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From "Thomas Nielsen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-2998) Add support for ROW_NUMBER() window function
Date Mon, 08 Oct 2007 11:46:50 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2998?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12533104
] 

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

Working my way through the optimization of the simple query:
   select * from (select row_number() as r, t.* from t) as tr where r < 2;
I see that during preprocessing the WHERE clause is converted to a PredicateList. The predicate
BinaryOperatorNode (my '<' lessThan) is successfully categorize()'d as pushable, which
is a good thing!
However, ProjectRestrictNode.pushExpressionsIntoSelect() in PRN.pushExpressions() does not
do anything. I would have thought this was where the predicate would be pushed into the select
subquery.
As a side note DERBY-649 seems to have fixed a similar issue by pushing predicates into UnionNodes.
Investigation ongoing.

> 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: row_number_prototype-2b.diff, row_number_prototype-2b.stat
>
>
> 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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