HP 3000 Manuals HP 3000 Manuals
Isolation Levels
Isolation levels allow you to control the degree of concurrency by
regulating the extent to which operations performed by one user in a
multi-user environment can be affected by operations performed by another
user.
ALLBASE/SQL allows four different isolation levels:
* Repeatable Read (RR)
* Cursor Stability (CS)
* Read Committed (RC)
* Read Uncommitted (RU)
If an ODBC application does not specifiy an isolation level when
connecting to ALLBASE/SQL, the ALLBASE/SQL default isolation level of RR
is used. The RR isolation level holds locks on data until a COMMIT WORK
or ROLLBACK WORK statement is issued. For information on isolation
levels, refer to the section "Concurrency Control through Locks and
Isolation Levels" in the ALLBASE/SQL Reference Manual.
To improve concurrency and performance, you can override the ALLBASE/SQL
default isolation level with one of the following methods:
* Change the isolation level through the ODBC Administrator.
* Change the isolation level through the Logon Information dialog
box. Click on the Connection Options button.
NOTE It is recommended that the default isolation level only be changed
for read-only applications. If you change the default isolation
level for applications that you plan to use for update, you cannot
be guaranteed the integrity of your data because the application
may be depending on the default isolation level of ALLBASE/SQL for
data integrity.