diff --git a/src/backend/catalog/partition.c b/src/backend/catalog/partition.c
index dd4a8d3..36bcb3f 100644
--- a/src/backend/catalog/partition.c
+++ b/src/backend/catalog/partition.c
@@ -1227,7 +1227,7 @@ check_default_allows_bound(Relation parent, Relation default_rel,
 	 * not contain any row that would belong to the new partition, we can
 	 * avoid scanning the default partition.
 	 */
-	if (PartConstraintImpliedByRelConstraint(default_rel, def_part_constraints))
+	if (ConstraintImpliedByRelConstraint(default_rel, def_part_constraints))
 	{
 		ereport(INFO,
 				(errmsg("updated partition constraint for default partition \"%s\" is implied by existing constraints",
@@ -1271,8 +1271,8 @@ check_default_allows_bound(Relation parent, Relation default_rel,
 			 * that it will not contain any row that would belong to the new
 			 * partition, we can avoid scanning the child table.
 			 */
-			if (PartConstraintImpliedByRelConstraint(part_rel,
-													 def_part_constraints))
+			if (ConstraintImpliedByRelConstraint(part_rel,
+												 def_part_constraints))
 			{
 				ereport(INFO,
 						(errmsg("updated partition constraint for default partition \"%s\" is implied by existing constraints",
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index d979ce2..35eac39 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -162,7 +162,7 @@ typedef struct AlteredTableInfo
 	/* Information saved by Phases 1/2 for Phase 3: */
 	List	   *constraints;	/* List of NewConstraint */
 	List	   *newvals;		/* List of NewColumnValue */
-	bool		new_notnull;	/* T if we added new NOT NULL constraints */
+	bool		verify_new_notnull; /* T if we should recheck NOT NULL */
 	int			rewrite;		/* Reason for forced rewrite, if any */
 	Oid			newTableSpace;	/* new tablespace; 0 means no change */
 	bool		chgPersistence; /* T if SET LOGGED/UNLOGGED is used */
@@ -370,6 +370,7 @@ static ObjectAddress ATExecDropNotNull(Relation rel, const char *colName, LOCKMO
 static void ATPrepSetNotNull(Relation rel, bool recurse, bool recursing);
 static ObjectAddress ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,
 				 const char *colName, LOCKMODE lockmode);
+static bool NotNullImpliedByRelConstraints(Relation rel, Form_pg_attribute attr);
 static ObjectAddress ATExecColumnDefault(Relation rel, const char *colName,
 					Node *newDefault, LOCKMODE lockmode);
 static ObjectAddress ATExecAddIdentity(Relation rel, const char *colName,
@@ -4304,7 +4305,7 @@ ATRewriteTables(AlterTableStmt *parsetree, List **wqueue, LOCKMODE lockmode)
 			 * Test the current data within the table against new constraints
 			 * generated by ALTER TABLE commands, but don't rebuild data.
 			 */
-			if (tab->constraints != NIL || tab->new_notnull ||
+			if (tab->constraints != NIL || tab->verify_new_notnull ||
 				tab->partition_constraint != NULL)
 				ATRewriteTable(tab, InvalidOid, lockmode);

@@ -4465,7 +4466,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 	}

 	notnull_attrs = NIL;
-	if (newrel || tab->new_notnull)
+	if (newrel || tab->verify_new_notnull)
 	{
 		/*
 		 * If we are rebuilding the tuples OR if we added any new NOT NULL
@@ -5461,7 +5462,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		 * null, but since it's filled specially, there's no need to test
 		 * anything.)
 		 */
-		tab->new_notnull |= colDef->is_not_null;
+		tab->verify_new_notnull |= colDef->is_not_null;
 	}

 	/*
@@ -5863,8 +5864,11 @@ ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,

 		CatalogTupleUpdate(attr_rel, &tuple->t_self, tuple);

-		/* Tell Phase 3 it needs to test the constraint */
-		tab->new_notnull = true;
+		if (!NotNullImpliedByRelConstraints(rel, (Form_pg_attribute) GETSTRUCT(tuple)))
+		{
+			/* Tell Phase 3 it needs to test the constraint */
+			tab->verify_new_notnull = true;
+		}

 		ObjectAddressSubSet(address, RelationRelationId,
 							RelationGetRelid(rel), attnum);
@@ -5881,6 +5885,46 @@ ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,
 }

 /*
+ * NotNullImpliedByRelConstraints
+ *		Does rel's existing constraints imply NOT NULL for given attribute
+ */
+static bool
+NotNullImpliedByRelConstraints(Relation rel, Form_pg_attribute attr)
+{
+	List	   *notNullConstraint = NIL;
+	NullTest   *nnulltest = makeNode(NullTest);
+
+	nnulltest->arg = (Expr *) makeVar(1,
+									  attr->attnum,
+									  attr->atttypid,
+									  attr->atttypmod,
+									  attr->attcollation,
+									  0);
+	nnulltest->nulltesttype = IS_NOT_NULL;
+
+	/*
+	 * same thing as in ConstraintImpliedByRelConstraint argisrow=false is
+	 * correct even for a composite column, because attnotnull does not
+	 * represent a SQL-spec IS NOT NULL test in such a case, just IS DISTINCT
+	 * FROM NULL.
+	 */
+	nnulltest->argisrow = false;
+	nnulltest->location = -1;
+	notNullConstraint = lappend(notNullConstraint, nnulltest);
+
+	if (ConstraintImpliedByRelConstraint(rel, notNullConstraint))
+	{
+		ereport(DEBUG1,
+				(errmsg("verifying table \"%s\" NOT NULL constraint "
+						"on %s attribute by existed constraints",
+						RelationGetRelationName(rel), NameStr(attr->attname))));
+		return true;
+	}
+
+	return false;
+}
+
+/*
  * ALTER TABLE ALTER COLUMN SET/DROP DEFAULT
  *
  * Return the address of the affected column.
@@ -13618,15 +13662,14 @@ ComputePartitionAttrs(Relation rel, List *partParams, AttrNumber *partattrs,
 }

 /*
- * PartConstraintImpliedByRelConstraint
- *		Does scanrel's existing constraints imply the partition constraint?
+ * ConstraintImpliedByRelConstraint
+ *		Does scanrel's existing constraints imply given constraint
  *
  * Existing constraints includes its check constraints and column-level
  * NOT NULL constraints and partConstraint describes the partition constraint.
  */
 bool
-PartConstraintImpliedByRelConstraint(Relation scanrel,
-									 List *partConstraint)
+ConstraintImpliedByRelConstraint(Relation scanrel, List *partConstraint)
 {
 	List	   *existConstraint = NIL;
 	TupleConstr *constr = RelationGetDescr(scanrel)->constr;
@@ -13724,7 +13767,7 @@ ValidatePartitionConstraints(List **wqueue, Relation scanrel,
 	 * Based on the table's existing constraints, determine if we can skip
 	 * scanning the table to validate the partition constraint.
 	 */
-	if (PartConstraintImpliedByRelConstraint(scanrel, partConstraint))
+	if (ConstraintImpliedByRelConstraint(scanrel, partConstraint))
 	{
 		if (!validate_default)
 			ereport(INFO,
@@ -13776,7 +13819,7 @@ ValidatePartitionConstraints(List **wqueue, Relation scanrel,
 				elog(ERROR, "unexpected whole-row reference found in partition key");

 			/* Can we skip scanning this part_rel? */
-			if (PartConstraintImpliedByRelConstraint(part_rel, my_partconstr))
+			if (ConstraintImpliedByRelConstraint(part_rel, my_partconstr))
 			{
 				if (!validate_default)
 					ereport(INFO,
diff --git a/src/include/commands/tablecmds.h b/src/include/commands/tablecmds.h
index da3ff5d..41e8cdf 100644
--- a/src/include/commands/tablecmds.h
+++ b/src/include/commands/tablecmds.h
@@ -88,7 +88,7 @@ extern void RangeVarCallbackOwnsTable(const RangeVar *relation,

 extern void RangeVarCallbackOwnsRelation(const RangeVar *relation,
 							 Oid relId, Oid oldRelId, void *noCatalogs);
-extern bool PartConstraintImpliedByRelConstraint(Relation scanrel,
-									 List *partConstraint);
+extern bool ConstraintImpliedByRelConstraint(Relation scanrel,
+								 List *partConstraint);

 #endif							/* TABLECMDS_H */