Routing queries

When using the TokenAwarePolicy, the driver uses the RoutingKey to determine which nodes is used as coordinator for a given statement.

Prepared statements

When using prepared statements, the driver will determine which of the query parameters compose the partition key based on the prepared statement metadata.

Consider a table users that has a single partition key, id.

PreparedStatement prepared = session.Prepare(
      "INSERT INTO users (id, name) VALUES (?, ?)");

When binding the parameters, the driver knows which parameter corresponds to the partition key.

BoundStatement bound = prepared.Bind(Guid.NewGuid(), "Franz Ferdinand");
session.Execute(bound);

As a rule of thumb, use prepared statements and the driver does all the routing for you.

Simple statements

If you need to use a simple statement with routing, you must specify the routing values.

var id = Guid.NewGuid();
var query = new SimpleStatement(
      "INSERT INTO users (id, name) VALUES (?, ?)", id, "Franz Ferdinand");
// You must specify the values that compose the partition key
query.SetRoutingValues(id);
session.Execute(query);

Batch statements

If you want to enable routing for batch statements, you must specify the routing values.

var partitionKey = Guid.NewGuid();
var batch = new Batch();
// ... Add statements to the query
// You must specify the values that compose the partition key
batch.SetRoutingValues(partitionKey);
session.Execute(batch);