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From "mohit.kaushik" <mohit.kaus...@orkash.com>
Subject Re: Scan vs Filter performance.
Date Tue, 29 Sep 2015 04:59:01 GMT
Hi Keith,

When we fetch a column or column family Ii seems, it does not seek and 
only scan by filtering the key/value pairs. But as you said if I design 
a custom iterator to fetch a column family, It may work faster.

But I want to know what would be the scenario if I define a locality 
group for the column family and run the same custom iterator on it which 
scan and seeks both? what would be he impact on performance (gain or loss)?

Thanks
Mohit Kaushik

On 09/28/2015 10:49 PM, Moises Baly wrote:
> Hi Keith,
>
> No I wasn't aware of that. So I'll move forward with the custom iterator.
>
> Thank you for your time,
>
> Moises
>
> On Mon, Sep 28, 2015 at 12:35 PM, Keith Turner <keith@deenlo.com 
> <mailto:keith@deenlo.com>> wrote:
>
>     On Mon, Sep 28, 2015 at 12:19 PM, Moises Baly
>     <moises@spatially.com <mailto:moises@spatially.com>> wrote:
>
>         Hi all:
>
>         I would like to perform a range scan on a table, tweaking the
>         definition of what goes into a particular key range. One way I
>         can think of is writing a filter on the key, and that would
>         work fine. But I think it would be slow compared to a scan /
>         seek custom iterator. How does the underlying login works?
>         Does Filter goes through all records, or since is sorted
>         follows the same underlying logic as a scan? Would a custom
>         iterator perform better?
>
>
>     Yes, filter will read all data.  Custom iterator that seeks may be
>     faster.
>
>     Are you aware of the following?
>
>     https://issues.apache.org/jira/browse/ACCUMULO-3961
>     https://github.com/apache/accumulo/pull/42
>
>
>         Thank you for your time,
>
>         Moises
>
>
>


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