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From Alan Gates <>
Subject Re: [VOTE] Sponsoring Howl as an Apache Incubator project
Date Thu, 03 Feb 2011 05:16:55 GMT

I understand your concern with having a copy of the metastore code in  
Howl.  However, let's separate code from governance.  The reason Howl  
has a copy of Hive's metastore is not because we're proposing it for  
the Incubator, it is because in the course of developing it over the  
last six months we've found that Howl development needs to move much  
faster than Hive development can.  This is appropriate, since Hive is  
a mature product and has at least one large customer that runs code in  
production very soon after it is checked in.  Thus the Hive community  
is rightly cautious about checking in changes to the metastore.  Howl,  
on the other hand, is new and innovating quickly, so it likes to get  
things checked in quickly.  Over the last six months every patch Howl  
has made to the Hive metastore code has made it back into Hive code.   
But it generally takes a few weeks or more to get in.

Whether Howl is a Hive subproject or an Incubator project it faces the  
same dilemma. The only other alternative that was suggested was to  
have Howl extern the metastore code from Hive and keep its patches in  
its build and apply them at build time.  But this is very fragile,  
since any changes in the Hive metastore code could invalidate all  
those patches.  We know that this is not sustainable in the long run,  
which is why the proposal calls out the need to resolve this one way  
or another as the project matures.

As far as reaching an end state where Hive and Howl are not  
compatible, we would view that as a failure for Howl.  The goal for  
Howl is to be a metastore for Pig, MapReduce, and Hive, not just 2 out  
3.  So we have a strong motivation to maintain that compatibility.

In terms of governance, given that we have significant contributions  
coming from members of the Pig team, the Hive team, and the core  
Hadoop team it seemed that giving Howl its own space in the Incubator  
made more sense than adding it as a subproject of any one of those  


On Feb 2, 2011, at 3:11 PM, Edward Capriolo wrote:

> On Wed, Feb 2, 2011 at 5:08 PM, Jeff Hammerbacher  
> <> wrote:
>> Awesome! Huge +1.
>> On Wed, Feb 2, 2011 at 1:18 PM, Alan Gates <>  
>> wrote:
>>> Howl is a table management system built to provide metadata and  
>>> storage
>>> management across data processing tools in Hadoop (Pig, Hive,  
>>> MapReduce,
>>> ...).  You can learn more details at 
>>> Howl.  For
>>> the last six months the code has been hosted at github.  The Howl  
>>> team would
>>> like to move the project into the Apache Incubator.  You can see the
>>> proposal for the project at 
>>> .
>>> In order to be accepted as an Incubator project Howl needs a  
>>> Sponsoring
>>> project.  I propose that we, the Pig project, sponsor Howl.  By  
>>> sponsoring
>>> Howl we are saying that we believe it is a good fit for the ASF  
>>> and that we
>>> will assist the Howl project to succeed.  You can read full  
>>> details of
>>> sponsoring a project at
>>> .
>>> Our bylaws don't explicitly cover such a vote, but I think lazy  
>>> majority
>>> should be reasonable.  All votes are welcome, PMC member votes  
>>> will be
>>> binding.
>>> Clearly I'm +1.
>>> Alan.
> I do think it is a great idea that hive/pig/ and map reduce share a
> meta store. However I am not sure I agree with the approach. IMHO Howl
> should be a hive sub project.
> "The initial release of Howl will allow interoperability of data
> between Pig, Map Reduce, and Hive"
> I believe the "The initial release of Howl should support hive"
> at this point hive should remove the /metastore code from inside hive
> and depend on howl.
> I say this because hive is very actively reworking the metastore right
> now for security, a new type of views, and indexes. I feel if the
> metastore branches from the hive as howl getting the two entities back
> together will be difficult. Having 99% of the same code base shared
> between hive and howl but not having compatibility between the two is
> my fear.

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