Github user vanzin commented on a diff in the pull request:
https://github.com/apache/spark/pull/7929#discussion_r36219965
--- Diff:
sql/hive/src/main/scala/org/apache/spark/sql/hive/client/ClientWrapper.scala ---
@@ -62,6 +63,39 @@ private[hive] class ClientWrapper(
extends ClientInterface
with Logging {
+ overrideHadoopShims()
+
+ // !! HACK ALERT !!
+ //
+ // This method is used to workaround CDH Hadoop versions like
2.0.0-mr1-cdh4.1.1.
+ //
+ // Internally, Hive `ShimLoader` tries to load different versions of
Hadoop shims by checking
+ // version information gathered from Hadoop jar files. If the major
version number is 1,
+ // `Hadoop20SShims` will be loaded. Otherwise, if the major version
number is 2, `Hadoop23Shims`
+ // will be chosen. However, CDH Hadoop versions like 2.0.0-mr1-cdh4.1.1
have 2 as major version
+ // number, but contain Hadoop 1 code. This confuses Hive `ShimLoader`
and loads wrong version of
--- End diff --
> Is it OK to assume that all these versions should be used together with
Hadoop20SShims, just like all the Hadoop 1.x.x versions?
No, that would be a wrong assumption. The first version in those strings is
the Hadoop version the artifact is based on - so `2.3.0-mr1-cdh5.1.5` would
contain, at the very least, the same API as Hadoop 2.3.0. So it should use the
2.3 shims. `mr1` here is irrelevant to identify the version of Hadoop.
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