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Avro >> mail # user >> GenericDatumReader and datum reuse


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GenericDatumReader and datum reuse
Hello,

While going thorough the API for GenericDatumReader, I came across this
read[1] method and it wasn't immediately clear to me as to what the "reuse"
of the datum really means.

So for instance if I have an evolving schema, should this datum be created
from the readerSchema or the writerSchema. So something like:

record = new GenericData.Record(readerSchema); // created with readerSchema

GenericDatumReader<GenericRecord> gdr newGenericDatumReader<GenericRecord>(writerSchema, readerSchema);

record = gdr.read(record, binaryDecoder);

Or is it better to simply leave it off as null?

record = gdr.read(null, binaryDecoder);
Thanks,

[1]
http://avro.apache.org/docs/1.7.4/api/java/org/apache/avro/generic/GenericDatumReader.html#read(D,
org.apache.avro.io.Decoder)
+
Doug Cutting 2013-10-31, 15:24