GitHub user dongjoon-hyun opened a pull request:
https://github.com/apache/spark/pull/14132
[SPARK-16475][SQL] Broadcast Hint for SQL Queries
## What changes were proposed in this pull request?
Broadcast hint is a way for users to manually annotate a query and suggest
to the query optimizer the join method. It is very useful when the query
optimizer cannot make optimal decision with respect to join methods due to
conservativeness or the lack of proper statistics. The DataFrame API has
broadcast hint since Spark 1.5. However, we do not have an equivalent
functionality in SQL queries. We propose adding Hive-style broadcast hint to
Spark SQL. For more information, please see the [design
document](https://issues.apache.org/jira/secure/attachment/12817061/BroadcastHintinSparkSQL.pdf).
- [x] SUPPORT `MAPJOIN` SYNTAX
- [ ] SUPPORT `BROADCAST JOIN` SYNTAX
## How was this patch tested?
Pass the Jenkins tests with new testcases.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/dongjoon-hyun/spark SPARK-16475
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/14132.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 #14132
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commit 6bd704e5d281bd8c7a1bddaee300688d016bc597
Author: Dongjoon Hyun <dongj...@apache.org>
Date: 2016-07-11T08:04:51Z
[SPARK-16475][SQL] Broadcast Hint for SQL Queries
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