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https://issues.apache.org/jira/browse/DERBY-672?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13416965#comment-13416965
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Knut Anders Hatlen commented on DERBY-672:
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The proposal doesn't say whether the class name argument itself could be a
parameterized type.
That is, could we have
public class MySum<T extends Number> implements Aggragator<T,T> { ... }
and then define aggregates for two different types using that single class
create derby aggregate int_sum for int returns int external name
'MySum<Integer>';
create derby aggregate bigint_sum for bigint returns bigint external name
'MySum<Long>';
?
Or would we have to define two separate sub-classes with fully specified types,
like
public class MyIntSum extends MySum<Integer> {}
public class MyBigintSum extends MySum<Long> {}
create derby aggregate int_sum for int returns int external name 'MyIntSum';
create derby aggregate bigint_sum for bigint returns bigint external name
'MyBigintSum';
?
> 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
>
> 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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