Cluster and schema metadata

You can retrieve the cluster topology and the schema metadata information using the Node.js driver.

After establishing the first connection, the driver retrieves the cluster topology details and exposes these through properties of the client object. This information is kept up to date using Cassandra event notifications.

The following example outputs hosts information about your cluster:

client.hosts.forEach(function (host) {
   console.log(host.address, host.datacenter, host.rack);
});

Additionally, the keyspaces information is already loaded into the Metadata object, once the client is connected:

console.log(Object.keys(client.metadata.keyspaces));

To retrieve the definition of a table, use the Metadata#getTable() method:

client.metadata.getTable('ks1', 'table1', function (err, tableInfo) {
   if (!err) {
      console.log('Table %s', table.name);
      table.columns.forEach(function (column) {
         console.log('Column %s with type %j', column.name, column.type);
      });
   }
});

When retrieving the same table definition concurrently, the driver queries once and invokes all callbacks with the retrieved information.