Solution : https://service.sap.com/sap/support/notes/1514016 (SAP Service marketplace login required)
Summary :
This SAP Note describes the two isolation levels used by the SAP application server ABAP on IBM DB2 databases: the default Uncommitted Read (UR) and the optional Committed Read (CS), known as Cursor Stability. It explains the context and importance of each level, showcasing how UR allows for more efficient, though potentially less accurate, data querying, while CS ensures data accuracy by obtaining share locks. The note also introduces the 'Currently Committed' (CC) semantics available from IBM DB2 Version 9.7, explaining how it ensures readers do not wait for ongoing write locks, thereby enhancing performance. Implementations options using CUR_COMMIT database parameter are discussed, advising on how to switch between CS and UR levels using ABAP function modules for custom isolation settings. Important considerations for setting CUR_COMMIT to 'ON' to prevent data inconsistencies, especially for UPDATE operations and specific scenarios like catalog table scans and DB2 pureScale environments, are highlighted.
Key words :
previously committed data requires physical disk reads, terms cur_commit db2 db6 luw reason, sap profile parameter 'dbs/db6/dbsl_ur_to_cc= ', cur commit disk log reads, cur commit total log reads, require slightly increased log space, ibm db2-based sap systems, sap application server abap supports, existing row takes place, unnecessary lock wait situations
Related Notes :
| 1486779 | DB6: CUR_COMMIT=ON with 6.40 SAP kernel |
| 1420036 | DB6: DB2 9.8 pureScale Standard Parameter Settings |
| 1351160 | DB6: Using DB2 9.7 with SAP Software |
| 1329179 | DB6: DB2 9.7 Standard Parameter Settings |