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From William Slacum <wilhelm.von.cl...@accumulo.net>
Subject Re: TimeSpan Iterator
Date Tue, 28 Aug 2012 17:02:10 GMT
It could be inefficient if you can't narrow down your search of a table to
specific ranges, via an index or some hint stored in the key that you can
use to seek() around. You're left with doing an exhaustive search of the
data, even if clients will only see data that matches your filtering
criteria.

On Tue, Aug 28, 2012 at 12:51 PM, <Bob.Thorman@l-3com.com> wrote:

> Billie****
>
> ** **
>
> Your comment “Users should be aware that this is not an efficient
> operation, though.” may help me decide if my current use of a secondary
> time index is better then.  Right now I maintain a table that has
> timestamps as the rowid whose values are the rowid in a metadata table.
> Therefore I do one range scan based on the timestamp.  Then a second lookup
> of the metadata rowid.  Is this more efficient?  ****
>
> ** **
>
> *From:* Billie Rinaldi [mailto:billie@apache.org]
> *Sent:* Tuesday, August 28, 2012 11:46
>
> *To:* user@accumulo.apache.org; john.armstrong@ccri.com
> *Subject:* Re: TimeSpan Iterator****
>
> ** **
>
> On Tue, Aug 28, 2012 at 6:33 AM, John Armstrong <jrja@ccri.com> wrote:****
>
> On 08/28/2012 09:26 AM, Bob.Thorman@l-3com.com wrote:****
>
> Does anyone know of a TimeSpan Iterator that will fetch rows based on
> the accumulo timestamp?****
>
> ** **
>
> We actually wrote our own TimestampRangeIterator and TimestampSetIterator
> classes.  I don't know if 1.4 has any in the core libraries.  It's not very
> hard though.****
>
>
> There's a TimestampFilter in org.apache.accumulo.core.iterators.user in
> 1.4.  It uses a range of timestamps.  Users should be aware that this is
> not an efficient operation, though.
>
> Billie****
>

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