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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: Confused about get_slice SliceRange behavior with bloom filter
Date Sun, 13 Feb 2011 15:11:05 GMT
On Sun, Feb 13, 2011 at 12:37 AM, E S <tr1sklion@yahoo.com> wrote:
> I've gotten myself really confused by
> http://wiki.apache.org/cassandra/ArchitectureInternals and am hoping someone can
> help me understand what the io behavior of this operation would be.
>
> When I do a get_slice for a column range, will it seek to every SSTable?  I had
> thought that it would use the bloom filter on the row key so that it would only
> do a seek to SSTables that have a very high probability of containing columns
> for that row.

Yes.

> In the linked doc above, it seems to say that it is only used for
> exact column names.  Am I misunderstanding this?

Yes.  You may be confusing multi-row behavior with multi-column.

> On a related note, if instead of using a SliceRange I provide an explicit list
> of columns, will I have to read all SSTables that have values for the columns

Yes.

> or is it smart enough to stop after finding a value from the most recent
> SSTable?

There is no way to know which value is most recent without having to
read it first.

-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support
http://www.datastax.com

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