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From Ioakim Perros <imper...@gmail.com>
Subject Re: Retrieving 2 separate timestamps' values
Date Tue, 28 Aug 2012 01:41:46 GMT
Unfortunately the way I am reading/writing data from/to parts of my table would be incompatible
with this solution. 

In any case, thank you very much for your time.

On Aug 28, 2012, at 4:10, Mohit Anchlia <mohitanchlia@gmail.com> wrote:

> Have you thought of making your row key as key+timestamp? And then you can
> do scan on the columns itself?
> 
> On Mon, Aug 27, 2012 at 5:53 PM, Ioakim Perros <imperros@gmail.com> wrote:
> 
>> Of course, thank you for responding.
>> 
>> I have an iterative procedure where I get and put data from/to an HBase
>> table, and I am setting at each Put the timestamp equal to each iteration's
>> number, as it is efficient to check for convergence in this way (by just
>> retrieving the 2 last versions of my columns).
>> 
>> Some amounts of my equations are the same through iterations, and I save
>> them (serialized) at two specific columns of my table with timestamp equal
>> to zero. The rest of my table's columns contain the (serialized)
>> alternating results of my iterations.
>> 
>> The thing is that the cached amounts are necessary to be read at each and
>> every iteration, but it would not be efficient to scan all versions of all
>> columns of my table, just to retrieve the previous iteration's results plus
>> the initially saved cached amounts.
>> 
>> For example, being at iteration 30 I would like to retrieve only columns 3
>> and 4 with timestamp 29 and columns 0 and 1 with timestamp 0.
>> 
>> With the current HBase's API, I am not sure if this is possible and the
>> solution I described at my previous message (by storing columns 0 and 1 at
>> all timestamps up to 40 for example) seems inefficient.
>> 
>> Any ideas?
>> 
>> Thanks and regards,
>> IP
>> 
>> 
>> On 08/28/2012 03:33 AM, Mohit Anchlia wrote:
>> 
>>> You timestamp as in version? Can you describe your scenario with more
>>> concrete example?
>>> 
>>> On Mon, Aug 27, 2012 at 5:01 PM, Ioakim Perros <imperros@gmail.com>
>>> wrote:
>>> 
>>> Hi,
>>>> 
>>>> Is there any way of retrieving two values with totally different
>>>> timestamps from a table?
>>>> 
>>>> I am using timestamps as iteration counts, and I would like to be able to
>>>> get at each iteration (besides the previous iteration results from table)
>>>> some pre-computed amounts I save at some columns with timestamp 0,
>>>> avoiding
>>>> the cost of retrieving all table's versions.
>>>> 
>>>> The only way I have come up with is to save the pre-computed amounts
>>>> redundantly at all timestamps up to the maximum possible.
>>>> 
>>>> Does anyone have an idea on a more efficient way of dealing with this?
>>>> 
>>>> Thanks and regards,
>>>> IP
>>>> 
>>>> 
>> 

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