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https://issues.apache.org/jira/browse/TAJO-774?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14003823#comment-14003823
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ASF GitHub Bot commented on TAJO-774:
-------------------------------------
GitHub user hyunsik opened a pull request:
https://github.com/apache/tajo/pull/13
TAJO-774: Implement logical plan part and physical executor for window
function.
This patch adds the logical planning part, distributed planning part, and
sort-based window aggregation physical executors. They enables Tajo to use
existing aggregation functions in OVER clause and add row_number() and rank().
This implementation has some limits. First of all, this patch does not
support multiple different partition key groups in a query.
Example:
```
SELECT rank OVER(PARTITION BY P ORDER BY K), avg OVER( PARTITION BY P) ...
```
In above case, a query contains two OVER clauses which have the same
PARTITION KEY group. So, it becomes available in this patch. But, the following
case is not available.
```
SELECT rank OVER(PARTITION BY P ORDER BY K), avg OVER( PARTITION BY W) ...
```
In addition, there is one limit. This patch does not support the definition
clause for window specification. I'll add this feature later.
The followings are examples provided by this patch.
```
SELECT sum(l_quantity) OVER () FROM LINEITEM
SELECT l_orderkey, l_quantity, sum(l_quantity) OVER (PARTITION BY
l_orderkey) FROM LINEITEM
SELECT l_orderkey, l_discount, sum(l_discount) OVER (PARTITION BY
l_orderkey), sum(l_quantity) OVER (PARTITION BY l_orderkey) FROM
LINEITEM
SELECT l_orderkey, l_partkey, rank() OVER (ORDER BY l_orderkey) r1, rank()
OVER(ORDER BY l_partkey desc) r2 FROM LINEITEM
```
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/hyunsik/tajo TAJO-774_2
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/tajo/pull/13.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 #13
----
commit 95d1026043d711156e6d3ea62eacf8a9552fff7c
Author: Hyunsik Choi <[email protected]>
Date: 2014-05-20T18:34:18Z
TAJO-774: Implement logical plan part and physical executor for window
function.
----
> Implement logical plan part and physical executor for window function.
> ----------------------------------------------------------------------
>
> Key: TAJO-774
> URL: https://issues.apache.org/jira/browse/TAJO-774
> Project: Tajo
> Issue Type: Sub-task
> Components: planner/optimizer
> Reporter: Hyunsik Choi
> Assignee: Hyunsik Choi
> Fix For: 0.9.0
>
>
> See the title. The main objective of this issue is to implement the logical
> planning part for window function support.
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