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https://issues.apache.org/jira/browse/FLINK-2678?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15133937#comment-15133937
]
ASF GitHub Bot commented on FLINK-2678:
---------------------------------------
Github user tillrohrmann commented on a diff in the pull request:
https://github.com/apache/flink/pull/1566#discussion_r51997479
--- Diff:
flink-core/src/main/java/org/apache/flink/api/java/typeutils/runtime/ObjectArrayComparator.java
---
@@ -0,0 +1,199 @@
+/*
+ * 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.java.typeutils.runtime;
+
+import org.apache.flink.api.common.typeutils.TypeComparator;
+import org.apache.flink.api.common.typeutils.TypeSerializer;
+import org.apache.flink.core.memory.DataInputView;
+import org.apache.flink.core.memory.DataOutputView;
+import org.apache.flink.core.memory.MemorySegment;
+
+import java.io.IOException;
+import java.lang.reflect.Array;
+import java.util.Arrays;
+
+
+public class ObjectArrayComparator<T,C> extends TypeComparator<T[]>
implements java.io.Serializable {
+
+ private static final long serialVersionUID = 1L;
+
+ private transient T[] reference;
+
+ protected final boolean ascendingComparison;
+
+ private final TypeSerializer<T[]> serializer;
+
+ private TypeComparator<? super Object> comparatorInfo;
+
+ // For use by getComparators
+ @SuppressWarnings("rawtypes")
+ private final TypeComparator[] comparators = new TypeComparator[]
{this};
+
+ public ObjectArrayComparator(boolean ascending, TypeSerializer<T[]>
serializer, TypeComparator<? super Object> comparatorInfo) {
+ this.ascendingComparison = ascending;
+ this.serializer = serializer;
+ this.comparatorInfo = comparatorInfo;
+ }
+
+ @Override
+ public void setReference(T[] reference) {
+ this.reference = reference;
+ }
+
+ @Override
+ public boolean equalToReference(T[] candidate) {
+ return compare(this.reference, candidate) == 0;
+ }
+
+ @Override
+ public int compareToReference(TypeComparator<T[]> referencedComparator)
{
+ int comp = compare(((ObjectArrayComparator<T,C>)
referencedComparator).reference, reference);
+ return comp;
+ }
+
+ @Override
+ public int compareSerialized(DataInputView firstSource, DataInputView
secondSource) throws IOException {
+ T[] firstArray = serializer.deserialize(firstSource);
+ T[] secondArray = serializer.deserialize(secondSource);
+
+ int comp = compare(firstArray, secondArray);
+ return comp;
+ }
+
+ @Override
+ public int extractKeys(Object record, Object[] target, int index) {
+ target[index] = record;
+ return 1;
+ }
+
+ @Override
+ public TypeComparator[] getFlatComparators() {
+ return comparators;
+ }
+
+ @Override
+ public boolean supportsNormalizedKey() {
+ return false;
+ }
+
+ @Override
+ public boolean supportsSerializationWithKeyNormalization() {
+ return false;
+ }
+
+ @Override
+ public int getNormalizeKeyLen() {
+ return 0;
+ }
+
+ @Override
+ public boolean isNormalizedKeyPrefixOnly(int keyBytes) {
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public void putNormalizedKey(T[] record, MemorySegment target, int
offset, int numBytes) {
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public void writeWithKeyNormalization(T[] record, DataOutputView
target) throws IOException {
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public T[] readWithKeyDenormalization(T[] reuse, DataInputView source)
throws IOException {
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public boolean invertNormalizedKey() {
+ return !ascendingComparison;
+ }
+
+ @Override
+ public int hash(T[] record) {
+ return Arrays.hashCode(record);
+ }
+
+ private int compareValues(Object first, Object second) {
+ /**
+ * uses the chosen comparator ( of primitive or composite type
) & compares the provided objects as input
+ */
+ return comparatorInfo.compare(first, second);
+ }
+
+ @SuppressWarnings("unchecked")
+ private int parseGenericArray(Object firstArray, Object secondArray) {
--- End diff --
I think this is not the right way to go. Simply check then length of the
arrays in the `compare` method and then call for all the elements the type
comparator of the element type of the array.
> DataSet API does not support multi-dimensional arrays as keys
> -------------------------------------------------------------
>
> Key: FLINK-2678
> URL: https://issues.apache.org/jira/browse/FLINK-2678
> Project: Flink
> Issue Type: Wish
> Components: DataSet API
> Reporter: Till Rohrmann
> Assignee: Subhobrata Dey
> Priority: Minor
>
> The DataSet API does not support grouping/sorting on field which are
> multi-dimensional arrays. It could be helpful to also support these types.
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