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Posted to reviews@spark.apache.org by hvanhovell <gi...@git.apache.org> on 2017/02/07 21:45:23 UTC
[GitHub] spark pull request #16843: [SPARK-18609][SPARK-18841][SQL] Fix redundant Ali...
GitHub user hvanhovell opened a pull request:
https://github.com/apache/spark/pull/16843
[SPARK-18609][SPARK-18841][SQL] Fix redundant Alias removal in the optimizer [Backport-2.1]
This is a backport of https://github.com/apache/spark/commit/73ee73945e369a862480ef4ac64e55c797bd7d90
## What changes were proposed in this pull request?
The optimizer tries to remove redundant alias only projections from the query plan using the `RemoveAliasOnlyProject` rule. The current rule identifies removes such a project and rewrites the project's attributes in the **entire** tree. This causes problems when parts of the tree are duplicated (for instance a self join on a temporary view/CTE) and the duplicated part contains the alias only project, in this case the rewrite will break the tree.
This PR fixes these problems by using a blacklist for attributes that are not to be moved, and by making sure that attribute remapping is only done for the parent tree, and not for unrelated parts of the query plan.
The current tree transformation infrastructure works very well if the transformation at hand requires little or a global contextual information. In this case we need to know both the attributes that were not to be moved, and we also needed to know which child attributes were modified. This cannot be done easily using the current infrastructure, and solutions typically involves transversing the query plan multiple times (which is super slow). I have moved around some code in `TreeNode`, `QueryPlan` and `LogicalPlan`to make this much more straightforward; this basically allows you to manually traverse the tree.
## How was this patch tested?
I have added unit tests to `RemoveRedundantAliasAndProjectSuite` and I have added integration tests to the `SQLQueryTestSuite.union` and `SQLQueryTestSuite.cte` test cases.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/hvanhovell/spark SPARK-18609-2.1
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/16843.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 #16843
----
commit 4f0c368b6642d1cfa524cb20de0d1b98e7c35f72
Author: Herman van Hovell <hv...@databricks.com>
Date: 2017-02-07T21:28:59Z
[SPARK-18609][SPARK-18841][SQL] Fix redundant Alias removal in the optimizer
This is a backport of https://github.com/apache/spark/commit/73ee73945e369a862480ef4ac64e55c797bd7d90
## What changes were proposed in this pull request?
The optimizer tries to remove redundant alias only projections from the query plan using the `RemoveAliasOnlyProject` rule. The current rule identifies removes such a project and rewrites the project's attributes in the **entire** tree. This causes problems when parts of the tree are duplicated (for instance a self join on a temporary view/CTE) and the duplicated part contains the alias only project, in this case the rewrite will break the tree.
This PR fixes these problems by using a blacklist for attributes that are not to be moved, and by making sure that attribute remapping is only done for the parent tree, and not for unrelated parts of the query plan.
The current tree transformation infrastructure works very well if the transformation at hand requires little or a global contextual information. In this case we need to know both the attributes that were not to be moved, and we also needed to know which child attributes were modified. This cannot be done easily using the current infrastructure, and solutions typically involves transversing the query plan multiple times (which is super slow). I have moved around some code in `TreeNode`, `QueryPlan` and `LogicalPlan`to make this much more straightforward; this basically allows you to manually traverse the tree.
## How was this patch tested?
I have added unit tests to `RemoveRedundantAliasAndProjectSuite` and I have added integration tests to the `SQLQueryTestSuite.union` and `SQLQueryTestSuite.cte` test cases.
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[GitHub] spark issue #16843: [SPARK-18609][SPARK-18841][SQL] Fix redundant Alias remo...
Posted by AmplabJenkins <gi...@git.apache.org>.
Github user AmplabJenkins commented on the issue:
https://github.com/apache/spark/pull/16843
Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/SparkPullRequestBuilder/72539/
Test PASSed.
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[GitHub] spark pull request #16843: [SPARK-18609][SPARK-18841][SQL] Fix redundant Ali...
Posted by hvanhovell <gi...@git.apache.org>.
Github user hvanhovell closed the pull request at:
https://github.com/apache/spark/pull/16843
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[GitHub] spark issue #16843: [SPARK-18609][SPARK-18841][SQL] Fix redundant Alias remo...
Posted by AmplabJenkins <gi...@git.apache.org>.
Github user AmplabJenkins commented on the issue:
https://github.com/apache/spark/pull/16843
Merged build finished. Test PASSed.
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[GitHub] spark issue #16843: [SPARK-18609][SPARK-18841][SQL] Fix redundant Alias remo...
Posted by hvanhovell <gi...@git.apache.org>.
Github user hvanhovell commented on the issue:
https://github.com/apache/spark/pull/16843
Merging this to 2.1.
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[GitHub] spark issue #16843: [SPARK-18609][SPARK-18841][SQL] Fix redundant Alias remo...
Posted by SparkQA <gi...@git.apache.org>.
Github user SparkQA commented on the issue:
https://github.com/apache/spark/pull/16843
**[Test build #72539 has started](https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/72539/testReport)** for PR 16843 at commit [`4f0c368`](https://github.com/apache/spark/commit/4f0c368b6642d1cfa524cb20de0d1b98e7c35f72).
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[GitHub] spark issue #16843: [SPARK-18609][SPARK-18841][SQL] Fix redundant Alias remo...
Posted by SparkQA <gi...@git.apache.org>.
Github user SparkQA commented on the issue:
https://github.com/apache/spark/pull/16843
**[Test build #72539 has finished](https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/72539/testReport)** for PR 16843 at commit [`4f0c368`](https://github.com/apache/spark/commit/4f0c368b6642d1cfa524cb20de0d1b98e7c35f72).
* This patch passes all tests.
* This patch merges cleanly.
* This patch adds no public classes.
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