You can log resource usage data in the DBC.Acctg table by creating substitution variables in the account ID part of the user logon string. These Account String Expansion (ASE) variables let you to measure query and AMP usage more precisely. You can gather statistics for capacity planning, gather information for use in charge back and accounting, and track resource consumption.
The variables allow you to include date and time information in the string. Using ASE is a best practice. If ASE is activated, Teradata Database collects statistics based on the variables used during the active session, and stores the information into the underlying table of the DBC.AmpUsage view.