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From Apache Wiki <wikidi...@apache.org>
Subject [Cassandra Wiki] Update of "API" by PeterSchuller
Date Tue, 11 Jan 2011 18:47:44 GMT
Dear Wiki user,

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

The "API" page has been changed by PeterSchuller.
The comment on this change is: Reflect DCQUORUM->LOCAL_QUORUM and addition of EACH_QUORUM
in 0.7.
http://wiki.apache.org/cassandra/API?action=diff&rev1=72&rev2=73

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

  ||`ZERO` ||Ensure nothing. A write happens asynchronously in background. Until [[https://issues.apache.org/jira/browse/CASSANDRA-685|CASSANDRA-685]]
is fixed: If too many of these queue up, buffers will explode and bad things will happen.
||
  ||`ANY` ||(Requires 0.6) Ensure that the write has been written to at least 1 node, including
HintedHandoff recipients. ||
  ||`ONE` ||Ensure that the write has been written to at least 1 replica's commit log and
memory table before responding to the client. ||
- ||`QUORUM` ||Ensure that the write has been written to `N / 2 + 1` replicas before responding
to the client. ||
+ ||`QUORUM` || Ensure that the write has been written to `N / 2 + 1` replicas before responding
to the client. ||
- ||`DCQUORUM` ||As above but takes into account the rack aware placement strategy. See https://issues.apache.org/jira/browse/CASSANDRA-492
||
+ ||`DCQUORUM` || (No longer in 0.7) Ensure that the write has been written to <ReplicationFactor>
/ 2 + 1 nodes, within the local datacenter (requires NetworkTopologyStrategy) ||
+ ||`LOCAL_QUORUM` || (Requires 0.7) Ensure that the write has been written to <ReplicationFactor>
/ 2 + 1 nodes, within the local datacenter (requires NetworkTopologyStrategy) ||
+ ||`EACH_QUORUM`  || (Requires 0.7) Ensure that the write has been written to <ReplicationFactor>
/ 2 + 1 nodes in each datacenter (requires NetworkTopologyStrategy) ||
  ||`ALL` ||Ensure that the write is written to all `N` replicas before responding to the
client.  Any unresponsive replicas will fail the operation. ||
  
  
@@ -50, +52 @@

  ||`ANY` ||Not supported. You probably want ONE instead. ||
  ||`ONE` ||Will return the record returned by the first replica to respond. A consistency
check is always done in a background thread to fix any consistency issues when `ConsistencyLevel.ONE`
is used. This means subsequent calls will have correct data even if the initial read gets
an older value.  (This is called ReadRepair) ||
  ||`QUORUM` ||Will query all replicas and return the record with the most recent timestamp
once it has at least a majority of replicas (`N / 2 + 1`) reported.  Again, the remaining
replicas will be checked in the background. ||
- ||`DCQUORUM` ||When using rack aware placement strategy reads are keept within a data center.
See https://issues.apache.org/jira/browse/CASSANDRA-492 ||
+ ||`DCQUORUM` ||(No longer in 0.7) When using rack aware placement strategy reads are keept
within a data center. See https://issues.apache.org/jira/browse/CASSANDRA-492 ||
+ ||`LOCAL_QUORUM` ||(Requires 0.7) Returns the record with the most recent timestamp once
a majority of replicas within the local datacenter have replied. ||
+ ||`EACH_QUORUM` || (Requires 0.7) Returns the record with the most recent timestamp once
a majority of replicas within each datacenter have replied. ||
  ||`ALL` ||Will query all replicas and return the record with the most recent timestamp once
all replicas have replied.  Any unresponsive replicas will fail the operation. ||
- 
  
  '''Note: '''Thrift prior to version 0.6 defaults to a Write Consistency Level of ZERO. Different
language toolkits may have their own Consistency Level defaults as well. To ensure the desired
Consistency Level, you should always explicitly set the Consistency Level.
  

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