diff --git a/extensions-contrib/materialized-view-selection/src/main/java/org/apache/druid/query/materializedview/DerivativeDataSourceManager.java b/extensions-contrib/materialized-view-selection/src/main/java/org/apache/druid/query/materializedview/DerivativeDataSourceManager.java
index eeacc68c837..199067bb84b 100644
--- a/extensions-contrib/materialized-view-selection/src/main/java/org/apache/druid/query/materializedview/DerivativeDataSourceManager.java
+++ b/extensions-contrib/materialized-view-selection/src/main/java/org/apache/druid/query/materializedview/DerivativeDataSourceManager.java
@@ -246,7 +246,7 @@ public class DerivativeDataSourceManager
                       return null;
                     }
                 )
-                .first();
+                .list();
             return intervals.isEmpty() ? 0L : totalSize / intervals.size();
           }
         }