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https://issues.apache.org/jira/browse/BEAM-5074?focusedWorklogId=131177&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-131177
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ASF GitHub Bot logged work on BEAM-5074:
----------------------------------------
Author: ASF GitHub Bot
Created on: 04/Aug/18 06:54
Start Date: 04/Aug/18 06:54
Worklog Time Spent: 10m
Work Description: amaliujia opened a new pull request #6145:
[BEAM-5074][SQL] improve BeamSqlRowComparator
URL: https://github.com/apache/beam/pull/6145
Refactoring BeamSqlRowComparator a bit to make it can return comparison
results in either natural order or reversed order.
In the past, BeamSqlRowComparator only returned comparison results in
reversed order. It was because BeamSortRel only supports `ORDER BY LIMIT` by
using `Top` (`Top` by default returns elements in descending order). For
example, if there is a query `SELECT * FROM table ORDER BY id ASC LIMIT 1`,
and assuming there are two rows in table with id `1` and `2` separately, in
order to return the right result by using `Top`, `BeamSqlRowComparator` have
to tell `Top` that the row with id `1` is bigger (which means comparator
returns in reversed order).
In order to support `ORDER BY ASC` and ORDER BY DESC`, there is a need to
have a comparator that returns in natural order (if 1 < 2, then returns -1 to
indicate 1 < 2). So in this PR, BeamSqlRowComparator is changed to achieve
this goal.
------------------------
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Post-Commit Tests Status (on master branch)
------------------------------------------------------------------------------------------------
Lang | SDK | Apex | Dataflow | Flink | Gearpump | Samza | Spark
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Go | [](https://builds.apache.org/job/beam_PostCommit_Go_GradleBuild/lastCompletedBuild/)
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Java | [](https://builds.apache.org/job/beam_PostCommit_Java_GradleBuild/lastCompletedBuild/)
| [](https://builds.apache.org/job/beam_PostCommit_Java_ValidatesRunner_Apex_Gradle/lastCompletedBuild/)
| [](https://builds.apache.org/job/beam_PostCommit_Java_ValidatesRunner_Dataflow_Gradle/lastCompletedBuild/)
| [](https://builds.apache.org/job/beam_PostCommit_Java_ValidatesRunner_Flink_Gradle/lastCompletedBuild/)
| [](https://builds.apache.org/job/beam_PostCommit_Java_ValidatesRunner_Gearpump_Gradle/lastCompletedBuild/)
| [](https://builds.apache.org/job/beam_PostCommit_Java_ValidatesRunner_Samza_Gradle/lastCompletedBuild/)
| [](https://builds.apache.org/job/beam_PostCommit_Java_ValidatesRunner_Spark_Gradle/lastCompletedBuild/)
Python | [](https://builds.apache.org/job/beam_PostCommit_Python_Verify/lastCompletedBuild/)
| --- | [](https://builds.apache.org/job/beam_PostCommit_Py_VR_Dataflow/lastCompletedBuild/)
</br> [](https://builds.apache.org/job/beam_PostCommit_Py_ValCont/lastCompletedBuild/)
| --- | --- | --- | ---
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Issue Time Tracking
-------------------
Worklog Id: (was: 131177)
Time Spent: 10m
Remaining Estimate: 0h
> Make BeamSqlRowComparator more general
> --------------------------------------
>
> Key: BEAM-5074
> URL: https://issues.apache.org/jira/browse/BEAM-5074
> Project: Beam
> Issue Type: Improvement
> Components: dsl-sql
> Reporter: Rui Wang
> Assignee: Rui Wang
> Priority: Major
> Time Spent: 10m
> Remaining Estimate: 0h
>
> BeamSqlRowComparator returns reversed comparison results (if a < b in terms
> of value, BeamSqlRowComparator returns a > b).
>
> Add a flag to turn on/off this reversed effect. The reason of doing this is
> to help implement ORDER BY ASC/DESC in the normal way.
>
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