Constant REVERSEDUP 

pub const REVERSEDUP: Flags;

This option specifies that duplicate data items should be compared as strings in reverse order.

NOTE: As with REVERSEKEY, this indicates a right-to-left comparison, not an order reversal.

Example

let db = lmdb::Database::open(
  &env, Some("reversed"), &lmdb::DatabaseOptions::new(
    lmdb::db::DUPSORT | lmdb::db::REVERSEDUP |
    lmdb::db::CREATE)).unwrap();
let txn = lmdb::WriteTransaction::new(&env).unwrap();
{
  let mut access = txn.access();
  let f = lmdb::put::Flags::empty();
  access.put(&db, "Colorado", "Denver", f).unwrap();
  access.put(&db, "Colorado", "Golden", f).unwrap();
  access.put(&db, "Colorado", "Lakewood", f).unwrap();

  let mut cursor = txn.cursor(&db).unwrap();
  // doowekaL, nedloG, revneD
  assert_eq!(("Colorado", "Lakewood"), cursor.first(&access).unwrap());
  assert_eq!(("Colorado", "Golden"), cursor.next(&access).unwrap());
  assert_eq!(("Colorado", "Denver"), cursor.next(&access).unwrap());
}
txn.commit().unwrap();