>>18I guess HTSQL offers the most flexibility. The way I had anticipated it was that all peers would sync all data indiscriminately. But the user might not be interested in all information, and if the amount of information is large, the clients should be able to make more specific queries to single out the data that's valuable to the user. So, there could be two possible solutions. One is to just provide HTSQL, and let the application define the database schemas and keep access secure. Another is to create a half-baked poorly implemented reinvention of HTSQL, which may or may not be better than HTSQL. A limited subset of HTSQL could be supported for security, keeping out expensive queries, or for simplifying the required database backend.