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. The driver allows you to execute multiple statements atomically without the need to concatenate multiple queries.

The method batch() accepts the list of queries as first parameter. Each query can be either just a statement string, or { query, params } object:

const query1 = 'INSERT INTO user_profiles (email) VALUES (\'example@example.com\`)';
const query2 = 'UPDATE user_profiles SET email = ? WHERE key = ?';
const query3 = 'INSERT INTO user_track (key, text, date) VALUES (?, ?, ?)';
const queries = [
  query1,
  { query: query2, params: [emailAddress, 'hendrix'] },
  { query: query3, 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 statements, you will get the best performance and your JavaScript parameters correctly mapped to Cassandra types. The driver will prepare each statement once on each host and execute the batch every time with the different parameters provided.

Note that 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). Refer to CQL documentation for information about correct and incorrect use of batches.