Isolation
By default, TimesTen uses read committed isolation. The Isolation attribute specifies the initial transaction isolation level for the connection. For a description of the isolation levels, see Concurrency Control Through Isolation and Locking in Oracle TimesTen In-Memory Database Operations Guide.
The value can be modified by an ALTER SESSION statement, described in Oracle TimesTen In-Memory Database SQL Reference . For example:
ALTER SESSION SET ISOLATION_LEVEL=serializable;
CREATE CACHE GROUP
, ALTER CACHE GROUP
and DROP CACHE GROUP
statements are not supported in serializable isolation mode.
If the passthrough or the propagate cache feature is used, the TimesTen isolation level setting is inherited by the Oracle session. TimesTen serializable mode is mapped to Oracle's serializable mode. TimesTen read committed mode is mapped to Oracle's read committed mode. For more details on the passthrough attribute, see PassThrough.
With PassThrough
set to 3, you must use an ALTER SESSION
statement to permanently modify the isolation level on the Oracle database connection. For example on a connection to the DSN repdb1_221
:
-
Call
ttIsql
and connect to theDSN
withPassThrough
level3:
% ttIsql; Command> connect "dsn=repdb1_221;passthrough=3"; Connection successful:. . .PassThrough=3; <default setting Autocommit=1>
-
Turn off
AutoCommit
:Command> autocommit=0;
-
Temporarily change the
PassThrough
level to0
:Command> passthrough=0;
-
Alter the isolation level to serializable:
Command> prepare 1 ALTER SESSION SET ISOLATION_LEVEL=serializable; commit; exec=1;
Required Privilege
No privilege is required to change the value of this attribute.
Usage in TimesTen Scaleout and TimesTen Classic
This attribute is supported in TimesTen Classic.
In TimesTen Scaleout, only Isolation=1
is supported.
Setting
Set Isolation
as follows:
Where to set the attribute | How the attribute is represented | Setting |
---|---|---|
C or Java programs or UNIX and Linux systems |
|
|
Windows ODBC Data Source Administrator |
Not applicable |