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From Philip Stanhope <pstanh...@wimba.com>
Subject Re: keyrange for get_range_slices
Date Thu, 10 Jun 2010 14:39:33 GMT
No ... and I personally don't have a problem with this if you think about what is actually
going on under the covers.

Note, however, that this is an expensive operation and as a result if there are parallel updates
to the indexes while you are performing a full keyscan (rowscan) you will potentially miss
keys because they are inserted earlier in the index than you are currently processing.

A further concern is that the keys (and indexes) are spread around a cluster. Unless R=N you
will be hitting the network during this type of scan.

Lastly, be careful about how you specify the SlicePredicate. A keyscan can easily turn into
a "dump the entire datastore" if you aren't careful.

On Jun 10, 2010, at 10:03 AM, Dop Sun wrote:

> Hi,
>  
> As documented in the http://wiki.apache.org/cassandra/API, the key range for get_range_slices
are both inclusive.
>  
> As discussed in this thread: http://groups.google.com/group/jassandra-user/browse_thread/thread/c2e56453cde067d3,
there is a case that user want to discover all keys (huge number) in a column family.
>  
> What I think  is doing batchly: using empty string as start and finish first, then using
the last key returned as start and query second.
>  
> My question is: using this method, the last key returned for the first query, will be
returned again in the second query as the first key. And it’s a duplication. Is there any
other API to discover keys without duplications in current implementation?
>  
> Thanks,
> Regards,
> Dop


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