Major Description
We want to use Pig to process arbitrary Avro data and store results as Avro files. AvroStorage() extends two PigFuncs: LoadFunc and StoreFunc.
Due to discrepancies of Avro and Pig data models, AvroStorage has:
1. Limited support for "record": we do not support recursively defined record because the number of fields in such records is data dependent.
2. Limited support for "union": we only accept nullable union like ["null", "some-type"].
For simplicity, we also make the following assumptions:
If the input directory is a leaf directory, then we assume Avro data files in it have the same schema;
If the input directory contains sub-directories, then we assume Avro data files in all sub-directories have the same schema.
AvroStorage takes no input parameters when used as a LoadFunc (except for "debug [debug-level]").
Users can provide parameters to AvroStorage when used as a StoreFunc. If they don't, Avro schema of output data is derived from its
Pig schema.
Detailed documentation can be found in http://linkedin.jira.com/wiki/display/HTOOLS/AvroStorage+-+Pig+support+for+Avro+data