diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index d90c739952a..2d4dcd75564 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -13683,6 +13683,21 @@ ValidatePartitionConstraints(List **wqueue, Relation scanrel,
 			/* There can never be a whole-row reference here */
 			if (found_whole_row)
 				elog(ERROR, "unexpected whole-row reference found in partition key");
+
+			/* Can we skip scanning this part_rel? */
+			if (PartConstraintImpliedByRelConstraint(part_rel, my_partconstr))
+			{
+				if (!validate_default)
+					ereport(INFO,
+							(errmsg("partition constraint for table \"%s\" is implied by existing constraints",
+									RelationGetRelationName(part_rel))));
+				else
+					ereport(INFO,
+							(errmsg("updated partition constraint for default partition \"%s\" is implied by existing constraints",
+									RelationGetRelationName(part_rel))));
+				heap_close(part_rel, NoLock);
+				continue;
+			}
 		}
 
 		/* Grab a work queue entry. */
diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out
index 807eb913f6d..cda8ce556cb 100644
--- a/src/test/regress/expected/alter_table.out
+++ b/src/test/regress/expected/alter_table.out
@@ -3474,6 +3474,20 @@ DETAIL:  "part_5" is already a child of "list_parted2".
 ALTER TABLE list_parted2 ATTACH PARTITION list_parted2 FOR VALUES IN (0);
 ERROR:  circular inheritance not allowed
 DETAIL:  "list_parted2" is already a child of "list_parted2".
+-- If the partitioned table being attached does not have a constraint that
+-- would allow validation scan to be skipped, but an individual partition
+-- does, then the partition's validation scan is skipped.
+CREATE TABLE quuux (a int, b text) PARTITION BY LIST (a);
+CREATE TABLE quuux_default PARTITION OF quuux DEFAULT PARTITION BY LIST (b);
+CREATE TABLE quuux_default1 PARTITION OF quuux_default (
+	CONSTRAINT check_1 CHECK (a IS NOT NULL AND a = 1)
+) FOR VALUES IN ('b');
+CREATE TABLE quuux1 (a int, b text);
+ALTER TABLE quuux ATTACH PARTITION quuux1 FOR VALUES IN (1); -- validate!
+CREATE TABLE quuux2 (a int, b text);
+ALTER TABLE quuux ATTACH PARTITION quuux2 FOR VALUES IN (2); -- skip validation
+INFO:  updated partition constraint for default partition "quuux_default1" is implied by existing constraints
+DROP TABLE quuux;
 --
 -- DETACH PARTITION
 --
diff --git a/src/test/regress/sql/alter_table.sql b/src/test/regress/sql/alter_table.sql
index 37cca72620a..d0daacf3e9a 100644
--- a/src/test/regress/sql/alter_table.sql
+++ b/src/test/regress/sql/alter_table.sql
@@ -2285,6 +2285,20 @@ ALTER TABLE list_parted2 ATTACH PARTITION part_2 FOR VALUES IN (2);
 ALTER TABLE part_5 ATTACH PARTITION list_parted2 FOR VALUES IN ('b');
 ALTER TABLE list_parted2 ATTACH PARTITION list_parted2 FOR VALUES IN (0);
 
+-- If the partitioned table being attached does not have a constraint that
+-- would allow validation scan to be skipped, but an individual partition
+-- does, then the partition's validation scan is skipped.
+CREATE TABLE quuux (a int, b text) PARTITION BY LIST (a);
+CREATE TABLE quuux_default PARTITION OF quuux DEFAULT PARTITION BY LIST (b);
+CREATE TABLE quuux_default1 PARTITION OF quuux_default (
+	CONSTRAINT check_1 CHECK (a IS NOT NULL AND a = 1)
+) FOR VALUES IN ('b');
+CREATE TABLE quuux1 (a int, b text);
+ALTER TABLE quuux ATTACH PARTITION quuux1 FOR VALUES IN (1); -- validate!
+CREATE TABLE quuux2 (a int, b text);
+ALTER TABLE quuux ATTACH PARTITION quuux2 FOR VALUES IN (2); -- skip validation
+DROP TABLE quuux;
+
 --
 -- DETACH PARTITION
 --