Specifies the maximum parallelism for the query. A zero or negative value means the number of logical cpus will be used as the parallelism for the query. There is also a server wide max_parallelism parameter which defaults to 1. If a request includes max_parallelism, it will be capped by the server max_parallelism. If a request does not include max_parallelism, the server wide max_parallelism will be used.