Originally posted by abhaysk
Due to which RowId changes & index will be holding OLD rowid so it goes to INVALID state.
Abhay, here i would like to comment that status values for indexes can be 'VALID' or 'UNUSABLE'. Other stored objects can be 'VALID' or 'INVALID.' Either all_indexes, DBA_INDEXES or USER_INDEXES should be querried for the status of indexes.

HTH