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https://issues.apache.org/jira/browse/DERBY-2998?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Thomas Nielsen updated DERBY-2998:
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Attachment: d2998-3.diff
d2998-3.stat
Attaching a new, working, but still not properly optimized, patch for the
ROW_NUMBER() implementation.
This patch inserts a OLAPNode in the QueryTree, and generates an OLAPResultSet
fetching rows from any given source ResultSet. The implementation of OLAPNode
and OLAPResultSet is based on IndexToBaseRowNode and IndexRowToBaseRowResultSet
respectively.
The missing optimization is due to the restriction (whereClause) not being
properly recognized or passed to the inner select in the ROW_NUMBER() construct:
select * from (select row_number() as r, t.* from t) as tr where r <= N;
The code in OLAPResultSet will check the restriction for all rows it sees, if
defined.
As of now, the whereClause is changed to wherePredicates before passing them to
the inner Select. But for the inner select each Predicate in the
wherePredicates have (Prediacte.)scoped=false.
Patch still not intended for commit...
> 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: d2998-3.diff, d2998-3.stat,
> row_number_prototype-2c.diff, row_number_prototype-2c.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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