The Data Dictionary tables are checked only if the check specifies ALL TABLES (non-concurrent mode) or explicitly specifies to check database DBC. In this case, the Teradata system must be quiescent with logons disabled.
Data Dictionary processing defaults to batch scan mode for performance reasons. If a dictionary error occurs, processing automatically switches to serial scan mode for its more comprehensive error handling functionality. However, serial scan mode is slower, and on large systems can take significant time.
Use the STATUS command to check on the progress of the Data Dictionary scan.
Use the ABORT command to abort the Data Dictionary scan along with the CHECK command itself. To skip the Data Dictionary scan, issue the CHECK command while logons are enabled.