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From "Thomas Nielsen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-2998) Add support for ROW_NUMBER() window function
Date Tue, 28 Aug 2007 07:41:30 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2998?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12523179
] 

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

First off, we will need support for unnamed windows for this jira to be completed

I'm off on the deep end of the pool, and could use some help and/or input on completing the
prototype patch... 

I have extended the grammar, handling the row_number() function as an option in selectSubList().
Might not be the ideal place for all olap functions, but let's leave it there for the prototype
patch.

The basic idea is that bytecode is  generated for the extended QueryTreeNode classes in the
nodetree, and the bytecode will be run when the statement is actually executed after optimization.
First I tried using the count aggregate as a "template" for row_number(). I learned a lot
about how aggregates work in derby, but it weered off in the wrong direction.

Second attempt introduce a new RowNumberColumNode that extends ConstantNode, hoping to assign
an incremental number when building the ResultSet. ResultSetList.generateCore() seems to be
the place where this should be done? Is there some existing machinery that I should/can hook
into for doing the incrementation, like the autoincrement functionality for insert? Would
it be better to extend from VirtualColumnNode instead of ConstantNode since the column isn't
actually stored?

My knowledge of the inner workings of derby are still fairly limited, and there isn't really
a lot on the wiki on this except the header, so your help is greatly appreciated.

> 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
>
> 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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