What you pass to session.execute().
- three types: simple (textual query), bound (prepared) and batch.
- built-in implementations are immutable. Setters always return a new object, don't ignore the result.
To execute a CQL query, you create a Statement instance and pass it to Session#execute or Session#executeAsync. The driver provides various implementations:
- SimpleStatement: a simple implementation built directly from a character string. Typically used for queries that are executed only once or a few times.
- BoundStatement (from PreparedStatement): obtained by binding values to a prepared query. Typically used for queries that are executed often, with different values.
- BatchStatement: a statement that groups multiple statements to be executed as a batch.
All statement types share a common set of execution attributes, that can be set through either setters or a builder:
- execution profile name, or the profile itself if it's been built dynamically.
- idempotent flag.
- tracing flag.
- query timestamp.
- page size and paging state.
- per-query keyspace (Cassandra 4 or above).
- token-aware routing information (keyspace and key/token).
- normal and serial consistency level.
- query timeout.
- custom payload to send arbitrary key/value pairs with the request (you should only need this if you have a custom query handler on the server).
When setting these attributes, keep in mind that statements are immutable, and every method returns a different instance:
SimpleStatement statement =
SimpleStatement.newInstance("SELECT release_version FROM system.local");
// Won't work: statement isn't modified in place
statement.setConfigProfileName("oltp");
statement.setIdempotent(true);
// Instead, reassign the statement every time:
statement = statement.setConfigProfileName("oltp").setIdempotent(true);All of these mutating methods are annotated with @CheckReturnValue. Some code analysis tools --
such as ErrorProne -- can check correct usage at build time, and report
mistakes as compiler errors.
Note that some attributes can either be set programmatically, or inherit a default value defined in the configuration. Namely, these are: idempotent flag, query timeout, consistency levels and page size. We recommended the configuration approach whenever possible (you can create execution profiles to capture common combinations of those options).
.. toctree::
:hidden:
:glob:
batch/*
per_query_keyspace/*
prepared/*
simple/*