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Date: Thu, 31 Oct 2013 11:24:27 -0400
Message-ID: 
 <CALEq1Z-qp5XwypKp-0Q8s6pKY12kYY27MoBYSBiiP=vv4OSM7A@mail.gmail.com>
Subject: Re: GenericDatumReader and datum reuse
From: Doug Cutting <cutting@apache.org>
To: "user@avro.apache.org" <user@avro.apache.org>
Content-Type: text/plain; charset=UTF-8

A simple approach to reuse is to pass the value previously returned from read():

GenericRecord record = null;
while (...) {
  record = reader.read(record, decoder);
  ... code that does not retain a pointer to record ...
}

Doug

On Wed, Oct 30, 2013 at 3:07 PM, kulkarni.swarnim@gmail.com
<kulkarni.swarnim@gmail.com> wrote:
> 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 = new
> GenericDatumReader<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)