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SPARK-1770: Load balance elements when repartitioning. #727
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This patch adds better balancing when performing a repartition of an RDD. Previously the elements in the RDD were hash partitioned, meaning if the RDD was skewed certain partitions would end up being very large. This commit adds load balancing of elements across the repartitioned RDD splits. The load balancing is not perfect: a given output partition can have up to N more elements than the average if there are N input partitions. However, some randomization is used to minimize the probabiliy that this happens.
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This patch adds better balancing when performing a repartition of an RDD. Previously the elements in the RDD were hash partitioned, meaning if the RDD was skewed certain partitions would end up being very large. This commit adds load balancing of elements across the repartitioned RDD splits. The load balancing is not perfect: a given output partition can have up to N more elements than the average if there are N input partitions. However, some randomization is used to minimize the probabiliy that this happens. Author: Patrick Wendell <[email protected]> Closes #727 from pwendell/load-balance and squashes the following commits: f9da752 [Patrick Wendell] Response to Matei's feedback acfa46a [Patrick Wendell] SPARK-1770: Load balance elements when repartitioning. (cherry picked from commit 7d9cc92) Signed-off-by: Patrick Wendell <[email protected]>
Merged build finished. All automated tests passed. |
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This patch adds better balancing when performing a repartition of an RDD. Previously the elements in the RDD were hash partitioned, meaning if the RDD was skewed certain partitions would end up being very large. This commit adds load balancing of elements across the repartitioned RDD splits. The load balancing is not perfect: a given output partition can have up to N more elements than the average if there are N input partitions. However, some randomization is used to minimize the probabiliy that this happens. Author: Patrick Wendell <[email protected]> Closes apache#727 from pwendell/load-balance and squashes the following commits: f9da752 [Patrick Wendell] Response to Matei's feedback acfa46a [Patrick Wendell] SPARK-1770: Load balance elements when repartitioning.
…MapRFileSystem not found for spark-hive integration jobs (apache#727)
…MapRFileSystem not found for spark-hive integration jobs (apache#727)
…MapRFileSystem not found for spark-hive integration jobs (apache#727)
This patch adds better balancing when performing a repartition of an
RDD. Previously the elements in the RDD were hash partitioned, meaning
if the RDD was skewed certain partitions would end up being very large.
This commit adds load balancing of elements across the repartitioned
RDD splits. The load balancing is not perfect: a given output partition
can have up to N more elements than the average if there are N input
partitions. However, some randomization is used to minimize the
probabiliy that this happens.