate mode (0 if none)
  *	aggminvtransfn		inverse function for moving-aggregate mode (0 if none)
  *	aggmfinalfn			final function for moving-aggregate mode (0 if none)
@@ -43,6 +45,7 @@
  *	aggtranstype		type of aggregate's transition (state) data
  *	aggtransspace		estimated size of state data (0 for default estimate)
  *	aggmtranstype		type of moving-aggregate state data (0 if none)
+ *	aggserialtype		datatype to serialize state to. (0 if none)
  *	aggmtransspace		estimated size of moving-agg state (0 for default est)
  *	agginitval			initial value for transition state (can be NULL)
  *	aggminitval			initial value for moving-agg state (can be NULL)
@@ -58,6 +61,8 @@ CATALOG(pg_aggregate,2600) BKI_WITHOUT_OIDS
 	regproc		aggtransfn;
 	regproc		aggfinalfn;
 	regproc		aggcombinefn;
+	regproc		aggserialfn;
+	regproc		aggdeserialfn;
 	regproc		aggmtransfn;
 	regproc		aggminvtransfn;
 	regproc		aggmfinalfn;
@@ -65,6 +70,7 @@ CATALOG(pg_aggregate,2600) BKI_WITHOUT_OIDS
 	bool		aggmfinalextra;
 	Oid			aggsortop;
 	Oid			aggtranstype;
+	Oid			aggserialtype;
 	int32		aggtransspace;
 	Oid			aggmtranstype;
 	int32		aggmtransspace;
@@ -87,25 +93,28 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  * ----------------
  */
 
-#define Natts_pg_aggregate					18
+#define Natts_pg_aggregate					21
 #define Anum_pg_aggregate_aggfnoid			1
 #define Anum_pg_aggregate_aggkind			2
 #define Anum_pg_aggregate_aggnumdirectargs	3
 #define Anum_pg_aggregate_aggtransfn		4
 #define Anum_pg_aggregate_aggfinalfn		5
 #define Anum_pg_aggregate_aggcombinefn		6
-#define Anum_pg_aggregate_aggmtransfn		7
-#define Anum_pg_aggregate_aggminvtransfn	8
-#define Anum_pg_aggregate_aggmfinalfn		9
-#define Anum_pg_aggregate_aggfinalextra		10
-#define Anum_pg_aggregate_aggmfinalextra	11
-#define Anum_pg_aggregate_aggsortop			12
-#define Anum_pg_aggregate_aggtranstype		13
-#define Anum_pg_aggregate_aggtransspace		14
-#define Anum_pg_aggregate_aggmtranstype		15
-#define Anum_pg_aggregate_aggmtransspace	16
-#define Anum_pg_aggregate_agginitval		17
-#define Anum_pg_aggregate_aggminitval		18
+#define Anum_pg_aggregate_aggserialfn		7
+#define Anum_pg_aggregate_aggdeserialfn		8
+#define Anum_pg_aggregate_aggmtransfn		9
+#define Anum_pg_aggregate_aggminvtransfn	10
+#define Anum_pg_aggregate_aggmfinalfn		11
+#define Anum_pg_aggregate_aggfinalextra		12
+#define Anum_pg_aggregate_aggmfinalextra	13
+#define Anum_pg_aggregate_aggsortop			14
+#define Anum_pg_aggregate_aggtranstype		15
+#define Anum_pg_aggregate_aggserialtype		16
+#define Anum_pg_aggregate_aggtransspace		17
+#define Anum_pg_aggregate_aggmtranstype		18
+#define Anum_pg_aggregate_aggmtransspace	19
+#define Anum_pg_aggregate_agginitval		20
+#define Anum_pg_aggregate_aggminitval		21
 
 /*
  * Symbolic values for aggkind column.  We distinguish normal aggregates
@@ -129,184 +138,184 @@ typedef FormData_pg_aggregate *Form_pg_aggregate;
  */
 
 /* avg */
-DATA(insert ( 2100	n 0 int8_avg_accum	numeric_poly_avg	-	int8_avg_accum	int8_avg_accum_inv	numeric_poly_avg	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg			-	int4_avg_accum	int4_avg_accum_inv	int8_avg			f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg			-	int2_avg_accum	int2_avg_accum_inv	int8_avg			f f 0	1016	0	1016	0	"{0,0}" "{0,0}" ));
-DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg		-	numeric_avg_accum numeric_accum_inv numeric_avg			f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2104	n 0 float4_accum	float8_avg			-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2105	n 0 float8_accum	float8_avg			-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2106	n 0 interval_accum	interval_avg		-	interval_accum	interval_accum_inv interval_avg			f f 0	1187	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
+DATA(insert ( 2100	n 0 int8_avg_accum	numeric_poly_avg	-					-	-	int8_avg_accum	int8_avg_accum_inv	numeric_poly_avg	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2101	n 0 int4_avg_accum	int8_avg			-					-	-	int4_avg_accum	int4_avg_accum_inv	int8_avg			f f 0	1016	0	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2102	n 0 int2_avg_accum	int8_avg			-					-	-	int2_avg_accum	int2_avg_accum_inv	int8_avg			f f 0	1016	0	0	1016	0	"{0,0}" "{0,0}" ));
+DATA(insert ( 2103	n 0 numeric_avg_accum numeric_avg		numeric_avg_combine	numeric_avg_serialize	numeric_avg_deserialize	numeric_avg_accum numeric_accum_inv numeric_avg			f f 0	2281	25	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2104	n 0 float4_accum	float8_avg			-					-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2105	n 0 float8_accum	float8_avg			-					-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2106	n 0 interval_accum	interval_avg		-					-	-	interval_accum	interval_accum_inv interval_avg			f f 0	1187	0	0	1187	0	"{0 second,0 second}" "{0 second,0 second}" ));
 
 /* sum */
-DATA(insert ( 2107	n 0 int8_avg_accum	numeric_poly_sum	-					int8_avg_accum	int8_avg_accum_inv	numeric_poly_sum	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2108	n 0 int4_sum		-					int8pl				int4_avg_accum	int4_avg_accum_inv	int2int4_sum		f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2109	n 0 int2_sum		-					int8pl				int2_avg_accum	int2_avg_accum_inv	int2int4_sum		f f 0	20		0	1016	0	_null_ "{0,0}" ));
-DATA(insert ( 2110	n 0 float4pl		-					float4pl			-				-					-					f f 0	700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2111	n 0 float8pl		-					float8pl			-				-					-					f f 0	701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2112	n 0 cash_pl			-					cash_pl				cash_pl			cash_mi				-					f f 0	790		0	790		0	_null_ _null_ ));
-DATA(insert ( 2113	n 0 interval_pl		-					interval_pl			interval_pl		interval_mi			-					f f 0	1186	0	1186	0	_null_ _null_ ));
-DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum		-					numeric_avg_accum	numeric_accum_inv	numeric_sum		f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2107	n 0 int8_avg_accum	numeric_poly_sum	-					-	-	int8_avg_accum	int8_avg_accum_inv	numeric_poly_sum	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2108	n 0 int4_sum		-					int8pl				-	-	int4_avg_accum	int4_avg_accum_inv	int2int4_sum		f f 0	20		0	0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2109	n 0 int2_sum		-					int8pl				-	-	int2_avg_accum	int2_avg_accum_inv	int2int4_sum		f f 0	20		0	0	1016	0	_null_ "{0,0}" ));
+DATA(insert ( 2110	n 0 float4pl		-					float4pl			-	-	-				-					-					f f 0	700		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2111	n 0 float8pl		-					float8pl			-	-	-				-					-					f f 0	701		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2112	n 0 cash_pl			-					cash_pl				-	-	cash_pl			cash_mi				-					f f 0	790		0	0	790		0	_null_ _null_ ));
+DATA(insert ( 2113	n 0 interval_pl		-					interval_pl			-	-	interval_pl		interval_mi			-					f f 0	1186	0	0	1186	0	_null_ _null_ ));
+DATA(insert ( 2114	n 0 numeric_avg_accum	numeric_sum		numeric_avg_combine	numeric_avg_serialize	numeric_avg_deserialize	numeric_avg_accum	numeric_accum_inv	numeric_sum		f f 0	2281	25	128 2281	128 _null_ _null_ ));
 
 /* max */
-DATA(insert ( 2115	n 0 int8larger		-				int8larger			-				-				-				f f 413		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2116	n 0 int4larger		-				int4larger			-				-				-				f f 521		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2117	n 0 int2larger		-				int2larger			-				-				-				f f 520		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2118	n 0 oidlarger		-				oidlarger			-				-				-				f f 610		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2119	n 0 float4larger	-				float4larger		-				-				-				f f 623		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2120	n 0 float8larger	-				float8larger		-				-				-				f f 674		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2121	n 0 int4larger		-				int4larger			-				-				-				f f 563		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2122	n 0 date_larger		-				date_larger			-				-				-				f f 1097	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2123	n 0 time_larger		-				time_larger			-				-				-				f f 1112	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2124	n 0 timetz_larger	-				timetz_larger		-				-				-				f f 1554	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2125	n 0 cashlarger		-				cashlarger			-				-				-				f f 903		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2126	n 0 timestamp_larger	-			timestamp_larger	-				-				-				f f 2064	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2127	n 0 timestamptz_larger	-			timestamptz_larger	-				-				-				f f 1324	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2128	n 0 interval_larger -				interval_larger		-				-				-				f f 1334	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2129	n 0 text_larger		-				text_larger			-				-				-				f f 666		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2130	n 0 numeric_larger	-				numeric_larger		-				-				-				f f 1756	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2050	n 0 array_larger	-				array_larger		-				-				-				f f 1073	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2244	n 0 bpchar_larger	-				bpchar_larger		-				-				-				f f 1060	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2797	n 0 tidlarger		-				tidlarger			-				-				-				f f 2800	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3526	n 0 enum_larger		-				enum_larger			-				-				-				f f 3519	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3564	n 0 network_larger	-				network_larger		-				-				-				f f 1205	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2115	n 0 int8larger		-				int8larger			-	-	-				-				-				f f 413		20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2116	n 0 int4larger		-				int4larger			-	-	-				-				-				f f 521		23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2117	n 0 int2larger		-				int2larger			-	-	-				-				-				f f 520		21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2118	n 0 oidlarger		-				oidlarger			-	-	-				-				-				f f 610		26		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2119	n 0 float4larger	-				float4larger		-	-	-				-				-				f f 623		700		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2120	n 0 float8larger	-				float8larger		-	-	-				-				-				f f 674		701		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2121	n 0 int4larger		-				int4larger			-	-	-				-				-				f f 563		702		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2122	n 0 date_larger		-				date_larger			-	-	-				-				-				f f 1097	1082	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2123	n 0 time_larger		-				time_larger			-	-	-				-				-				f f 1112	1083	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2124	n 0 timetz_larger	-				timetz_larger		-	-	-				-				-				f f 1554	1266	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2125	n 0 cashlarger		-				cashlarger			-	-	-				-				-				f f 903		790		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2126	n 0 timestamp_larger	-			timestamp_larger	-	-	-				-				-				f f 2064	1114	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2127	n 0 timestamptz_larger	-			timestamptz_larger	-	-	-				-				-				f f 1324	1184	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2128	n 0 interval_larger -				interval_larger		-	-	-				-				-				f f 1334	1186	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2129	n 0 text_larger		-				text_larger			-	-	-				-				-				f f 666		25		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2130	n 0 numeric_larger	-				numeric_larger		-	-	-				-				-				f f 1756	1700	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2050	n 0 array_larger	-				array_larger		-	-	-				-				-				f f 1073	2277	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2244	n 0 bpchar_larger	-				bpchar_larger		-	-	-				-				-				f f 1060	1042	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2797	n 0 tidlarger		-				tidlarger			-	-	-				-				-				f f 2800	27		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3526	n 0 enum_larger		-				enum_larger			-	-	-				-				-				f f 3519	3500	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3564	n 0 network_larger	-				network_larger		-	-	-				-				-				f f 1205	869		0	0	0		0	_null_ _null_ ));
 
 /* min */
-DATA(insert ( 2131	n 0 int8smaller		-				int8smaller			-				-				-				f f 412		20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2132	n 0 int4smaller		-				int4smaller			-				-				-				f f 97		23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2133	n 0 int2smaller		-				int2smaller			-				-				-				f f 95		21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2134	n 0 oidsmaller		-				oidsmaller			-				-				-				f f 609		26		0	0		0	_null_ _null_ ));
-DATA(insert ( 2135	n 0 float4smaller	-				float4smaller		-				-				-				f f 622		700		0	0		0	_null_ _null_ ));
-DATA(insert ( 2136	n 0 float8smaller	-				float8smaller		-				-				-				f f 672		701		0	0		0	_null_ _null_ ));
-DATA(insert ( 2137	n 0 int4smaller		-				int4smaller			-				-				-				f f 562		702		0	0		0	_null_ _null_ ));
-DATA(insert ( 2138	n 0 date_smaller	-				date_smaller		-				-				-				f f 1095	1082	0	0		0	_null_ _null_ ));
-DATA(insert ( 2139	n 0 time_smaller	-				time_smaller		-				-				-				f f 1110	1083	0	0		0	_null_ _null_ ));
-DATA(insert ( 2140	n 0 timetz_smaller	-				timetz_smaller		-				-				-				f f 1552	1266	0	0		0	_null_ _null_ ));
-DATA(insert ( 2141	n 0 cashsmaller		-				cashsmaller			-				-				-				f f 902		790		0	0		0	_null_ _null_ ));
-DATA(insert ( 2142	n 0 timestamp_smaller	-			timestamp_smaller	-				-				-				f f 2062	1114	0	0		0	_null_ _null_ ));
-DATA(insert ( 2143	n 0 timestamptz_smaller -			timestamptz_smaller	-				-				-				f f 1322	1184	0	0		0	_null_ _null_ ));
-DATA(insert ( 2144	n 0 interval_smaller	-			interval_smaller	-				-				-				f f 1332	1186	0	0		0	_null_ _null_ ));
-DATA(insert ( 2145	n 0 text_smaller	-				text_smaller		-				-				-				f f 664		25		0	0		0	_null_ _null_ ));
-DATA(insert ( 2146	n 0 numeric_smaller -				numeric_smaller		-				-				-				f f 1754	1700	0	0		0	_null_ _null_ ));
-DATA(insert ( 2051	n 0 array_smaller	-				array_smaller		-				-				-				f f 1072	2277	0	0		0	_null_ _null_ ));
-DATA(insert ( 2245	n 0 bpchar_smaller	-				bpchar_smaller		-				-				-				f f 1058	1042	0	0		0	_null_ _null_ ));
-DATA(insert ( 2798	n 0 tidsmaller		-				tidsmaller			-				-				-				f f 2799	27		0	0		0	_null_ _null_ ));
-DATA(insert ( 3527	n 0 enum_smaller	-				enum_smaller		-				-				-				f f 3518	3500	0	0		0	_null_ _null_ ));
-DATA(insert ( 3565	n 0 network_smaller -				network_smaller		-				-				-				f f 1203	869		0	0		0	_null_ _null_ ));
+DATA(insert ( 2131	n 0 int8smaller		-				int8smaller			-	-	-				-				-				f f 412		20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2132	n 0 int4smaller		-				int4smaller			-	-	-				-				-				f f 97		23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2133	n 0 int2smaller		-				int2smaller			-	-	-				-				-				f f 95		21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2134	n 0 oidsmaller		-				oidsmaller			-	-	-				-				-				f f 609		26		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2135	n 0 float4smaller	-				float4smaller		-	-	-				-				-				f f 622		700		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2136	n 0 float8smaller	-				float8smaller		-	-	-				-				-				f f 672		701		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2137	n 0 int4smaller		-				int4smaller			-	-	-				-				-				f f 562		702		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2138	n 0 date_smaller	-				date_smaller		-	-	-				-				-				f f 1095	1082	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2139	n 0 time_smaller	-				time_smaller		-	-	-				-				-				f f 1110	1083	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2140	n 0 timetz_smaller	-				timetz_smaller		-	-	-				-				-				f f 1552	1266	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2141	n 0 cashsmaller		-				cashsmaller			-	-	-				-				-				f f 902		790		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2142	n 0 timestamp_smaller	-			timestamp_smaller	-	-	-				-				-				f f 2062	1114	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2143	n 0 timestamptz_smaller -			timestamptz_smaller	-	-	-				-				-				f f 1322	1184	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2144	n 0 interval_smaller	-			interval_smaller	-	-	-				-				-				f f 1332	1186	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2145	n 0 text_smaller	-				text_smaller		-	-	-				-				-				f f 664		25		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2146	n 0 numeric_smaller -				numeric_smaller		-	-	-				-				-				f f 1754	1700	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2051	n 0 array_smaller	-				array_smaller		-	-	-				-				-				f f 1072	2277	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2245	n 0 bpchar_smaller	-				bpchar_smaller		-	-	-				-				-				f f 1058	1042	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2798	n 0 tidsmaller		-				tidsmaller			-	-	-				-				-				f f 2799	27		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3527	n 0 enum_smaller	-				enum_smaller		-	-	-				-				-				f f 3518	3500	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3565	n 0 network_smaller -				network_smaller		-	-	-				-				-				f f 1203	869		0	0	0		0	_null_ _null_ ));
 
 /* count */
-DATA(insert ( 2147	n 0 int8inc_any		-				int8pl	int8inc_any		int8dec_any		-				f f 0		20		0	20		0	"0" "0" ));
-DATA(insert ( 2803	n 0 int8inc			-				int8pl	int8inc			int8dec			-				f f 0		20		0	20		0	"0" "0" ));
+DATA(insert ( 2147	n 0 int8inc_any		-				int8pl	-	-	int8inc_any		int8dec_any		-				f f 0		20		0	0	20		0	"0" "0" ));
+DATA(insert ( 2803	n 0 int8inc			-				int8pl	-	-	int8inc			int8dec			-				f f 0		20		0	0	20		0	"0" "0" ));
 
 /* var_pop */
-DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop			-	int8_accum		int8_accum_inv	numeric_var_pop			f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2719	n 0 int4_accum	numeric_poly_var_pop	-	int4_accum		int4_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2720	n 0 int2_accum	numeric_poly_var_pop	-	int2_accum		int2_accum_inv	numeric_poly_var_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2721	n 0 float4_accum	float8_var_pop		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2722	n 0 float8_accum	float8_var_pop		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop		-	numeric_accum numeric_accum_inv numeric_var_pop			f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2718	n 0 int8_accum	numeric_var_pop			-	-	-	int8_accum		int8_accum_inv	numeric_var_pop			f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2719	n 0 int4_accum	numeric_poly_var_pop	-	-	-	int4_accum		int4_accum_inv	numeric_poly_var_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2720	n 0 int2_accum	numeric_poly_var_pop	-	-	-	int2_accum		int2_accum_inv	numeric_poly_var_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2721	n 0 float4_accum	float8_var_pop		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2722	n 0 float8_accum	float8_var_pop		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2723	n 0 numeric_accum	numeric_var_pop		-	-	-	numeric_accum numeric_accum_inv numeric_var_pop			f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* var_samp */
-DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp		-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2642	n 0 int4_accum	numeric_poly_var_samp	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2643	n 0 int2_accum	numeric_poly_var_samp	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2644	n 0 float4_accum	float8_var_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2645	n 0 float8_accum	float8_var_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp	-	numeric_accum	numeric_accum_inv numeric_var_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2641	n 0 int8_accum	numeric_var_samp		-	-	-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2642	n 0 int4_accum	numeric_poly_var_samp	-	-	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2643	n 0 int2_accum	numeric_poly_var_samp	-	-	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2644	n 0 float4_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2645	n 0 float8_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2646	n 0 numeric_accum	numeric_var_samp	-	-	-	numeric_accum	numeric_accum_inv numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* variance: historical Postgres syntax for var_samp */
-DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp		-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2149	n 0 int4_accum	numeric_poly_var_samp	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2150	n 0 int2_accum	numeric_poly_var_samp	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2151	n 0 float4_accum	float8_var_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2152	n 0 float8_accum	float8_var_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp	-	numeric_accum numeric_accum_inv numeric_var_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2148	n 0 int8_accum	numeric_var_samp		-	-	-	int8_accum		int8_accum_inv	numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2149	n 0 int4_accum	numeric_poly_var_samp	-	-	-	int4_accum		int4_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2150	n 0 int2_accum	numeric_poly_var_samp	-	-	-	int2_accum		int2_accum_inv	numeric_poly_var_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2151	n 0 float4_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2152	n 0 float8_accum	float8_var_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2153	n 0 numeric_accum	numeric_var_samp	-	-	-	numeric_accum numeric_accum_inv numeric_var_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* stddev_pop */
-DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop		-	int8_accum	int8_accum_inv	numeric_stddev_pop		f f 0	2281	128	2281	128 _null_ _null_ ));
-DATA(insert ( 2725	n 0 int4_accum	numeric_poly_stddev_pop	-	int4_accum	int4_accum_inv	numeric_poly_stddev_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2726	n 0 int2_accum	numeric_poly_stddev_pop	-	int2_accum	int2_accum_inv	numeric_poly_stddev_pop	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-	-				-				-					f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-	-				-				-					f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop	-	numeric_accum numeric_accum_inv numeric_stddev_pop	f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2724	n 0 int8_accum	numeric_stddev_pop		-	-	-	int8_accum	int8_accum_inv	numeric_stddev_pop		f f 0	2281	0	128	2281	128 _null_ _null_ ));
+DATA(insert ( 2725	n 0 int4_accum	numeric_poly_stddev_pop	-	-	-	int4_accum	int4_accum_inv	numeric_poly_stddev_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2726	n 0 int2_accum	numeric_poly_stddev_pop	-	-	-	int2_accum	int2_accum_inv	numeric_poly_stddev_pop	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2727	n 0 float4_accum	float8_stddev_pop	-	-	-	-				-				-					f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2728	n 0 float8_accum	float8_stddev_pop	-	-	-	-				-				-					f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2729	n 0 numeric_accum	numeric_stddev_pop	-	-	-	numeric_accum numeric_accum_inv numeric_stddev_pop	f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* stddev_samp */
-DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp			-	int8_accum	int8_accum_inv	numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2713	n 0 int4_accum	numeric_poly_stddev_samp	-	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2714	n 0 int2_accum	numeric_poly_stddev_samp	-	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp		-	-				-				-						f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp		-	numeric_accum numeric_accum_inv numeric_stddev_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2712	n 0 int8_accum	numeric_stddev_samp			-	-	-	int8_accum	int8_accum_inv	numeric_stddev_samp			f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2713	n 0 int4_accum	numeric_poly_stddev_samp	-	-	-	int4_accum	int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2714	n 0 int2_accum	numeric_poly_stddev_samp	-	-	-	int2_accum	int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2715	n 0 float4_accum	float8_stddev_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2716	n 0 float8_accum	float8_stddev_samp		-	-	-	-				-				-						f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2717	n 0 numeric_accum	numeric_stddev_samp		-	-	-	numeric_accum numeric_accum_inv numeric_stddev_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* stddev: historical Postgres syntax for stddev_samp */
-DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp			-	int8_accum		int8_accum_inv	numeric_stddev_samp			f f 0	2281	128 2281	128 _null_ _null_ ));
-DATA(insert ( 2155	n 0 int4_accum	numeric_poly_stddev_samp	-	int4_accum		int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2156	n 0 int2_accum	numeric_poly_stddev_samp	-	int2_accum		int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	48	2281	48	_null_ _null_ ));
-DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp		-	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp		-	-				-				-							f f 0	1022	0	0		0	"{0,0,0}" _null_ ));
-DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp		-	numeric_accum	numeric_accum_inv numeric_stddev_samp		f f 0	2281	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2154	n 0 int8_accum	numeric_stddev_samp			-	-	-	int8_accum		int8_accum_inv	numeric_stddev_samp			f f 0	2281	0	128 2281	128 _null_ _null_ ));
+DATA(insert ( 2155	n 0 int4_accum	numeric_poly_stddev_samp	-	-	-	int4_accum		int4_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2156	n 0 int2_accum	numeric_poly_stddev_samp	-	-	-	int2_accum		int2_accum_inv	numeric_poly_stddev_samp	f f 0	2281	0	48	2281	48	_null_ _null_ ));
+DATA(insert ( 2157	n 0 float4_accum	float8_stddev_samp		-	-	-	-				-				-							f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2158	n 0 float8_accum	float8_stddev_samp		-	-	-	-				-				-							f f 0	1022	0	0	0		0	"{0,0,0}" _null_ ));
+DATA(insert ( 2159	n 0 numeric_accum	numeric_stddev_samp		-	-	-	numeric_accum	numeric_accum_inv numeric_stddev_samp		f f 0	2281	0	128 2281	128 _null_ _null_ ));
 
 /* SQL2003 binary regression aggregates */
-DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-	-				-				-			f f 0	20		0	0		0	"0" _null_ ));
-DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
-DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-	-				-				-			f f 0	1022	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2818	n 0 int8inc_float8_float8	-					-	-	-	-				-				-			f f 0	20		0	0	0		0	"0" _null_ ));
+DATA(insert ( 2819	n 0 float8_regr_accum	float8_regr_sxx			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2820	n 0 float8_regr_accum	float8_regr_syy			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2821	n 0 float8_regr_accum	float8_regr_sxy			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2822	n 0 float8_regr_accum	float8_regr_avgx		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2823	n 0 float8_regr_accum	float8_regr_avgy		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2824	n 0 float8_regr_accum	float8_regr_r2			-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2825	n 0 float8_regr_accum	float8_regr_slope		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2826	n 0 float8_regr_accum	float8_regr_intercept	-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2827	n 0 float8_regr_accum	float8_covar_pop		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2828	n 0 float8_regr_accum	float8_covar_samp		-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
+DATA(insert ( 2829	n 0 float8_regr_accum	float8_corr				-	-	-	-				-				-			f f 0	1022	0	0	0		0	"{0,0,0,0,0,0}" _null_ ));
 
 /* boolean-and and boolean-or */
-DATA(insert ( 2517	n 0 booland_statefunc	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2518	n 0 boolor_statefunc	-	-	bool_accum	bool_accum_inv	bool_anytrue	f f 59	16		0	2281	16	_null_ _null_ ));
-DATA(insert ( 2519	n 0 booland_statefunc	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2517	n 0 booland_statefunc	-	-	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16	0		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2518	n 0 boolor_statefunc	-	-	-	-	bool_accum	bool_accum_inv	bool_anytrue	f f 59	16	0		0	2281	16	_null_ _null_ ));
+DATA(insert ( 2519	n 0 booland_statefunc	-	-	-	-	bool_accum	bool_accum_inv	bool_alltrue	f f 58	16	0		0	2281	16	_null_ _null_ ));
 
 /* bitwise integer */
-DATA(insert ( 2236	n 0 int2and		-				int2and	-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2237	n 0 int2or		-				int2or	-				-				-				f f 0	21		0	0		0	_null_ _null_ ));
-DATA(insert ( 2238	n 0 int4and		-				int4and	-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2239	n 0 int4or		-				int4or	-				-				-				f f 0	23		0	0		0	_null_ _null_ ));
-DATA(insert ( 2240	n 0 int8and		-				int8and	-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2241	n 0 int8or		-				int8or	-				-				-				f f 0	20		0	0		0	_null_ _null_ ));
-DATA(insert ( 2242	n 0 bitand		-				bitand	-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
-DATA(insert ( 2243	n 0 bitor		-				bitor	-				-				-				f f 0	1560	0	0		0	_null_ _null_ ));
+DATA(insert ( 2236	n 0 int2and		-				int2and	-	-	-				-				-				f f 0	21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2237	n 0 int2or		-				int2or	-	-	-				-				-				f f 0	21		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2238	n 0 int4and		-				int4and	-	-	-				-				-				f f 0	23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2239	n 0 int4or		-				int4or	-	-	-				-				-				f f 0	23		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2240	n 0 int8and		-				int8and	-	-	-				-				-				f f 0	20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2241	n 0 int8or		-				int8or	-	-	-				-				-				f f 0	20		0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2242	n 0 bitand		-				bitand	-	-	-				-				-				f f 0	1560	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 2243	n 0 bitor		-				bitor	-	-	-				-				-				f f 0	1560	0	0	0		0	_null_ _null_ ));
 
 /* xml */
-DATA(insert ( 2901	n 0 xmlconcat2	-				-		-				-				-				f f 0	142		0	0		0	_null_ _null_ ));
+DATA(insert ( 2901	n 0 xmlconcat2	-				-		-	-	-				-				-				f f 0	142		0	0	0		0	_null_ _null_ ));
 
 /* array */
-DATA(insert ( 2335	n 0 array_agg_transfn		array_agg_finalfn		-	-		-				-				t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn	-	-		-				-				t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 2335	n 0 array_agg_transfn		array_agg_finalfn		-	-	-	-		-				-				t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 4053	n 0 array_agg_array_transfn array_agg_array_finalfn	-	-	-	-		-				-				t f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* text */
-DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3538	n 0 string_agg_transfn	string_agg_finalfn	-	-	-	-				-				-				f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* bytea */
-DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-	-				-				-		f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3545	n 0 bytea_string_agg_transfn	bytea_string_agg_finalfn	-	-	-	-				-				-		f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* json */
-DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -	-				-				-				f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_finalfn			-	-	-	-				-				-				f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3197	n 0 json_object_agg_transfn json_object_agg_finalfn -	-	-	-				-				-				f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* jsonb */
-DATA(insert ( 3267	n 0 jsonb_agg_transfn	jsonb_agg_finalfn				-	-				-				-			f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3270	n 0 jsonb_object_agg_transfn jsonb_object_agg_finalfn	-	-				-				-			f f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3267	n 0 jsonb_agg_transfn	jsonb_agg_finalfn				-	-	-	-				-				-			f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3270	n 0 jsonb_object_agg_transfn jsonb_object_agg_finalfn	-	-	-	-				-				-			f f 0	2281	0	0	0		0	_null_ _null_ ));
 
 /* ordered-set and hypothetical-set aggregates */
-DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-	-		-		-		f f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
-DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-	-		-		-		t f 0	2281	0	0		0	_null_ _null_ ));
+DATA(insert ( 3972	o 1 ordered_set_transition			percentile_disc_final					-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3974	o 1 ordered_set_transition			percentile_cont_float8_final			-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3976	o 1 ordered_set_transition			percentile_cont_interval_final			-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3978	o 1 ordered_set_transition			percentile_disc_multi_final				-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3980	o 1 ordered_set_transition			percentile_cont_float8_multi_final		-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3982	o 1 ordered_set_transition			percentile_cont_interval_multi_final	-	-	-	-		-		-		f f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3984	o 0 ordered_set_transition			mode_final								-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3986	h 1 ordered_set_transition_multi	rank_final								-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3988	h 1 ordered_set_transition_multi	percent_rank_final						-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3990	h 1 ordered_set_transition_multi	cume_dist_final							-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
+DATA(insert ( 3992	h 1 ordered_set_transition_multi	dense_rank_final						-	-	-	-		-		-		t f 0	2281	0	0	0		0	_null_ _null_ ));
 
 
 /*
@@ -326,6 +335,8 @@ extern ObjectAddress AggregateCreate(const char *aggName,
 				List *aggtransfnName,
 				List *aggfinalfnName,
 				List *aggcombinefnName,
+				List *aggserialfnName,
+				List *aggdeserialfnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
@@ -333,6 +344,7 @@ extern ObjectAddress AggregateCreate(const char *aggName,
 				bool mfinalfnExtraArgs,
 				List *aggsortopName,
 				Oid aggTransType,
+				Oid aggSerialType,
 				int32 aggTransSpace,
 				Oid aggmTransType,
 				int32 aggmTransSpace,
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 244aa4d..4de1aea 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -2416,6 +2416,12 @@ DESCR("aggregate final function");
 DATA(insert OID = 1833 (  numeric_accum    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_accum _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
 DATA(insert OID = 2858 (  numeric_avg_accum    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_avg_accum _null_ _null_ _null_ ));
+DESCR("aggregate combine function");
+DATA(insert OID = 3318 (  numeric_avg_combine    PGNSP PGUID 12 1 0 0 0 f f f f t f i s 2 0 2281 "2281 2281" _null_ _null_ _null_ _null_ _null_ numeric_avg_combine _null_ _null_ _null_ ));
+DESCR("aggregate serial function");
+DATA(insert OID = 3319 (  numeric_avg_serialize    PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 25 "2281" _null_ _null_ _null_ _null_ _null_ numeric_avg_serialize _null_ _null_ _null_ ));
+DESCR("aggregate deserial function");
+DATA(insert OID = 3320 (  numeric_avg_deserialize    PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 2281 "25" _null_ _null_ _null_ _null_ _null_ numeric_avg_deserialize _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
 DATA(insert OID = 3548 (  numeric_accum_inv    PGNSP PGUID 12 1 0 0 0 f f f f f f i s 2 0 2281 "2281 1700" _null_ _null_ _null_ _null_ _null_ numeric_accum_inv _null_ _null_ _null_ ));
 DESCR("aggregate transition function");
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 07cd20a..69a1dad 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1853,6 +1853,7 @@ typedef struct AggState
 	bool		agg_done;		/* indicates completion of Agg scan */
 	bool		combineStates;	/* input tuples contain transition states */
 	bool		finalizeAggs;	/* should we call the finalfn on agg states? */
+	bool		serialStates;	/* should partial states be serialized? */
 	int			projected_set;	/* The last projected grouping set */
 	int			current_set;	/* The current grouping set being evaluated */
 	Bitmapset  *grouped_cols;	/* grouped cols in current projection */
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index e823c83..b5d0e56 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -728,6 +728,7 @@ typedef struct Agg
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
 	bool		combineStates;	/* input tuples contain transition states */
 	bool		finalizeAggs;	/* should we call the finalfn on agg states? */
+	bool		serialStates;	/* should partial states be serialized? */
 	Oid		   *grpOperators;	/* equality operators to compare with */
 	long		numGroups;		/* estimated number of groups in input */
 	List	   *groupingSets;	/* grouping sets to use */
diff --git a/src/include/optimizer/clauses.h b/src/include/optimizer/clauses.h
index 3b3fd0f..d381ff0 100644
--- a/src/include/optimizer/clauses.h
+++ b/src/include/optimizer/clauses.h
@@ -27,6 +27,25 @@ typedef struct
 	List	  **windowFuncs;	/* lists of WindowFuncs for each winref */
 } WindowFuncLists;
 
+/*
+ * PartialAggType
+ *	PartialAggType stores whether partial aggregation is allowed and
+ *	which context it is allowed in. We require three states here as there are
+ *	two different contexts in which partial aggregation is safe. For aggregates
+ *	which have an 'stype' of INTERNAL, within a single backend process it is
+ *	okay to pass a pointer to the aggregate state, as the memory to which the
+ *	pointer points to will belong to the same process. In cases where the
+ *	aggregate state must be passed between different processes, for example
+ *	during parallel aggregation, passing the pointer is not okay due to the
+ *	fact that the memory being referenced won't be accessible from another
+ *	process.
+ */
+typedef enum
+{
+	PAT_ANY = 0,		/* Any type of partial aggregation is ok. */
+	PAT_INTERNAL_ONLY,	/* Some aggregates support only internal mode. */
+	PAT_DISABLED		/* Some aggregates don't support partial mode at all */
+} PartialAggType;
 
 extern Expr *make_opclause(Oid opno, Oid opresulttype, bool opretset,
 			  Expr *leftop, Expr *rightop,
@@ -47,6 +66,7 @@ extern Node *make_and_qual(Node *qual1, Node *qual2);
 extern Expr *make_ands_explicit(List *andclauses);
 extern List *make_ands_implicit(Expr *clause);
 
+extern PartialAggType aggregates_allow_partial(Node *clause);
 extern bool contain_agg_clause(Node *clause);
 extern void count_agg_clauses(PlannerInfo *root, Node *clause,
 				  AggClauseCosts *costs);
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index 7ae7367..c1819f6 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -61,7 +61,7 @@ extern Agg *make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 AggStrategy aggstrategy, const AggClauseCosts *aggcosts,
 		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
 		 List *groupingSets, long numGroups, bool combineStates,
-		 bool finalizeAggs, Plan *lefttree);
+		 bool finalizeAggs, bool serialStates, Plan *lefttree);
 extern WindowAgg *make_windowagg(PlannerInfo *root, List *tlist,
 			   List *windowFuncs, Index winref,
 			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
diff --git a/src/include/parser/parse_agg.h b/src/include/parser/parse_agg.h
index 699b61c..43be714 100644
--- a/src/include/parser/parse_agg.h
+++ b/src/include/parser/parse_agg.h
@@ -51,6 +51,18 @@ extern void build_aggregate_combinefn_expr(Oid agg_state_type,
 										   Oid combinefn_oid,
 										   Expr **combinefnexpr);
 
+extern void build_aggregate_serialfn_expr(Oid agg_state_type,
+										  Oid agg_serial_type,
+										  Oid agg_input_collation,
+										  Oid serialfn_oid,
+										  Expr **serialfnexpr);
+
+extern void build_aggregate_deserialfn_expr(Oid agg_state_type,
+											Oid agg_serial_type,
+											Oid agg_input_collation,
+											Oid deserialfn_oid,
+											Expr **deserialfnexpr);
+
 extern void build_aggregate_finalfn_expr(Oid *agg_input_types,
 						int num_finalfn_inputs,
 						Oid agg_state_type,
diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h
index 477fde1..0c7bc55 100644
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@@ -1038,6 +1038,9 @@ extern Datum float4_numeric(PG_FUNCTION_ARGS);
 extern Datum numeric_float4(PG_FUNCTION_ARGS);
 extern Datum numeric_accum(PG_FUNCTION_ARGS);
 extern Datum numeric_avg_accum(PG_FUNCTION_ARGS);
+extern Datum numeric_avg_combine(PG_FUNCTION_ARGS);
+extern Datum numeric_avg_serialize(PG_FUNCTION_ARGS);
+extern Datum numeric_avg_deserialize(PG_FUNCTION_ARGS);
 extern Datum numeric_accum_inv(PG_FUNCTION_ARGS);
 extern Datum int2_accum(PG_FUNCTION_ARGS);
 extern Datum int4_accum(PG_FUNCTION_ARGS);
diff --git a/src/test/regress/expected/create_aggregate.out b/src/test/regress/expected/create_aggregate.out
index 66e073d..14f73c4 100644
--- a/src/test/regress/expected/create_aggregate.out
+++ b/src/test/regress/expected/create_aggregate.out
@@ -101,24 +101,93 @@ CREATE AGGREGATE sumdouble (float8)
     msfunc = float8pl,
     minvfunc = float8mi
 );
--- Test aggregate combine function
+-- aggregate combine and serialization functions
+-- Ensure stype and serialtype can't be the same
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = internal
+);
+ERROR:  aggregate serial data type cannot be "internal"
+-- if serialtype is specified we need a serialfunc and deserialfunc
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text
+);
+ERROR:  aggregate serialfunc must be specified when serialtype is specified
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize
+);
+ERROR:  aggregate deserialfunc must be specified when serialtype is specified
+-- serialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_deserialize,
+	deserialfunc = numeric_avg_deserialize
+);
+ERROR:  function numeric_avg_deserialize(internal) does not exist
+-- deserialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_serialize
+);
+ERROR:  function numeric_avg_serialize(text) does not exist
+-- ensure return type of serialfunc is checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = bytea,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize
+);
+ERROR:  return type of serial function numeric_avg_serialize is not bytea
+-- ensure combine function parameters are checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = int4larger
+);
+ERROR:  function int4larger(internal, internal) does not exist
 -- ensure create aggregate works.
-CREATE AGGREGATE mysum (int)
+CREATE AGGREGATE myavg (numeric)
 (
-	stype = int,
-	sfunc = int4pl,
-	combinefunc = int4pl
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	finalfunc = numeric_avg,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = numeric_avg_combine
 );
 -- Ensure all these functions made it into the catalog
-SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype
+SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype,aggserialfn,aggdeserialfn,aggserialtype
 FROM pg_aggregate
-WHERE aggfnoid = 'mysum'::REGPROC;
- aggfnoid | aggtransfn | aggcombinefn | aggtranstype 
-----------+------------+--------------+--------------
- mysum    | int4pl     | int4pl       |           23
+WHERE aggfnoid = 'myavg'::REGPROC;
+ aggfnoid |    aggtransfn     |    aggcombinefn     | aggtranstype |      aggserialfn      |      aggdeserialfn      | aggserialtype 
+----------+-------------------+---------------------+--------------+-----------------------+-------------------------+---------------
+ myavg    | numeric_avg_accum | numeric_avg_combine |         2281 | numeric_avg_serialize | numeric_avg_deserialize |            25
 (1 row)
 
-DROP AGGREGATE mysum (int);
+DROP AGGREGATE myavg (numeric);
 -- invalid: nonstrict inverse with strict forward function
 CREATE FUNCTION float8mi_n(float8, float8) RETURNS float8 AS
 $$ SELECT $1 - $2; $$
diff --git a/src/test/regress/sql/create_aggregate.sql b/src/test/regress/sql/create_aggregate.sql
index dfcbc5a..8395e5d 100644
--- a/src/test/regress/sql/create_aggregate.sql
+++ b/src/test/regress/sql/create_aggregate.sql
@@ -115,22 +115,91 @@ CREATE AGGREGATE sumdouble (float8)
     minvfunc = float8mi
 );
 
--- Test aggregate combine function
+-- aggregate combine and serialization functions
+
+-- Ensure stype and serialtype can't be the same
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = internal
+);
+
+-- if serialtype is specified we need a serialfunc and deserialfunc
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text
+);
+
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize
+);
+
+-- serialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_deserialize,
+	deserialfunc = numeric_avg_deserialize
+);
+
+-- deserialfunc must have correct parameters
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_serialize
+);
+
+-- ensure return type of serialfunc is checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = bytea,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize
+);
+
+-- ensure combine function parameters are checked
+CREATE AGGREGATE myavg (numeric)
+(
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = int4larger
+);
 
 -- ensure create aggregate works.
-CREATE AGGREGATE mysum (int)
+CREATE AGGREGATE myavg (numeric)
 (
-	stype = int,
-	sfunc = int4pl,
-	combinefunc = int4pl
+	stype = internal,
+	sfunc = numeric_avg_accum,
+	finalfunc = numeric_avg,
+	serialtype = text,
+	serialfunc = numeric_avg_serialize,
+	deserialfunc = numeric_avg_deserialize,
+	combinefunc = numeric_avg_combine
 );
 
 -- Ensure all these functions made it into the catalog
-SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype
+SELECT aggfnoid,aggtransfn,aggcombinefn,aggtranstype,aggserialfn,aggdeserialfn,aggserialtype
 FROM pg_aggregate
-WHERE aggfnoid = 'mysum'::REGPROC;
+WHERE aggfnoid = 'myavg'::REGPROC;
 
-DROP AGGREGATE mysum (int);
+DROP AGGREGATE myavg (numeric);
 
 -- invalid: nonstrict inverse with strict forward function
 

diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 9c6f885..0de578a 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -12454,8 +12454,8 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	{
 		appendPQExpBuffer(query, "SELECT aggtransfn, "
 						  "aggfinalfn, aggtranstype::pg_catalog.regtype, "
-						  "aggmtransfn, aggminvtransfn, aggmfinalfn, "
-						  "aggmtranstype::pg_catalog.regtype, "
+						  "'-' AS aggcombinefn, aggmtransfn, aggminvtransfn, "
+						  "aggmfinalfn, aggmtranstype::pg_catalog.regtype, "
 						  "aggfinalextra, aggmfinalextra, "
 						  "aggsortop::pg_catalog.regoperator, "
 						  "(aggkind = 'h') AS hypothetical, "
@@ -12473,9 +12473,10 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	{
 		appendPQExpBuffer(query, "SELECT aggtransfn, "
 						  "aggfinalfn, aggtranstype::pg_catalog.regtype, "
-						  "'-' AS aggmtransfn, '-' AS aggminvtransfn, "
-						  "'-' AS aggmfinalfn, 0 AS aggmtranstype, "
-						  "false AS aggfinalextra, false AS aggmfinalextra, "
+						  "'-' AS aggcombinefn, '-' AS aggmtransfn, "
+						  "'-' AS aggminvtransfn, '-' AS aggmfinalfn, "
+						  "0 AS aggmtranstype, false AS aggfinalextra, "
+						  "false AS aggmfinalextra, "
 						  "aggsortop::pg_catalog.regoperator, "
 						  "false AS hypothetical, "
 						  "0 AS aggtransspace, agginitval, "
@@ -12492,9 +12493,10 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	{
 		appendPQExpBuffer(query, "SELECT aggtransfn, "
 						  "aggfinalfn, aggtranstype::pg_catalog.regtype, "
-						  "'-' AS aggmtransfn, '-' AS aggminvtransfn, "
-						  "'-' AS aggmfinalfn, 0 AS aggmtranstype, "
-						  "false AS aggfinalextra, false AS aggmfinalextra, "
+						  "'-' AS aggcombinefn, '-' AS aggmtransfn, "
+						  "'-' AS aggminvtransfn, '-' AS aggmfinalfn, "
+						  "0 AS aggmtranstype, false AS aggfinalextra, "
+						  "false AS aggmfinalextra, "
 						  "aggsortop::pg_catalog.regoperator, "
 						  "false AS hypothetical, "
 						  "0 AS aggtransspace, agginitval, "
@@ -12509,10 +12511,10 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	{
 		appendPQExpBuffer(query, "SELECT aggtransfn, "
 						  "aggfinalfn, aggtranstype::pg_catalog.regtype, "
-						  "'-' AS aggmtransfn, '-' AS aggminvtransfn, "
-						  "'-' AS aggmfinalfn, 0 AS aggmtranstype, "
-						  "false AS aggfinalextra, false AS aggmfinalextra, "
-						  "0 AS aggsortop, "
+						  "'-' AS aggcombinefn, '-' AS aggmtransfn, "
+						  "'-' AS aggminvtransfn, '-' AS aggmfinalfn, "
+						  "0 AS aggmtranstype, false AS aggfinalextra, "
+						  "false AS aggmfinalextra, 0 AS aggsortop, "
 						  "false AS hypothetical, "
 						  "0 AS aggtransspace, agginitval, "
 						  "0 AS aggmtransspace, NULL AS aggminitval, "
@@ -12526,10 +12528,10 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	{
 		appendPQExpBuffer(query, "SELECT aggtransfn, aggfinalfn, "
 						  "format_type(aggtranstype, NULL) AS aggtranstype, "
-						  "'-' AS aggmtransfn, '-' AS aggminvtransfn, "
-						  "'-' AS aggmfinalfn, 0 AS aggmtranstype, "
-						  "false AS aggfinalextra, false AS aggmfinalextra, "
-						  "0 AS aggsortop, "
+						  "'-' AS aggcombinefn, '-' AS aggmtransfn, "
+						  "'-' AS aggminvtransfn, '-' AS aggmfinalfn, "
+						  "0 AS aggmtranstype, false AS aggfinalextra, "
+						  "false AS aggmfinalextra, 0 AS aggsortop, "
 						  "false AS hypothetical, "
 						  "0 AS aggtransspace, agginitval, "
 						  "0 AS aggmtransspace, NULL AS aggminitval, "
@@ -12543,10 +12545,10 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 		appendPQExpBuffer(query, "SELECT aggtransfn1 AS aggtransfn, "
 						  "aggfinalfn, "
 						  "(SELECT typname FROM pg_type WHERE oid = aggtranstype1) AS aggtranstype, "
-						  "'-' AS aggmtransfn, '-' AS aggminvtransfn, "
-						  "'-' AS aggmfinalfn, 0 AS aggmtranstype, "
-						  "false AS aggfinalextra, false AS aggmfinalextra, "
-						  "0 AS aggsortop, "
+						  "'-' AS aggcombinefn, '-' AS aggmtransfn, "
+						  "'-' AS aggminvtransfn, '-' AS aggmfinalfn, "
+						  "0 AS aggmtranstype, false AS aggfinalextra, "
+						  "false AS aggmfinalextra, 0 AS aggsortop, "
 						  "false AS hypothetical, "
 						  "0 AS aggtransspace, agginitval1 AS agginitval, "
 						  "0 AS aggmtransspace, NULL AS aggminitval, "