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https://issues.apache.org/jira/browse/HBASE-1512?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ted Yu updated HBASE-1512:
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Attachment: AggregateCpProtocol.java
AggregateProtocolImpl.java
AggregationClient.java
ColumnInterpreter.java
Reattaching.
My attempt is to allow client to pass column interpreter to region server.
Still more work to be done to make the return type of column interpreter
generic.
Also, column interpreter doesn't have access to table name currently. This may
be minor issue because user can enforce uniform naming convention to map column
name to actual type.
TestAggFunctions passes.
> Coprocessors: Support aggregate functions
> -----------------------------------------
>
> Key: HBASE-1512
> URL: https://issues.apache.org/jira/browse/HBASE-1512
> Project: HBase
> Issue Type: Sub-task
> Components: coprocessors
> Reporter: stack
> Attachments: 1512.zip, AggregateCpProtocol.java,
> AggregateProtocolImpl.java, AggregationClient.java, ColumnInterpreter.java,
> patch-1512-2.txt, patch-1512.txt
>
>
> Chatting with jgray and holstad at the kitchen table about counts, sums, and
> other aggregating facility, facility generally where you want to calculate
> some meta info on your table, it seems like it wouldn't be too hard making a
> filter type that could run a function server-side and return the result ONLY
> of the aggregation or whatever.
> For example, say you just want to count rows, currently you scan, server
> returns all data to client and count is done by client counting up row keys.
> A bunch of time and resources have been wasted returning data that we're not
> interested in. With this new filter type, the counting would be done
> server-side and then it would make up a new result that was the count only
> (kinda like mysql when you ask it to count, it returns a 'table' with a count
> column whose value is count of rows). We could have it so the count was
> just done per region and return that. Or we could maybe make a small change
> in scanner too so that it aggregated the per-region counts.
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