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https://issues.apache.org/jira/browse/HBASE-1512?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13020381#comment-13020381
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jirapos...@reviews.apache.org commented on HBASE-1512:
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bq. On 2011-04-15 18:02:26, Ted Yu wrote:
bq. >
/src/main/java/org/apache/hadoop/hbase/client/coprocessor/AggregationClient.java,
line 98
bq. > <https://reviews.apache.org/r/585/diff/4/?file=15694#file15694line98>
bq. >
bq. > w.r.t. Gary's comment, we need another boolean flag in MaxCallBack
so that we can distinguish whether MaxCallBack.update() has been called.
bq. > Currently ci.getMinValue() would be returned if there is no
qualifying row (possibly due to the effect of Filter).
MaxCallBack.update() will still be called once per region, even if no rows
matched. It will just return the initial value that was set. This is why I
think the initial value should be null. So when update() is called with null,
it can be handled appropriately.
In the same vein, I think "max" in MaxCallBack should initialize to null as
well.
- Gary
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On 2011-04-13 08:37:14, Ted Yu wrote:
bq.
bq. -----------------------------------------------------------
bq. This is an automatically generated e-mail. To reply, visit:
bq. https://reviews.apache.org/r/585/
bq. -----------------------------------------------------------
bq.
bq. (Updated 2011-04-13 08:37:14)
bq.
bq.
bq. Review request for hbase and Gary Helmling.
bq.
bq.
bq. Summary
bq. -------
bq.
bq. This patch provides reference implementation for aggregate function
support through Coprocessor framework.
bq. ColumnInterpreter interface allows client to specify how the value's byte
array is interpreted.
bq. Some of the thoughts are summarized at
http://zhihongyu.blogspot.com/2011/03/genericizing-endpointcoprocessor.html
bq.
bq. Himanshu Vashishtha started the work. I provided some review comments and
some of the code.
bq.
bq.
bq. This addresses bug HBASE-1512.
bq. https://issues.apache.org/jira/browse/HBASE-1512
bq.
bq.
bq. Diffs
bq. -----
bq.
bq.
/src/main/java/org/apache/hadoop/hbase/client/coprocessor/AggregationClient.java
PRE-CREATION
bq.
/src/main/java/org/apache/hadoop/hbase/client/coprocessor/LongColumnInterpreter.java
PRE-CREATION
bq.
/src/main/java/org/apache/hadoop/hbase/coprocessor/AggregateCpProtocol.java
PRE-CREATION
bq.
/src/main/java/org/apache/hadoop/hbase/coprocessor/AggregateProtocolImpl.java
PRE-CREATION
bq.
/src/main/java/org/apache/hadoop/hbase/coprocessor/ColumnInterpreter.java
PRE-CREATION
bq. /src/test/java/org/apache/hadoop/hbase/coprocessor/TestAggFunctions.java
PRE-CREATION
bq.
bq. Diff: https://reviews.apache.org/r/585/diff
bq.
bq.
bq. Testing
bq. -------
bq.
bq. TestAggFunctions passes.
bq.
bq.
bq. Thanks,
bq.
bq. Ted
bq.
bq.
> 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-1512-3.txt, patch-1512-4.txt, patch-1512-5.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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