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Hadoop, mail # general - 0.20.2 HDFS incompatible with 0.20.1


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Todd Lipcon 2010-01-05, 19:29
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Allen Wittenauer 2010-01-05, 20:06
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Owen OMalley 2010-01-05, 22:06
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Re: 0.20.2 HDFS incompatible with 0.20.1
Sanjay Radia 2010-01-06, 00:39

On Jan 5, 2010, at 2:06 PM, Owen O'Malley wrote:

>
> On Jan 5, 2010, at 11:29 AM, Todd Lipcon wrote:
>
> > 1) Although we certainly do not guarantee wire compatibility between
> > minor
> > versions (0.20 -> 0.21) have we previously implied wire  
> compatibility
> > between bugfix releases?
>
> Correction. Pre-1.0, the 0.N to 0.N+1 is a major upgrade. After 1.0,
> 1.N to 1.N+1 is a minor. In both cases, X.Y.z to X.Y.z+1 is a patch
> release.
>
> I thought we had it documented somewhere, but can't find it. There is
> some discussion of compatibility in HADOOP-5071 that should be pulled
> out into a wiki page.
>
Hadoop-5071 documents the *proposed* post 1.0 rules quite well.

>
> The standing rules are that you don't incompatibly break APIs or wire
> protocols in patch release. So, this patch violates the rule and
> should have had a vote called before it was applied to branch-0.20.
> (And arguably branch-0.21, although since it hasn't been released, it
> isn't nearly the same level or problem.
>
> > 2) Is the above something we *should* be guaranteeing already?
>
> Patch releases:
>    1. Must be backwards API compatible without a client recompile.
>    2. Must be on the wire compatible.
>
> Exceptions require a vote of the committers. We should also put a
> notice of any exceptions at the top of the release notes.
>
This is also my understanding of the current rules.
For patch releases,  the current pre-1.0 rules and the *proposed*  
post-1.0 rules in Hadoop-5071 are the same - no breakage of APIs or  
wire protocol in a patch release.
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Doug Cutting 2010-01-06, 16:10
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Jean-Daniel Cryans 2010-01-06, 18:23
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Owen OMalley 2010-01-06, 18:26
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Dhruba Borthakur 2010-01-06, 18:31
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Owen OMalley 2010-01-06, 18:33
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Todd Lipcon 2010-01-06, 18:54
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Allen Wittenauer 2010-01-06, 20:00
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Sanjay Radia 2010-01-06, 21:36