Filter
Top Products
Schema DDL Realm concept
U929-J-Z125-9-76 109
Dokuschablonen 19x24 Version 7.3us für FrameMaker V7.x vom 14.02.2007 © cognitas GmbH 2001-2007
24. Oktober 2007 Stand 09:30.23 Pfad: G:\vogt\fsc\uds\Manuale\en\udsent_e\udsent.k04
Handling concurrent access
When a transaction is opened, the database programmer states the realms to be accessed
within the transaction (see the “Application Programming” manual, READY). He can also
define usage modes for realms, restricting or prohibiting concurrent access to these realms
by other transactions. The subdivision of the database into realms helps keep mutual inter-
ference by transactions to a minimum.
Data which is often accessed concurrently can be stored in different realms, and the realms
can be assigned different disk drives. This allows concurrent accesses by different transac-
tions, which again reduces access time.
Logical association of data
Data can be distributed over the different realms so that programs need access only some
of the existing realms. Realms can be connected or disconnected at the user’s discretion
by means of the BMEND utility or, in a session, by means of the administration with DAL
commands. There is no need to waste resources on realms which are rarely used.
4.10.1 Defining a realm
AREA NAME IS realm-name
realm-name specifies the name of the realm assigned by the user. No further specifications
are required to define a realm. Its size is specified at database creation (see the “Creation
and Restructuring” manual, Database creation).