CODEWITHSUNDEEP
cassandraconsistency
Raedwald
Raedwald

Reputation: 48712

Semantics of EACH_QUORUM with only one Cassandra data-centre

The documentation for Cassandra consistency levels says about the EACH_QUORUM consistency level:

A write must be written to the commit log and memtable on a quorum of replica nodes in all data centers. Used in multiple data center clusters...

What are the semantics of the EACH_QUORUM consistency level when there is only one data centre? I can think of two possibilities:

Upvotes: 1

Views: 260

Answers (1)

Raedwald
Raedwald

Reputation: 48712

After some experimentation, using Cassandra 2.1.5 and the Datastax Java driver 2.1.5, I discovered that the implemented (if not the intended semantics) are that the EACH_QUORUM consistency level works only when you have more than one data-centre. The Java driver fails EACH_QUORUM writes when there is only one data-centre, throwing an UnavailableException that complains that 0 nodes are available. Writes using QUORUM work OK.

Therefore do not use EACH_QUORUM consistency-level if you have only one data-centre. Use QUORUM instead.

Upvotes: 2

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