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From "Thomas Nielsen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-2998) Add support for ROW_NUMBER() window function
Date Fri, 29 Feb 2008 08:56:53 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2998?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12573639#action_12573639
] 

Thomas Nielsen commented on DERBY-2998:
---------------------------------------

I obviously have a lot to learn when it comes to writing my explainations in jira... :)

Your initial analysis is identical to what I've found, and explained in an exceptional manner.

> To make a long story short, I tried various "tweaks" (or perhaps "hacks" is a better
word) to get the virtual column ids for PRN0 to remain correct without > having to clone
SELECT's columns. In the end I couldn't find a clean way to do so.

The cloning of the RCL in PRN.genProjectRestrictNode (fragment A) was the only way out I could
find, and that again resulted in the changes 2) and 3).

I really like the fact that your "proposal" doesn't need cloning the RCL (fragment A) - makes
it all a lot cleaner.

Even though your snippet 4) feels like a hack, it might be able to pull this logic into PRN.modifyAccessPath()?
The simplified tree looks like:
    SELECT() - PRN () - SELECT() 
We then call into the PRNs modifyAccessPath(), that again calls into the lower select modifyAccessPath()
where we pull the WindowNodes up and modify the RCL. Once this is done, we could check for
the presence of a PRN->WindowNode as the top of the intial PRNs childResult, and pull the
modified RCL up into the initial PRN? By doing so I imagine we may be able to eliminate any
other problems caused by potential later/additional optimizer modifications to the querytree.
I'll give it a try at least, and see what happens.

> Add support for ROW_NUMBER() window function
> --------------------------------------------
>
>                 Key: DERBY-2998
>                 URL: https://issues.apache.org/jira/browse/DERBY-2998
>             Project: Derby
>          Issue Type: Sub-task
>          Components: SQL
>            Reporter: Thomas Nielsen
>            Assignee: Thomas Nielsen
>            Priority: Minor
>         Attachments: d2998-10.diff, d2998-10.stat, d2998-11.diff, d2998-12.diff, d2998-12.stat,
d2998-13.diff, d2998-13.stat, d2998-14.diff, d2998-14.stat, d2998-15.diff, d2998-15.stat,
d2998-16.diff, d2998-16.stat, d2998-17.diff, d2998-17.stat, d2998-18.diff, d2998-18.stat,
d2998-4.diff, d2998-4.stat, d2998-5.diff, d2998-5.stat, d2998-6.diff, d2998-6.stat, d2998-7.diff,
d2998-7.stat, d2998-8.diff, d2998-8.stat, d2998-9-derby.log, d2998-9.diff, d2998-9.stat, d2998-doc-1.diff,
d2998-doc-1.stat, d2998-test.diff, d2998-test.stat, d2998-test2.diff, d2998-test2.stat, d2998-test3.diff,
d2998-test3.stat, d2998-test4.diff, d2998-test4.stat, d2998-test6.diff, d2998-test7.diff,
d2998-test8.diff
>
>
> As part of implementing the overall OLAP Operations features of SQL (DERBY-581), implement
the ROW_NUMBER() window function.
> More information about this feature is available at http://wiki.apache.org/db-derby/OLAPRowNumber

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