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From "A B (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-2998) Add support for ROW_NUMBER() window function
Date Tue, 26 Feb 2008 16:50:51 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2998?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12572556#action_12572556
] 

A B commented on DERBY-2998:
----------------------------

I have not had a chance to look at patch 17 yet, but I just had some follow-up feedback based
on your recent comments:

> I'm not too satisfied with the variable name 'level' but it was the best I could think
of...

I think even something naive like "windowFunctionLevel" would be fine for now.  I'd rather
avoid the generic name "level" since there is already a "level" field that exists in FromTable.java,
of which WindowNode is an indirect subclass (so if you're debugging, two different "level"
fields show up).

> That again calls into the chain of WindowResultSets and PRNs, and eventually
> ends up in a a BulkTableScanResultSet.getNextRowCore() or similar to
> actually fetch *one* row.

If the intent is to fetch exactly *one* row, then would it be beneficial  to disable bulk
fetching on the base table?  Otherwise, WindowResultSet may only want to fetch a single a
row but, due to bulk fetching, we could end up with 16 (or whatever the bulk size is).  Not
a huge problem by any means, but a potential point for improvement if you haven't already
dealt with it (maybe you have and I just missed it).

> It seems we don't take the fact that we know we have an ascending column
> into consideration any more (we used to). I'll have to have another look at this.

Is this something that has been fixed with patch 17?  Or is it still work in progress? (I
haven't tried it out yet).

> 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, d2998-4.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
>
>
> 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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