Are there some or other kinds of indexes on JSON data fields? The thing is I would not need any kind of JSON manipulation unless it includes INDEX assisted quer

Are there some or other kinds of indexes on JSON data fields? The thing is I would not need any kind of JSON manipulation unless it includes INDEX assisted queries. Doing linear lookups is pretty stupid even if it includes fancy accessors and validators for field formatting. I am far from being considered expert on the topic .. but there is no mention of calculated indexes on JSON formatted fields... -- are there indexes that assisted queries against JSON datastructures stored in JSON type fields?