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From "Bryan Pendleton (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-2998) Add support for ROW_NUMBER() window function
Date Tue, 28 Aug 2007 16:35:32 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2998?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12523273
] 

Bryan Pendleton commented on DERBY-2998:
----------------------------------------

Thomas, thanks for posting your findings so far. Knowing what doesn't work can
be very useful, and is certainly worth recording. We will all be doing a lot of learning
about Derby; that's the fun of open source!

Here's a suggestion: perhaps you could investigate how "expressions" are computed,
by tracing through the compilation and execution of statements such as:

  select substring(last_name from 1 for 10) from employee

  select case when age < 21 then 'minor' else 'adult' end from dependents

  select cost + cost * 0.0825 as cost_including_taxes from sales_history

Can
  select row_number(), last_name, emp_id from employee
be modeled in the same fashion?

I agree that eventually we will have to consider the "window" concept to have a true
implementation of this feature, but perhaps to start we can just build a simple
scalar function that has reasonable behavior for its particular result set, and see
what we can learn from that prototype implementation.



> 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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