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From Keith Turner <ke...@deenlo.com>
Subject Re: timestamp order
Date Tue, 23 Apr 2013 11:59:49 GMT
On Mon, Apr 22, 2013 at 8:59 PM, Venkat <rkreddy@gmail.com> wrote:

> It looks like versioningiterator gives me the past versions for a cell
>  .... but I need to look across rows ..
>
> I am inserting time series data for set of machines into accumulo and i am
> using a combo of machineid + timestamp as the row ID and metric as the cq.
>  So for me to get the last time a metric has been inserted for an asset, i
> need to look across row IDs and get the last 5 rows that got inserted with
> that metric ...
>

You could consider sorting your data such that the most recent timestamps
come first.   If you insert (machineid + (999999999999 - timestamp)).   To
get the 5 most recent row, start scanning at (machineid + 999999999999) and
stop when you have 5 rows.   I picked a completely arbitrary number of 9's
for the example, not sure what time resolution its appropriate for.


>
>
>
> On Mon, Apr 22, 2013 at 2:48 PM, Billie Rinaldi <billie.rinaldi@gmail.com>wrote:
>
>> You could use a VersioningIterator with maxVersions set to 5.
>>
>> Billie
>>
>>
>>
>> On Mon, Apr 22, 2013 at 11:29 AM, Venkat <rkreddy@gmail.com> wrote:
>>
>>> hello accumulo,
>>>
>>> what is a good way to get rows in chronological order ?   i am trying to
>>> get to a use case of "give me the last 5 inserted for this particular cf,
>>> cq ..."  timestampfilter works well when I know the times but i dont know
>>> the exact times of insertion.
>>>
>>
>>
>

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