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From "Rick Hillegas (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-672) Re-enable user defined aggregates
Date Fri, 22 Mar 2013 14:07:24 GMT

     [ https://issues.apache.org/jira/browse/DERBY-672?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Rick Hillegas updated DERBY-672:
--------------------------------

    Attachment: derby-672-22-aa-makeModeAggregateStateSerializable.diff

Attaching derby-672-22-aa-makeModeAggregateStateSerializable.diff. This patch makes a helper
class Serializable. The helper class is used by the test class ModeAggregate. The UserDefinedAggregatesTest
runs cleanly for me with this patch. Committed at subversion revision 1459784.

I discovered that the helper class needs to be Serializable while writing experiments to try
to force Derby to perform the merge() phase of aggregation. In my experiment, a grouped aggregate
with millions of groups ended up serializing partial results to disk and this tripped across
the unserializability of the helper class. It would be worthwhile to file an issue to add
some advice to the Reference Manual: the Aggregator interface extends Serializable, which
means that all of the state in your UDA needs to be serializable.

Touches the following file:

M       java/testing/org/apache/derbyTesting/functionTests/tests/lang/ModeAggregate.java

                
> 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: d672-no-exceptions.diff, 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, derby-672-11-ab-tests.diff, derby-672-12-aa-implicitCasts.diff,
derby-672-13-aa-differentReturnType.diff, derby-672-14-aa-collations.diff, derby-672-15-aa-setCollation.diff,
derby-672-16-aa-forbidInGroupBy.diff, derby-672-17-aa-moreTests.diff, derby-672-18-aa-udaInJar.diff,
derby-672-19-aa-precisionChecks.diff, derby-672-20-aa-exactBounds.diff, derby-672-21-aa-typeDependencies.diff,
derby-672-22-aa-makeModeAggregateStateSerializable.diff, UserDefinedAggregates.html, UserDefinedAggregates.html,
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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