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From Apache Wiki <wikidi...@apache.org>
Subject [Cassandra Wiki] Update of "MemtableThresholds" by PaulParadise
Date Thu, 21 Oct 2010 23:13:23 GMT
Dear Wiki user,

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The "MemtableThresholds" page has been changed by PaulParadise.
The comment on this change is: Updating a few renamed fields..
http://wiki.apache.org/cassandra/MemtableThresholds?action=diff&rev1=19&rev2=20

--------------------------------------------------

  
  Listed below are the thresholds found in `storage-conf.xml`, along with a description.
  
- === MemtableSizeInMB ===
+ === MemtableThroughputInMB ===
  As the name indicates, this sets the max size in megabytes that the  Memtable will store
before triggering a threshold violation and causing it to be flushed to disk. It corresponds
to the size of the values inserted, (plus the size of the containing column).
  
  If left unconfigured (missing from the config), this defaults to 128MB.
  
- ''Note: in version 0.7b2+, the value will be applied on a [[https://issues.apache.org/jira/browse/CASSANDRA-1007|per
column-family basis]].''
+ ''Note: This was referred to as MemtableSizeInMB in versons of Casandra before 0.6.0. In
version 0.7b2+, the value will be applied on a [[https://issues.apache.org/jira/browse/CASSANDRA-1007|per
column-family basis]].''
  
- === MemtableObjectCountInMillions ===
+ === MemtableOperationsInMillions ===
  This directive sets a threshold on the number of columns stored.
  
  Left unconfigured (missing from the config), this defaults to 0.1  (or 100,000 objects).
The config file's inital setting of 0.3 (or 300,000 objects) is a conservative starting point.
  
- ''Note: in version 0.7b2+, the value will be applied on a [[https://issues.apache.org/jira/browse/CASSANDRA-1007|per
column-family basis]].''
+ ''Note: This was referred to as MemtableObjectCountInMillions in versons of Casandra before
0.6.0. In version 0.7b2+, the value will be applied on a [[https://issues.apache.org/jira/browse/CASSANDRA-1007|per
column-family basis]].''
  
  == Using Jconsole To Optimize Thresholds ==
  Cassandra's column-family mbeans have a number of attributes that can prove invaluable in
determining optimal thresholds. One way to access this instrumentation is by using Jconsole,
a graphical monitoring and management application that ships with your JDK.

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