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From Ted Yu <yuzhih...@gmail.com>
Subject Re: groupby(prefix(rowkey)) with multiple custom aggregated columns
Date Fri, 07 Aug 2015 21:19:14 GMT
Please take a look
at hbase-client/src/main/java/org/apache/hadoop/hbase/client/coprocessor/AggregationClient.java
which shows several other aggregations.

BTW group by functionality would involve some more work since rows for the
same group may span multiple regions.


On Fri, Aug 7, 2015 at 9:42 AM, Nicolae Marasoiu <nicolae.marasoiu@gmail.com
> wrote:

> Hi,
> I need to implement a limited sql like filter+group+order, and the group is
> on a fixed-length prefix of the rowkey (fixed per query), and the results
> are multiple metrics including some custom ones like statistical unique
> counts.
> I noticed that available tooling with coprocessors, like
> ColumnAggregationProtocol, involve just one metric e.g. one sum(column). We
> collect many, and of course it is more efficient to scan the data once.
> Please advise,
> Nicu

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