Get a signed Parquet download URL

Returns a short-lived signed URL for downloading the dataset as Parquet. Always serves the latest active version. A read-scoped API key is required **unless** the dataset is currently keyless (within its `keyless_until` window), in which case the request succeeds with no key at all. A key that fails verification is always rejected with 401, even against a keyless dataset, OpenAPI's `security` requirement below is only accurate for non-keyless datasets; see the description here for the full, conditional rule.

curl -X GET "https://example.com/datasets/string/data"

{  "slug": "string",  "format": "parquet",  "url": "http://example.com",  "expires_at": "2019-08-24T14:15:22Z",  "row_count": 0,  "columns": [    "string"  ]}