The optimizer uses a stored row count to determine the number of rows in a table, which is maintained automatically by the system.
Normally, an updated value is stored in the database whenever the database goes through an orderly shutdown (as long as the database is not read-only). Stored row counts become inaccurate if there is a non-orderly shutdown (for example, a power failure or other type of system crash).
You can correct the optimizer's row count without shutting down the
system;