Github user tillrohrmann commented on a diff in the pull request: https://github.com/apache/flink/pull/1465#discussion_r47903615 --- Diff: flink-staging/flink-table/src/main/scala/org/apache/flink/api/table/typeinfo/RowComparator.scala --- @@ -0,0 +1,468 @@ +/* + * 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.api.table.typeinfo + +import java.util + +import org.apache.flink.api.common.typeutils.base.BasicTypeComparator +import org.apache.flink.api.common.typeutils.{CompositeTypeComparator, TypeComparator, TypeSerializer} +import org.apache.flink.api.java.typeutils.runtime.TupleComparatorBase +import org.apache.flink.api.table.Row +import org.apache.flink.api.table.typeinfo.NullMaskUtils.readIntoNullMask +import org.apache.flink.api.table.typeinfo.RowComparator.NullChecker +import org.apache.flink.core.memory.{MemorySegment, DataOutputView, DataInputView} +import org.apache.flink.types.{KeyFieldOutOfBoundsException, NullKeyFieldException} + +/** + * Comparator for [[Row]]. + */ +class RowComparator private ( + /** key positions describe which fields are keys in what order */ + val keyPositions: Array[Int], + /** comparators for the key fields, in the same order as the key fields */ + val comparators: Array[TypeComparator[_]], + /** serializers to deserialize the first n fields for comparison */ + val serializers: Array[TypeSerializer[_]], + /** auxiliary fields for normalized key support */ + private var normalizedKeyLengths: Array[Int], + private var numLeadingNormalizableKeys: Int, + private var normalizableKeyPrefixLen: Int, + private var invertNormKey: Boolean) + extends CompositeTypeComparator[Row] with Serializable { + + // null masks for serialized comparison + private val nullMask1 = new Array[Boolean](serializers.length) + private val nullMask2 = new Array[Boolean](serializers.length) + + // cache for the deserialized key field objects + @transient + private var deserializedKeyFields1: Array[Any] = null --- End diff -- We could make this an `Option` to get rid of the `null` value.
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