diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/OptimizeMetadataOnlyQuery.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/OptimizeMetadataOnlyQuery.scala
index d59b3c6f0caf..7dcde9845d52 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/OptimizeMetadataOnlyQuery.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/OptimizeMetadataOnlyQuery.scala
@@ -99,7 +99,8 @@ case class OptimizeMetadataOnlyQuery(
           case l @ LogicalRelation(fsRelation: HadoopFsRelation, _, _) =>
             val partAttrs = getPartitionAttrs(fsRelation.partitionSchema.map(_.name), l)
             val partitionData = fsRelation.location.listFiles(Nil, Nil)
-            LocalRelation(partAttrs, partitionData.map(_.values))
+            // `toArray` forces materialization to make the seq serializable
+            LocalRelation(partAttrs, partitionData.map(_.values).toArray)
 
           case relation: HiveTableRelation =>
             val partAttrs = getPartitionAttrs(relation.tableMeta.partitionColumnNames, relation)
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/OptimizeMetadataOnlyQuerySuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/OptimizeMetadataOnlyQuerySuite.scala
index 58c310596ca6..6c66902127d0 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/OptimizeMetadataOnlyQuerySuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/OptimizeMetadataOnlyQuerySuite.scala
@@ -117,4 +117,12 @@ class OptimizeMetadataOnlyQuerySuite extends QueryTest with SharedSQLContext {
     "select partcol1, max(partcol2) from srcpart where partcol1 = 0 group by rollup (partcol1)",
     "select partcol2 from (select partcol2 from srcpart where partcol1 = 0 union all " +
       "select partcol2 from srcpart where partcol1 = 1) t group by partcol2")
+
+  test("SPARK-21884 Fix StackOverflowError on MetadataOnlyQuery") {
+    withTable("t_1000") {
+      sql("CREATE TABLE t_1000 (a INT, p INT) USING PARQUET PARTITIONED BY (p)")
+      (1 to 1000).foreach(p => sql(s"ALTER TABLE t_1000 ADD PARTITION (p=$p)"))
+      sql("SELECT COUNT(DISTINCT p) FROM t_1000").collect()
+    }
+  }
 }