GitHub user jinxing64 opened a pull request: https://github.com/apache/spark/pull/18713
[SPARK-21509][SQL] Add a config to enable adaptive query execution only for the last que⦠## What changes were proposed in this pull request? Feature of adaptive query execution is a good way to avoid generating too many small files on HDFS, like mentioned in SPARK-16188. When feature of adaptive query execution is enabled, all shuffles will be coordinated. The drawbacks: 1. It's hard to balance the num of reducers(this decides the processing speed) and file size on HDFS 2. It generates some more shuffles(https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/exchange/EnsureRequirements.scala#L101) 3. It generates lots of jobs, which have extra cost for scheduling. We can add a config and enable adaptive query execution only for the last shuffle. ## How was this patch tested? Unit test. You can merge this pull request into a Git repository by running: $ git pull https://github.com/jinxing64/spark SPARK-21509 Alternatively you can review and apply these changes as the patch at: https://github.com/apache/spark/pull/18713.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 #18713 ---- commit efb8cd36de0e0b96a8efe855b6243c1f553ce195 Author: jinxing <jinxing6...@126.com> Date: 2017-07-22T04:22:36Z Add a config to enable adaptive query execution only for the last query execution. ---- --- If your project is set up for it, you can reply to this email and have your reply appear on GitHub as well. If your project does not have this feature enabled and wishes so, or if the feature is enabled but not working, please contact infrastructure at infrastruct...@apache.org or file a JIRA ticket with INFRA. --- --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org