| import{_ as d,C as s,O as l,P as r,ah as o,Q as e,U as t,ai as n,aW as a}from"./framework-e4340ccd.js";const u={},c=a('<h2 id="hadoop-tsfile" tabindex="-1"><a class="header-anchor" href="#hadoop-tsfile" aria-hidden="true">#</a> Hadoop-TsFile</h2><p>TsFile 的 Hadoop 连接器实现了对 Hadoop 读取外部 Tsfile 类型的文件格式的支持。让用户可以使用 Hadoop 的 map、reduce 等操作对 Tsfile 文件进行读取、写入和查询。</p><p>有了这个连接器,用户可以</p><ul><li>将单个 Tsfile 文件加载进 Hadoop,不论文件是存储在本地文件系统或者是 HDFS 中</li><li>将某个特定目录下的所有文件加载进 Hadoop,不论文件是存储在本地文件系统或者是 HDFS 中</li><li>将 Hadoop 处理完后的结果以 Tsfile 的格式保存</li></ul><h3 id="系统环境要求" tabindex="-1"><a class="header-anchor" href="#系统环境要求" aria-hidden="true">#</a> 系统环境要求</h3><table><thead><tr><th>Hadoop 版本</th><th>Java 版本</th><th>TsFile 版本</th></tr></thead><tbody><tr><td><code>2.7.3</code></td><td><code>1.8</code></td><td><code>1.0.0+</code></td></tr></tbody></table>',6),v={href:"https://github.com/apache/iotdb/tree/master/tsfile",target:"_blank",rel:"noopener noreferrer"},b=a(`<h3 id="数据类型对应关系" tabindex="-1"><a class="header-anchor" href="#数据类型对应关系" aria-hidden="true">#</a> 数据类型对应关系</h3><table><thead><tr><th>TsFile 数据类型</th><th>Hadoop writable</th></tr></thead><tbody><tr><td>BOOLEAN</td><td>BooleanWritable</td></tr><tr><td>INT32</td><td>IntWritable</td></tr><tr><td>INT64</td><td>LongWritable</td></tr><tr><td>FLOAT</td><td>FloatWritable</td></tr><tr><td>DOUBLE</td><td>DoubleWritable</td></tr><tr><td>TEXT</td><td>Text</td></tr></tbody></table><h3 id="关于-tsfinputformat-的说明" tabindex="-1"><a class="header-anchor" href="#关于-tsfinputformat-的说明" aria-hidden="true">#</a> 关于 TSFInputFormat 的说明</h3><p>TSFInputFormat 继承了 Hadoop 中 FileInputFormat 类,重写了其中切片的方法。</p><p>目前的切片方法是根据每个 ChunkGroup 的中点的 offset 是否属于 Hadoop 所切片的 startOffset 和 endOffset 之间,来判断是否将该 ChunkGroup 放入此切片。</p><p>TSFInputFormat 将 tsfile 中的数据以多个<code>MapWritable</code>记录的形式返回给用户。</p><p>假设我们想要从 Tsfile 中获得名为<code>d1</code>的设备的数据,该设备有三个传感器,名称分别为<code>s1</code>, <code>s2</code>, <code>s3</code>。</p><p><code>s1</code>的类型是<code>BOOLEAN</code>, <code>s2</code>的类型是 <code>DOUBLE</code>, <code>s3</code>的类型是<code>TEXT</code>.</p><p><code>MapWritable</code>的结构如下所示:</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>{ |
| "time_stamp": 10000000, |
| "device_id": d1, |
| "s1": true, |
| "s2": 3.14, |
| "s3": "middle" |
| } |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>在 Hadoop 的 Map job 中,你可以采用如下方法获得你想要的任何值</p><p><code>mapwritable.get(new Text("s1"))</code></p><blockquote><p>注意:<code>MapWritable</code>中所有的键值类型都是<code>Text</code>。</p></blockquote><h3 id="使用示例" tabindex="-1"><a class="header-anchor" href="#使用示例" aria-hidden="true">#</a> 使用示例</h3><h4 id="读示例-求和" tabindex="-1"><a class="header-anchor" href="#读示例-求和" aria-hidden="true">#</a> 读示例:求和</h4><p>首先,我们需要在 TSFInputFormat 中配置我们需要哪些数据</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>// configure reading time enable |
| TSFInputFormat.setReadTime(job, true); |
| // configure reading deviceId enable |
| TSFInputFormat.setReadDeviceId(job, true); |
| // configure reading which deltaObjectIds |
| String[] deviceIds = {"device_1"}; |
| TSFInputFormat.setReadDeviceIds(job, deltaObjectIds); |
| // configure reading which measurementIds |
| String[] measurementIds = {"sensor_1", "sensor_2", "sensor_3"}; |
| TSFInputFormat.setReadMeasurementIds(job, measurementIds); |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>然后,必须指定 mapper 和 reducer 输出的键和值类型</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>// set inputformat and outputformat |
| job.setInputFormatClass(TSFInputFormat.class); |
| // set mapper output key and value |
| job.setMapOutputKeyClass(Text.class); |
| job.setMapOutputValueClass(DoubleWritable.class); |
| // set reducer output key and value |
| job.setOutputKeyClass(Text.class); |
| job.setOutputValueClass(DoubleWritable.class); |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>接着,就可以编写包含具体的处理数据逻辑的<code>mapper</code>和<code>reducer</code>类了。</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>public static class TSMapper extends Mapper<NullWritable, MapWritable, Text, DoubleWritable> { |
| |
| @Override |
| protected void map(NullWritable key, MapWritable value, |
| Mapper<NullWritable, MapWritable, Text, DoubleWritable>.Context context) |
| throws IOException, InterruptedException { |
| |
| Text deltaObjectId = (Text) value.get(new Text("device_id")); |
| context.write(deltaObjectId, (DoubleWritable) value.get(new Text("sensor_3"))); |
| } |
| } |
| |
| public static class TSReducer extends Reducer<Text, DoubleWritable, Text, DoubleWritable> { |
| |
| @Override |
| protected void reduce(Text key, Iterable<DoubleWritable> values, |
| Reducer<Text, DoubleWritable, Text, DoubleWritable>.Context context) |
| throws IOException, InterruptedException { |
| |
| double sum = 0; |
| for (DoubleWritable value : values) { |
| sum = sum + value.get(); |
| } |
| context.write(key, new DoubleWritable(sum)); |
| } |
| } |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div>`,21),m={href:"https://github.com/apache/iotdb/blob/master/example/hadoop/src/main/java/org/apache/iotdb/hadoop/tsfile/TSFMRReadExample.java",target:"_blank",rel:"noopener noreferrer"},p=a(`<h3 id="写示例-计算平均数并写入-tsfile-中" tabindex="-1"><a class="header-anchor" href="#写示例-计算平均数并写入-tsfile-中" aria-hidden="true">#</a> 写示例:计算平均数并写入 Tsfile 中</h3><p>除了<code>OutputFormatClass</code>,剩下的配置代码跟上面的读示例是一样的</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>job.setOutputFormatClass(TSFOutputFormat.class); |
| // set reducer output key and value |
| job.setOutputKeyClass(NullWritable.class); |
| job.setOutputValueClass(HDFSTSRecord.class); |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>然后,是包含具体的处理数据逻辑的<code>mapper</code>和<code>reducer</code>类。</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>public static class TSMapper extends Mapper<NullWritable, MapWritable, Text, MapWritable> { |
| |
| @Override |
| protected void map(NullWritable key, MapWritable value, |
| Mapper<NullWritable, MapWritable, Text, MapWritable>.Context context) |
| throws IOException, InterruptedException { |
| |
| Text deltaObjectId = (Text) value.get(new Text("device_id")); |
| long timestamp = ((LongWritable)value.get(new Text("timestamp"))).get(); |
| if (timestamp % 100000 == 0) { |
| context.write(deltaObjectId, new MapWritable(value)); |
| } |
| } |
| } |
| |
| /** |
| * This reducer calculate the average value. |
| */ |
| public static class TSReducer extends Reducer<Text, MapWritable, NullWritable, HDFSTSRecord> { |
| |
| @Override |
| protected void reduce(Text key, Iterable<MapWritable> values, |
| Reducer<Text, MapWritable, NullWritable, HDFSTSRecord>.Context context) throws IOException, InterruptedException { |
| long sensor1_value_sum = 0; |
| long sensor2_value_sum = 0; |
| double sensor3_value_sum = 0; |
| long num = 0; |
| for (MapWritable value : values) { |
| num++; |
| sensor1_value_sum += ((LongWritable)value.get(new Text("sensor_1"))).get(); |
| sensor2_value_sum += ((LongWritable)value.get(new Text("sensor_2"))).get(); |
| sensor3_value_sum += ((DoubleWritable)value.get(new Text("sensor_3"))).get(); |
| } |
| HDFSTSRecord tsRecord = new HDFSTSRecord(1L, key.toString()); |
| DataPoint dPoint1 = new LongDataPoint("sensor_1", sensor1_value_sum / num); |
| DataPoint dPoint2 = new LongDataPoint("sensor_2", sensor2_value_sum / num); |
| DataPoint dPoint3 = new DoubleDataPoint("sensor_3", sensor3_value_sum / num); |
| tsRecord.addTuple(dPoint1); |
| tsRecord.addTuple(dPoint2); |
| tsRecord.addTuple(dPoint3); |
| context.write(NullWritable.get(), tsRecord); |
| } |
| } |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div>`,5),h={href:"https://github.com/apache/iotdb/blob/master/example/hadoop/src/main/java/org/apache/iotdb/hadoop/tsfile/TSMRWriteExample.java",target:"_blank",rel:"noopener noreferrer"};function x(g,T){const i=s("ExternalLinkIcon");return l(),r("div",null,[o(` |
| |
| 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. |
| |
| `),c,e("blockquote",null,[e("p",null,[t("注意:关于如何下载和使用 Tsfile, 请参考以下链接:"),e("a",v,[t("https://github.com/apache/iotdb/tree/master/tsfile"),n(i)]),t(".")])]),b,e("blockquote",null,[e("p",null,[t("注意:完整的代码示例可以在如下链接中找到:"),e("a",m,[t("https://github.com/apache/iotdb/blob/master/example/hadoop/src/main/java/org/apache/iotdb/hadoop/tsfile/TSFMRReadExample.java"),n(i)])])]),p,e("blockquote",null,[e("p",null,[t("注意:完整的代码示例可以在如下链接中找到:"),e("a",h,[t("https://github.com/apache/iotdb/blob/master/example/hadoop/src/main/java/org/apache/iotdb/hadoop/tsfile/TSMRWriteExample.java"),n(i)])])])])}const _=d(u,[["render",x],["__file","MapReduce-TsFile.html.vue"]]);export{_ as default}; |