postgres
diff --git a/‎src/backend/catalog/index.c
Copy file name to clipboardExpand all lines: src/backend/catalog/index.c
+7-1Lines changed: 7 additions & 1 deletion b/‎src/backend/catalog/index.c
Copy file name to clipboardExpand all lines: src/backend/catalog/index.c
+7-1Lines changed: 7 additions & 1 deletion
diff --git a/‎src/test/regress/expected/create_index.out
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+13Lines changed: 13 additions & 0 deletions b/‎src/test/regress/expected/create_index.out
Copy file name to clipboardExpand all lines: src/test/regress/expected/create_index.out
+13Lines changed: 13 additions & 0 deletions
diff --git a/‎src/test/regress/sql/create_index.sql
Copy file name to clipboardExpand all lines: src/test/regress/sql/create_index.sql
+9Lines changed: 9 additions & 0 deletions b/‎src/test/regress/sql/create_index.sql
Copy file name to clipboardExpand all lines: src/test/regress/sql/create_index.sql
+9Lines changed: 9 additions & 0 deletions
@@ -1527,7 +1527,13 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName)
 	newIndexForm->indimmediate = oldIndexForm->indimmediate;
 	oldIndexForm->indimmediate = true;
 
-	/* Mark old index as valid and new as invalid as index_set_state_flags */
+	/* Preserve indisclustered in the new index */
+	newIndexForm->indisclustered = oldIndexForm->indisclustered;
+
+	/*
+	 * Mark the old index as valid, and the new index as invalid similarly
+	 * to what index_set_state_flags() does.
+	 */
 	newIndexForm->indisvalid = true;
 	oldIndexForm->indisvalid = false;
 	oldIndexForm->indisclustered = false;
 
@@ -2128,6 +2128,19 @@ SELECT obj_description('testcomment_idx1'::regclass, 'pg_class');
 (1 row)
 
 DROP TABLE testcomment;
+-- Check that indisclustered updates are preserved
+CREATE TABLE concur_clustered(i int);
+CREATE INDEX concur_clustered_i_idx ON concur_clustered(i);
+ALTER TABLE concur_clustered CLUSTER ON concur_clustered_i_idx;
+REINDEX TABLE CONCURRENTLY concur_clustered;
+SELECT indexrelid::regclass, indisclustered FROM pg_index
+  WHERE indrelid = 'concur_clustered'::regclass;
+       indexrelid       | indisclustered 
+------------------------+----------------
+ concur_clustered_i_idx | t
+(1 row)
+
+DROP TABLE concur_clustered;
 -- Partitions
 -- Create some partitioned tables
 CREATE TABLE concur_reindex_part (c1 int, c2 int) PARTITION BY RANGE (c1);
 
@@ -858,6 +858,15 @@ SELECT obj_description('testcomment_idx1'::regclass, 'pg_class');
 REINDEX TABLE CONCURRENTLY testcomment ;
 SELECT obj_description('testcomment_idx1'::regclass, 'pg_class');
 DROP TABLE testcomment;
+-- Check that indisclustered updates are preserved
+CREATE TABLE concur_clustered(i int);
+CREATE INDEX concur_clustered_i_idx ON concur_clustered(i);
+ALTER TABLE concur_clustered CLUSTER ON concur_clustered_i_idx;
+REINDEX TABLE CONCURRENTLY concur_clustered;
+SELECT indexrelid::regclass, indisclustered FROM pg_index
+  WHERE indrelid = 'concur_clustered'::regclass;
+DROP TABLE concur_clustered;
+
 -- Partitions
 -- Create some partitioned tables
 CREATE TABLE concur_reindex_part (c1 int, c2 int) PARTITION BY RANGE (c1);