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From Chris Douglas <cdoug...@apache.org>
Subject Re: [VOTE] Direction for Hadoop development
Date Mon, 06 Dec 2010 18:40:37 GMT
SequenceFile is an experimental file format; as long as it continues
to support existing data, I see no reason to block its continued
evolution. TFile is also part of the common project. The project could
support still more, provided the tools and documentation were
available to help users select the one that fits their use case.

This question is backwards. If the assertion is that a part of the
framework's development should be arrested, that claim requires a
discussion and vote. The PMC should not have to weigh in on allowing
code to change. -C

On Mon, Dec 6, 2010 at 9:16 AM, Owen O'Malley <oom@yahoo-inc.com> wrote:
> On Dec 1, 2010, at 11:11 AM, Owen O'Malley wrote:
> All,
>   We really need some guidance on the general direction for the project.
> Please comment and/or vote. If no one cares, then I'll probably commit it to
> Yahoo's internal branch.
> -- Owen
>> The question is how the Hadoop project wants to move forward.
>> It was motivated by Doug's veto of HADOOP-6685, which was based on his
>> personal decisions about how the project should go forward and not on
>> anything that had been decided by the PMC.
>> These decisions are much more important to MapReduce, which is a
>> framework, than HDFS which is a client/server model.
>> 1. Should Hadoop include a user-facing library of useful code?
>> There has been a suggestion that user-facing library code, such as
>> SequenceFile, TFile, DistCp, etc. should be deprecated and that Hadoop
>> should allow third party projects like Avro to supply the user-facing
>> library code that makes Hadoop usable. I think it is critical that we keep
>> those components as part of Hadoop and extend them as the framework evolves.
>> Users depend heavily on SequenceFile for storing their data in Hadoop and
>> they should not  be deprecated as Doug has suggested.
>> 2. Should MapReduce support non-Writables through the pipeline out of the
>> box?
>> There has also been a discussion about whether we should support
>> non-Writables natively. There is already library code in Avro that lets
>> users use Avro types in a custom MapReduce API. A general MapReduce API that
>> encompasses all of the serialization frameworks and does not lock users into
>> a particular one is much more powerful.
>> Furthermore, making it convenient for the users, by including the plugins
>> in the default configuration and class path, will enable the use of Avro,
>> Thrift and ProtoBuf objects by people who would rather not focus on
>> serialization. Avro and Writables should not be the only first class
>> serializations that Hadoop supports by default.
>> 3. Should a framework dependency on ProtoBuf be allowed?
>> Doug has added several framework dependences on Avro. The question is
>> whether it is acceptable to use the ProtoBuf library in the framework. Avro
>> is good for uses where there are a lot of objects of the same type. ProtoBuf
>> is better for small number of objects. The question is whether Avro, JSON,
>> and XML should be the only serialization libraries that are acceptable to
>> use in the framework.

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