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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-672) Re-enable user defined aggregates
Date Wed, 10 Oct 2012 09:41:03 GMT

    [ https://issues.apache.org/jira/browse/DERBY-672?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13473128#comment-13473128
] 

Knut Anders Hatlen commented on DERBY-672:
------------------------------------------

Two more nits:

LobMode.Accumulator.compareTo() doesn't satisfy the contract of Comparable.compareTo() in
its handling of null values. It's supposed to throw NPE if the object is null, but the implemented
method returns 1. Just removing the null check at the beginning of the method should be enough
to make it satisfy the contract.

LobMode.terminate() would be more concise if it used the Collections.max() library method.
Then we could also remove the SuppressWarnings annotation from the method, as we no longer
needed an intermediate, weakly typed array representation of the accumulators. The body of
the method could be as simple as return _accumulators.isEmpty() ? null : Collections.max(_accumulators.values()).getValue().

(Both of these comments also apply to the already existing GenericMode and ModeAggregate classes,
by the way.)
                
> Re-enable user defined aggregates
> ---------------------------------
>
>                 Key: DERBY-672
>                 URL: https://issues.apache.org/jira/browse/DERBY-672
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>            Reporter: Rick Hillegas
>            Assignee: Rick Hillegas
>         Attachments: derby-672-01-aa-ddl.diff, derby-672-02-ac-nonDistinct.diff, derby-672-03-aa-distinct.diff,
derby-672-03-ab-distinct.diff, derby-672-04-aa-fixJSR169test.diff, derby-672-05-aa-java7testOrderProblem.diff,
derby-672-06-aa-grantRevoke.diff, derby-672-07-aa-fixJSR169again.diff, derby-672-08-aa-fixJSR169yetAgain.diff,
derby-672-09-ab-udtAggregates.diff, derby-672-10-af-typeBounds.diff, derby-672-11-aa-tests.diff,
UserDefinedAggregates.html, UserDefinedAggregates.html
>
>
> Nicolas Dufour in an email thread titled "functions and list" started on November 2,
2005 requests the ability to create user defined aggregates.
> This functionality used to be in Cloudscape. It was disabled presumably because it was
considered non-standard. However, most of the machinery needed for this feature is still in
the code. We should re-enable user defined aggregates after we agree on acceptable syntax.

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