Github user srowen commented on a diff in the pull request:
https://github.com/apache/spark/pull/7929#discussion_r36174915
--- 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 --
If you look at Hadoop releases, you'll find
`getPathWithoutSchemeAndAuthority` in Hadoop 2.1, but not Hadoop 2.0. So, the
CDH release is "correct", and this comment is incorrect. I think the reason
point is just that this isn't the correct condition to check to detect Hadoop
2.0, if that's really the intent.
However it seems like there are bigger problems if Hadoop 2.0 code is
activated by looking for Hadoop 1 code? and failing that, Hadoop 2.3 code is
used for any 2.x release? maybe there's just a naming issue here.
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