Batch statements

It’s common for applications to require atomic batching of multiple INSERT, UPDATE, or DELETE statements, even in different partitions or column families. Thanks to the Cassandra protocol changes introduced in Cassandra 2.0, the driver allows you to execute multiple statements efficiently without the need to concatenate multiple queries.

The method batch() accepts the queries as first parameter:

const query1 = 'UPDATE user_profiles SET email = ? WHERE key = ?';
const query2 = 'INSERT INTO user_track (key, text, date) VALUES (?, ?, ?)';
const queries = [
   { query: query1, params: [emailAddress, 'hendrix'] },
   { query: query2, params: ['hendrix', 'Changed email', new Date()] } 
];
// Promise-based call
client.batch(queries, { prepare: true })
  .then(function() {
    // All queries have been executed successfully
  })
  .catch(function(err) {
    // None of the changes have been applied
  });

Or using the callback-based invocation

client.batch(queries, { prepare: true }, function (err) {
   // All queries have been executed successfully
   // Or none of the changes have been applied, check err
});

By preparing your queries, you will get the best performance and your JavaScript parameters correctly mapped to Cassandra types. The driver will prepare each query once on each host and execute the batch every time with the different parameters provided.

Note that Cassandra batches are not suitable for bulk loading, there are dedicated tools for that. Batches allow you to group related updates in a single request, so keep the batch size small (in the order of tens). Starting from Cassandra version 2.0.8, the server issues a warning if the batch size is greater than 5K.