I think it's hard to say definitively whether or not you would see a
performance gain in using a custom iterator over a locality group. If
you have many other columns in each row, it would likely be more
efficient to operate only over the single column. For a small number of
columns with more rows, I would guess you wouldn't see a large
performance gain. It would be an interesting experiment.
Does that make sense?
mohit.kaushik wrote:
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 <[email protected]
<mailto:[email protected]>> wrote:
On Mon, Sep 28, 2015 at 12:19 PM, Moises Baly
<[email protected] <mailto:[email protected]>> 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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