Between gets all documents between two keys. Accepts three optional arguments: index, leftBound, and rightBound. If index is set to the name of a secondary index, between will return all documents where that index’s value is in the specified range (it uses the primary key by default). leftBound or rightBound may be set to open or closed to indicate whether or not to include that endpoint of the range (by default, leftBound is closed and rightBound is open).
You may also use the special constants r.minval and r.maxval for boundaries, which represent “less than any index key” and “more than any index key” respectively. For instance, if you use r.minval as the lower key, then between will return all documents whose primary keys (or indexes) are less than the specified upper key.