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From Stack <st...@duboce.net>
Subject Re: Why does a delete behave like this?
Date Mon, 09 Dec 2013 23:27:01 GMT
Qualification:  My response misleads.  I was responding to delete of an
explicit version and got carried away.  Please see Lars' answer for the
proper response.

On Mon, Dec 9, 2013 at 1:30 PM, Stack <stack@duboce.net> wrote:

> On Mon, Dec 9, 2013 at 4:47 PM, Niels Basjes <Niels@basjes.nl> wrote:
>> Why has it been designed/implemented like this?
>> What is the logic behind this model?
> Hey Niels:
> It is probably fair to call this an instance of implementation leaking and
> polluted our data model.  We should fix it.
> Currently, deletes always sort before all other types when all other
> coordinates are the same (same row, same column family, same timestamp,
> etc.)  IIRC, it was done this way along time ago because it made delete
> reasoning 'easier'.  This forced sort ordering is why you see the behavior
> you note in your shell experiments.
> Our Sergey recently has suggested we undo our factoring in 'type' when
> sorting KeyValues/Cells; rather, we would distinguish pivoting on sequence
> id when all else matches.  Awkwardly, we'd then have to let user add
> sequence id when querying a specific Cell.  This would not be easy to do.
>  Sequence id is an internal, amorphous notion at the moment -- it exists
> while KeyValues are in flight but is (mostly) dropped after KeyValues
> persist to hfiles -- but it looks like it is fast becoming more tangible
> given some issues that arise around WAL replay at recovery time and in
> corner cases replicating.
> What is your thinking on this Niels?  Its current implementation
> interrupts your ability building an app on hbase?
> Thanks,
> St.Ack

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