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From Masood Mortazavi <masoodmortaz...@gmail.com>
Subject Consistency Level of CLI
Date Thu, 25 Feb 2010 19:08:41 GMT
What is the write and read consistency level for the CLI tool
"cassandra-cli" ?

Do the "set" and "get" commands in the "cli" allow the Consistency Level to
be specified for a given "set" or "get"?

Is there a current specification of CLI anywhere on the wiki?

( How are JIRA's related to the CLI tagged in the JIRA system assuming they
are "tagged" separately? In other words, is there an identifier for them? )

Regards,
m.

==========================
The Cassandra "API" describes write and read consistency levels as follows:
http://wiki.apache.org/cassandra/API
Write

*Level*

*Behavior*

ZERO

Ensure nothing. A write happens asynchronously in background

ANY

(Coming in 0.6) Ensure that the write has been written to at least 1 node,
including hinted recipients.

ONE

Ensure that the write has been written to at least 1 node's commit log and
memory table before responding to the client.

QUORUM

Ensure that the write has been written to <ReplicationFactor> / 2 + 1 nodes
before responding to the client.

ALL

Ensure that the write is written to all <ReplicationFactor> nodes before
responding to the client. Any unresponsive nodes will fail the operation.

Read

*Level*

*Behavior*

ZERO

Not supported, because it doesn't make sense.

ANY

Not supported. You probably want ONE instead.

ONE

Will return the record returned by the first node 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
read repair.)

QUORUM

Will query all storage nodes and return the record with the most recent
timestamp once it has at least a majority of replicas reported. Again, the
remaining replicas will be checked in the background.

ALL

Will query all storage nodes and return the record with the most recent
timestamp once all nodes have replied. Any unresponsive nodes will fail the
operatio

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