GitHub user saucam opened a pull request:
https://github.com/apache/spark/pull/3830
SPARK-4968: takeOrdered to skip reduce step in case mappers return no
partitions
takeOrdered should skip reduce step in case mapped RDDs have no partitions.
This prevents the mentioned exception :
4. run query
SELECT * FROM testTable WHERE market = 'market2' ORDER BY End_Time DESC
LIMIT 100;
Error trace
java.lang.UnsupportedOperationException: empty collection
at org.apache.spark.rdd.RDD$$anonfun$reduce$1.apply(RDD.scala:863)
at org.apache.spark.rdd.RDD$$anonfun$reduce$1.apply(RDD.scala:863)
at scala.Option.getOrElse(Option.scala:120)
at org.apache.spark.rdd.RDD.reduce(RDD.scala:863)
at org.apache.spark.rdd.RDD.takeOrdered(RDD.scala:1136)
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/saucam/spark fix_takeorder
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/3830.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #3830
----
commit 5974d10c619dac2ca2433d331e43ed48e6822f90
Author: Yash Datta <[email protected]>
Date: 2014-12-29T19:06:32Z
SPARK-4968: takeOrdered to skip reduce step in case mappers return no
partitions
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