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https://issues.apache.org/jira/browse/FLINK-3944?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15327693#comment-15327693
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ASF GitHub Bot commented on FLINK-3944:
---------------------------------------
GitHub user fhueske opened a pull request:
https://github.com/apache/flink/pull/2098
[revert] [FLINK-3944] [tableAPI] Reverts "Add rewrite rules to reorder
Cartesian products and joins."
This reverts commit 85793a25a78ba5be96fabc2a26569318c6b53853.
Added rewrite rules blow up search space which cannot be effectively pruned
without cardinality estimates.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/fhueske/flink tableCrossRevert
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/2098.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 #2098
----
commit df438a9fe5e9fcd191c371a888056c49aa246992
Author: Fabian Hueske <fhue...@apache.org>
Date: 2016-06-13T16:18:42Z
[revert] [FLINK-3944] [tableAPI] Reverts "Add rewrite rules to reorder
Cartesian products and joins."
This reverts commit 85793a25a78ba5be96fabc2a26569318c6b53853.
Added rewrite rules blow up search space which cannot be effectively pruned
without cardinality estimates.
----
> Add optimization rules to reorder Cartesian products and joins
> --------------------------------------------------------------
>
> Key: FLINK-3944
> URL: https://issues.apache.org/jira/browse/FLINK-3944
> Project: Flink
> Issue Type: Bug
> Components: Table API
> Affects Versions: 1.1.0
> Reporter: Fabian Hueske
> Assignee: Fabian Hueske
> Priority: Critical
> Fix For: 1.1.0
>
>
> Currently, we do not support the execution of Cartesian products.
> Because we do not optimize the order of joins (due to missing statistics),
> joins are executed in the order in which they are specified. This works well
> for the Table API, however it can be problematic in case of SQL queries where
> the order of tables in the FROM clause should not matter.
> In case of SQL queries, it can happen that the optimized plan contains
> Cartesian products because joins are not reordered. If we add optimization
> rules that switch Cartesian products and joins, such situations can be
> resolved.
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