GitHub user cloud-fan opened a pull request:
https://github.com/apache/spark/pull/18559
[SPARK-21335][SQL] support un-aliased subquery
## What changes were proposed in this pull request?
un-aliased subquery is supported by Spark SQL for a long time. Its semantic
was not well defined and had confusing behaviors, and it's not a standard SQL
syntax, so we disallowed it in
https://issues.apache.org/jira/browse/SPARK-20690 .
However, this is a breaking change, and we do have existing queries using
un-aliased subquery. We should add the support back and fix its semantic.
This PR fixes the un-aliased subquery by assigning a default alias name.
## How was this patch tested?
new regression test
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/cloud-fan/spark sub-query
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/18559.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 #18559
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commit 4d99c11802efa2d6ee5c36de5941226bf12e1a55
Author: Wenchen Fan <[email protected]>
Date: 2017-07-07T04:03:34Z
support un-aliased subquery
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