diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index fc89352b661..5fd8b51312c 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -722,7 +722,6 @@ static void QueuePartitionConstraintValidation(List **wqueue, Relation scanrel,
 											   List *partConstraint,
 											   bool validate_default);
 static void CloneRowTriggersToPartition(Relation parent, Relation partition);
-static void DetachAddConstraintIfNeeded(List **wqueue, Relation partRel);
 static void DropClonedTriggersFromPartition(Oid partitionId);
 static ObjectAddress ATExecDetachPartition(List **wqueue, AlteredTableInfo *tab,
 										   Relation rel, RangeVar *name,
@@ -20941,12 +20940,6 @@ ATExecDetachPartition(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		char	   *parentrelname;
 		char	   *partrelname;
 
-		/*
-		 * Add a new constraint to the partition being detached, which
-		 * supplants the partition constraint (unless there is one already).
-		 */
-		DetachAddConstraintIfNeeded(wqueue, partRel);
-
 		/*
 		 * We're almost done now; the only traces that remain are the
 		 * pg_inherits tuple and the partition's relpartbounds.  Before we can
@@ -21403,49 +21396,6 @@ ATExecDetachPartitionFinalize(Relation rel, RangeVar *name)
 	return address;
 }
 
-/*
- * DetachAddConstraintIfNeeded
- *		Subroutine for ATExecDetachPartition.  Create a constraint that
- *		takes the place of the partition constraint, but avoid creating
- *		a dupe if a constraint already exists which implies the needed
- *		constraint.
- */
-static void
-DetachAddConstraintIfNeeded(List **wqueue, Relation partRel)
-{
-	List	   *constraintExpr;
-
-	constraintExpr = RelationGetPartitionQual(partRel);
-	constraintExpr = (List *) eval_const_expressions(NULL, (Node *) constraintExpr);
-
-	/*
-	 * Avoid adding a new constraint if the needed constraint is implied by an
-	 * existing constraint
-	 */
-	if (!PartConstraintImpliedByRelConstraint(partRel, constraintExpr))
-	{
-		AlteredTableInfo *tab;
-		Constraint *n;
-
-		tab = ATGetQueueEntry(wqueue, partRel);
-
-		/* Add constraint on partition, equivalent to the partition constraint */
-		n = makeNode(Constraint);
-		n->contype = CONSTR_CHECK;
-		n->conname = NULL;
-		n->location = -1;
-		n->is_no_inherit = false;
-		n->raw_expr = NULL;
-		n->cooked_expr = nodeToString(make_ands_explicit(constraintExpr));
-		n->is_enforced = true;
-		n->initially_valid = true;
-		n->skip_validation = true;
-		/* It's a re-add, since it nominally already exists */
-		ATAddCheckNNConstraint(wqueue, tab, partRel, n,
-							   true, false, true, ShareUpdateExclusiveLock);
-	}
-}
-
 /*
  * DropClonedTriggersFromPartition
  *		subroutine for ATExecDetachPartition to remove any triggers that were
diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out
index a08f115b0e5..5e98bbf2425 100644
--- a/src/test/regress/expected/alter_table.out
+++ b/src/test/regress/expected/alter_table.out
@@ -4470,27 +4470,15 @@ ALTER TABLE range_parted2 DETACH PARTITION part_rp CONCURRENTLY;
 Partition key: RANGE (a)
 Number of partitions: 0
 
--- constraint should be created
-\d part_rp
-              Table "public.part_rp"
- Column |  Type   | Collation | Nullable | Default 
---------+---------+-----------+----------+---------
- a      | integer |           |          | 
-Check constraints:
-    "part_rp_a_check" CHECK (a IS NOT NULL AND a >= 0 AND a < 100)
-
-CREATE TABLE part_rp100 PARTITION OF range_parted2 (CHECK (a>=123 AND a<133 AND a IS NOT NULL)) FOR VALUES FROM (100) to (200);
-ALTER TABLE range_parted2 DETACH PARTITION part_rp100 CONCURRENTLY;
--- redundant constraint should not be created
-\d part_rp100
-             Table "public.part_rp100"
- Column |  Type   | Collation | Nullable | Default 
---------+---------+-----------+----------+---------
- a      | integer |           |          | 
-Check constraints:
-    "part_rp100_a_check" CHECK (a >= 123 AND a < 133 AND a IS NOT NULL)
-
 DROP TABLE range_parted2;
+-- Test that hash partitions continue to work after they're concurrently
+-- detached (bugs #18371, #19070)
+CREATE TABLE hash_parted2 (a int) PARTITION BY HASH(a);
+CREATE TABLE part_hp PARTITION OF hash_parted2 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+ALTER TABLE hash_parted2 DETACH PARTITION part_hp CONCURRENTLY;
+DROP TABLE hash_parted2;
+INSERT INTO part_hp VALUES (1);
+DROP TABLE part_hp;
 -- Check ALTER TABLE commands for partitioned tables and partitions
 -- cannot add/drop column to/from *only* the parent
 ALTER TABLE ONLY list_parted2 ADD COLUMN c int;
diff --git a/src/test/regress/sql/alter_table.sql b/src/test/regress/sql/alter_table.sql
index 90bf5c17682..417202430a5 100644
--- a/src/test/regress/sql/alter_table.sql
+++ b/src/test/regress/sql/alter_table.sql
@@ -2826,14 +2826,17 @@ DROP TABLE part_rpd;
 -- works fine
 ALTER TABLE range_parted2 DETACH PARTITION part_rp CONCURRENTLY;
 \d+ range_parted2
--- constraint should be created
-\d part_rp
-CREATE TABLE part_rp100 PARTITION OF range_parted2 (CHECK (a>=123 AND a<133 AND a IS NOT NULL)) FOR VALUES FROM (100) to (200);
-ALTER TABLE range_parted2 DETACH PARTITION part_rp100 CONCURRENTLY;
--- redundant constraint should not be created
-\d part_rp100
 DROP TABLE range_parted2;
 
+-- Test that hash partitions continue to work after they're concurrently
+-- detached (bugs #18371, #19070)
+CREATE TABLE hash_parted2 (a int) PARTITION BY HASH(a);
+CREATE TABLE part_hp PARTITION OF hash_parted2 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+ALTER TABLE hash_parted2 DETACH PARTITION part_hp CONCURRENTLY;
+DROP TABLE hash_parted2;
+INSERT INTO part_hp VALUES (1);
+DROP TABLE part_hp;
+
 -- Check ALTER TABLE commands for partitioned tables and partitions
 
 -- cannot add/drop column to/from *only* the parent