Hi,

> However, up to now, we could use these artifacts with Hadoop 3.0 and they
> worked. (Or we just didn't hit the incompatibilities in our test suite.)

I have a question reg Phoenix 5.x supporting Hadoop 3 only.
I believe this means Phoenix 5.x cannot work with HBase 2.x that
is compiled with Hadoop 2.x (HBase 2.x will have Hadoop 2
jars in classpath whereas Phoenix 5.x requires Hadoop 3 jars).
Is this correct?

If this is correct, shall we not support Hadoop 2 because HBase 2
still has default Hadoop profile: 2.0? Moreover, what is the root 
cause behind Phoenix 5.x only supporting Hadoop 3.x?
As per the compatibility guidelines [1], HBase 2.3 is fully compatible
with Hadoop 2.10.x.

Apologies for these questions might be repeated ones but 
somehow I still could not trace back the root cause.


1. https://hbase.apache.org/book.html#basic.prerequisites


On 2020/07/07 08:39:23, Istvan Toth <[email protected]> wrote: 
> Hi!
> 
> (https://issues.apache.org/jira/browse/PHOENIX-5993 is open for this, but I
> am repeating it here for greater visibility)
> 
> The HBase artifacts downloadable from maven central are built with Hadoop
> 2.x
> 
> However, up to now, we could use these artifacts with Hadoop 3.0 and they
> worked. (Or we just didn't hit the incompatibilities in our test suite.)
> 
> This seems to have changed with 2.2.5, as the public maven artifact doesn't
> work with Hadoop 3.0.3 or 3.1.2 .
> 
> This is a known issue in HBase, and documented, but this means that
> 
> Any client JAR we'd build with Hbase 2.2.5 would have the same problem.
> We cannot run our tests with Hbase 2.2.5
> HBase's suggested solution is to rebuild HBase with the Hadoop version used
> in the cluster, and use that. This, however, doesn't fit into our test or
> distribution process.
> 
> I'm looking for your input on how to fix this.
> 
> The options I could think of are:
> 
> - Ask HBase to fix it for us (it doesn't seem to be a priority)
>  - HBase could publish artifacts for Hadoop3
>  - Or could try to stick the common subset of Hadoop APIs
> - Re-publish the official HBase releases built with Hadoop 3 under the
> org.apache.phoenix groupId
> - Hack up our build system to rebuild HBase from source, and use that for
> Phoenix
> 
> None of these are particularly compelling, but I expect that this will have
> to be solved somehow if we want to keep up with future Hadoop releases.
> 
> Looking forward to hearing your ideas and opinion on this
> 
> Istvan
> 

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