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Accumulo >> mail # user >> Using maxVersions=7 but rows disappear


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Re: Using maxVersions=7 but rows disappear
I don't think you'd necessarily need a an aggregator for that, although it doesn't seem like that's what you're doing here in the first place. Wouldn't it be easier to set a summation iterator that also keeps a count of of observations to do some server side math and then combine it all on the client? That way you can have a time series and to get weekly averages you just change your scan range.
On Apr 10, 2012, at 10:16 PM, David Medinets wrote:

> I'm still thinking about how to use accumulo to calculate weekly
> moving averages. I thought that using the maxVersions settings might
> work to maintain the last 7 values. Then a program could simply sum
> the values of a given row. So this is what I did:
>
> bin/accumulo shell -u root -p password
>> createtable rolling
> rolling> config -t rolling -s table.iterator.scan.vers.opt.maxVersions=7
> rolling> insert row cf cq 1
> rolling> insert row cf cq 2
> rolling> insert row cf cq 3
> rolling> insert row cf cq 4
> rolling> insert row cf cq 5
> rolling> insert row cf cq 6
> rolling> insert row cf cq 7
> rolling> insert row cf cq 8
> rolling> scan
> row cf:cq []    8
> row cf:cq []    7
> row cf:cq []    6
> row cf:cq []    5
> row cf:cq []    4
> row cf:cq []    3
> row cf:cq []    2
>
> This is exactly what I wanted to see. So I wrote a simple scanner
> program to read the table. Then I did another scan:
>
> rolling> scan
> row cf:cq []    8
>
> Where did the rest of the records go?