Limits how many bytes BigQuery will allow a job to consume before it is cancelled.
When this value is provided, all jobs will use this value as their default billing cap. If a job uses more than this many bytes, BigQuery will cancel it and it will not be billed. By default there is no cap and all jobs will be billed for however many bytes they consume.
This only has an effect when using DestinationTable or when using the InsertJob stored procedure. BigQuery does not allow standard query jobs to have byte limits.