Hi.

Updated and rebased patch.

Ilya Gladyshev писал 2021-11-02 00:31:
Hi,
On 21.10.2021 13:55, Alexander Pyhalov wrote:

Hi. Updated patch.
Now aggregates with internal states can be pushed down, if they are
marked as pushdown safe (this flag is set to true for min/max/sum),
have internal states and associated converters.

I don't quite understand why this is restricted only to aggregates
that have 'internal' state, I feel like that should be possible for
any aggregate that has a function to convert its final result back to
aggregate state to be pushed down. While I couldn't come up with a
useful example for this, except maybe for an aggregate whose
aggfinalfn is used purely for cosmetic purposes (e.g. format the
result into a string), I still feel that it is an unnecessary
restriction.


I don't feel comfortable with it for the following reasons.
- Now partial converters translate aggregate result to serialized internal representation.
In case when aggregate type is different from internal state,
we'd have to translate it to non-serialized internal representation,
so converters should skip serialization step. This seems like introducing two
kind of converters.
- I don't see any system aggregates which would benefit from this.

However, it doesn't seem to be complex, and if it seems to be desirable,
it can be done.
For now introduced check that transtype matches aggregate type (or is internal)
in partial_agg_ok().


A few minor review notes to the patch:

+static List *build_conv_list(RelOptInfo *foreignrel);

this should probably be up top among other declarations.


Moved it upper.


@@ -1433,6 +1453,48 @@ postgresGetForeignPlan(PlannerInfo *root,
                             outer_plan);
 }

+/*
+ * Generate attinmeta if there are some converters:
+ * they are expecxted to return BYTEA, but real input type is likely
different.
+ */

typo in word "expecxted".

Fixed.


@@ -139,10 +147,13 @@ typedef struct PgFdwScanState
                                  * for a foreign join scan. */
     TupleDesc    tupdesc;        /* tuple descriptor of scan */
     AttInMetadata *attinmeta;    /* attribute datatype conversion
metadata */
+    AttInMetadata *rcvd_attinmeta;    /* metadata for received
tuples, NULL if
+                                     * there's no converters */

Looks like rcvd_attinmeta is redundant and you could use attinmeta for
conversion metadata.

Seems so, removed it.

--
Best regards,
Alexander Pyhalov,
Postgres Professional
From 71de85154f9ac78e99f4ce8bf9aa341fee748609 Mon Sep 17 00:00:00 2001
From: Alexander Pyhalov <a.pyha...@postgrespro.ru>
Date: Thu, 14 Oct 2021 17:30:34 +0300
Subject: [PATCH] Partial aggregates push down

---
 contrib/postgres_fdw/deparse.c                |  57 ++++-
 .../postgres_fdw/expected/postgres_fdw.out    | 185 ++++++++++++++++-
 contrib/postgres_fdw/postgres_fdw.c           | 196 +++++++++++++++++-
 contrib/postgres_fdw/sql/postgres_fdw.sql     |  27 ++-
 src/backend/catalog/pg_aggregate.c            |  28 ++-
 src/backend/commands/aggregatecmds.c          |  23 +-
 src/backend/utils/adt/numeric.c               |  96 +++++++++
 src/bin/pg_dump/pg_dump.c                     |  21 +-
 src/include/catalog/catversion.h              |   2 +-
 src/include/catalog/pg_aggregate.dat          | 106 +++++-----
 src/include/catalog/pg_aggregate.h            |  10 +-
 src/include/catalog/pg_proc.dat               |   6 +
 src/test/regress/expected/oidjoins.out        |   1 +
 13 files changed, 674 insertions(+), 84 deletions(-)

diff --git a/contrib/postgres_fdw/deparse.c b/contrib/postgres_fdw/deparse.c
index d98bd666818..8cee12c1b2a 100644
--- a/contrib/postgres_fdw/deparse.c
+++ b/contrib/postgres_fdw/deparse.c
@@ -196,6 +196,7 @@ static bool is_subquery_var(Var *node, RelOptInfo *foreignrel,
 static void get_relation_column_alias_ids(Var *node, RelOptInfo *foreignrel,
 										  int *relno, int *colno);
 
+static bool partial_agg_ok(Aggref *agg);
 
 /*
  * Examine each qual clause in input_conds, and classify them into two groups,
@@ -831,8 +832,10 @@ foreign_expr_walker(Node *node,
 				if (!IS_UPPER_REL(glob_cxt->foreignrel))
 					return false;
 
-				/* Only non-split aggregates are pushable. */
-				if (agg->aggsplit != AGGSPLIT_SIMPLE)
+				if ((agg->aggsplit != AGGSPLIT_SIMPLE) && (agg->aggsplit != AGGSPLIT_INITIAL_SERIAL))
+					return false;
+
+				if (agg->aggsplit == AGGSPLIT_INITIAL_SERIAL && !partial_agg_ok(agg))
 					return false;
 
 				/* As usual, it must be shippable. */
@@ -3249,7 +3252,7 @@ deparseAggref(Aggref *node, deparse_expr_cxt *context)
 	bool		use_variadic;
 
 	/* Only basic, non-split aggregation accepted. */
-	Assert(node->aggsplit == AGGSPLIT_SIMPLE);
+	Assert(node->aggsplit == AGGSPLIT_SIMPLE || node->aggsplit == AGGSPLIT_INITIAL_SERIAL);
 
 	/* Check if need to print VARIADIC (cf. ruleutils.c) */
 	use_variadic = node->aggvariadic;
@@ -3719,3 +3722,51 @@ get_relation_column_alias_ids(Var *node, RelOptInfo *foreignrel,
 	/* Shouldn't get here */
 	elog(ERROR, "unexpected expression in subquery output");
 }
+
+/*
+ * Check that partial aggregate agg is fine to push down
+ */
+static bool
+partial_agg_ok(Aggref *agg)
+{
+	HeapTuple	aggtup;
+	Form_pg_aggregate aggform;
+
+	Assert(agg->aggsplit == AGGSPLIT_INITIAL_SERIAL);
+
+	/* We don't support complex partial aggregates */
+	if (agg->aggdistinct || agg->aggvariadic || agg->aggkind != AGGKIND_NORMAL || agg->aggorder != NIL)
+		return false;
+
+	aggtup = SearchSysCache1(AGGFNOID, ObjectIdGetDatum(agg->aggfnoid));
+	if (!HeapTupleIsValid(aggtup))
+		elog(ERROR, "cache lookup failed for function %u", agg->aggfnoid);
+	aggform = (Form_pg_aggregate) GETSTRUCT(aggtup);
+
+	/* Only aggregates, marked as pushdown safe, are allowed */
+	if (!aggform->aggpartialpushdownsafe)
+	{
+		ReleaseSysCache(aggtup);
+		return false;
+	}
+
+	/*
+	 * If an aggregate requires serialization/deserialization, partial
+	 * converter should be defined
+	 */
+	if (agg->aggtranstype == INTERNALOID && aggform->aggpartialconverterfn == InvalidOid)
+	{
+		ReleaseSysCache(aggtup);
+		return false;
+	}
+
+	/* In this case we currently don't use converter */
+	if (agg->aggtranstype != INTERNALOID && get_func_rettype(agg->aggfnoid) != agg->aggtranstype)
+	{
+		ReleaseSysCache(aggtup);
+		return false;
+	}
+
+	ReleaseSysCache(aggtup);
+	return true;
+}
diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index fd141a0fa5c..80c507783e6 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -9279,13 +9279,13 @@ RESET enable_partitionwise_join;
 -- ===================================================================
 -- test partitionwise aggregates
 -- ===================================================================
-CREATE TABLE pagg_tab (a int, b int, c text) PARTITION BY RANGE(a);
+CREATE TABLE pagg_tab (a int, b int, c text, d numeric) PARTITION BY RANGE(a);
 CREATE TABLE pagg_tab_p1 (LIKE pagg_tab);
 CREATE TABLE pagg_tab_p2 (LIKE pagg_tab);
 CREATE TABLE pagg_tab_p3 (LIKE pagg_tab);
-INSERT INTO pagg_tab_p1 SELECT i % 30, i % 50, to_char(i/30, 'FM0000') FROM generate_series(1, 3000) i WHERE (i % 30) < 10;
-INSERT INTO pagg_tab_p2 SELECT i % 30, i % 50, to_char(i/30, 'FM0000') FROM generate_series(1, 3000) i WHERE (i % 30) < 20 and (i % 30) >= 10;
-INSERT INTO pagg_tab_p3 SELECT i % 30, i % 50, to_char(i/30, 'FM0000') FROM generate_series(1, 3000) i WHERE (i % 30) < 30 and (i % 30) >= 20;
+INSERT INTO pagg_tab_p1 SELECT i % 30, i % 50, to_char(i/30, 'FM0000'), i % 40 FROM generate_series(1, 3000) i WHERE (i % 30) < 10;
+INSERT INTO pagg_tab_p2 SELECT i % 30, i % 50, to_char(i/30, 'FM0000'), i % 40 FROM generate_series(1, 3000) i WHERE (i % 30) < 20 and (i % 30) >= 10;
+INSERT INTO pagg_tab_p3 SELECT i % 30, i % 50, to_char(i/30, 'FM0000'), i % 40 FROM generate_series(1, 3000) i WHERE (i % 30) < 30 and (i % 30) >= 20;
 -- Create foreign partitions
 CREATE FOREIGN TABLE fpagg_tab_p1 PARTITION OF pagg_tab FOR VALUES FROM (0) TO (10) SERVER loopback OPTIONS (table_name 'pagg_tab_p1');
 CREATE FOREIGN TABLE fpagg_tab_p2 PARTITION OF pagg_tab FOR VALUES FROM (10) TO (20) SERVER loopback OPTIONS (table_name 'pagg_tab_p2');
@@ -9344,8 +9344,8 @@ SELECT a, sum(b), min(b), count(*) FROM pagg_tab GROUP BY a HAVING avg(b) < 22 O
 -- Should have all the columns in the target list for the given relation
 EXPLAIN (VERBOSE, COSTS OFF)
 SELECT a, count(t1) FROM pagg_tab t1 GROUP BY a HAVING avg(b) < 22 ORDER BY 1;
-                               QUERY PLAN                               
-------------------------------------------------------------------------
+                                QUERY PLAN                                 
+---------------------------------------------------------------------------
  Sort
    Output: t1.a, (count(((t1.*)::pagg_tab)))
    Sort Key: t1.a
@@ -9356,21 +9356,21 @@ SELECT a, count(t1) FROM pagg_tab t1 GROUP BY a HAVING avg(b) < 22 ORDER BY 1;
                Filter: (avg(t1.b) < '22'::numeric)
                ->  Foreign Scan on public.fpagg_tab_p1 t1
                      Output: t1.a, t1.*, t1.b
-                     Remote SQL: SELECT a, b, c FROM public.pagg_tab_p1
+                     Remote SQL: SELECT a, b, c, d FROM public.pagg_tab_p1
          ->  HashAggregate
                Output: t1_1.a, count(((t1_1.*)::pagg_tab))
                Group Key: t1_1.a
                Filter: (avg(t1_1.b) < '22'::numeric)
                ->  Foreign Scan on public.fpagg_tab_p2 t1_1
                      Output: t1_1.a, t1_1.*, t1_1.b
-                     Remote SQL: SELECT a, b, c FROM public.pagg_tab_p2
+                     Remote SQL: SELECT a, b, c, d FROM public.pagg_tab_p2
          ->  HashAggregate
                Output: t1_2.a, count(((t1_2.*)::pagg_tab))
                Group Key: t1_2.a
                Filter: (avg(t1_2.b) < '22'::numeric)
                ->  Foreign Scan on public.fpagg_tab_p3 t1_2
                      Output: t1_2.a, t1_2.*, t1_2.b
-                     Remote SQL: SELECT a, b, c FROM public.pagg_tab_p3
+                     Remote SQL: SELECT a, b, c, d FROM public.pagg_tab_p3
 (25 rows)
 
 SELECT a, count(t1) FROM pagg_tab t1 GROUP BY a HAVING avg(b) < 22 ORDER BY 1;
@@ -9406,6 +9406,173 @@ SELECT b, avg(a), max(a), count(*) FROM pagg_tab GROUP BY b HAVING sum(a) < 700
                      ->  Foreign Scan on fpagg_tab_p3 pagg_tab_2
 (15 rows)
 
+-- It's unsafe to push down having clause when there are partial aggregates
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT b, max(a), count(*) FROM pagg_tab GROUP BY b HAVING sum(a) < 700 ORDER BY 1;
+                                                    QUERY PLAN                                                    
+------------------------------------------------------------------------------------------------------------------
+ Sort
+   Output: pagg_tab.b, (max(pagg_tab.a)), (count(*))
+   Sort Key: pagg_tab.b
+   ->  Finalize HashAggregate
+         Output: pagg_tab.b, max(pagg_tab.a), count(*)
+         Group Key: pagg_tab.b
+         Filter: (sum(pagg_tab.a) < 700)
+         ->  Append
+               ->  Partial HashAggregate
+                     Output: pagg_tab.b, PARTIAL max(pagg_tab.a), PARTIAL count(*), PARTIAL sum(pagg_tab.a)
+                     Group Key: pagg_tab.b
+                     ->  Foreign Scan on public.fpagg_tab_p1 pagg_tab
+                           Output: pagg_tab.b, pagg_tab.a
+                           Remote SQL: SELECT a, b FROM public.pagg_tab_p1
+               ->  Partial HashAggregate
+                     Output: pagg_tab_1.b, PARTIAL max(pagg_tab_1.a), PARTIAL count(*), PARTIAL sum(pagg_tab_1.a)
+                     Group Key: pagg_tab_1.b
+                     ->  Foreign Scan on public.fpagg_tab_p2 pagg_tab_1
+                           Output: pagg_tab_1.b, pagg_tab_1.a
+                           Remote SQL: SELECT a, b FROM public.pagg_tab_p2
+               ->  Partial HashAggregate
+                     Output: pagg_tab_2.b, PARTIAL max(pagg_tab_2.a), PARTIAL count(*), PARTIAL sum(pagg_tab_2.a)
+                     Group Key: pagg_tab_2.b
+                     ->  Foreign Scan on public.fpagg_tab_p3 pagg_tab_2
+                           Output: pagg_tab_2.b, pagg_tab_2.a
+                           Remote SQL: SELECT a, b FROM public.pagg_tab_p3
+(26 rows)
+
+-- Partial aggregates are fine to push down without having clause
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT b, max(a), count(*) FROM pagg_tab GROUP BY b ORDER BY 1;
+                                          QUERY PLAN                                           
+-----------------------------------------------------------------------------------------------
+ Sort
+   Output: pagg_tab.b, (max(pagg_tab.a)), (count(*))
+   Sort Key: pagg_tab.b
+   ->  Finalize HashAggregate
+         Output: pagg_tab.b, max(pagg_tab.a), count(*)
+         Group Key: pagg_tab.b
+         ->  Append
+               ->  Foreign Scan
+                     Output: pagg_tab.b, (PARTIAL max(pagg_tab.a)), (PARTIAL count(*))
+                     Relations: Aggregate on (public.fpagg_tab_p1 pagg_tab)
+                     Remote SQL: SELECT b, max(a), count(*) FROM public.pagg_tab_p1 GROUP BY 1
+               ->  Foreign Scan
+                     Output: pagg_tab_1.b, (PARTIAL max(pagg_tab_1.a)), (PARTIAL count(*))
+                     Relations: Aggregate on (public.fpagg_tab_p2 pagg_tab_1)
+                     Remote SQL: SELECT b, max(a), count(*) FROM public.pagg_tab_p2 GROUP BY 1
+               ->  Foreign Scan
+                     Output: pagg_tab_2.b, (PARTIAL max(pagg_tab_2.a)), (PARTIAL count(*))
+                     Relations: Aggregate on (public.fpagg_tab_p3 pagg_tab_2)
+                     Remote SQL: SELECT b, max(a), count(*) FROM public.pagg_tab_p3 GROUP BY 1
+(19 rows)
+
+SELECT b, max(a), count(*) FROM pagg_tab GROUP BY b ORDER BY 1;
+ b  | max | count 
+----+-----+-------
+  0 |  20 |    60
+  1 |  21 |    60
+  2 |  22 |    60
+  3 |  23 |    60
+  4 |  24 |    60
+  5 |  25 |    60
+  6 |  26 |    60
+  7 |  27 |    60
+  8 |  28 |    60
+  9 |  29 |    60
+ 10 |  20 |    60
+ 11 |  21 |    60
+ 12 |  22 |    60
+ 13 |  23 |    60
+ 14 |  24 |    60
+ 15 |  25 |    60
+ 16 |  26 |    60
+ 17 |  27 |    60
+ 18 |  28 |    60
+ 19 |  29 |    60
+ 20 |  20 |    60
+ 21 |  21 |    60
+ 22 |  22 |    60
+ 23 |  23 |    60
+ 24 |  24 |    60
+ 25 |  25 |    60
+ 26 |  26 |    60
+ 27 |  27 |    60
+ 28 |  28 |    60
+ 29 |  29 |    60
+ 30 |  20 |    60
+ 31 |  21 |    60
+ 32 |  22 |    60
+ 33 |  23 |    60
+ 34 |  24 |    60
+ 35 |  25 |    60
+ 36 |  26 |    60
+ 37 |  27 |    60
+ 38 |  28 |    60
+ 39 |  29 |    60
+ 40 |  20 |    60
+ 41 |  21 |    60
+ 42 |  22 |    60
+ 43 |  23 |    60
+ 44 |  24 |    60
+ 45 |  25 |    60
+ 46 |  26 |    60
+ 47 |  27 |    60
+ 48 |  28 |    60
+ 49 |  29 |    60
+(50 rows)
+
+-- Partial aggregates are fine to push down
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT max(a), count(*), sum(d) FROM pagg_tab;
+                                             QUERY PLAN                                             
+----------------------------------------------------------------------------------------------------
+ Finalize Aggregate
+   Output: max(pagg_tab.a), count(*), sum(pagg_tab.d)
+   ->  Append
+         ->  Foreign Scan
+               Output: (PARTIAL max(pagg_tab.a)), (PARTIAL count(*)), (PARTIAL sum(pagg_tab.d))
+               Relations: Aggregate on (public.fpagg_tab_p1 pagg_tab)
+               Remote SQL: SELECT max(a), count(*), sum(d) FROM public.pagg_tab_p1
+         ->  Foreign Scan
+               Output: (PARTIAL max(pagg_tab_1.a)), (PARTIAL count(*)), (PARTIAL sum(pagg_tab_1.d))
+               Relations: Aggregate on (public.fpagg_tab_p2 pagg_tab_1)
+               Remote SQL: SELECT max(a), count(*), sum(d) FROM public.pagg_tab_p2
+         ->  Foreign Scan
+               Output: (PARTIAL max(pagg_tab_2.a)), (PARTIAL count(*)), (PARTIAL sum(pagg_tab_2.d))
+               Relations: Aggregate on (public.fpagg_tab_p3 pagg_tab_2)
+               Remote SQL: SELECT max(a), count(*), sum(d) FROM public.pagg_tab_p3
+(15 rows)
+
+SELECT max(a), count(*), sum(d) FROM pagg_tab;
+ max | count |  sum  
+-----+-------+-------
+  29 |  3000 | 58500
+(1 row)
+
+-- Shouldn't try to push down
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT max(a), count(distinct b) FROM pagg_tab;
+                          QUERY PLAN                           
+---------------------------------------------------------------
+ Aggregate
+   Output: max(pagg_tab.a), count(DISTINCT pagg_tab.b)
+   ->  Append
+         ->  Foreign Scan on public.fpagg_tab_p1 pagg_tab_1
+               Output: pagg_tab_1.a, pagg_tab_1.b
+               Remote SQL: SELECT a, b FROM public.pagg_tab_p1
+         ->  Foreign Scan on public.fpagg_tab_p2 pagg_tab_2
+               Output: pagg_tab_2.a, pagg_tab_2.b
+               Remote SQL: SELECT a, b FROM public.pagg_tab_p2
+         ->  Foreign Scan on public.fpagg_tab_p3 pagg_tab_3
+               Output: pagg_tab_3.a, pagg_tab_3.b
+               Remote SQL: SELECT a, b FROM public.pagg_tab_p3
+(12 rows)
+
+SELECT max(a), count(distinct b) FROM pagg_tab;
+ max | count 
+-----+-------
+  29 |    50
+(1 row)
+
 -- ===================================================================
 -- access rights and superuser
 -- ===================================================================
diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index 45a09337d08..bad03c49e49 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -18,6 +18,8 @@
 #include "access/sysattr.h"
 #include "access/table.h"
 #include "catalog/pg_class.h"
+#include "catalog/pg_aggregate.h"
+#include "catalog/pg_proc.h"
 #include "commands/defrem.h"
 #include "commands/explain.h"
 #include "commands/vacuum.h"
@@ -48,6 +50,7 @@
 #include "utils/rel.h"
 #include "utils/sampling.h"
 #include "utils/selfuncs.h"
+#include "utils/syscache.h"
 
 PG_MODULE_MAGIC;
 
@@ -80,7 +83,12 @@ enum FdwScanPrivateIndex
 	 * String describing join i.e. names of relations being joined and types
 	 * of join, added when the scan is join
 	 */
-	FdwScanPrivateRelations
+	FdwScanPrivateRelations,
+
+	/*
+	 * List of functions to convert partial aggregate result
+	 */
+	FdwScanPrivateConvertors
 };
 
 /*
@@ -143,6 +151,7 @@ typedef struct PgFdwScanState
 	/* extracted fdw_private data */
 	char	   *query;			/* text of SELECT command */
 	List	   *retrieved_attrs;	/* list of retrieved attribute numbers */
+	List	   *conv_list;		/* list of converters */
 
 	/* for remote query execution */
 	PGconn	   *conn;			/* connection for the scan */
@@ -474,6 +483,7 @@ static void store_returning_result(PgFdwModifyState *fmstate,
 								   TupleTableSlot *slot, PGresult *res);
 static void finish_foreign_modify(PgFdwModifyState *fmstate);
 static void deallocate_query(PgFdwModifyState *fmstate);
+static List *build_conv_list(RelOptInfo *foreignrel);
 static List *build_remote_returning(Index rtindex, Relation rel,
 									List *returningList);
 static void rebuild_fdw_scan_tlist(ForeignScan *fscan, List *tlist);
@@ -510,6 +520,7 @@ static HeapTuple make_tuple_from_result_row(PGresult *res,
 											Relation rel,
 											AttInMetadata *attinmeta,
 											List *retrieved_attrs,
+											List *conv_list,
 											ForeignScanState *fsstate,
 											MemoryContext temp_context);
 static void conversion_error_callback(void *arg);
@@ -517,7 +528,7 @@ static bool foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel,
 							JoinType jointype, RelOptInfo *outerrel, RelOptInfo *innerrel,
 							JoinPathExtraData *extra);
 static bool foreign_grouping_ok(PlannerInfo *root, RelOptInfo *grouped_rel,
-								Node *havingQual);
+								Node *havingQual, bool partial);
 static List *get_useful_pathkeys_for_relation(PlannerInfo *root,
 											  RelOptInfo *rel);
 static List *get_useful_ecs_for_relation(PlannerInfo *root, RelOptInfo *rel);
@@ -526,7 +537,8 @@ static void add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
 static void add_foreign_grouping_paths(PlannerInfo *root,
 									   RelOptInfo *input_rel,
 									   RelOptInfo *grouped_rel,
-									   GroupPathExtraData *extra);
+									   GroupPathExtraData *extra,
+									   bool partial);
 static void add_foreign_ordered_paths(PlannerInfo *root,
 									  RelOptInfo *input_rel,
 									  RelOptInfo *ordered_rel);
@@ -541,7 +553,6 @@ static void merge_fdw_options(PgFdwRelationInfo *fpinfo,
 							  const PgFdwRelationInfo *fpinfo_i);
 static int	get_batch_size_option(Relation rel);
 
-
 /*
  * Foreign-data wrapper handler function: return a struct with pointers
  * to my callback routines.
@@ -1233,6 +1244,7 @@ postgresGetForeignPlan(PlannerInfo *root,
 	List	   *local_exprs = NIL;
 	List	   *params_list = NIL;
 	List	   *fdw_scan_tlist = NIL;
+	List	   *fdw_conv_list = NIL;
 	List	   *fdw_recheck_quals = NIL;
 	List	   *retrieved_attrs;
 	StringInfoData sql;
@@ -1336,6 +1348,9 @@ postgresGetForeignPlan(PlannerInfo *root,
 		/* Build the list of columns to be fetched from the foreign server. */
 		fdw_scan_tlist = build_tlist_to_deparse(foreignrel);
 
+		/* Build the list of converters for partial aggregates. */
+		fdw_conv_list = build_conv_list(foreignrel);
+
 		/*
 		 * Ensure that the outer plan produces a tuple whose descriptor
 		 * matches our scan tuple slot.  Also, remove the local conditions
@@ -1415,6 +1430,8 @@ postgresGetForeignPlan(PlannerInfo *root,
 	if (IS_JOIN_REL(foreignrel) || IS_UPPER_REL(foreignrel))
 		fdw_private = lappend(fdw_private,
 							  makeString(fpinfo->relation_name));
+	if (IS_UPPER_REL(foreignrel))
+		fdw_private = lappend(fdw_private, fdw_conv_list);
 
 	/*
 	 * Create the ForeignScan node for the given relation.
@@ -1433,6 +1450,48 @@ postgresGetForeignPlan(PlannerInfo *root,
 							outer_plan);
 }
 
+/*
+ * Generate attinmeta if there are some converters:
+ * they are expected to return BYTEA, but real input type is likely different.
+ */
+static AttInMetadata *
+get_rcvd_attinmeta(TupleDesc tupdesc, List *conv_list)
+{
+	TupleDesc	rcvd_tupdesc;
+
+	Assert(conv_list != NIL);
+
+	rcvd_tupdesc = CreateTupleDescCopy(tupdesc);
+	for (int i = 0; i < rcvd_tupdesc->natts; i++)
+	{
+		Oid			converter = InvalidOid;
+		Form_pg_attribute att = TupleDescAttr(rcvd_tupdesc, i);
+
+		converter = list_nth_oid(conv_list, i);
+		if (converter != InvalidOid)
+		{
+			HeapTuple	proctup;
+			Form_pg_proc procform;
+
+			proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(converter));
+
+			if (!HeapTupleIsValid(proctup))
+				elog(ERROR, "cache lookup failed for function %u", converter);
+
+			procform = (Form_pg_proc) GETSTRUCT(proctup);
+
+			if (procform->pronargs != 1)
+				elog(ERROR, "converter %s is expected to have one argument", NameStr(procform->proname));
+
+			att->atttypid = procform->proargtypes.values[0];
+
+			ReleaseSysCache(proctup);
+		}
+	}
+
+	return TupleDescGetAttInMetadata(rcvd_tupdesc);
+}
+
 /*
  * Construct a tuple descriptor for the scan tuples handled by a foreign join.
  */
@@ -1545,6 +1604,12 @@ postgresBeginForeignScan(ForeignScanState *node, int eflags)
 									 FdwScanPrivateSelectSql));
 	fsstate->retrieved_attrs = (List *) list_nth(fsplan->fdw_private,
 												 FdwScanPrivateRetrievedAttrs);
+
+	if (list_length(fsplan->fdw_private) > FdwScanPrivateConvertors)
+		fsstate->conv_list = (List *) list_nth(fsplan->fdw_private,
+											   FdwScanPrivateConvertors);
+
+
 	fsstate->fetch_size = intVal(list_nth(fsplan->fdw_private,
 										  FdwScanPrivateFetchSize));
 
@@ -1571,7 +1636,10 @@ postgresBeginForeignScan(ForeignScanState *node, int eflags)
 		fsstate->tupdesc = get_tupdesc_for_join_scan_tuples(node);
 	}
 
-	fsstate->attinmeta = TupleDescGetAttInMetadata(fsstate->tupdesc);
+	if (fsstate->conv_list != NIL)
+		fsstate->attinmeta = get_rcvd_attinmeta(fsstate->tupdesc, fsstate->conv_list);
+	else
+		fsstate->attinmeta = TupleDescGetAttInMetadata(fsstate->tupdesc);
 
 	/*
 	 * Prepare for processing of parameters used in remote query, if any.
@@ -3822,6 +3890,7 @@ fetch_more_data(ForeignScanState *node)
 										   fsstate->rel,
 										   fsstate->attinmeta,
 										   fsstate->retrieved_attrs,
+										   fsstate->conv_list,
 										   node,
 										   fsstate->temp_cxt);
 		}
@@ -4309,6 +4378,7 @@ store_returning_result(PgFdwModifyState *fmstate,
 											fmstate->rel,
 											fmstate->attinmeta,
 											fmstate->retrieved_attrs,
+											NIL,
 											NULL,
 											fmstate->temp_cxt);
 
@@ -4603,6 +4673,7 @@ get_returning_data(ForeignScanState *node)
 												dmstate->rel,
 												dmstate->attinmeta,
 												dmstate->retrieved_attrs,
+												NIL,
 												node,
 												dmstate->temp_cxt);
 			ExecStoreHeapTuple(newtup, slot, false);
@@ -5183,6 +5254,7 @@ analyze_row_processor(PGresult *res, int row, PgFdwAnalyzeState *astate)
 													   astate->rel,
 													   astate->attinmeta,
 													   astate->retrieved_attrs,
+													   NIL,
 													   NULL,
 													   astate->temp_cxt);
 
@@ -6083,7 +6155,7 @@ postgresGetForeignJoinPaths(PlannerInfo *root,
  */
 static bool
 foreign_grouping_ok(PlannerInfo *root, RelOptInfo *grouped_rel,
-					Node *havingQual)
+					Node *havingQual, bool partial)
 {
 	Query	   *query = root->parse;
 	PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) grouped_rel->fdw_private;
@@ -6097,6 +6169,11 @@ foreign_grouping_ok(PlannerInfo *root, RelOptInfo *grouped_rel,
 	if (query->groupingSets)
 		return false;
 
+
+	/* It's unsafe to push having statements with partial aggregates */
+	if (partial && havingQual)
+		return false;
+
 	/* Get the fpinfo of the underlying scan relation. */
 	ofpinfo = (PgFdwRelationInfo *) fpinfo->outerrel->fdw_private;
 
@@ -6336,6 +6413,7 @@ postgresGetForeignUpperPaths(PlannerInfo *root, UpperRelationKind stage,
 
 	/* Ignore stages we don't support; and skip any duplicate calls. */
 	if ((stage != UPPERREL_GROUP_AGG &&
+		 stage != UPPERREL_PARTIAL_GROUP_AGG &&
 		 stage != UPPERREL_ORDERED &&
 		 stage != UPPERREL_FINAL) ||
 		output_rel->fdw_private)
@@ -6350,7 +6428,11 @@ postgresGetForeignUpperPaths(PlannerInfo *root, UpperRelationKind stage,
 	{
 		case UPPERREL_GROUP_AGG:
 			add_foreign_grouping_paths(root, input_rel, output_rel,
-									   (GroupPathExtraData *) extra);
+									   (GroupPathExtraData *) extra, false);
+			break;
+		case UPPERREL_PARTIAL_GROUP_AGG:
+			add_foreign_grouping_paths(root, input_rel, output_rel,
+									   (GroupPathExtraData *) extra, true);
 			break;
 		case UPPERREL_ORDERED:
 			add_foreign_ordered_paths(root, input_rel, output_rel);
@@ -6375,7 +6457,8 @@ postgresGetForeignUpperPaths(PlannerInfo *root, UpperRelationKind stage,
 static void
 add_foreign_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel,
 						   RelOptInfo *grouped_rel,
-						   GroupPathExtraData *extra)
+						   GroupPathExtraData *extra,
+						   bool partial)
 {
 	Query	   *parse = root->parse;
 	PgFdwRelationInfo *ifpinfo = input_rel->fdw_private;
@@ -6391,8 +6474,9 @@ add_foreign_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel,
 		!root->hasHavingQual)
 		return;
 
-	Assert(extra->patype == PARTITIONWISE_AGGREGATE_NONE ||
-		   extra->patype == PARTITIONWISE_AGGREGATE_FULL);
+	Assert(((extra->patype == PARTITIONWISE_AGGREGATE_NONE ||
+			 extra->patype == PARTITIONWISE_AGGREGATE_FULL) && !partial) ||
+		   (extra->patype == PARTITIONWISE_AGGREGATE_PARTIAL && partial));
 
 	/* save the input_rel as outerrel in fpinfo */
 	fpinfo->outerrel = input_rel;
@@ -6412,7 +6496,7 @@ add_foreign_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel,
 	 * Use HAVING qual from extra. In case of child partition, it will have
 	 * translated Vars.
 	 */
-	if (!foreign_grouping_ok(root, grouped_rel, extra->havingQual))
+	if (!foreign_grouping_ok(root, grouped_rel, extra->havingQual, partial))
 		return;
 
 	/*
@@ -7108,6 +7192,30 @@ complete_pending_request(AsyncRequest *areq)
 							  TupIsNull(areq->result) ? 0.0 : 1.0);
 }
 
+/*
+ * Interface to fmgr to call converters
+ */
+static Datum
+call_converter(Oid converter, Oid collation, Datum value, bool isnull, bool *res_isnull)
+{
+	LOCAL_FCINFO(fcinfo, 1);
+	FmgrInfo	flinfo;
+	Datum		result;
+
+	fmgr_info(converter, &flinfo);
+
+	InitFunctionCallInfoData(*fcinfo, &flinfo, 1, collation, NULL, NULL);
+
+	fcinfo->args[0].value = value;
+	fcinfo->args[0].isnull = isnull;
+
+	result = FunctionCallInvoke(fcinfo);
+
+	if (res_isnull)
+		*res_isnull = fcinfo->isnull;
+	return result;
+}
+
 /*
  * Create a tuple from the specified row of the PGresult.
  *
@@ -7127,6 +7235,7 @@ make_tuple_from_result_row(PGresult *res,
 						   Relation rel,
 						   AttInMetadata *attinmeta,
 						   List *retrieved_attrs,
+						   List *conv_list,
 						   ForeignScanState *fsstate,
 						   MemoryContext temp_context)
 {
@@ -7209,6 +7318,20 @@ make_tuple_from_result_row(PGresult *res,
 											  valstr,
 											  attinmeta->attioparams[i - 1],
 											  attinmeta->atttypmods[i - 1]);
+			if (conv_list != NIL)
+			{
+				Oid			converter = list_nth_oid(conv_list, i - 1);
+
+				if (converter != InvalidOid)
+				{
+					Form_pg_attribute att = TupleDescAttr(tupdesc, i);
+					bool		res_isnull;
+
+					values[i - 1] = call_converter(converter, att->attcollation, values[i - 1], nulls[i - 1], &res_isnull);
+
+					nulls[i - 1] = res_isnull;
+				}
+			}
 		}
 		else if (i == SelfItemPointerAttributeNumber)
 		{
@@ -7472,3 +7595,54 @@ get_batch_size_option(Relation rel)
 
 	return batch_size;
 }
+
+/*
+ * For UPPER_REL build a list of converters, corresponding to tlist entries.
+ */
+static List *
+build_conv_list(RelOptInfo *foreignrel)
+{
+	List	   *conv_list = NIL;
+	PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
+	ListCell   *lc;
+
+	if (IS_UPPER_REL(foreignrel))
+	{
+		/* For UPPER_REL tlist matches grouped_tlist */
+		foreach(lc, fpinfo->grouped_tlist)
+		{
+			TargetEntry *tlentry = (TargetEntry *) lfirst(lc);
+			Oid			converter_oid = InvalidOid;
+
+			if (IsA(tlentry->expr, Aggref))
+			{
+				Aggref	   *agg = (Aggref *) tlentry->expr;
+
+				if (agg->aggsplit == AGGSPLIT_INITIAL_SERIAL && agg->aggtranstype == INTERNALOID)
+				{
+					HeapTuple	aggtup;
+					Form_pg_aggregate aggform;
+
+					aggtup = SearchSysCache1(AGGFNOID, ObjectIdGetDatum(agg->aggfnoid));
+					if (!HeapTupleIsValid(aggtup))
+						elog(ERROR, "cache lookup failed for function %u", agg->aggfnoid);
+
+					aggform = (Form_pg_aggregate) GETSTRUCT(aggtup);
+
+					converter_oid = aggform->aggpartialconverterfn;
+					Assert(converter_oid != InvalidOid);
+
+					ReleaseSysCache(aggtup);
+				}
+			}
+
+			/*
+			 * We append InvalidOid to conv_list to preserve one-to-one
+			 * mapping between tlist and conv_list members.
+			 */
+			conv_list = lappend_oid(conv_list, converter_oid);
+		}
+	}
+
+	return conv_list;
+}
diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index 43c30d492da..a9771a9cc57 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -2729,15 +2729,15 @@ RESET enable_partitionwise_join;
 -- test partitionwise aggregates
 -- ===================================================================
 
-CREATE TABLE pagg_tab (a int, b int, c text) PARTITION BY RANGE(a);
+CREATE TABLE pagg_tab (a int, b int, c text, d numeric) PARTITION BY RANGE(a);
 
 CREATE TABLE pagg_tab_p1 (LIKE pagg_tab);
 CREATE TABLE pagg_tab_p2 (LIKE pagg_tab);
 CREATE TABLE pagg_tab_p3 (LIKE pagg_tab);
 
-INSERT INTO pagg_tab_p1 SELECT i % 30, i % 50, to_char(i/30, 'FM0000') FROM generate_series(1, 3000) i WHERE (i % 30) < 10;
-INSERT INTO pagg_tab_p2 SELECT i % 30, i % 50, to_char(i/30, 'FM0000') FROM generate_series(1, 3000) i WHERE (i % 30) < 20 and (i % 30) >= 10;
-INSERT INTO pagg_tab_p3 SELECT i % 30, i % 50, to_char(i/30, 'FM0000') FROM generate_series(1, 3000) i WHERE (i % 30) < 30 and (i % 30) >= 20;
+INSERT INTO pagg_tab_p1 SELECT i % 30, i % 50, to_char(i/30, 'FM0000'), i % 40 FROM generate_series(1, 3000) i WHERE (i % 30) < 10;
+INSERT INTO pagg_tab_p2 SELECT i % 30, i % 50, to_char(i/30, 'FM0000'), i % 40 FROM generate_series(1, 3000) i WHERE (i % 30) < 20 and (i % 30) >= 10;
+INSERT INTO pagg_tab_p3 SELECT i % 30, i % 50, to_char(i/30, 'FM0000'), i % 40 FROM generate_series(1, 3000) i WHERE (i % 30) < 30 and (i % 30) >= 20;
 
 -- Create foreign partitions
 CREATE FOREIGN TABLE fpagg_tab_p1 PARTITION OF pagg_tab FOR VALUES FROM (0) TO (10) SERVER loopback OPTIONS (table_name 'pagg_tab_p1');
@@ -2771,6 +2771,25 @@ SELECT a, count(t1) FROM pagg_tab t1 GROUP BY a HAVING avg(b) < 22 ORDER BY 1;
 EXPLAIN (COSTS OFF)
 SELECT b, avg(a), max(a), count(*) FROM pagg_tab GROUP BY b HAVING sum(a) < 700 ORDER BY 1;
 
+-- It's unsafe to push down having clause when there are partial aggregates
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT b, max(a), count(*) FROM pagg_tab GROUP BY b HAVING sum(a) < 700 ORDER BY 1;
+
+-- Partial aggregates are fine to push down without having clause
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT b, max(a), count(*) FROM pagg_tab GROUP BY b ORDER BY 1;
+SELECT b, max(a), count(*) FROM pagg_tab GROUP BY b ORDER BY 1;
+
+-- Partial aggregates are fine to push down
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT max(a), count(*), sum(d) FROM pagg_tab;
+SELECT max(a), count(*), sum(d) FROM pagg_tab;
+
+-- Shouldn't try to push down
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT max(a), count(distinct b) FROM pagg_tab;
+SELECT max(a), count(distinct b) FROM pagg_tab;
+
 -- ===================================================================
 -- access rights and superuser
 -- ===================================================================
diff --git a/src/backend/catalog/pg_aggregate.c b/src/backend/catalog/pg_aggregate.c
index 1f63d8081b2..639ea4cf9a6 100644
--- a/src/backend/catalog/pg_aggregate.c
+++ b/src/backend/catalog/pg_aggregate.c
@@ -60,6 +60,7 @@ AggregateCreate(const char *aggName,
 				List *aggcombinefnName,
 				List *aggserialfnName,
 				List *aggdeserialfnName,
+				List *aggpartialconverterfnName,
 				List *aggmtransfnName,
 				List *aggminvtransfnName,
 				List *aggmfinalfnName,
@@ -74,7 +75,8 @@ AggregateCreate(const char *aggName,
 				int32 aggmTransSpace,
 				const char *agginitval,
 				const char *aggminitval,
-				char proparallel)
+				char proparallel,
+				bool partialPushdownSafe)
 {
 	Relation	aggdesc;
 	HeapTuple	tup;
@@ -88,6 +90,7 @@ AggregateCreate(const char *aggName,
 	Oid			combinefn = InvalidOid; /* can be omitted */
 	Oid			serialfn = InvalidOid;	/* can be omitted */
 	Oid			deserialfn = InvalidOid;	/* can be omitted */
+	Oid			partialconverterfn = InvalidOid;	/* can be omitted */
 	Oid			mtransfn = InvalidOid;	/* can be omitted */
 	Oid			minvtransfn = InvalidOid;	/* can be omitted */
 	Oid			mfinalfn = InvalidOid;	/* can be omitted */
@@ -569,6 +572,27 @@ AggregateCreate(const char *aggName,
 							format_type_be(finaltype))));
 	}
 
+	/*
+	 * Validate the partial converter, if present.
+	 */
+	if (aggpartialconverterfnName)
+	{
+		fnArgs[0] = finaltype;
+
+		partialconverterfn = lookup_agg_function(aggpartialconverterfnName, 1,
+											  fnArgs, InvalidOid,
+											  &rettype);
+
+		if (rettype != BYTEAOID)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("return type of partial serialization function %s is not %s",
+							NameListToString(aggserialfnName),
+							format_type_be(BYTEAOID))));
+
+	}
+
+
 	/* handle sortop, if supplied */
 	if (aggsortopName)
 	{
@@ -664,6 +688,7 @@ AggregateCreate(const char *aggName,
 	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_aggpartialconverterfn - 1] = ObjectIdGetDatum(partialconverterfn);
 	values[Anum_pg_aggregate_aggmtransfn - 1] = ObjectIdGetDatum(mtransfn);
 	values[Anum_pg_aggregate_aggminvtransfn - 1] = ObjectIdGetDatum(minvtransfn);
 	values[Anum_pg_aggregate_aggmfinalfn - 1] = ObjectIdGetDatum(mfinalfn);
@@ -676,6 +701,7 @@ AggregateCreate(const char *aggName,
 	values[Anum_pg_aggregate_aggtransspace - 1] = Int32GetDatum(aggTransSpace);
 	values[Anum_pg_aggregate_aggmtranstype - 1] = ObjectIdGetDatum(aggmTransType);
 	values[Anum_pg_aggregate_aggmtransspace - 1] = Int32GetDatum(aggmTransSpace);
+	values[Anum_pg_aggregate_aggpartialpushdownsafe - 1] = BoolGetDatum(partialPushdownSafe);
 	if (agginitval)
 		values[Anum_pg_aggregate_agginitval - 1] = CStringGetTextDatum(agginitval);
 	else
diff --git a/src/backend/commands/aggregatecmds.c b/src/backend/commands/aggregatecmds.c
index 046cf2df08f..3b7c1597315 100644
--- a/src/backend/commands/aggregatecmds.c
+++ b/src/backend/commands/aggregatecmds.c
@@ -69,11 +69,13 @@ DefineAggregate(ParseState *pstate,
 	List	   *combinefuncName = NIL;
 	List	   *serialfuncName = NIL;
 	List	   *deserialfuncName = NIL;
+	List	   *partialconverterfuncName = NIL;
 	List	   *mtransfuncName = NIL;
 	List	   *minvtransfuncName = NIL;
 	List	   *mfinalfuncName = NIL;
 	bool		finalfuncExtraArgs = false;
 	bool		mfinalfuncExtraArgs = false;
+	bool		partialPushdownSafe = false;
 	char		finalfuncModify = 0;
 	char		mfinalfuncModify = 0;
 	List	   *sortoperatorName = NIL;
@@ -142,6 +144,8 @@ DefineAggregate(ParseState *pstate,
 			serialfuncName = defGetQualifiedName(defel);
 		else if (strcmp(defel->defname, "deserialfunc") == 0)
 			deserialfuncName = defGetQualifiedName(defel);
+		else if (strcmp(defel->defname, "partialconverterfunc") == 0)
+			partialconverterfuncName = defGetQualifiedName(defel);
 		else if (strcmp(defel->defname, "msfunc") == 0)
 			mtransfuncName = defGetQualifiedName(defel);
 		else if (strcmp(defel->defname, "minvfunc") == 0)
@@ -189,6 +193,8 @@ DefineAggregate(ParseState *pstate,
 			minitval = defGetString(defel);
 		else if (strcmp(defel->defname, "parallel") == 0)
 			parallel = defGetString(defel);
+		else if (strcmp(defel->defname, "partial_pushdown_safe") == 0)
+			partialPushdownSafe = defGetBoolean(defel);
 		else
 			ereport(WARNING,
 					(errcode(ERRCODE_SYNTAX_ERROR),
@@ -372,6 +378,18 @@ DefineAggregate(ParseState *pstate,
 				 errmsg("must specify both or neither of serialization and deserialization functions")));
 	}
 
+	if (partialconverterfuncName)
+	{
+		/*
+		 * Converter is only needed/allowed for transtype INTERNAL.
+		 */
+		if (transTypeId != INTERNALOID)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("partial converters may be specified only when the aggregate transition data type is %s",
+							format_type_be(INTERNALOID))));
+	}
+
 	/*
 	 * If a moving-aggregate transtype is specified, look that up.  Same
 	 * restrictions as for transtype.
@@ -457,6 +475,8 @@ DefineAggregate(ParseState *pstate,
 						   combinefuncName, /* combine function name */
 						   serialfuncName,	/* serial function name */
 						   deserialfuncName,	/* deserial function name */
+						   partialconverterfuncName,	/* partial converter function
+													 * name */
 						   mtransfuncName,	/* fwd trans function name */
 						   minvtransfuncName,	/* inv trans function name */
 						   mfinalfuncName,	/* final function name */
@@ -471,7 +491,8 @@ DefineAggregate(ParseState *pstate,
 						   mtransSpace, /* transition space */
 						   initval, /* initial condition */
 						   minitval,	/* initial condition */
-						   proparallel);	/* parallel safe? */
+						   proparallel, /* parallel safe? */
+						   partialPushdownSafe);	/* partial pushdown safe? */
 }
 
 /*
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index 1de744855f3..e26e3e2de41 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -5770,6 +5770,52 @@ int8_avg_deserialize(PG_FUNCTION_ARGS)
 	PG_RETURN_POINTER(result);
 }
 
+/*
+ * int8_sum_to_internal_serialize
+ *		Convert int8 argument to serialized internal representation
+ */
+Datum
+int8_sum_to_internal_serialize(PG_FUNCTION_ARGS)
+{
+	PolyNumAggState *state = NULL;
+	StringInfoData buf;
+	bytea	   *result;
+	NumericVar	tmp_var;
+
+	state = (Int128AggState *) palloc0(sizeof(Int128AggState));
+	state->calcSumX2 = false;
+
+	if (!PG_ARGISNULL(0))
+	{
+#ifdef HAVE_INT128
+		do_int128_accum(state, (int128) PG_GETARG_INT64(0));
+#else
+		do_numeric_accum(state, int64_to_numeric(PG_GETARG_INT64(0)));
+#endif
+	}
+
+	init_var(&tmp_var);
+
+	pq_begintypsend(&buf);
+
+	/* N */
+	pq_sendint64(&buf, state->N);
+
+	/* sumX */
+#ifdef HAVE_INT128
+	int128_to_numericvar(state->sumX, &tmp_var);
+#else
+	accum_sum_final(&state->sumX, &tmp_var);
+#endif
+	numericvar_serialize(&buf, &tmp_var);
+
+	result = pq_endtypsend(&buf);
+
+	free_var(&tmp_var);
+
+	PG_RETURN_BYTEA_P(result);
+}
+
 /*
  * Inverse transition functions to go with the above.
  */
@@ -5995,6 +6041,56 @@ numeric_sum(PG_FUNCTION_ARGS)
 	PG_RETURN_NUMERIC(result);
 }
 
+/*
+ * numeric_sum_to_internal_serialize
+ *		Convert numeric argument to serialized internal representation
+ */
+Datum
+numeric_sum_to_internal_serialize(PG_FUNCTION_ARGS)
+{
+	NumericAggState *state = NULL;
+	StringInfoData buf;
+	bytea	   *result;
+	NumericVar	tmp_var;
+
+	state = makeNumericAggStateCurrentContext(false);
+
+	if (!PG_ARGISNULL(0))
+		do_numeric_accum(state, PG_GETARG_NUMERIC(0));
+
+	init_var(&tmp_var);
+
+	pq_begintypsend(&buf);
+
+	/* N */
+	pq_sendint64(&buf, state->N);
+
+	/* sumX */
+	accum_sum_final(&state->sumX, &tmp_var);
+	numericvar_serialize(&buf, &tmp_var);
+
+	/* maxScale */
+	pq_sendint32(&buf, state->maxScale);
+
+	/* maxScaleCount */
+	pq_sendint64(&buf, state->maxScaleCount);
+
+	/* NaNcount */
+	pq_sendint64(&buf, state->NaNcount);
+
+	/* pInfcount */
+	pq_sendint64(&buf, state->pInfcount);
+
+	/* nInfcount */
+	pq_sendint64(&buf, state->nInfcount);
+
+	result = pq_endtypsend(&buf);
+
+	free_var(&tmp_var);
+
+	PG_RETURN_BYTEA_P(result);
+}
+
 /*
  * Workhorse routine for the standard deviance and variance
  * aggregates. 'state' is aggregate's transition state.
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index b9635a95b6f..5d9509ace0e 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -14076,11 +14076,13 @@ dumpAgg(Archive *fout, const AggInfo *agginfo)
 	const char *aggcombinefn;
 	const char *aggserialfn;
 	const char *aggdeserialfn;
+	const char *aggpartialconverterfn;
 	const char *aggmtransfn;
 	const char *aggminvtransfn;
 	const char *aggmfinalfn;
 	bool		aggfinalextra;
 	bool		aggmfinalextra;
+	bool		aggpartialpushdownsafe;
 	char		aggfinalmodify;
 	char		aggmfinalmodify;
 	const char *aggsortop;
@@ -14165,11 +14167,19 @@ dumpAgg(Archive *fout, const AggInfo *agginfo)
 	if (fout->remoteVersion >= 110000)
 		appendPQExpBufferStr(query,
 							 "aggfinalmodify,\n"
-							 "aggmfinalmodify\n");
+							 "aggmfinalmodify,\n");
 	else
 		appendPQExpBufferStr(query,
 							 "'0' AS aggfinalmodify,\n"
-							 "'0' AS aggmfinalmodify\n");
+							 "'0' AS aggmfinalmodify,\n");
+	if (fout->remoteVersion >= 150000)
+		appendPQExpBufferStr(query,
+							 "aggpartialconverterfn,\n"
+							 "aggpartialpushdownsafe\n");
+	else
+		appendPQExpBufferStr(query,
+							 "'-' AS aggpartialconverterfn,\n"
+							 "false as aggpartialpushdownsafe\n");
 
 	appendPQExpBuffer(query,
 					  "FROM pg_catalog.pg_aggregate a, pg_catalog.pg_proc p "
@@ -14187,6 +14197,8 @@ dumpAgg(Archive *fout, const AggInfo *agginfo)
 	aggcombinefn = PQgetvalue(res, 0, PQfnumber(res, "aggcombinefn"));
 	aggserialfn = PQgetvalue(res, 0, PQfnumber(res, "aggserialfn"));
 	aggdeserialfn = PQgetvalue(res, 0, PQfnumber(res, "aggdeserialfn"));
+	aggpartialconverterfn = PQgetvalue(res, 0, PQfnumber(res, "aggpartialconverterfn"));
+	aggpartialpushdownsafe = (PQgetvalue(res, 0, PQfnumber(res, "aggpartialpushdownsafe"))[0] == 't');
 	aggmtransfn = PQgetvalue(res, 0, PQfnumber(res, "aggmtransfn"));
 	aggminvtransfn = PQgetvalue(res, 0, PQfnumber(res, "aggminvtransfn"));
 	aggmfinalfn = PQgetvalue(res, 0, PQfnumber(res, "aggmfinalfn"));
@@ -14281,6 +14293,11 @@ dumpAgg(Archive *fout, const AggInfo *agginfo)
 	if (strcmp(aggdeserialfn, "-") != 0)
 		appendPQExpBuffer(details, ",\n    DESERIALFUNC = %s", aggdeserialfn);
 
+	if (strcmp(aggpartialconverterfn, "-") != 0)
+		appendPQExpBuffer(details, ",\n    PARTIALCONVERTERFUNC = %s", aggpartialconverterfn);
+	if (aggpartialpushdownsafe)
+		appendPQExpBufferStr(details, ",\n    PARTIAL_PUSHDOWN_SAFE");
+
 	if (strcmp(aggmtransfn, "-") != 0)
 	{
 		appendPQExpBuffer(details, ",\n    MSFUNC = %s,\n    MINVFUNC = %s,\n    MSTYPE = %s",
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 9faf017457a..35c399e77dd 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202110272
+#define CATALOG_VERSION_NO	202111021
 
 #endif
diff --git a/src/include/catalog/pg_aggregate.dat b/src/include/catalog/pg_aggregate.dat
index fc6d3bfd945..61c4d812b34 100644
--- a/src/include/catalog/pg_aggregate.dat
+++ b/src/include/catalog/pg_aggregate.dat
@@ -56,26 +56,27 @@
   aggserialfn => 'int8_avg_serialize', aggdeserialfn => 'int8_avg_deserialize',
   aggmtransfn => 'int8_avg_accum', aggminvtransfn => 'int8_avg_accum_inv',
   aggmfinalfn => 'numeric_poly_sum', aggtranstype => 'internal',
-  aggtransspace => '48', aggmtranstype => 'internal', aggmtransspace => '48' },
+  aggtransspace => '48', aggmtranstype => 'internal', aggmtransspace => '48',
+  aggpartialconverterfn => 'int8_sum_to_internal_serialize', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'sum(int4)', aggtransfn => 'int4_sum', aggcombinefn => 'int8pl',
   aggmtransfn => 'int4_avg_accum', aggminvtransfn => 'int4_avg_accum_inv',
   aggmfinalfn => 'int2int4_sum', aggtranstype => 'int8',
-  aggmtranstype => '_int8', aggminitval => '{0,0}' },
+  aggmtranstype => '_int8', aggminitval => '{0,0}', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'sum(int2)', aggtransfn => 'int2_sum', aggcombinefn => 'int8pl',
   aggmtransfn => 'int2_avg_accum', aggminvtransfn => 'int2_avg_accum_inv',
   aggmfinalfn => 'int2int4_sum', aggtranstype => 'int8',
-  aggmtranstype => '_int8', aggminitval => '{0,0}' },
+  aggmtranstype => '_int8', aggminitval => '{0,0}', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'sum(float4)', aggtransfn => 'float4pl',
-  aggcombinefn => 'float4pl', aggtranstype => 'float4' },
+  aggcombinefn => 'float4pl', aggtranstype => 'float4', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'sum(float8)', aggtransfn => 'float8pl',
-  aggcombinefn => 'float8pl', aggtranstype => 'float8' },
+  aggcombinefn => 'float8pl', aggtranstype => 'float8', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'sum(money)', aggtransfn => 'cash_pl', aggcombinefn => 'cash_pl',
   aggmtransfn => 'cash_pl', aggminvtransfn => 'cash_mi',
-  aggtranstype => 'money', aggmtranstype => 'money' },
+  aggtranstype => 'money', aggmtranstype => 'money', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'sum(interval)', aggtransfn => 'interval_pl',
   aggcombinefn => 'interval_pl', aggmtransfn => 'interval_pl',
   aggminvtransfn => 'interval_mi', aggtranstype => 'interval',
-  aggmtranstype => 'interval' },
+  aggmtranstype => 'interval', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'sum(numeric)', aggtransfn => 'numeric_avg_accum',
   aggfinalfn => 'numeric_sum', aggcombinefn => 'numeric_avg_combine',
   aggserialfn => 'numeric_avg_serialize',
@@ -83,146 +84,149 @@
   aggmtransfn => 'numeric_avg_accum', aggminvtransfn => 'numeric_accum_inv',
   aggmfinalfn => 'numeric_sum', aggtranstype => 'internal',
   aggtransspace => '128', aggmtranstype => 'internal',
-  aggmtransspace => '128' },
+  aggmtransspace => '128', aggpartialconverterfn => 'numeric_sum_to_internal_serialize', aggpartialpushdownsafe => 't' },
 
 # max
 { aggfnoid => 'max(int8)', aggtransfn => 'int8larger',
   aggcombinefn => 'int8larger', aggsortop => '>(int8,int8)',
-  aggtranstype => 'int8' },
+  aggtranstype => 'int8', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(int4)', aggtransfn => 'int4larger',
   aggcombinefn => 'int4larger', aggsortop => '>(int4,int4)',
-  aggtranstype => 'int4' },
+  aggtranstype => 'int4', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(int2)', aggtransfn => 'int2larger',
   aggcombinefn => 'int2larger', aggsortop => '>(int2,int2)',
-  aggtranstype => 'int2' },
+  aggtranstype => 'int2', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(oid)', aggtransfn => 'oidlarger',
   aggcombinefn => 'oidlarger', aggsortop => '>(oid,oid)',
-  aggtranstype => 'oid' },
+  aggtranstype => 'oid', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(float4)', aggtransfn => 'float4larger',
   aggcombinefn => 'float4larger', aggsortop => '>(float4,float4)',
-  aggtranstype => 'float4' },
+  aggtranstype => 'float4', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(float8)', aggtransfn => 'float8larger',
   aggcombinefn => 'float8larger', aggsortop => '>(float8,float8)',
-  aggtranstype => 'float8' },
+  aggtranstype => 'float8', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(date)', aggtransfn => 'date_larger',
   aggcombinefn => 'date_larger', aggsortop => '>(date,date)',
-  aggtranstype => 'date' },
+  aggtranstype => 'date', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(time)', aggtransfn => 'time_larger',
   aggcombinefn => 'time_larger', aggsortop => '>(time,time)',
-  aggtranstype => 'time' },
+  aggtranstype => 'time', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(timetz)', aggtransfn => 'timetz_larger',
   aggcombinefn => 'timetz_larger', aggsortop => '>(timetz,timetz)',
-  aggtranstype => 'timetz' },
+  aggtranstype => 'timetz', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(money)', aggtransfn => 'cashlarger',
   aggcombinefn => 'cashlarger', aggsortop => '>(money,money)',
-  aggtranstype => 'money' },
+  aggtranstype => 'money', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(timestamp)', aggtransfn => 'timestamp_larger',
   aggcombinefn => 'timestamp_larger', aggsortop => '>(timestamp,timestamp)',
-  aggtranstype => 'timestamp' },
+  aggtranstype => 'timestamp', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(timestamptz)', aggtransfn => 'timestamptz_larger',
   aggcombinefn => 'timestamptz_larger',
   aggsortop => '>(timestamptz,timestamptz)', aggtranstype => 'timestamptz' },
 { aggfnoid => 'max(interval)', aggtransfn => 'interval_larger',
   aggcombinefn => 'interval_larger', aggsortop => '>(interval,interval)',
-  aggtranstype => 'interval' },
+  aggtranstype => 'interval', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(text)', aggtransfn => 'text_larger',
   aggcombinefn => 'text_larger', aggsortop => '>(text,text)',
-  aggtranstype => 'text' },
+  aggtranstype => 'text', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(numeric)', aggtransfn => 'numeric_larger',
   aggcombinefn => 'numeric_larger', aggsortop => '>(numeric,numeric)',
-  aggtranstype => 'numeric' },
+  aggtranstype => 'numeric', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(anyarray)', aggtransfn => 'array_larger',
   aggcombinefn => 'array_larger', aggsortop => '>(anyarray,anyarray)',
-  aggtranstype => 'anyarray' },
+  aggtranstype => 'anyarray', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(bpchar)', aggtransfn => 'bpchar_larger',
   aggcombinefn => 'bpchar_larger', aggsortop => '>(bpchar,bpchar)',
-  aggtranstype => 'bpchar' },
+  aggtranstype => 'bpchar', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(tid)', aggtransfn => 'tidlarger',
   aggcombinefn => 'tidlarger', aggsortop => '>(tid,tid)',
-  aggtranstype => 'tid' },
+  aggtranstype => 'tid', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(anyenum)', aggtransfn => 'enum_larger',
   aggcombinefn => 'enum_larger', aggsortop => '>(anyenum,anyenum)',
-  aggtranstype => 'anyenum' },
+  aggtranstype => 'anyenum', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(inet)', aggtransfn => 'network_larger',
   aggcombinefn => 'network_larger', aggsortop => '>(inet,inet)',
-  aggtranstype => 'inet' },
+  aggtranstype => 'inet', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'max(pg_lsn)', aggtransfn => 'pg_lsn_larger',
   aggcombinefn => 'pg_lsn_larger', aggsortop => '>(pg_lsn,pg_lsn)',
-  aggtranstype => 'pg_lsn' },
+  aggtranstype => 'pg_lsn', aggpartialpushdownsafe => 't' },
 
 # min
 { aggfnoid => 'min(int8)', aggtransfn => 'int8smaller',
   aggcombinefn => 'int8smaller', aggsortop => '<(int8,int8)',
-  aggtranstype => 'int8' },
+  aggtranstype => 'int8', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(int4)', aggtransfn => 'int4smaller',
   aggcombinefn => 'int4smaller', aggsortop => '<(int4,int4)',
-  aggtranstype => 'int4' },
+  aggtranstype => 'int4', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(int2)', aggtransfn => 'int2smaller',
   aggcombinefn => 'int2smaller', aggsortop => '<(int2,int2)',
-  aggtranstype => 'int2' },
+  aggtranstype => 'int2', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(oid)', aggtransfn => 'oidsmaller',
   aggcombinefn => 'oidsmaller', aggsortop => '<(oid,oid)',
-  aggtranstype => 'oid' },
+  aggtranstype => 'oid', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(float4)', aggtransfn => 'float4smaller',
   aggcombinefn => 'float4smaller', aggsortop => '<(float4,float4)',
-  aggtranstype => 'float4' },
+  aggtranstype => 'float4', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(float8)', aggtransfn => 'float8smaller',
   aggcombinefn => 'float8smaller', aggsortop => '<(float8,float8)',
-  aggtranstype => 'float8' },
+  aggtranstype => 'float8', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(date)', aggtransfn => 'date_smaller',
   aggcombinefn => 'date_smaller', aggsortop => '<(date,date)',
-  aggtranstype => 'date' },
+  aggtranstype => 'date', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(time)', aggtransfn => 'time_smaller',
   aggcombinefn => 'time_smaller', aggsortop => '<(time,time)',
-  aggtranstype => 'time' },
+  aggtranstype => 'time', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(timetz)', aggtransfn => 'timetz_smaller',
   aggcombinefn => 'timetz_smaller', aggsortop => '<(timetz,timetz)',
-  aggtranstype => 'timetz' },
+  aggtranstype => 'timetz', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(money)', aggtransfn => 'cashsmaller',
   aggcombinefn => 'cashsmaller', aggsortop => '<(money,money)',
-  aggtranstype => 'money' },
+  aggtranstype => 'money', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(timestamp)', aggtransfn => 'timestamp_smaller',
   aggcombinefn => 'timestamp_smaller', aggsortop => '<(timestamp,timestamp)',
-  aggtranstype => 'timestamp' },
+  aggtranstype => 'timestamp', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(timestamptz)', aggtransfn => 'timestamptz_smaller',
   aggcombinefn => 'timestamptz_smaller',
-  aggsortop => '<(timestamptz,timestamptz)', aggtranstype => 'timestamptz' },
+  aggsortop => '<(timestamptz,timestamptz)', aggtranstype => 'timestamptz',
+  aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(interval)', aggtransfn => 'interval_smaller',
   aggcombinefn => 'interval_smaller', aggsortop => '<(interval,interval)',
-  aggtranstype => 'interval' },
+  aggtranstype => 'interval', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(text)', aggtransfn => 'text_smaller',
   aggcombinefn => 'text_smaller', aggsortop => '<(text,text)',
-  aggtranstype => 'text' },
+  aggtranstype => 'text', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(numeric)', aggtransfn => 'numeric_smaller',
   aggcombinefn => 'numeric_smaller', aggsortop => '<(numeric,numeric)',
-  aggtranstype => 'numeric' },
+  aggtranstype => 'numeric', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(anyarray)', aggtransfn => 'array_smaller',
   aggcombinefn => 'array_smaller', aggsortop => '<(anyarray,anyarray)',
-  aggtranstype => 'anyarray' },
+  aggtranstype => 'anyarray', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(bpchar)', aggtransfn => 'bpchar_smaller',
   aggcombinefn => 'bpchar_smaller', aggsortop => '<(bpchar,bpchar)',
-  aggtranstype => 'bpchar' },
+  aggtranstype => 'bpchar', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(tid)', aggtransfn => 'tidsmaller',
   aggcombinefn => 'tidsmaller', aggsortop => '<(tid,tid)',
-  aggtranstype => 'tid' },
+  aggtranstype => 'tid', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(anyenum)', aggtransfn => 'enum_smaller',
   aggcombinefn => 'enum_smaller', aggsortop => '<(anyenum,anyenum)',
-  aggtranstype => 'anyenum' },
+  aggtranstype => 'anyenum', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(inet)', aggtransfn => 'network_smaller',
   aggcombinefn => 'network_smaller', aggsortop => '<(inet,inet)',
-  aggtranstype => 'inet' },
+  aggtranstype => 'inet', aggpartialpushdownsafe => 't' },
 { aggfnoid => 'min(pg_lsn)', aggtransfn => 'pg_lsn_smaller',
   aggcombinefn => 'pg_lsn_smaller', aggsortop => '<(pg_lsn,pg_lsn)',
-  aggtranstype => 'pg_lsn' },
+  aggtranstype => 'pg_lsn' , aggpartialpushdownsafe => 't'},
 
 # count
 { aggfnoid => 'count(any)', aggtransfn => 'int8inc_any',
   aggcombinefn => 'int8pl', aggmtransfn => 'int8inc_any',
   aggminvtransfn => 'int8dec_any', aggtranstype => 'int8',
-  aggmtranstype => 'int8', agginitval => '0', aggminitval => '0' },
+  aggmtranstype => 'int8', agginitval => '0', aggminitval => '0',
+  aggpartialpushdownsafe => 't' },
 { aggfnoid => 'count()', aggtransfn => 'int8inc', aggcombinefn => 'int8pl',
   aggmtransfn => 'int8inc', aggminvtransfn => 'int8dec', aggtranstype => 'int8',
-  aggmtranstype => 'int8', agginitval => '0', aggminitval => '0' },
+  aggmtranstype => 'int8', agginitval => '0', aggminitval => '0',
+  aggpartialpushdownsafe => 't' },
 
 # var_pop
 { aggfnoid => 'var_pop(int8)', aggtransfn => 'int8_accum',
diff --git a/src/include/catalog/pg_aggregate.h b/src/include/catalog/pg_aggregate.h
index 08c9379ba77..2c63102ff31 100644
--- a/src/include/catalog/pg_aggregate.h
+++ b/src/include/catalog/pg_aggregate.h
@@ -55,6 +55,9 @@ CATALOG(pg_aggregate,2600,AggregateRelationId)
 	/* function to convert bytea to transtype (0 if none) */
 	regproc		aggdeserialfn BKI_DEFAULT(-) BKI_LOOKUP_OPT(pg_proc);
 
+	/* function to convert aggregate result to bytea (0 if none) */
+	regproc		aggpartialconverterfn BKI_DEFAULT(-) BKI_LOOKUP_OPT(pg_proc);
+
 	/* forward function for moving-aggregate mode (0 if none) */
 	regproc		aggmtransfn BKI_DEFAULT(-) BKI_LOOKUP_OPT(pg_proc);
 
@@ -91,6 +94,9 @@ CATALOG(pg_aggregate,2600,AggregateRelationId)
 	/* estimated size of moving-agg state (0 for default est) */
 	int32		aggmtransspace BKI_DEFAULT(0);
 
+	/* true if partial aggregate is fine to push down */
+	bool		aggpartialpushdownsafe BKI_DEFAULT(f);
+
 #ifdef CATALOG_VARLEN			/* variable-length fields start here */
 
 	/* initial value for transition state (can be NULL) */
@@ -161,6 +167,7 @@ extern ObjectAddress AggregateCreate(const char *aggName,
 									 List *aggcombinefnName,
 									 List *aggserialfnName,
 									 List *aggdeserialfnName,
+									 List *aggpartialconverterfnName,
 									 List *aggmtransfnName,
 									 List *aggminvtransfnName,
 									 List *aggmfinalfnName,
@@ -175,6 +182,7 @@ extern ObjectAddress AggregateCreate(const char *aggName,
 									 int32 aggmTransSpace,
 									 const char *agginitval,
 									 const char *aggminitval,
-									 char proparallel);
+									 char proparallel,
+									 bool partialPushdownSafe);
 
 #endif							/* PG_AGGREGATE_H */
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index d068d6532ec..1cf23b15df0 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -4798,6 +4798,12 @@
 { oid => '2786', descr => 'aggregate serial function',
   proname => 'int8_avg_serialize', prorettype => 'bytea',
   proargtypes => 'internal', prosrc => 'int8_avg_serialize' },
+{ oid => '9630', descr => 'partial aggregate converter function',
+  proname => 'int8_sum_to_internal_serialize', prorettype => 'bytea',
+  proargtypes => 'int8', prosrc => 'int8_sum_to_internal_serialize' },
+{ oid => '9631', descr => 'partial aggregate converter function',
+  proname => 'numeric_sum_to_internal_serialize', prorettype => 'bytea',
+  proargtypes => 'numeric', prosrc => 'numeric_sum_to_internal_serialize' },
 { oid => '2787', descr => 'aggregate deserial function',
   proname => 'int8_avg_deserialize', prorettype => 'internal',
   proargtypes => 'bytea internal', prosrc => 'int8_avg_deserialize' },
diff --git a/src/test/regress/expected/oidjoins.out b/src/test/regress/expected/oidjoins.out
index 215eb899be3..864151bbca3 100644
--- a/src/test/regress/expected/oidjoins.out
+++ b/src/test/regress/expected/oidjoins.out
@@ -145,6 +145,7 @@ NOTICE:  checking pg_aggregate {aggfinalfn} => pg_proc {oid}
 NOTICE:  checking pg_aggregate {aggcombinefn} => pg_proc {oid}
 NOTICE:  checking pg_aggregate {aggserialfn} => pg_proc {oid}
 NOTICE:  checking pg_aggregate {aggdeserialfn} => pg_proc {oid}
+NOTICE:  checking pg_aggregate {aggpartialconverterfn} => pg_proc {oid}
 NOTICE:  checking pg_aggregate {aggmtransfn} => pg_proc {oid}
 NOTICE:  checking pg_aggregate {aggminvtransfn} => pg_proc {oid}
 NOTICE:  checking pg_aggregate {aggmfinalfn} => pg_proc {oid}
-- 
2.25.1

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