GitHub user liancheng opened a pull request:
https://github.com/apache/spark/pull/15565
[DO NOT MERGE][17972][SQL] Another try of PR #15517
## What changes were proposed in this pull request?
This is another try of PR #15517, which aims to solve the exponential slow
down of query planning time. It's still a PoC. I'm opening this PR to check
whether Jenkins complains.
This PR adds a new method `Dataset.cached`, which returns a new Dataset
with a cached version of the logical plan of the current Dataset, so that we
can truncate the cached sub plan tree.
The existing `Dataset.cache()` method doesn't fit because it mutates inner
states of the current Dataset.
The microbenchmark results are basically the same with the one described in
#15517.
## How was this patch tested?
N/A. Existing tests should be enough.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/liancheng/spark fix-slow-planning-2
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/15565.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 #15565
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commit 0fea96b92114ff7e58ac4b80974231c06ea540c8
Author: Cheng Lian <[email protected]>
Date: 2016-10-20T08:49:45Z
Add Dataset.cached
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