I think better to change function int db_get_message (u64_t id) on u64_t db_get_message(u64_t id) the error returns length of the message or if error -1 or on int db_get_message (u64_t id, u64_t *len)
How think? I think creation function db_put_message (id) and db_get_message (id) will considerably simplify operation with various databases as other syntax SQL of inquiries is identical.
