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From Terry Healy <the...@bnl.gov>
Subject Output from AVRO mapper
Date Thu, 20 Dec 2012 17:32:22 GMT
I'm just getting started using AVRO within Map/Reduce and trying to
convert some existing non-AVRO code to use AVRO input. So far the data
that previously was stored in tab delimited files has been converted to
.avro successfully as checked with avro-tools.

Where I'm getting hung up extending beyond my book-based examples is in
attempting to read from AVRO (using generic records) where the mapper
output is NOT in AVRO format. I can't seem to reconcile extending
AvroMapper and NOT using AvroCollector.

Here are snippets of code that show my non-AVRO M/R code and my
[failing] attempts to make this change. If anyone can help me along it
would be very much appreciated.


Pre-Avro version: (Works fine with .tsv input format)

    public static class HdFlowMapper extends MapReduceBase
            implements Mapper<Text, HdFlowWritable, LongPair,
HdFlowWritable> {

        public void map(Text key, HdFlowWritable value,
                OutputCollector<LongPair, HdFlowWritable> output,
                Reporter reporter) throws IOException {

                outKey = new LongPair(value.getSrcIp(), value.getFirst());

                HdFlowWritable outValue = value; // pass it all through
                output.collect(outKey, outValue);

AVRO attempt:


        SCHEMA = new Schema.Parser().parse(NetflowSchema);
        AvroJob.setInputSchema(conf, SCHEMA);
        //AvroJob.setOutputSchema(conf, SCHEMA);
        AvroJob.setMapperClass(conf, AvroFlowMapper.class);
        AvroJob.setReducerClass(conf, AvroFlowReducer.class);


     	public static class AvroFlowMapper<K> extends AvroMapper<K,
OutputCollector> {

	** IDE: "Method does not override or implement a method from a supertype"

        public void map(K datum, OutputCollector<LongPair,
AvroFlowWritable> collector, Reporter reporter) throws IOException {

            GenericRecord record = (GenericRecord) datum;
            afw = new AvroFlowWritable(record);
	    // ...
            collector.collect(outKey, afw);


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