[Cassandra Wiki] Update of "Counters" by johanoskarsson

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The "Counters" page has been changed by johanoskarsson.
http://wiki.apache.org/cassandra/Counters?action=diff&rev1=2&rev2=3

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  = Counters in Cassandra =
  
  == Getting started ==
+ 
+ In order to use counters in Cassandra you need to first set up a cluster, see the [[http://wiki.apache.org/cassandra/GettingStarted|Getting started]] guide for more information. Currently the counters code is slated for a release in Cassandra 0.8.0.
+ 
+ ==== Configuration ====
+ 
+ When first setting up the cluster you can specify a column or super column that will act as counters.
+ For example using the cassandra.yaml configuration file:
+ 
+ {{{
+ - name: Counter1
+   default_validation_class: CounterColumnType
+ 
+ - name: SuperCounter1
+   column_type: Super
+   default_validation_class: CounterColumnType
+ }}}
+ 
+ ==== Incrementing and accessing counters ====
+ 
+ Once the cluster is up and running with these settings you can simply increment or decrement long values from the counters as follows (example is using the python thrift client):
+  
+ {{{
+ client.add('key1', ColumnParent(column_family='Counter1'), CounterColumn('c1', 100), ConsistencyLevel.ONE)
+ client.add('key1', ColumnParent(column_family='Counter1'), CounterColumn('c1', -50), ConsistencyLevel.ONE)
+ }}}
+ 
+ And read it back
+ {{{
+ rv = client.get_counter('key1', ColumnPath(column_family='Counter1', column='c1'), ConsistencyLevel.ONE)
+ }}}
+ 
+ Please read the rest of this wiki page, especially Technical limitations and Operational considerations to make sure this actually does what you need.
+ 
  == Interface ==
  == Technical limitations ==
  == Operational considerations ==
  == Further reading ==
+ See [[https://issues.apache.org/jira/browse/CASSANDRA-1072|CASSANDRA-1072]] and especially the [[https://issues.apache.org/jira/secure/attachment/12459754/Partitionedcountersdesigndoc.pdf|design doc]] for further information about how this works.