如何将.txt文件转换为Hadoop的序列文件格式 [英] How to convert .txt file to Hadoop's sequence file format

问题描述

为了有效地利用 Hadoop 中的map-reduce作业，我需要将数据存储在 hadoop的序列文件格式。然而，目前的数据只是平坦的.txt格式。任何人都可以建议我可以将.txt文件转换为序列文件？

To effectively utilise map-reduce jobs in Hadoop, i need data to be stored in hadoop's sequence file format. However,currently the data is only in flat .txt format.Can anyone suggest a way i can convert a .txt file to a sequence file?

推荐答案

所以方式更简单的答案只是一个具有SequenceFile输出的身份作业。


在java中看起来像这样：

So the way more simplest answer is just an "identity" job that has a SequenceFile output.

Looks like this in java:

    public static void main(String[] args) throws IOException,
        InterruptedException, ClassNotFoundException {

    Configuration conf = new Configuration();
    Job job = new Job(conf);
    job.setJobName("Convert Text");
    job.setJarByClass(Mapper.class);

    job.setMapperClass(Mapper.class);
    job.setReducerClass(Reducer.class);

    // increase if you need sorting or a special number of files
    job.setNumReduceTasks(0);

    job.setOutputKeyClass(LongWritable.class);
    job.setOutputValueClass(Text.class);

    job.setOutputFormatClass(SequenceFileOutputFormat.class);
    job.setInputFormatClass(TextInputFormat.class);

    TextInputFormat.addInputPath(job, new Path("/lol"));
    SequenceFileOutputFormat.setOutputPath(job, new Path("/lolz"));

    // submit and wait for completion
    job.waitForCompletion(true);
   }

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