Best Practices for SAP BI using DB2 9 for z/OS - IBM Redbooks

condition, generated by SAP BI upon the deletion criteria specified by the BI
user.
Example 4-2 New implementation of very large data deletions
repeat
DELETE FROM
WHERE (kf1, kf2, ..., kfn) IN
( SELECT kf1, kf2, ..., kfn FROM
WHERE
FETCH FIRST ROWS ONLY );
COMMIT WORK;
until nrows_deleted < paketsize.
To split up this delete into a loop of delete operations with each one deleting
rows only, the statement FETCH FIRST n ROWS ONLY could be
used. After each execution of the DELETE statement, a commit is performed.
The loop continues until all rows specified are deleted.
So the deletion of the data is performed in a loop with a COMMIT after every
deletion of one small packet of rows (packetsize can be configured). This new
SAP BI implementation for data deletion will be available for the next SAP BI
release coming after BI 7.0. SAP plans to make this new implementation for
selective deletion also available for the BI 7.00 release, running with DB2 9 by
setting a special RSADMIN parameter. This will be documented in a future SAP
note.
Example 4-3 shows the delete statement that is generated to delete a maximum
of 100,000 rows from the E- fact table of cube IUSALES.
Example 4-3 Using FETCH FIRST n ROWS ONLY for E- fact table
DELETE FROM "/BIC/EIUSALES"
WHERE ("KEY_IUSALESP", "KEY_IUSALEST", "KEY_IUSALESU", "KEY_IUSALES1",
"KEY_IUSALES2", "KEY_IUSALES3")
IN ( SELECT "KEY_IUSALESP",
"KEY_IUSALEST","KEY_IUSALESU","KEY_IUSALES1","KEY_IUSALES2","KEY_IUS
ALES3"
FROM "/BIC/EIUSALES"
WHERE
FETCH FIRST 100000 ROWS ONLY )
52 Best Practices for SAP BI using DB2 9 for z/OS