Hi! We use BigQuery and work with arrays.

We try to define models such as:

cube('a', {
     sql: `unnest(metrics)`,
     ...
});

cube('b', {
     joins: {
          a: {
              relationship: 'one_to_many',
              sql: `(true)`
           }
      },
      ...
});

The generated SQL looks like:

LEFT JOIN (unnest(metrics)) AS a ON (true)

and BigQuery throws an error:

Expected keyword JOIN but got ")" at [5:37]

Feature request: Add a check if the SQL is unnest(..) and do not wrap it with additional brackets.