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HBase, mail # dev - HBase .92 maven artifacts compiled against different releases of Hadoop


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Re: HBase .92 maven artifacts compiled against different releases of Hadoop
Gary Helmling 2011-11-11, 19:04
> Some effort was put into restore and forward porting features to ensure HBase 0.90.x and Hadoop 0.20.205.0 can work together.  I recommend that one HBase release should be certified for one major release of Hadoop to reduce risk.  Perhaps when public Hadoop API are rock solid, then it will become feasible to have a version of HBase that work across multiple version of Hadoop.

Since 0.20.205.0 is the build default, a lot of the testing will
naturally take place on this combination.  But there are clearly
others interested in (and investing a lot of testing effort in)
running on 0.22 and 0.23, so we can't exclude those as unsupported.

>
> In proposed HBase structure layout change (HBASE-4337), the packaging process excludes inclusion of Hadoop jar file, and pick up from constructed class path.  In the effort of ensuring Hadoop related technology can work together in integrated fashion (File system layout change in HADOOP-6255).

This is good, when the packaging system supports flexible enough
dependencies to allow different Hadoop versions to satisfy the package
"Depends:", but I don't think it gets us all the way there.

We still want to provide tarball distributions that contain a bundled
Hadoop jar for easy standalone setup and testing.

Maven dependencies seem to be the other limiting factor.  If I setup a
java program that uses the HBase client and declare that dependency, I
get a transitive dependency on Hadoop (good), but what version?  If
I'm running Hadoop 0.22, but the published maven artifact for HBase
depends on 205, can I override that dependency in my POM?  Or do we
need to publish separate maven artifacts for each Hadoop version, so
that the dependencies for each possible combination can be met (using
versioning or the version classifier)?

I really don't know enough about maven dependency management.  Can we
specify a version like (0.20.205.0|0.22|0.23)?  Or is there any way
for Hadoop to do a "Provides:" on a virtual package name that those 3
can share?

--gh