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Date: Tue, 10 Apr 2012 22:51:26 -0400
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Subject: Re: Using maxVersions=7 but rows disappear
From: David Medinets <david.medinets@gmail.com>
To: user@accumulo.apache.org
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I thought there were issues associated with doing mutations inside iterator=
s?

On Tue, Apr 10, 2012 at 10:35 PM, William Slacum <wslacum@gmail.com> wrote:
> I don't think you'd necessarily need a an aggregator for that, although i=
t doesn't seem like that's what you're doing here in the first place. Would=
n'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 cli=
ent? That way you can have a time series and to get weekly averages you jus=
t 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=
=3D7
>> 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 [] =A0 =A08
>> row cf:cq [] =A0 =A07
>> row cf:cq [] =A0 =A06
>> row cf:cq [] =A0 =A05
>> row cf:cq [] =A0 =A04
>> row cf:cq [] =A0 =A03
>> row cf:cq [] =A0 =A02
>>
>> 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 [] =A0 =A08
>>
>> Where did the rest of the records go?
>