[jira] Commented: (DERBY-2998) Add support for ROW_NUMBER() window function

["Thomas Nielsen (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DERBY-2998?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12525072 ] 

Thomas Nielsen commented on DERBY-2998:
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In ResultSetList.generateCore() - the method that actually does the work - I now handle the case of a RownumberColumnNode instance, and attempt to invoke the incrementor function in RowNumberAggregator over in exec. RowNumberAggregator extends SystemAggregator as of now. 

When execution gets to GenericPreparedStatement.getActivation() my "select row_number() from t;" fails with:

ERROR XBCM2: Cannot create an instance of generated class org.apache.derby.exe.ac601a400fx0114xd591xad7axffffe275b2700.
ERROR XJ001: Java exception: '(class: org/apache/derby/exe/ac601a400fx0114xd591xad7axffffe275b2700, method: e1 signature: ()Ljava/lang/Object;) Incompatible object argument for function call: java.lang.VerifyError'.

>From what I can tell this means I'm either missing a generated class, or I'm passing the wrong type of argument to my RowNumberAggregator incrementor method?

It would probably be good idea move the handling from ResultSetList.generateCore()  to RowNumberColumnNode.generateExpression()? 
And the incrementor would perhaps be better placed in BaseAcitvation instead?

Right now I feel like pounding nails with a shovel - you just know there's a better tool available for the job, you just have to find it...

> 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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