CODEWITHSUNDEEP
cassandracassandra-2.0datastax-java-driver
Laxmikant
Laxmikant

Reputation: 1611

What will happen if I set normal consistency level to conditional write (LWT)?

I have 6 node cluster with replication factor 3. I am using normal consistency level as QUORUM and serial consistency level as SERIAL.

I have a conditional write query (IF EXIST). What will happen if I set both normal and serial to this statement using datastax java driver like below.

//preparedStatement has a conditional query.
BoundStatement boundStatement = new BoundStatement(preparedStatement);
boundStatement.setSerialConsistencyLevel(ConsistencyLevel.SERIAL);
//is this required??
boundStatement.setConsistencyLevel(ConsistencyLevel.QUORUM);

My queries:

  1. Will the normal consistency QUORUM will be ignored OR it will be taken into account ?
  2. Should I set only serial consistency level in this case ?

I referred to below link but it does not explain much https://docs.datastax.com/en/cassandra/3.x/cassandra/dml/dmlConfigSerialConsistency.html

The learn phase, which defines what read operations will be guaranteed to complete immediately if lightweight writes are occurring uses a normal consistency level.

Please explain in simple terms.

Upvotes: 4

Views: 702

Answers (1)

adutra
adutra

Reputation: 4536

The serial consistency level is only used for the Paxos phase of a lightweight transaction. If that phase succeeds, then the actual mutation (read or write) will take place using the "normal" consistency level specified.

So to answer your questions:

Will the normal consistency QUORUM will be ignored OR it will be taken into account ?

It will be taken into account if the lightweight transaction succeeds and the mutation is performed.

Should I set only serial consistency level in this case ?

Every statement carries a consistency level. If you don't specify anything at statement level, the defaults defined at cluster level apply.

Upvotes: 7

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