Limitations and Frequently Asked Questions

Limitations

There are some limitations in the Mapper design:

  • Secondary indexes and SOLR queries are not supported.
  • Case sensitive CQL identifiers (enclosed with double quotation marks) are not supported.
  • When mapping a model to multiple tables/views
    • Columns with the same name must be of the same type.
    • Updating primary keys of any of the tables is not supported and will result in additional rows being created on the server side.
  • The following CQL features are not supported
    • Deleting an individual map key/value pair is not supported, as in DELETE favs['author'] FROM ...
    • Updating single UDT fields map key/values is not supported, e.g: id.field = 3

Note that some limitations can be overcome by using Custom Queries.

FAQ

Should I specify the keyspace per mapping?

If you are using a single keyspace containing all your data, its recommended that you set the keyspace name when creating the Client instance. For example:

const client = new Client({ contactPoints, localDataCenter, keyspace: 'killrvideo' });
const mapper = new Mapper(client);

When dealing with multiple keyspaces, you can specify the keyspace of the tables for each model using the MappingOptions:

const client = new Client({ contactPoints, localDataCenter });
const mapper = new Mapper(client, {
  models: {
    'Video': { 
      tables: [ 'videos', 'user_videos', 'latest_videos' ],
      keyspace: 'killrvideo'
    }
  }
});

How can I set the consistency level of a Mapper execution

The last parameter of the ModelMapper execution methods is the execution profile. The execution profiles allow you define a group of options (consistency level, timeouts, …) and reuse them on different execution invocations.

await videoMapper.find({ userId }, { fields: [ 'name', 'addedDate' ]}, 'my-exec-profile');

You can read the Mapper documentation on execution options for more information.