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From Apache Wiki <wikidi...@apache.org>
Subject [Cassandra Wiki] Update of "FAQ" by Nick Pavlica
Date Sat, 01 May 2010 18:09:57 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Cassandra Wiki" for change notification.

The "FAQ" page has been changed by Nick Pavlica.
http://wiki.apache.org/cassandra/FAQ?action=diff&rev1=62&rev2=63

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   * The main limitation on a column and super column size is that all the data for a single
key and column must fit (on disk) on a single machine(node) in the cluster.  Because keys
alone are used to determine the nodes responsible for replicating their data, the amount of
data associated with a single key has this upper bound. This is an inherent limitation of
the distribution model.
  
-  * When large columns are created and retrieved, that columns data is loaded into RAM which
 can get resource intensive quickly.  Consider, loading  200 rows with columns  that store
10Mb image files each into RAM.  That small result set would consume about 2Gb of RAM.  Clearly
as more and more large columns are loaded,  RAM would start to get consumed quickly.  This
can be worked around, but will take some upfront planning and testing to get a workable solution
for most applications.  You can find more information regarding this behavior here: [[MemtableThresholds|memtables]].
+  * When large columns are created and retrieved, that columns data is loaded into RAM which
 can get resource intensive quickly.  Consider, loading  200 rows with columns  that store
10Mb image files each into RAM.  That small result set would consume about 2Gb of RAM.  Clearly
as more and more large columns are loaded,  RAM would start to get consumed quickly.  This
can be worked around, but will take some upfront planning and testing to get a workable solution
for most applications.  You can find more information regarding this behavior here: [[MemtableThresholds|memtables]],
and a possible solution in 0.7 here: [[https://issues.apache.org/jira/browse/CASSANDRA-16|CASSANDRA-16
]].
  
   * Please refer to the notes in the Cassandra limitations section for more information:
[[CassandraLimitations|Cassandra Limitations]]
  

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