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https://issues.apache.org/jira/browse/CASSANDRA-8053?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14195994#comment-14195994
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Robert Stupp commented on CASSANDRA-8053:
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forgot to mention:
Via {{state-type}} and {{final-type}} people can use UDT or tuple types or
collections (see CASSANDRA-7563) for the state - so they have plenty of room
for their temporary data.
It's discussable whether we should allow some "generic" {{any}} type for the
{{state-type}}, if {{final-type}} is present - for example to allow people to
use e.g. {{java.util.HashMap}} as the state variable type. Could be expressed
by omitting {{STYPE <type>}} and requiring {{FINALFUNC}} + {{FINALTYPE <type>}}
then.
The state is always passed as a parameter named {{state}} into the state and
final functions.
> Support for user defined aggregate functions
> --------------------------------------------
>
> Key: CASSANDRA-8053
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8053
> Project: Cassandra
> Issue Type: New Feature
> Reporter: Robert Stupp
> Assignee: Robert Stupp
> Labels: cql, udf
> Fix For: 3.0
>
>
> CASSANDRA-4914 introduces aggregate functions.
> This ticket is about to decide how we can support "user defined aggregate
> functions". UD aggregate functions should be supported for all UDF flavors
> (class, java, jsr223).
> Things to consider:
> * Special implementations for each scripting language should be omitted
> * No exposure of internal APIs (e.g. {{AggregateFunction}} interface)
> * No need for users to deal with serializers / codecs
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