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Hive, mail # dev - Tez branch and tez based patches


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Re: Tez branch and tez based patches
Alan Gates 2013-07-16, 00:37

On Jul 13, 2013, at 9:48 AM, Edward Capriolo wrote:

> I have started to see several re factoring patches around tez.
> https://issues.apache.org/jira/browse/HIVE-4843
>
> This is the only mention on the hive list I can find with tez:
> "Makes sense. I will create the branch soon.
>
> Thanks,
> Ashutosh
>
>
> On Tue, Jun 11, 2013 at 7:44 PM, Gunther Hagleitner <
> [EMAIL PROTECTED]> wrote:
>
>> Hi,
>>
>> I am starting to work on integrating Tez into Hive (see HIVE-4660, design
>> doc has already been uploaded - any feedback will be much appreciated).
>> This will be a fair amount of work that will take time to stabilize/test.
>> I'd like to propose creating a branch in order to be able to do this
>> incrementally and collaboratively. In order to progress rapidly with this,
>> I would also like to go "commit-then-review".
>>
>> Thanks,
>> Gunther.
>> "
>
> These refactor-ings are largely destructive to a number of bugs and
> language improvements in hive.The language improvements and bug fixes that
> have been sitting in Jira for quite some time now marked patch-available
> and are waiting for review.
>
> There are a few things I want to point out:
> 1) Normally we create design docs in out wiki (which it is not)
> 2) Normally when the change is significantly complex we get multiple
> committers to comment on it (which we did not)
> On point 2 no one -1  the branch, but this is really something that should
> have required a +1 from 3 committers.

The Hive bylaws,  https://cwiki.apache.org/confluence/display/Hive/Bylaws , lay out what votes are needed for what.  I don't see anything there about needing 3 +1s for a branch.  Branching would seem to fall under code change, which requires one vote and a minimum length of 1 day.

>
> I for one am not completely sold on Tez.
> http://incubator.apache.org/projects/tez.html.
> "directed-acyclic-graph of tasks for processing data" this description
> sounds like many things which have never become popular. One to think of is
> oozie "Oozie Workflow jobs are Directed Acyclical Graphs (DAGs) of
> actions.". I am sure I can find a number of libraries/frameworks that make
> this same claim. In general I do not feel like we have done our homework
> and pre-requisites to justify all this work. If we have done the homework,
> I am sure that it has not been communicated and accepted by hive developers
> at large.

A request for better documentation on Tez and a project road map seems totally reasonable.

>
> If we have a branch, why are we also committing on trunk? Scanning through
> the tez doc the only language I keep finding language like "minimal changes
> to the planner" yet, there is ALREADY lots of large changes going on!
>
> Really none of the above would bother me accept for the fact that these
> "minimal changes" are causing many "patch available" ready-for-review bugs
> and core hive features to need to be re based.
>
> I am sure I have mentioned this before, but I have to spend 12+ hours to
> test a single patch on my laptop. A few days ago I was testing a new core
> hive feature. After all the tests passed and before I was able to commit,
> someone unleashed a tez patch on trunk which caused the thing I was testing
> for 12 hours to need to be rebased.
>
>
> I'm not cool with this.Next time that happens to me I will seriously
> consider reverting the patch. Bug fixes and new hive features are more
> important to me then integrating with incubator projects.

(With my Apache member hat on)  Reverting patches that aren't breaking the build is considered very bad form in Apache.  It does make sense to request that when people are going to commit a patch that will break many other patches they first give a few hours of notice so people can say something if they're about to commit another patch and avoid your fate of needing to rerun the tests.  The other thing is we need to get get the automated build of patches working on Hive so committers are forced to run all of the tests themselves.  We are working on it, but we're not there yet.

Alan.