Found below examples in above link. which are not valid as per
Note: Do not use group with group_level because they are not compatible.
If you specify a group_level of 2 then you must specify a key using at least the year and month information. For example, you can specify an explicit key, such as [2012,8] :
You can query it for a range:
You can also specify a year, month and day, while still grouping at a higher level. For example, to group by year/month while selecting by specific dates:
Specifying compound keys that are shorter than the specified group level may output unexpected results due to the selection mechanism and the way startkey and endkey are used to start and stop the selection of output rows.