2543442 - DB6: Long running work processes on tables with LOB columns

Some activities have higher response times than normal/expected.

In transaction SM66/SM50, the corresponding work processes are shown as reading from tables with LOB (Large Object) columns.

RAWSTRING and STRING are ABAP dictionary datatypes that are represented by BLOB and CLOB columns respectively in the database.

Some of the most common tables are DYNPSOURCE, DYNPLOAD, REPOSRC, REPOLOAD, FPLAYOUTT, and FPCONTEXT.

The system appears to recover after several minutes but the issue repeats sporadically.

To confirm if the tables listed in SM66/SM50 contain LOB columns, use the following query:

SELECT table_name, column_name FROM dba_lobs WHERE owner = '<sapuser>';

Additionally, the STAD record of the long running step as shown in following figures:

Most of the time is spent on Database request time, and the average direct/sequential read time per row will be very high as shown in the STAD record above.

It may also show most of the time is spent in processing time as shown in the STAD record below.

Load and generate activities often select from tables with LOB columns and the client work process requesting the load/generate will accumulate processing time.

SAP Netweaver

Database: IBM DB2 for Linux, UNIX, and Windows

• DB2 10.1 lower than fix pack FP5SAP
• DB2 10.5 lower than fix pack FP6SAP

System hang, Performance , KBA , BC-DB-DB6 , DB2 Universal Database for Unix / NT , SV-PERF , Performance Problems , Problem