diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index c19b331..a9cce14 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -626,12 +626,12 @@ EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft1 t1 WHERE c1 IS NULL;        -- Nu
    Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" IS NULL))
 (3 rows)
 
-EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft1 t1 WHERE c1 IS NOT NULL;    -- NullTest
-                                             QUERY PLAN                                              
------------------------------------------------------------------------------------------------------
+EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft1 t1 WHERE c1 IS NOT NULL and c3 is not null;    -- NullTest
+                                            QUERY PLAN                                            
+--------------------------------------------------------------------------------------------------
  Foreign Scan on public.ft1 t1
    Output: c1, c2, c3, c4, c5, c6, c7, c8
-   Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" IS NOT NULL))
+   Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE ((c3 IS NOT NULL))
 (3 rows)
 
 EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft1 t1 WHERE round(abs(c1), 0) = 1; -- FuncExpr
diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index 5f65d9d..2d816db 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -292,7 +292,7 @@ RESET enable_nestloop;
 EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft1 t1 WHERE t1.c1 = 1;         -- Var, OpExpr(b), Const
 EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft1 t1 WHERE t1.c1 = 100 AND t1.c2 = 0; -- BoolExpr
 EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft1 t1 WHERE c1 IS NULL;        -- NullTest
-EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft1 t1 WHERE c1 IS NOT NULL;    -- NullTest
+EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft1 t1 WHERE c1 IS NOT NULL and c3 is not null;    -- NullTest
 EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft1 t1 WHERE round(abs(c1), 0) = 1; -- FuncExpr
 EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft1 t1 WHERE c1 = -c1;          -- OpExpr(l)
 EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft1 t1 WHERE 1 = c1!;           -- OpExpr(r)
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index 2d7e1d8..5de67ce 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -344,6 +344,7 @@ set_rel_size(PlannerInfo *root, RelOptInfo *rel,
 		switch (rel->rtekind)
 		{
 			case RTE_RELATION:
+				remove_restrictions_implied_by_constraints(root, rel, rte);
 				if (rte->relkind == RELKIND_FOREIGN_TABLE)
 				{
 					/* Foreign table */
@@ -1047,6 +1048,7 @@ set_append_rel_size(PlannerInfo *root, RelOptInfo *rel,
 			set_dummy_rel_pathlist(childrel);
 			continue;
 		}
+		remove_restrictions_implied_by_constraints(root, childrel, childRTE);
 
 		/*
 		 * CE failed, so finish copying/modifying targetlist and join quals.
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index a1ebd4a..fc663d6 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -1444,6 +1444,51 @@ relation_excluded_by_constraints(PlannerInfo *root,
 	return false;
 }
 
+/*
+ * Remove from restrictions list items implied by table constraints
+ */
+void remove_restrictions_implied_by_constraints(PlannerInfo *root,
+												RelOptInfo *rel, RangeTblEntry *rte)
+{
+	List	   *constraint_pred;
+	List	   *safe_constraints = NIL;
+	List	   *safe_restrictions = NIL;
+	ListCell   *lc;
+
+	if (rte->rtekind != RTE_RELATION || rte->inh)
+		return;
+
+	/*
+	 * OK to fetch the constraint expressions.  Include "col IS NOT NULL"
+	 * expressions for attnotnull columns, in case we can refute those.
+	 */
+	constraint_pred = get_relation_constraints(root, rte->relid, rel, true);
+
+	/*
+	 * We do not currently enforce that CHECK constraints contain only
+	 * immutable functions, so it's necessary to check here. We daren't draw
+	 * conclusions from plan-time evaluation of non-immutable functions. Since
+	 * they're ANDed, we can just ignore any mutable constraints in the list,
+	 * and reason about the rest.
+	 */
+	foreach(lc, constraint_pred)
+	{
+		Node	   *pred = (Node*) lfirst(lc);
+
+		if (!contain_mutable_functions(pred))
+			safe_constraints = lappend(safe_constraints, pred);
+	}
+
+	foreach(lc, rel->baserestrictinfo)
+	{
+		RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
+		if (!predicate_implied_by(list_make1(rinfo->clause), safe_constraints, false)) {
+			safe_restrictions = lappend(safe_restrictions, rinfo);
+		}
+	}
+	rel->baserestrictinfo = safe_restrictions;
+}
+
 
 /*
  * build_physical_tlist
diff --git a/src/backend/optimizer/util/predtest.c b/src/backend/optimizer/util/predtest.c
index 536d24b..f373d92 100644
--- a/src/backend/optimizer/util/predtest.c
+++ b/src/backend/optimizer/util/predtest.c
@@ -17,6 +17,7 @@
 
 #include "catalog/pg_proc.h"
 #include "catalog/pg_type.h"
+#include "catalog/pg_operator.h"
 #include "executor/executor.h"
 #include "miscadmin.h"
 #include "nodes/nodeFuncs.h"
@@ -1407,6 +1408,13 @@ static const StrategyNumber BT_refute_table[6][6] = {
 	{none, none, BTEQ, none, none, none}	/* NE */
 };
 
+#define Int2LessOperator 95
+#define Int2LessOrEqualOperator 522
+#define Int4LessOrEqualOperator 523
+#define Int8LessOrEqualOperator 414
+#define DateLessOrEqualOperator 1096
+#define DateLessOperator 1095
+
 
 /*
  * operator_predicate_proof
@@ -1600,6 +1608,17 @@ operator_predicate_proof(Expr *predicate, Node *clause, bool refute_it)
 	if (clause_const->constisnull)
 		return false;
 
+	if (!refute_it
+		&& ((pred_op == Int4LessOrEqualOperator && clause_op == Int4LessOperator)
+			|| (pred_op == Int8LessOrEqualOperator && clause_op == Int8LessOperator)
+			|| (pred_op == Int2LessOrEqualOperator && clause_op == Int2LessOperator)
+			|| (pred_op == DateLessOrEqualOperator && clause_op == DateLessOperator))
+		&& pred_const->constbyval && clause_const->constbyval
+		&& pred_const->constvalue + 1 == clause_const->constvalue)
+	{
+		return true;
+	}
+
 	/*
 	 * Lookup the constant-comparison operator using the system catalogs and
 	 * the operator implication tables.
diff --git a/src/include/optimizer/plancat.h b/src/include/optimizer/plancat.h
index 71f0faf..09e8927 100644
--- a/src/include/optimizer/plancat.h
+++ b/src/include/optimizer/plancat.h
@@ -38,6 +38,9 @@ extern int32 get_relation_data_width(Oid relid, int32 *attr_widths);
 extern bool relation_excluded_by_constraints(PlannerInfo *root,
 								 RelOptInfo *rel, RangeTblEntry *rte);
 
+extern void remove_restrictions_implied_by_constraints(PlannerInfo *root,
+													   RelOptInfo *rel, RangeTblEntry *rte);
+
 extern List *build_physical_tlist(PlannerInfo *root, RelOptInfo *rel);
 
 extern bool has_unique_index(RelOptInfo *rel, AttrNumber attno);
diff --git a/src/test/regress/expected/inherit.out b/src/test/regress/expected/inherit.out
index 1fa9650..5610a4d 100644
--- a/src/test/regress/expected/inherit.out
+++ b/src/test/regress/expected/inherit.out
@@ -1668,34 +1668,30 @@ explain (costs off) select * from list_parted where a is not null;
 ---------------------------------
  Append
    ->  Seq Scan on part_ab_cd
-         Filter: (a IS NOT NULL)
    ->  Seq Scan on part_ef_gh
-         Filter: (a IS NOT NULL)
    ->  Seq Scan on part_null_xy
          Filter: (a IS NOT NULL)
-(7 rows)
+(5 rows)
 
 explain (costs off) select * from list_parted where a in ('ab', 'cd', 'ef');
                         QUERY PLAN                        
 ----------------------------------------------------------
  Append
    ->  Seq Scan on part_ab_cd
-         Filter: ((a)::text = ANY ('{ab,cd,ef}'::text[]))
    ->  Seq Scan on part_ef_gh
          Filter: ((a)::text = ANY ('{ab,cd,ef}'::text[]))
-(5 rows)
+(4 rows)
 
 explain (costs off) select * from list_parted where a = 'ab' or a in (null, 'cd');
                                       QUERY PLAN                                       
 ---------------------------------------------------------------------------------------
  Append
    ->  Seq Scan on part_ab_cd
-         Filter: (((a)::text = 'ab'::text) OR ((a)::text = ANY ('{NULL,cd}'::text[])))
    ->  Seq Scan on part_ef_gh
          Filter: (((a)::text = 'ab'::text) OR ((a)::text = ANY ('{NULL,cd}'::text[])))
    ->  Seq Scan on part_null_xy
          Filter: (((a)::text = 'ab'::text) OR ((a)::text = ANY ('{NULL,cd}'::text[])))
-(7 rows)
+(6 rows)
 
 explain (costs off) select * from list_parted where a = 'ab';
                 QUERY PLAN                
@@ -1748,30 +1744,25 @@ explain (costs off) select * from range_list_parted where a = 5;
 (5 rows)
 
 explain (costs off) select * from range_list_parted where b = 'ab';
-             QUERY PLAN             
-------------------------------------
+            QUERY PLAN            
+----------------------------------
  Append
    ->  Seq Scan on part_1_10_ab
-         Filter: (b = 'ab'::bpchar)
    ->  Seq Scan on part_10_20_ab
-         Filter: (b = 'ab'::bpchar)
    ->  Seq Scan on part_21_30_ab
-         Filter: (b = 'ab'::bpchar)
    ->  Seq Scan on part_40_inf_ab
-         Filter: (b = 'ab'::bpchar)
-(9 rows)
+(5 rows)
 
 explain (costs off) select * from range_list_parted where a between 3 and 23 and b in ('ab');
-                           QUERY PLAN                            
------------------------------------------------------------------
+           QUERY PLAN            
+---------------------------------
  Append
    ->  Seq Scan on part_1_10_ab
-         Filter: ((a >= 3) AND (a <= 23) AND (b = 'ab'::bpchar))
+         Filter: (a >= 3)
    ->  Seq Scan on part_10_20_ab
-         Filter: ((a >= 3) AND (a <= 23) AND (b = 'ab'::bpchar))
    ->  Seq Scan on part_21_30_ab
-         Filter: ((a >= 3) AND (a <= 23) AND (b = 'ab'::bpchar))
-(7 rows)
+         Filter: (a <= 23)
+(6 rows)
 
 /* Should select no rows because range partition key cannot be null */
 explain (costs off) select * from range_list_parted where a is null;
@@ -1787,44 +1778,34 @@ explain (costs off) select * from range_list_parted where b is null;
 ------------------------------------
  Append
    ->  Seq Scan on part_40_inf_null
-         Filter: (b IS NULL)
-(3 rows)
+(2 rows)
 
 explain (costs off) select * from range_list_parted where a is not null and a < 67;
-                   QUERY PLAN                   
-------------------------------------------------
+             QUERY PLAN             
+------------------------------------
  Append
    ->  Seq Scan on part_1_10_ab
-         Filter: ((a IS NOT NULL) AND (a < 67))
    ->  Seq Scan on part_1_10_cd
-         Filter: ((a IS NOT NULL) AND (a < 67))
    ->  Seq Scan on part_10_20_ab
-         Filter: ((a IS NOT NULL) AND (a < 67))
    ->  Seq Scan on part_10_20_cd
-         Filter: ((a IS NOT NULL) AND (a < 67))
    ->  Seq Scan on part_21_30_ab
-         Filter: ((a IS NOT NULL) AND (a < 67))
    ->  Seq Scan on part_21_30_cd
-         Filter: ((a IS NOT NULL) AND (a < 67))
    ->  Seq Scan on part_40_inf_ab
-         Filter: ((a IS NOT NULL) AND (a < 67))
+         Filter: (a < 67)
    ->  Seq Scan on part_40_inf_cd
-         Filter: ((a IS NOT NULL) AND (a < 67))
+         Filter: (a < 67)
    ->  Seq Scan on part_40_inf_null
-         Filter: ((a IS NOT NULL) AND (a < 67))
-(19 rows)
+         Filter: (a < 67)
+(13 rows)
 
 explain (costs off) select * from range_list_parted where a >= 30;
              QUERY PLAN             
 ------------------------------------
  Append
    ->  Seq Scan on part_40_inf_ab
-         Filter: (a >= 30)
    ->  Seq Scan on part_40_inf_cd
-         Filter: (a >= 30)
    ->  Seq Scan on part_40_inf_null
-         Filter: (a >= 30)
-(7 rows)
+(4 rows)
 
 drop table list_parted;
 drop table range_list_parted;
@@ -1860,7 +1841,7 @@ explain (costs off) select * from mcrparted where a = 10 and abs(b) = 5;	-- scan
    ->  Seq Scan on mcrparted1
          Filter: ((a = 10) AND (abs(b) = 5))
    ->  Seq Scan on mcrparted2
-         Filter: ((a = 10) AND (abs(b) = 5))
+         Filter: (abs(b) = 5)
 (5 rows)
 
 explain (costs off) select * from mcrparted where abs(b) = 5;	-- scans all partitions
@@ -1886,23 +1867,18 @@ explain (costs off) select * from mcrparted where a > -1;	-- scans all partition
    ->  Seq Scan on mcrparted0
          Filter: (a > '-1'::integer)
    ->  Seq Scan on mcrparted1
-         Filter: (a > '-1'::integer)
    ->  Seq Scan on mcrparted2
-         Filter: (a > '-1'::integer)
    ->  Seq Scan on mcrparted3
-         Filter: (a > '-1'::integer)
    ->  Seq Scan on mcrparted4
-         Filter: (a > '-1'::integer)
    ->  Seq Scan on mcrparted5
-         Filter: (a > '-1'::integer)
-(13 rows)
+(8 rows)
 
 explain (costs off) select * from mcrparted where a = 20 and abs(b) = 10 and c > 10;	-- scans mcrparted4
-                        QUERY PLAN                         
------------------------------------------------------------
+                  QUERY PLAN                  
+----------------------------------------------
  Append
    ->  Seq Scan on mcrparted4
-         Filter: ((c > 10) AND (a = 20) AND (abs(b) = 10))
+         Filter: ((c > 10) AND (abs(b) = 10))
 (3 rows)
 
 explain (costs off) select * from mcrparted where a = 20 and c > 20; -- scans mcrparted3, mcrparte4, mcrparte5
@@ -1912,7 +1888,7 @@ explain (costs off) select * from mcrparted where a = 20 and c > 20; -- scans mc
    ->  Seq Scan on mcrparted3
          Filter: ((c > 20) AND (a = 20))
    ->  Seq Scan on mcrparted4
-         Filter: ((c > 20) AND (a = 20))
+         Filter: (c > 20)
    ->  Seq Scan on mcrparted5
          Filter: ((c > 20) AND (a = 20))
 (7 rows)
@@ -1933,13 +1909,13 @@ explain (costs off) select min(a), max(a) from parted_minmax where b = '12345';
            ->  Merge Append
                  Sort Key: parted_minmax1.a
                  ->  Index Only Scan using parted_minmax1i on parted_minmax1
-                       Index Cond: ((a IS NOT NULL) AND (b = '12345'::text))
+                       Index Cond: (b = '12345'::text)
    InitPlan 2 (returns $1)
      ->  Limit
            ->  Merge Append
                  Sort Key: parted_minmax1_1.a DESC
                  ->  Index Only Scan Backward using parted_minmax1i on parted_minmax1 parted_minmax1_1
-                       Index Cond: ((a IS NOT NULL) AND (b = '12345'::text))
+                       Index Cond: (b = '12345'::text)
 (13 rows)
 
 select min(a), max(a) from parted_minmax where b = '12345';
diff --git a/src/test/regress/expected/rowsecurity.out b/src/test/regress/expected/rowsecurity.out
index de2ee4d..dee7443 100644
--- a/src/test/regress/expected/rowsecurity.out
+++ b/src/test/regress/expected/rowsecurity.out
@@ -1057,14 +1057,14 @@ NOTICE:  f_leak => awesome science fiction
 (4 rows)
 
 EXPLAIN (COSTS OFF) SELECT * FROM part_document WHERE f_leak(dtitle);
-                             QUERY PLAN                             
---------------------------------------------------------------------
+                     QUERY PLAN                      
+-----------------------------------------------------
  Append
    InitPlan 1 (returns $0)
      ->  Index Scan using uaccount_pkey on uaccount
            Index Cond: (pguser = CURRENT_USER)
    ->  Seq Scan on part_document_fiction
-         Filter: ((cid < 55) AND (dlevel <= $0) AND f_leak(dtitle))
+         Filter: ((dlevel <= $0) AND f_leak(dtitle))
 (6 rows)
 
 -- pp1 ERROR
@@ -1136,14 +1136,14 @@ NOTICE:  f_leak => awesome science fiction
 (4 rows)
 
 EXPLAIN (COSTS OFF) SELECT * FROM part_document WHERE f_leak(dtitle);
-                             QUERY PLAN                             
---------------------------------------------------------------------
+                     QUERY PLAN                      
+-----------------------------------------------------
  Append
    InitPlan 1 (returns $0)
      ->  Index Scan using uaccount_pkey on uaccount
            Index Cond: (pguser = CURRENT_USER)
    ->  Seq Scan on part_document_fiction
-         Filter: ((cid < 55) AND (dlevel <= $0) AND f_leak(dtitle))
+         Filter: ((dlevel <= $0) AND f_leak(dtitle))
 (6 rows)
 
 -- viewpoint from regress_rls_carol
