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Consistency

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Ioannis Papapanagiotou edited this page Sep 7, 2015 · 36 revisions

Consistency in the local region has been introduced to Dynomite in version 0.5.3. Consistency can be configured for read or write operations separately (clusterwide). There are two configurations.

DC_ONE: Reads and writes are propagated synchronously only to the node in the local Rack (Availability Zone) and asynchronously replicated to other Racks and regions.

DC_QUORUM: Reads and writes are propagated synchronously to quorum number of nodes in the local region and asynchronously to the rest. A quorum of responses are returned to the client.

Configuration

There are two way to configure consistency. The first is in the YAML file and it is picked up when on Dynomite's start. The entries in the YAML must appear as follows (the values are case insensitive):

read_consistency: dc_quorum
write_consistency: dc_quorum

and the second is during run time through the admin port (default 22222):

$ curl http://localhost:22222/set_consistency/read/dc_quorum

$ curl http://localhost:22222/set_consistency/write/dc_quorum

To check the node level consistency:

$ curl http://localhost:22222/get_consistency    
Read Consistency: DC_QUORUM
Write Consistency: DC_QUORUM
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