I've got a physical standby ( I created a test table and a nologging index on it (the underlying tablespace is NOT in a force logging mode). Then pushed some data. Then did a "select name, unrecoverable_change# from v$datafile;" on both primary and standby. Surprisingly, I didn't see any difference in the change# and the standby was infact caughtup. I, then opened the standby in readonly mode. The index does seem to exist there. Am not sure if it is getting populated though. I tried forcing a hint to use the index etc. But I can't tell if it's actually using it, since I can't explain plans on a read-only. I suppose I can run traces etc..but before I go down the path, can someone explain this phenomenon? What might be going on?