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Hadoop Sequence File
- Sample program to create a sequence file (compressed and uncompressed) from a text file, and another to read the sequence file.
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| This gist demonstrates how to create a sequence file (compressed and uncompressed), from a text file. | |
| Includes: | |
| --------- | |
| 1. Input data and script download | |
| 2. Input data-review | |
| 3. Data load commands | |
| 4. Mapper code | |
| 5. Driver code to create the sequence file out of a text file in HDFS | |
| 6. Command to run Java program | |
| 7. Results of the program run to create sequence file | |
| 8. Java program to read a sequence file, and convert to text file | |
| 9. Command to run program from #8, with results | |
| 10. Note on creating compressed sequence files | |
| 11. Driver code to create a compressed sequence file | |
| 12. Command to run program in #11 with results |
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| 01. Data and code download | |
| ----------------------------- | |
| Google: | |
| <<To be added>> | |
| Email me at airawat.blog@gmail.com if you encounter any issues | |
| gitHub: | |
| <<To be added>> | |
| Directory structure | |
| ------------------- | |
| formatProject | |
| data | |
| departments_sorted | |
| part-m-00000 | |
| formatConverterTextToSequence | |
| src | |
| FormatConverterMapper.java | |
| FormatConverterTextToSequenceDriver.java | |
| FormatConverterSequenceToTextDriver.java | |
| jars | |
| formatConverterTextToSequence.jar | |
| formatConverterSequenceToText.jar |
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| ************************************************** | |
| Input text file - departments_sorted/part-m-00000 | |
| ************************************************** | |
| $ more formatProject/data/departments_sorted/part-m-00000 | |
| d001 Marketing | |
| d002 Finance | |
| d003 Human Resources | |
| d004 Production | |
| d005 Development | |
| d006 Quality Management | |
| d007 Sales | |
| d008 Research | |
| d009 Customer Service |
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| ********************************************** | |
| hdfs load commands | |
| ********************************************** | |
| # Load data | |
| $ hadoop fs -put formatProject/ | |
| # Remove unnecessary files | |
| $ hadoop fs -rm -R formatProject/formatConverterTextToSequence/ | |
| $ hadoop fs -rm -R formatProject/formatConverterTextToMap/ |
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| /********************************************************************************************************* | |
| ** Mapper | |
| ** formatProject/FormatConverterTextToSequence/src/FormatConverterMapper.java | |
| ** Reads text file and emits the contents out as key-value pairs | |
| *********************************************************************************************************/ | |
| import java.io.IOException; | |
| import org.apache.hadoop.io.LongWritable; | |
| import org.apache.hadoop.io.Text; | |
| import org.apache.hadoop.mapreduce.Mapper; | |
| public class FormatConverterMapper extends | |
| Mapper<LongWritable, Text, LongWritable, Text> { | |
| @Override | |
| public void map(LongWritable key, Text value, Context context) | |
| throws IOException, InterruptedException { | |
| context.write(key, value); | |
| } | |
| } |
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| /********************************************************************************************************* | |
| ** Driver | |
| ** formatProject/FormatConverterTextToSequence/src/FormatConverterTextToSequenceDriver.java | |
| *********************************************************************************************************/ | |
| import org.apache.hadoop.fs.Path; | |
| import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; | |
| import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; | |
| import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat; | |
| import org.apache.hadoop.mapreduce.Job; | |
| import org.apache.hadoop.conf.Configured; | |
| import org.apache.hadoop.conf.Configuration; | |
| import org.apache.hadoop.util.Tool; | |
| import org.apache.hadoop.util.ToolRunner; | |
| public class FormatConverterTextToSequenceDriver extends Configured implements Tool { | |
| @Override | |
| public int run(String[] args) throws Exception { | |
| if (args.length != 2) { | |
| System.out.printf("Two parameters are required for FormatConverterTextToSequenceDriver-<input dir> <output dir>\n"); | |
| return -1; | |
| } | |
| Job job = new Job(getConf()); | |
| job.setJarByClass(FormatConverterTextToSequenceDriver.class); | |
| job.setJobName("Create Sequence File, from text file"); | |
| FileInputFormat.setInputPaths(job, new Path(args[0])); | |
| FileOutputFormat.setOutputPath(job, new Path(args[1])); | |
| job.setMapperClass(FormatConverterMapper.class); | |
| job.setOutputFormatClass(SequenceFileOutputFormat.class); | |
| job.setNumReduceTasks(0); | |
| boolean success = job.waitForCompletion(true); | |
| return success ? 0 : 1; | |
| } | |
| public static void main(String[] args) throws Exception { | |
| int exitCode = ToolRunner.run(new Configuration(), new FormatConverterTextToSequenceDriver(), args); | |
| System.exit(exitCode); | |
| } | |
| } |
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| ************************************************ | |
| **Command to create sequence file from text file | |
| ************************************************ | |
| $ hadoop jar formatProject/formatConverterTextToSequence/jars/formatConverterTextToSequence.jar FormatConverterTextToSequenceDriver formatProject/data/departments_sorted/part-m-00000 formatProject/data/departments_sequence | |
| . | |
| . | |
| . | |
| . | |
| $ hadoop fs -ls -R formatProject/data/departments_sequence | awk '{print $8}' | |
| formatProject/data/departments_sequence/_SUCCESS | |
| formatProject/data/departments_sequence/_logs | |
| formatProject/data/departments_sequence/_logs/history | |
| formatProject/data/departments_sequence/_logs/history/cdh-jt01_1376335706356_job_201308121428_0116_conf.xml | |
| formatProject/data/departments_sequence/_logs/history/job_201308121428_0116_1379087496898_akhanolk_Create+Sequence+File%2C+from+text+file | |
| formatProject/data/departments_sequence/part-m-00000 | |
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| ************************************************ | |
| **Results | |
| ************************************************ | |
| $ hadoop fs -text formatProject/data/departments_sequence/part-m-00000 | |
| 0 d001 Marketing | |
| 15 d002 Finance | |
| 28 d003 Human Resources | |
| 49 d004 Production | |
| 65 d005 Development | |
| 82 d006 Quality Management | |
| 106 d007 Sales | |
| 117 d008 Research | |
| 131 d009 Customer Service |
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| /********************************************************************************************************* | |
| ** Driver | |
| ** formatProject/FormatConverterTextToSequence/src/FormatConverterSequenceToTextDriver.java | |
| *********************************************************************************************************/ | |
| import org.apache.hadoop.fs.Path; | |
| import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; | |
| import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; | |
| import org.apache.hadoop.mapreduce.lib.input.SequenceFileInputFormat; | |
| import org.apache.hadoop.mapreduce.Job; | |
| import org.apache.hadoop.conf.Configured; | |
| import org.apache.hadoop.conf.Configuration; | |
| import org.apache.hadoop.util.Tool; | |
| import org.apache.hadoop.util.ToolRunner; | |
| public class FormatConverterSequenceToTextDriver extends Configured implements Tool { | |
| @Override | |
| public int run(String[] args) throws Exception { | |
| if (args.length != 2) { | |
| System.out | |
| .printf("Two parameters need to be supplied - <input dir> and <output dir>\n"); | |
| return -1; | |
| } | |
| Job job = new Job(getConf()); | |
| job.setJarByClass(FormatConverterSequenceToTextDriver.class); | |
| job.setJobName("Convert Sequence File and Output as Text"); | |
| FileInputFormat.setInputPaths(job, new Path(args[0])); | |
| FileOutputFormat.setOutputPath(job, new Path(args[1])); | |
| job.setInputFormatClass(SequenceFileInputFormat.class); | |
| job.setMapperClass(FormatConverterMapper.class); | |
| job.setNumReduceTasks(0); | |
| boolean success = job.waitForCompletion(true); | |
| return success ? 0 : 1; | |
| } | |
| public static void main(String[] args) throws Exception { | |
| int exitCode = ToolRunner.run(new Configuration(), new FormatConverterSequenceToTextDriver(), args); | |
| System.exit(exitCode); | |
| } | |
| } |
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| ************************************************************** | |
| **Command to create text file from sequence file & results | |
| ************************************************************** | |
| $ hadoop jar formatProject/formatConverterTextToSequence/jars/formatConverterSequenceToText.jar FormatConverterSequenceToTextDriver formatProject/data/departments_sequence/part-m-00000 formatProject/data/departments_text | |
| $ hadoop fs -ls -R formatProject/data/departments_text | awk '{print $8}' | |
| formatProject/data/departments_text/_SUCCESS | |
| formatProject/data/departments_text/_logs | |
| formatProject/data/departments_text/_logs/history | |
| formatProject/data/departments_text/_logs/history/cdh-jt01_1376335706356_job_201308121428_0118_conf.xml | |
| formatProject/data/departments_text/_logs/history/job_201308121428_0118_1379089420495_akhanolk_Convert+Sequence+File+and+Output+as+Text | |
| formatProject/data/departments_text/part-m-00000 | |
| $ hadoop fs -cat formatProject/data/departments_text/part-m-00000 | |
| 0 d001 Marketing | |
| 15 d002 Finance | |
| 28 d003 Human Resources | |
| 49 d004 Production | |
| 65 d005 Development | |
| 82 d006 Quality Management | |
| 106 d007 Sales | |
| 117 d008 Research | |
| 131 d009 Customer Service | |
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| ************************************************************** | |
| ** Compression and sequence files | |
| ************************************************************** | |
| To create an compressed sequence file - and block compression is the recommended option, there are just minor additions to code in the driver [formatProject/FormatConverterTextToSequence/src/FormatConverterTextToSequenceDriver.java] | |
| The sample code here uses SnappyCodec, and block compression. | |
| FileOutputFormat.setCompressOutput(job, true); | |
| FileOutputFormat.setOutputCompressorClass(job, SnappyCodec.class); | |
| SequenceFileOutputFormat.setOutputCompressionType(job,CompressionType.BLOCK); | |
| The next section includes the code. | |
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| /************************************************************************************************************* | |
| ** Driver | |
| ** formatProject/FormatConverterTextToSequence/src/FormatConverterTextToBlckCompSequenceDriver.java | |
| *************************************************************************************************************/ | |
| import org.apache.hadoop.fs.Path; | |
| import org.apache.hadoop.io.SequenceFile.CompressionType; | |
| import org.apache.hadoop.io.compress.SnappyCodec; | |
| import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; | |
| import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; | |
| import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat; | |
| import org.apache.hadoop.mapreduce.Job; | |
| import org.apache.hadoop.conf.Configured; | |
| import org.apache.hadoop.conf.Configuration; | |
| import org.apache.hadoop.util.Tool; | |
| import org.apache.hadoop.util.ToolRunner; | |
| public class FormatConverterTextToBlckCompSequenceDriver extends Configured implements Tool { | |
| @Override | |
| public int run(String[] args) throws Exception { | |
| if (args.length != 2) { | |
| System.out.printf("Two parameters are required for FormatConverterTextToBlckCompSequenceDriver-<input dir> <output dir>\n"); | |
| return -1; | |
| } | |
| Job job = new Job(getConf()); | |
| job.setJarByClass(FormatConverterTextToBlckCompSequenceDriver.class); | |
| job.setJobName("Create block compressed Sequence File, from text file"); | |
| FileInputFormat.setInputPaths(job, new Path(args[0])); | |
| FileOutputFormat.setOutputPath(job, new Path(args[1])); | |
| FileOutputFormat.setCompressOutput(job, true); | |
| FileOutputFormat.setOutputCompressorClass(job, SnappyCodec.class); | |
| job.setMapperClass(FormatConverterMapper.class); | |
| job.setOutputFormatClass(SequenceFileOutputFormat.class); | |
| SequenceFileOutputFormat.setOutputCompressionType(job,CompressionType.BLOCK); | |
| job.setNumReduceTasks(0); | |
| boolean success = job.waitForCompletion(true); | |
| return success ? 0 : 1; | |
| } | |
| public static void main(String[] args) throws Exception { | |
| int exitCode = ToolRunner.run(new Configuration(), new FormatConverterTextToBlckCompSequenceDriver(), args); | |
| System.exit(exitCode); | |
| } | |
| } |
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| ************************************************************************************* | |
| **Command to create block compressed(snappy) sequence file from text file + output | |
| ************************************************************************************* | |
| $ hadoop jar formatProject/formatConverterTextToSequence/jars/formatConverterTextToBlkCompSequence.jar FormatConverterTextToBlckCompSequenceDriver formatProject/data/departments_sorted/part-m-00000 formatProject/data/departments_sequence_blckcmp | |
| . | |
| $ hadoop fs -ls -R formatProject/data/departments_sequence_blckcmp | awk '{print $8}' | |
| formatProject/data/departments_sequence_blckcmp/_SUCCESS | |
| formatProject/data/departments_sequence_blckcmp/_logs | |
| formatProject/data/departments_sequence_blckcmp/_logs/history | |
| formatProject/data/departments_sequence_blckcmp/_logs/history/cdh-jt01_1376335706356_job_201308121428_0120_conf.xml | |
| formatProject/data/departments_sequence_blckcmp/_logs/history/job_201308121428_0120_1379091181653_akhanolk_Create+block+compressed+Sequence+File%2C+from+text+f | |
| formatProject/data/departments_sequence_blckcmp/part-m-00000 | |
| $ hadoop fs -text formatProject/data/departments_sequence_blckcmp/part-m-00000 | |
| 13/09/13 11:55:38 INFO compress.CodecPool: Got brand-new decompressor [.snappy] | |
| 13/09/13 11:55:38 INFO compress.CodecPool: Got brand-new decompressor [.snappy] | |
| 13/09/13 11:55:38 INFO compress.CodecPool: Got brand-new decompressor [.snappy] | |
| 13/09/13 11:55:38 INFO compress.CodecPool: Got brand-new decompressor [.snappy] | |
| 0 d001 Marketing | |
| 15 d002 Finance | |
| 28 d003 Human Resources | |
| 49 d004 Production | |
| 65 d005 Development | |
| 82 d006 Quality Management | |
| 106 d007 Sales | |
| 117 d008 Research | |
| 131 d009 Customer Service | |
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How do i remove character number at starting of the line for sequence file/converted text file.
eg.
0
15
28
49
65
82
etc...