pgaref commented on a change in pull request #651: URL: https://github.com/apache/orc/pull/651#discussion_r620451284
########## File path: java/core/src/java/org/apache/orc/impl/StringHashTableDictionary.java ########## @@ -0,0 +1,194 @@ +/* + * 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.orc.impl; + +import java.io.IOException; +import java.util.Arrays; + +import org.apache.hadoop.io.Text; + + +/** + * Using HashTable to represent a dictionary. The strings are stored as UTF-8 bytes + * and an offset for each entry. It is using chaining for collision resolution. + * + * This implementation is not thread-safe. It also assumes there's no reduction in the size of hash-table + * as it shouldn't happen in the use cases for this class. + */ +public class StringHashTableDictionary implements Dictionary { + + // containing all keys every seen in bytes. + private final DynamicByteArray byteArray = new DynamicByteArray(); + // containing starting offset of the key (in byte) in the byte array. + private final DynamicIntArray keyOffsets; + + private final Text newKey = new Text(); + + private DynamicIntArray[] hashBuckets; + + private int capacity; + + private int threshold; + + private float loadFactor; + + private static float DEFAULT_LOAD_FACTOR = 0.75f; + + private static final int BUCKET_SIZE = 20; Review comment: How did we come up with 20 here? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
