Github user marmbrus commented on a diff in the pull request:
https://github.com/apache/spark/pull/5538#discussion_r28535110
--- Diff:
sql/hive/src/main/scala/org/apache/spark/sql/hive/sqlUDFCurrentDB.scala ---
@@ -0,0 +1,43 @@
+/*
+ * 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.spark.sql.hive
+
+import org.apache.hadoop.hive.ql.exec.Description
+import org.apache.hadoop.hive.ql.session.SessionState
+import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector
+import org.apache.hadoop.hive.ql.udf.generic.GenericUDF
+import org.apache.spark.sql.hive.HiveShim
+
+// deterministic in the query range
+@Description(name = "current_database",
+ value = "_FUNC_() - returns currently using database name")
+class sqlUDFCurrentDB extends GenericUDF {
+
+ override def initialize(arguments: Array[ObjectInspector]):
ObjectInspector = {
+ val database = SessionState.get.getCurrentDatabase;
+ HiveShim.getStringWritableConstantObjectInspector(database);
+ }
+
+ override def evaluate(arguments: Array[GenericUDF.DeferredObject]):
Object = {
+ SessionState.get.getCurrentDatabase
--- End diff --
Yes, I understand, but that is definitely not clear from the code. Your
goal here is not just to make it work, but to make it clear to future
developers why it works so they don't break it. You need to add ScalaDoc to
this class stating that it only works on the driver, but that is okay because
this expression should always be constant folded.
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