[
https://issues.apache.org/jira/browse/PHOENIX-139?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Gabriel Reid resolved PHOENIX-139.
----------------------------------
Resolution: Fixed
Bulk resolve of closed issues imported from GitHub. This status was reached by
first re-opening all closed imported issues and then resolving them in bulk.
> Support COUNT DISTINCT
> ----------------------
>
> Key: PHOENIX-139
> URL: https://issues.apache.org/jira/browse/PHOENIX-139
> Project: Phoenix
> Issue Type: Task
> Reporter: James Taylor
> Assignee: Anoop Sam John
> Labels: enhancement
>
> Supporting COUNT DISTINCT will require returning more state to the client for
> the final merge operation. For this case, we need to keep a map in the
> aggregation coprocessors of each distinct value and their count. Then the key
> of the rows returned by the coprocessor will include the bytes of the
> distinct value. The merge on the client side would more or less stay the
> same, since the client merge (GroupedAggregatingResultIterator) is doing a
> final aggregation based on the keys of the rows it sees.
> Another additional built-in function that could be added would be an
> approximate count distinct function - there are some interesting algorithms
> for this used by other open source projects.
--
This message was sent by Atlassian JIRA
(v6.2#6252)
