diff --git a/core/raydp-main/src/main/scala/org/apache/spark/rdd/RayObjectRefRDD.scala b/core/raydp-main/src/main/scala/org/apache/spark/rdd/RayObjectRefRDD.scala
index 2c76643c..794d246d 100644
--- a/core/raydp-main/src/main/scala/org/apache/spark/rdd/RayObjectRefRDD.scala
+++ b/core/raydp-main/src/main/scala/org/apache/spark/rdd/RayObjectRefRDD.scala
@@ -27,24 +27,26 @@ import org.apache.spark.{Partition, SparkContext, TaskContext}
 import org.apache.spark.raydp.RayDPUtils
 import org.apache.spark.sql.Row
 
-private[spark] class RayObjectRefRDDPartition(idx: Int) extends Partition {
+private[spark] class RayObjectRefRDDPartition(idx: Int, hex: String) extends Partition {
   val index = idx
+  val objHex = hex
 }
 
 private[spark]
 class RayObjectRefRDD(
     sc: SparkContext,
+    blocksHex: List[String],
     locations: List[Array[Byte]])
   extends RDD[Row](sc, Nil) {
 
   override def getPartitions: Array[Partition] = {
-    (0 until locations.size()).map { i =>
-      new RayObjectRefRDDPartition(i).asInstanceOf[Partition]
+    (0 until blocksHex.size()).map { i =>
+      new RayObjectRefRDDPartition(i, blocksHex.get(i)).asInstanceOf[Partition]
     }.toArray
   }
 
   override def compute(split: Partition, context: TaskContext): Iterator[Row] = {
-    (Row(split.index) :: Nil).iterator
+    (Row(split.asInstanceOf[RayObjectRefRDDPartition].objHex) :: Nil).iterator
   }
 
   override def getPreferredLocations(split: Partition): Seq[String] = {
diff --git a/core/raydp-main/src/main/scala/org/apache/spark/sql/raydp/ObjectStoreReader.scala b/core/raydp-main/src/main/scala/org/apache/spark/sql/raydp/ObjectStoreReader.scala
index 31fbc366..43a9e806 100644
--- a/core/raydp-main/src/main/scala/org/apache/spark/sql/raydp/ObjectStoreReader.scala
+++ b/core/raydp-main/src/main/scala/org/apache/spark/sql/raydp/ObjectStoreReader.scala
@@ -29,14 +29,15 @@ import org.apache.spark.rdd.{RayDatasetRDD, RayObjectRefRDD}
 import org.apache.spark.sql.{DataFrame, SparkSession, SQLContext}
 import org.apache.spark.sql.catalyst.expressions.GenericRow
 import org.apache.spark.sql.execution.arrow.ArrowConverters
-import org.apache.spark.sql.types.{IntegerType, StructType}
+import org.apache.spark.sql.types.{StringType, StructType}
 
 object ObjectStoreReader {
   def createRayObjectRefDF(
       spark: SparkSession,
+      blocksHex: List[String],
       locations: List[Array[Byte]]): DataFrame = {
-    val rdd = new RayObjectRefRDD(spark.sparkContext, locations)
-    val schema = new StructType().add("idx", IntegerType)
+    val rdd = new RayObjectRefRDD(spark.sparkContext, blocksHex, locations)
+    val schema = new StructType().add("hex", StringType)
     spark.createDataFrame(rdd, schema)
   }
 
diff --git a/python/raydp/spark/dataset.py b/python/raydp/spark/dataset.py
index d6a64764..ee0b8d31 100644
--- a/python/raydp/spark/dataset.py
+++ b/python/raydp/spark/dataset.py
@@ -15,7 +15,6 @@
 # limitations under the License.
 
 import logging
-import uuid
 from typing import Callable, Dict, List, NoReturn, Optional, Iterable, Union
 
 import numpy as np
@@ -164,8 +163,7 @@ def _save_spark_df_to_object_store(df: sql.DataFrame, use_batch: bool = True,
 
     if _use_owner is True:
         holder = ray.get_actor(obj_holder_name)
-        df_id = uuid.uuid4()
-        ray.get(holder.add_objects.remote(df_id, blocks))
+        ray.get(holder.add_objects.remote(blocks))
 
     return blocks, block_sizes
 
@@ -210,12 +208,12 @@ def _convert_by_udf(spark: sql.SparkSession,
                     schema: StructType) -> DataFrame:
     holder_name  = spark.sparkContext.appName + RAYDP_SPARK_MASTER_SUFFIX
     holder = ray.get_actor(holder_name)
-    df_id = uuid.uuid4()
-    ray.get(holder.add_objects.remote(df_id, blocks))
+    ray.get(holder.add_objects.remote(blocks))
     jvm = spark.sparkContext._jvm
     object_store_reader = jvm.org.apache.spark.sql.raydp.ObjectStoreReader
     # create the rdd then dataframe to utilize locality
-    jdf = object_store_reader.createRayObjectRefDF(spark._jsparkSession, locations)
+    blocks_hex = [block.hex() for block in blocks]
+    jdf = object_store_reader.createRayObjectRefDF(spark._jsparkSession, blocks_hex, locations)
     current_namespace = ray.get_runtime_context().namespace
     ray_address = ray.get(holder.get_ray_address.remote())
     blocks_df = DataFrame(jdf, spark._wrapped if hasattr(spark, "_wrapped") else spark)
@@ -228,8 +226,8 @@ def _convert_blocks_to_dataframe(blocks):
         obj_holder = ray.get_actor(holder_name)
         for block in blocks:
             dfs = []
-            for idx in block["idx"]:
-                ref = ray.get(obj_holder.get_object.remote(df_id, idx))
+            for obj_hex in block["hex"]:
+                ref = ray.get(obj_holder.get_object.remote(obj_hex))
                 data = ray.get(ref)
                 dfs.append(data.to_pandas())
             yield pd.concat(dfs)
diff --git a/python/raydp/spark/ray_cluster_master.py b/python/raydp/spark/ray_cluster_master.py
index d5ff4617..6e9d43d3 100644
--- a/python/raydp/spark/ray_cluster_master.py
+++ b/python/raydp/spark/ray_cluster_master.py
@@ -212,11 +212,15 @@ def get_spark_home(self) -> str:
         assert self._started_up
         return self._spark_home
 
-    def add_objects(self, timestamp, objects):
-        self._objects[timestamp] = objects
+    def add_objects(self, objects):
+        for obj in objects:
+            self._objects[obj.hex()] = obj
 
-    def get_object(self, timestamp, idx):
-        return self._objects[timestamp][idx]
+    def get_object(self, obj_hex):
+        return self._objects[obj_hex]
+
+    def remove_object(self, obj_hex):
+        del self._objects[obj_hex]
 
     def get_ray_address(self):
         return ray.worker.global_worker.node.address