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From "Vyacheslav Zholudev (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (AVRO-969) Make possible usage of SpecificDatumWriter in avro-mapred
Date Tue, 06 Dec 2011 18:25:39 GMT

    [ https://issues.apache.org/jira/browse/AVRO-969?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13163727#comment-13163727
] 

Vyacheslav Zholudev commented on AVRO-969:
------------------------------------------

Yes, it should, but it does not for me (see AVRO-966) - can somebody confirm that it is a
bug or my misusage of avro specific objects? 
Also I thought that using SpecificDatumWriter rather than ReflectDatumWriter might be more
efficient for specific objects since generated methods can be used instead of reflection.
                
> Make possible usage of SpecificDatumWriter in avro-mapred
> ---------------------------------------------------------
>
>                 Key: AVRO-969
>                 URL: https://issues.apache.org/jira/browse/AVRO-969
>             Project: Avro
>          Issue Type: Improvement
>          Components: java
>    Affects Versions: 1.6.1
>            Reporter: Vyacheslav Zholudev
>
> I realized that ReflectDatumWriter is always used when running mapred job (in AvroOutputFormat.java).
Sometimes it leads to bugs like in AVRO-966.
> Why not just provide a property like {{WRITER_IS_REFLECT = "avro.map.writer.is.reflect";}}
to make a decision which DatumWriter should be used. 
> I created a small patch to solve this:
> {code:title=avro-mapred.patch|borderStyle=solid}
> Index: lang/java/mapred/src/main/java/org/apache/avro/mapred/AvroJob.java
> ===================================================================
> --- lang/java/mapred/src/main/java/org/apache/avro/mapred/AvroJob.java  (revision 1209417)
> +++ lang/java/mapred/src/main/java/org/apache/avro/mapred/AvroJob.java  (revision )
> @@ -53,6 +53,8 @@
>    /** The configuration key for reflection-based map output representation. */
>    public static final String MAP_OUTPUT_IS_REFLECT = "avro.map.output.is.reflect";
>  
> +  public static final String WRITER_IS_REFLECT = "avro.map.writer.is.reflect";
> +
>    /** Configure a job's map input schema. */
>    public static void setInputSchema(JobConf job, Schema s) {
>      job.set(INPUT_SCHEMA, s.toString());
> Index: lang/java/mapred/src/main/java/org/apache/avro/mapred/AvroOutputFormat.java
> ===================================================================
> --- lang/java/mapred/src/main/java/org/apache/avro/mapred/AvroOutputFormat.java (revision
1209417)
> +++ lang/java/mapred/src/main/java/org/apache/avro/mapred/AvroOutputFormat.java (revision
)
> @@ -23,6 +23,7 @@
>  import java.util.Map;
>  import java.net.URLDecoder;
>  
> +import org.apache.avro.specific.SpecificDatumWriter;
>  import org.apache.hadoop.io.NullWritable;
>  import org.apache.hadoop.fs.FileSystem;
>  import org.apache.hadoop.fs.Path;
> @@ -102,8 +103,9 @@
>        ? AvroJob.getMapOutputSchema(job)
>        : AvroJob.getOutputSchema(job);
>  
> -    final DataFileWriter<T> writer =
> -      new DataFileWriter<T>(new ReflectDatumWriter<T>());
> +    final DataFileWriter<T> writer = job.getBoolean(AvroJob.WRITER_IS_REFLECT,
false) ?
> +      new DataFileWriter<T>(new ReflectDatumWriter<T>()) :
> +      new DataFileWriter<T>(new SpecificDatumWriter<T>());
>      
>      configureDataFileWriter(writer, job);
> {code}
> Does it make sense? 

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