Entering content frame

Background documentation Isolation Level (UNIX/Linux) Locate the document in its SAP Library structure

Use

SAP DB allows concurrent transactions on database objects. To do this, it uses a lock concept that creates locks on rows and tables to contain individual transactions. The lock operation type plays an important role in this. This is determined by defining an isolation level.

The system default value for the lock operation type is Committed.

The set lock operation type can be overridden by the application using the function SQLSetConnectAttr and queried with SQLGetConnectAttr.

Syntax

IsolationLevel =
  Uncommitted
| Committed
| Repeatable
| Serializable

Overview of the possible lock operation types

 

Dirty Read

Non-repeatable Read

Phantom Read

Uncommitted

x

x

x

Committed

 

x

x

Repeatable

   

x

Serializable

     

Note

The lock operation type Uncommitted corresponds to the weakest isolation level (0), while Serializable corresponds to the strongest isolation level (4).

Procedure

To change the IsolationLevel option, follow the procedure described under Creating and Changing Data Sources Under UNIX/Linux.

The value defined in this way then applies for all connections of the data source.

Leaving content frame