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From "Andrew Purtell (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HBASE-1512) Coprocessors: Filter/aggregate functions
Date Wed, 16 Dec 2009 00:13:18 GMT

     [ https://issues.apache.org/jira/browse/HBASE-1512?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Andrew Purtell updated HBASE-1512:
----------------------------------

    Summary: Coprocessors: Filter/aggregate functions  (was: New filter type: a filter that
can return results that it has fabricated (use for doing sum, count, etc.))

> Coprocessors: Filter/aggregate functions
> ----------------------------------------
>
>                 Key: HBASE-1512
>                 URL: https://issues.apache.org/jira/browse/HBASE-1512
>             Project: Hadoop HBase
>          Issue Type: Sub-task
>            Reporter: stack
>
> 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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