GitHub user liancheng opened a pull request: https://github.com/apache/spark/pull/12527
[SPARK-14369][SQL] Locality support for FileScanRDD (This PR is a rebased version of PR #12153.) ## What changes were proposed in this pull request? This PR adds preliminary locality support for `FileFormat` data sources by overriding `FileScanRDD.preferredLocations()`. The strategy can be divided into two parts: 1. Block location lookup Unlike `HadoopRDD` or `NewHadoopRDD`, `FileScanRDD` doesn't have access to the underlying `InputFormat` or `InputSplit`, and thus can't rely on `InputSplit.getLocations()` to gather locality information. Instead, this PR queries block locations using `FileSystem.getBlockLocations()` after listing all `FileStatus`es in `HDFSFileCatalog` and convert all `FileStatus`es into `LocatedFileStatus`es. Note that although S3/S3A/S3N file systems don't provide valid locality information, their `getLocatedStatus()` implementations don't actually issue remote calls either. So there's no need to special case these file systems. 2. Selecting preferred locations For each `FilePartition`, we pick up top 3 locations that containing the most data to be retrieved. This isn't necessarily the best algorithm out there. Further improvements may be brought up in follow-up PRs. ## How was this patch tested? Tested by overriding default `FileSystem` implementation for `file:///` with a mocked one, which returns mocked block locations. You can merge this pull request into a Git repository by running: $ git pull https://github.com/liancheng/spark spark-14369-locality-rebased Alternatively you can review and apply these changes as the patch at: https://github.com/apache/spark/pull/12527.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 #12527 ---- commit 0358e33c1a796b7875f932c4d4aee28db505f696 Author: Cheng Lian <l...@databricks.com> Date: 2016-04-20T13:25:51Z Rebased PR #12153 ---- --- 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