Update
    Noupdate

    Specify the Update qualifier to update the stored cardinality
    values of tables and indexes. You can perform an update only when
    the stored cardinality values differ from the actual cardinality
    values. When updating cardinality values, Oracle Corporation
    recommends that you update the stored cardinality values with
    the actual cardinality values, not with an alternative value
    of your own choosing. Specifying a value other than the actual
    cardinality value can result in poor database performance. The
    default is the Noupdate qualifier.

    Using the Update qualifier allows you to update the stored
    cardinality values of the specified tables and indexes even when
    the RDB$SYSTEM storage area is designated for read-only access.
    If you have set the RDB$SYSTEM storage area to read-only access,
    Oracle RMU sets it to read/write during execution of the RMU
    Analyze Cardinality command with the Update qualifier. Oracle RMU
    resets the area to read-only when the operation completes.

    If you are updating the stored cardinality for a table or index,
    and a system failure occurs before the RDB$SYSTEM storage area is
    changed back to read-only access, use the SQL ALTER DATABASE
    statement to manually change the database back to read-only
    access.

    However, note that if you have set the area to read-only, the
    update operation specified with the Update qualifier commences
    only if the database is off line or the database is quiescent.

    If you specify a table name parameter with an RMU Analyze
    Cardinality command that includes the Update qualifier, the
    associated indexes are not updated; you must specify each table
    and index you want to be updated or accept the default (by not
    specifying any table or index names) and have all items updated.

    Oracle Corporation recommends that you use the Update qualifier
    during offline operations or during a period of low update
    activity. If you update a cardinality while it is changing
    (as a result of current database activity), the end result is
    unpredictable.

    Specify the Noupdate qualifier when you want to display the
    stored and actual cardinality values only for the specified
    tables and indexes.