Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/4732#discussion_r142167389
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/CRowKeySelector.scala
---
@@ -0,0 +1,51 @@
+/*
+ * 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.flink.table.runtime
+
+import org.apache.flink.api.common.typeinfo.TypeInformation
+import org.apache.flink.api.java.functions.KeySelector
+import org.apache.flink.api.java.typeutils.ResultTypeQueryable
+import org.apache.flink.table.runtime.types.CRow
+import org.apache.flink.types.Row
+
+/**
+ * Null-aware key selector.
+ */
+class CRowKeySelector(
+ val keyFields: Array[Int],
+ @transient var returnType: TypeInformation[Row])
+ extends KeySelector[CRow, Row]
+ with ResultTypeQueryable[Row] {
+
+ override def getKey(value: CRow): Row = {
+ val row = value.row
+ val fields = keyFields
+
+ val newKey = new Row(fields.length)
+ var i = 0
+ while (i < fields.length) {
+ newKey.setField(i, row.getField(fields(i)))
--- End diff --
if we do that, we can also make `Row.copy()` more efficient by adding a
private constructor that receives an `Object[]` and implementing `copy()` as
`return new Row(Arrays.copyOf(row.fields, row.fields.length));`
---
