For example, on HEAD, or TAIL, the number of documents, AND the offset should be able to use a value passed in or a parameter. The value of the snap is severely curtailed by not having that functionality. I have been using them to easily do a test on full data and figured I would tie them into my parameter system and was shocked when it provided an error.
ALSO, the number of documents should be settable to zero for NO documents. I came up with a nice idea to provide full or only applicable reports, and run all data, nothing, or just a subset, and this makes that harder to do and not worth it at this point.
there are probably other cases where this could be used. It may even be good to add it for retries and timeouts as that could maybe be tuned.
Also, it would be nice if the zip and similar snaps could stop on a record, rather than a byte, so a test(preview) would run with no error on the partial data. It took me a while to figure out what was going on, and it would be nice to be able to always use the same settings.