GitHub user scwf opened a pull request: https://github.com/apache/spark/pull/4354
[SPARK-5583][SQL][WIP] Support unique join in hive context Support unique join in hive context, the basic idea is transform unique join into outer join + filter in spark sql: FROM UNIQUEJOIN [PRESERVE] T1 a (a.key), [PRESERVE] T2 b (b.key), [PRESERVE] T3 c (c.key) ... If all the tables have PRESERVE keyword ==> T1 full out join T2 full out join T3 ... else If all the tables do not have PRESERVE keyword => T1 inner join T2 inner join T3 ... else ==> T = (T1 full out join T2 full out join T3 ...) Filter on T, filter condition = keep the rows with any preserve field is not null. for examples: 1 T1 a (a.key), PRESERVE T2 b (b.key), PRESERVE T3 c (c.key) ==> if b.key is not null or c.key is not null, we'll keep the row 2 T1 a (a.key), T2 b (b.key), PRESERVE T3 c (c.key) ==> if c.key is not null we'll keep the row Correct me if i am wrong. todos: add tests for this You can merge this pull request into a Git repository by running: $ git pull https://github.com/scwf/spark unique-join Alternatively you can review and apply these changes as the patch at: https://github.com/apache/spark/pull/4354.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 #4354 ---- commit b7e89a94cbeddcb53aac779d4b9d7de2d94e0325 Author: wangfei <wangf...@huawei.com> Date: 2015-02-03T05:29:09Z support unique join in hive context ---- --- 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