accumulo-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From David Medinets <david.medin...@gmail.com>
Subject Re: Using maxVersions=7 but rows disappear
Date Wed, 11 Apr 2012 02:51:26 GMT
I thought there were issues associated with doing mutations inside iterators?

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 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?
>

Mime
View raw message