17.00 - Usage Notes - Teradata Database

Teradata Vantage™ - Data Dictionary

prodname
Advanced SQL Engine
Teradata Database
vrm_release
17.00
created_date
June 2020
category
Administration
Programming Reference
featnum
B035-1092-170K

When a database, user, or table is created, allocated disk space is divided evenly among all AMPs. The AllSpace view returns one row of usage information for each AMP in the system configuration (or for all AMPs if the SUM aggregate is used).

When a database is created, a space row is added to each AMP, with the processor field in each row initialized to 0. The first time the space row is updated (such as when a table is created in the database, or when the system is restarted), the processor field in each row is updated to indicate the actual processor number.

When a query applies a SUM aggregate to either the MaxPerm or CurrentPerm column without a WHERE clause, or with a WHERE clause that references only one TableName or DatabaseName, the returned values are double the desired result.

For example, the following query, which returns the correct amount of space allocated to Peterson, also returns twice the amount of space currently being used by Peterson (see DiskSpaceV[X] and TableSizeV[X]).

SELECT SUM(MaxPerm), SUM(CurrentPerm)
   FROM DBC.AllSpaceV
   WHERE DatabaseName = ’Peterson’;

You can use the DBC.ClearPeakDisk macro to reset PeakPerm, PeakSpool, PeakPersistentSpool, and PeakTemp.

Corresponding Tables

The X view references these additional tables:

  • DBC.AccessRights
  • DBC.Owners
  • DBC.Roles 
  • DBC.RoleGrants

AppProxyUser and TrustUserName

These columns are not returned in the X or VX views.