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Review request for hive and Xuefu Zhang. Bugs: HIVE-8262 https://issues.apache.org/jira/browse/HIVE-8262 Repository: hive-git Description ------- In a few cases we need to cache a RDD to avoid recompute it for better performance. However, caching a map input RDD is different from caching a regular RDD due to SPARK-3693. The way to cache a Hadoop RDD, which is the input to MapWork, is to cache, the result RDD that is transformed from the original Hadoop RDD by applying a map function, in which <key, value> pairs are copied. To cache intermediate RDDs, such as that from a shuffle, is just calling .cache(). This task is to create a CacheTran to capture this, which can be used to plug in Spark Plan when caching is desirable. Diffs ----- ql/src/java/org/apache/hadoop/hive/ql/exec/spark/CachedTran.java PRE-CREATION Diff: https://reviews.apache.org/r/26181/diff/ Testing ------- Thanks, Chao Sun