diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index b2acf03c7c..9f78190992 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -19174,17 +19174,24 @@ validatePartitionedIndex(Relation partedIdx, Relation partedTbl)
 	if (tuples == RelationGetPartitionDesc(partedTbl, true)->nparts)
 	{
 		Relation	idxRel;
-		HeapTuple	newtup;
+		HeapTuple	indTup;
+		Form_pg_index indexForm;
 
 		idxRel = table_open(IndexRelationId, RowExclusiveLock);
+		indTup = SearchSysCacheCopy1(INDEXRELID,
+									 ObjectIdGetDatum(RelationGetRelid(partedIdx)));
+		if (!HeapTupleIsValid(indTup))
+			elog(ERROR, "cache lookup failed for index %u",
+				 RelationGetRelid(partedIdx));
+		indexForm = (Form_pg_index) GETSTRUCT(indTup);
 
-		newtup = heap_copytuple(partedIdx->rd_indextuple);
-		((Form_pg_index) GETSTRUCT(newtup))->indisvalid = true;
+		indexForm->indisvalid = true;
 		updated = true;
 
-		CatalogTupleUpdate(idxRel, &partedIdx->rd_indextuple->t_self, newtup);
+		CatalogTupleUpdate(idxRel, &indTup->t_self, indTup);
 
 		table_close(idxRel, RowExclusiveLock);
+		heap_freetuple(indTup);
 	}
 
 	/*
diff --git a/src/test/regress/expected/indexing.out b/src/test/regress/expected/indexing.out
index 3e5645c2ab..368e735de2 100644
--- a/src/test/regress/expected/indexing.out
+++ b/src/test/regress/expected/indexing.out
@@ -1486,3 +1486,66 @@ select indexrelid::regclass, indisvalid,
 (5 rows)
 
 drop table parted_isvalid_tab;
+-- Check state of replica indexes when attaching a partition.
+begin;
+create table parted_replica_tab (id int not null) partition by range (id);
+create table parted_replica_tab_1 partition of parted_replica_tab
+  for values from (1) to (10) partition by range (id);
+create table parted_replica_tab_11 partition of parted_replica_tab_1
+  for values from (1) to (5);
+create unique index parted_replica_idx
+  on only parted_replica_tab using btree (id);
+create unique index parted_replica_idx_1
+  on only parted_replica_tab_1 using btree (id);
+-- This triggers an update of pg_index.indisreplident for parted_replica_idx.
+alter table only parted_replica_tab_1 replica identity
+  using index parted_replica_idx_1;
+create unique index parted_replica_idx_11 on parted_replica_tab_11 USING btree (id);
+select indexrelid::regclass, indisvalid, indisreplident,
+       indrelid::regclass, inhparent::regclass
+  from pg_index idx left join
+       pg_inherits inh on (idx.indexrelid = inh.inhrelid)
+  where indexrelid::regclass::text like 'parted_replica%'
+  order by indexrelid::regclass::text collate "C";
+      indexrelid       | indisvalid | indisreplident |       indrelid        | inhparent 
+-----------------------+------------+----------------+-----------------------+-----------
+ parted_replica_idx    | f          | f              | parted_replica_tab    | 
+ parted_replica_idx_1  | f          | t              | parted_replica_tab_1  | 
+ parted_replica_idx_11 | t          | f              | parted_replica_tab_11 | 
+(3 rows)
+
+-- parted_replica_idx is not valid yet here, because parted_replica_idx_1
+-- is not valid.
+alter index parted_replica_idx ATTACH PARTITION parted_replica_idx_1;
+select indexrelid::regclass, indisvalid, indisreplident,
+       indrelid::regclass, inhparent::regclass
+  from pg_index idx left join
+       pg_inherits inh on (idx.indexrelid = inh.inhrelid)
+  where indexrelid::regclass::text like 'parted_replica%'
+  order by indexrelid::regclass::text collate "C";
+      indexrelid       | indisvalid | indisreplident |       indrelid        |     inhparent      
+-----------------------+------------+----------------+-----------------------+--------------------
+ parted_replica_idx    | f          | f              | parted_replica_tab    | 
+ parted_replica_idx_1  | f          | t              | parted_replica_tab_1  | parted_replica_idx
+ parted_replica_idx_11 | t          | f              | parted_replica_tab_11 | 
+(3 rows)
+
+-- parted_replica_idx becomes valid here.
+alter index parted_replica_idx_1 ATTACH PARTITION parted_replica_idx_11;
+alter table only parted_replica_tab_1 replica identity
+  using index parted_replica_idx_1;
+commit;
+select indexrelid::regclass, indisvalid, indisreplident,
+       indrelid::regclass, inhparent::regclass
+  from pg_index idx left join
+       pg_inherits inh on (idx.indexrelid = inh.inhrelid)
+  where indexrelid::regclass::text like 'parted_replica%'
+  order by indexrelid::regclass::text collate "C";
+      indexrelid       | indisvalid | indisreplident |       indrelid        |      inhparent       
+-----------------------+------------+----------------+-----------------------+----------------------
+ parted_replica_idx    | t          | f              | parted_replica_tab    | 
+ parted_replica_idx_1  | t          | t              | parted_replica_tab_1  | parted_replica_idx
+ parted_replica_idx_11 | t          | f              | parted_replica_tab_11 | parted_replica_idx_1
+(3 rows)
+
+drop table parted_replica_tab;
diff --git a/src/test/regress/sql/indexing.sql b/src/test/regress/sql/indexing.sql
index d6e5a06d95..6f60d1dc0f 100644
--- a/src/test/regress/sql/indexing.sql
+++ b/src/test/regress/sql/indexing.sql
@@ -808,3 +808,46 @@ select indexrelid::regclass, indisvalid,
   where indexrelid::regclass::text like 'parted_isvalid%'
   order by indexrelid::regclass::text collate "C";
 drop table parted_isvalid_tab;
+
+-- Check state of replica indexes when attaching a partition.
+begin;
+create table parted_replica_tab (id int not null) partition by range (id);
+create table parted_replica_tab_1 partition of parted_replica_tab
+  for values from (1) to (10) partition by range (id);
+create table parted_replica_tab_11 partition of parted_replica_tab_1
+  for values from (1) to (5);
+create unique index parted_replica_idx
+  on only parted_replica_tab using btree (id);
+create unique index parted_replica_idx_1
+  on only parted_replica_tab_1 using btree (id);
+-- This triggers an update of pg_index.indisreplident for parted_replica_idx.
+alter table only parted_replica_tab_1 replica identity
+  using index parted_replica_idx_1;
+create unique index parted_replica_idx_11 on parted_replica_tab_11 USING btree (id);
+select indexrelid::regclass, indisvalid, indisreplident,
+       indrelid::regclass, inhparent::regclass
+  from pg_index idx left join
+       pg_inherits inh on (idx.indexrelid = inh.inhrelid)
+  where indexrelid::regclass::text like 'parted_replica%'
+  order by indexrelid::regclass::text collate "C";
+-- parted_replica_idx is not valid yet here, because parted_replica_idx_1
+-- is not valid.
+alter index parted_replica_idx ATTACH PARTITION parted_replica_idx_1;
+select indexrelid::regclass, indisvalid, indisreplident,
+       indrelid::regclass, inhparent::regclass
+  from pg_index idx left join
+       pg_inherits inh on (idx.indexrelid = inh.inhrelid)
+  where indexrelid::regclass::text like 'parted_replica%'
+  order by indexrelid::regclass::text collate "C";
+-- parted_replica_idx becomes valid here.
+alter index parted_replica_idx_1 ATTACH PARTITION parted_replica_idx_11;
+alter table only parted_replica_tab_1 replica identity
+  using index parted_replica_idx_1;
+commit;
+select indexrelid::regclass, indisvalid, indisreplident,
+       indrelid::regclass, inhparent::regclass
+  from pg_index idx left join
+       pg_inherits inh on (idx.indexrelid = inh.inhrelid)
+  where indexrelid::regclass::text like 'parted_replica%'
+  order by indexrelid::regclass::text collate "C";
+drop table parted_replica_tab;