Github user jackylk commented on a diff in the pull request:
https://github.com/apache/carbondata/pull/1489#discussion_r150504312
--- Diff:
integration/spark-common/src/main/scala/org/apache/carbondata/events/DropDataMapEvents.scala
---
@@ -0,0 +1,54 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.carbondata.events
+
+import org.apache.spark.sql.SparkSession
+
+import org.apache.carbondata.core.metadata.schema.table.{CarbonTable,
DataMapSchema}
+
+
+/**
+ *
+ * @param ifExistsSet
+ * @param sparkSession
+ */
+case class DropDataMapPreEvent(
--- End diff --
describe in comment when this event will be triggered
---
