ADABAS allows for concurrent transactions on database objects. It uses a locking concept that sets locks to rows and tables for transaction encapsulation. There are SHARE locks and EXCLUSIVE locks. With SHARE locks, concurrent transactions can read the data but not modify it. With EXCLUSIVE locks, no other transaction can read or modify the locked rows. Reading data thus locked is only possible for transactions in lock mode "uncommitted".
Usually, the application determines the IsolationLevel by using the SQLSetConnectOption function. If an IsolationLevel other than the default (Committed) is desired, use the entry "isolationlevel" to override the default. This IsolationLevel will then be valid for all connections of the data source to the server. The defined IsolationLevel can be overridden with SQLSetConnectOption and requested using SQLGetConnectOption.
Syntax:
IsolationLevel = Uncommitted |
Committed | (Default)
Repeatable |
Serializable |
Overview on the possible lock modes:
Note:
The IsolationLevel "uncommitted" corresponds to the weakest level (0), "serializable" to the strongest level (4). For more information, see the manual CALL Interface (ODBC), "sqlsetconnectoption".