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https://issues.apache.org/jira/browse/STORM-1434?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15422735#comment-15422735
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Arun Mahadevan commented on STORM-1434:
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[~kabhwan]
Trident supports two kinds of aggregates on grouped streams,
aggregate - aggregates on each group within a batch
persistentAggregate - aggregates across batches (using the underlying state)
May be you can do an aggregate per batch (window being the batch boundary)
which fits with how you would run a group-by query on a regular table
I am not sure how would you represent a persistentAggregate operation in SQL.
May be something along the lines of INSERT into state(key, count) select key,
count(key) from stream group by key ON DUPLICATE KEY set key = key + count
> Support the GROUP BY clause in StormSQL
> ---------------------------------------
>
> Key: STORM-1434
> URL: https://issues.apache.org/jira/browse/STORM-1434
> Project: Apache Storm
> Issue Type: New Feature
> Components: storm-sql
> Reporter: Haohui Mai
>
> This jira tracks the effort of implement the support `GROUP BY` clause in
> StormSQL.
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