https://github.com/litecoin-project/litecoin/pull/392"RPC: Improve how optional indices are managed"
The idea in short is to create additional indices, like Unspent index
(which can be accessed through RPC method getaddressutxos)
not through manipulation of config file or command line args,
with subsequent -reindex-chainstate required, but through
calling a new RPC method that manages the indices.
E.g. to enable addressUnspent index, -reindex-chainstate would
take a few hours depending on the PC, whereas with this method
it takes several minutes.