diff --git a/omnioperator/omniop-spark-extension-ock/cpp/src/shuffle/ock_merge_reader.cpp b/omnioperator/omniop-spark-extension-ock/cpp/src/shuffle/ock_merge_reader.cpp
index 80ff1737977846dee4dad93049c35ffb44509f13..0aeac2c2a72ea928d64bb6a9a3e4f9b6a743e36d 100644
--- a/omnioperator/omniop-spark-extension-ock/cpp/src/shuffle/ock_merge_reader.cpp
+++ b/omnioperator/omniop-spark-extension-ock/cpp/src/shuffle/ock_merge_reader.cpp
@@ -200,6 +200,7 @@ bool OckMergeReader::CopyDataToVector(Vector *dstVector, uint32_t colIndex)
     auto *nullsAddress = (uint8_t *)dstVector->GetValueNulls();
     auto *valuesAddress = (uint8_t *)dstVector->GetValues();
     uint32_t *offsetsAddress = (uint32_t *)dstVector->GetValueOffsets();
+    dstVector->SetNullFlag(true);
     uint32_t totalSize = 0;
     uint32_t currentSize = 0;
 
diff --git a/omnioperator/omniop-spark-extension-ock/src/main/java/com/huawei/ock/spark/serialize/.keep b/omnioperator/omniop-spark-extension-ock/src/main/java/com/huawei/ock/spark/serialize/.keep
deleted file mode 100644
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..0000000000000000000000000000000000000000
diff --git a/omnioperator/omniop-spark-extension-ock/src/main/scala/com/huawei/.keep b/omnioperator/omniop-spark-extension-ock/src/main/scala/com/huawei/.keep
deleted file mode 100644
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..0000000000000000000000000000000000000000
diff --git a/omnioperator/omniop-spark-extension-ock/src/main/scala/com/huawei/ock/.keep b/omnioperator/omniop-spark-extension-ock/src/main/scala/com/huawei/ock/.keep
deleted file mode 100644
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..0000000000000000000000000000000000000000
diff --git a/omnioperator/omniop-spark-extension-ock/src/main/scala/com/huawei/ock/spark/.keep b/omnioperator/omniop-spark-extension-ock/src/main/scala/com/huawei/ock/spark/.keep
deleted file mode 100644
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..0000000000000000000000000000000000000000
diff --git a/omnioperator/omniop-spark-extension-ock/src/main/scala/org/.keep b/omnioperator/omniop-spark-extension-ock/src/main/scala/org/.keep
deleted file mode 100644
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..0000000000000000000000000000000000000000
diff --git a/omnioperator/omniop-spark-extension-ock/src/main/scala/org/apache/.keep b/omnioperator/omniop-spark-extension-ock/src/main/scala/org/apache/.keep
deleted file mode 100644
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..0000000000000000000000000000000000000000
diff --git a/omnioperator/omniop-spark-extension-ock/src/main/scala/org/apache/spark/.keep b/omnioperator/omniop-spark-extension-ock/src/main/scala/org/apache/spark/.keep
deleted file mode 100644
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..0000000000000000000000000000000000000000
diff --git a/omnioperator/omniop-spark-extension-ock/src/main/scala/org/apache/spark/shuffle/.keep b/omnioperator/omniop-spark-extension-ock/src/main/scala/org/apache/spark/shuffle/.keep
deleted file mode 100644
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..0000000000000000000000000000000000000000
diff --git a/omnioperator/omniop-spark-extension-ock/src/main/scala/org/apache/spark/shuffle/ock/.keep b/omnioperator/omniop-spark-extension-ock/src/main/scala/org/apache/spark/shuffle/ock/.keep
deleted file mode 100644
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..0000000000000000000000000000000000000000