07.02.2013 Views

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

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

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

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

ROTATE SQL statement. This defines the partition limits in such a way that they<br />

are one size greater in each case than the limit of the preceding partition. These<br />

partitions are used during the next update into the InfoCube.<br />

As a result of this procedure, the F- fact table generally has more partitions than<br />

requests. To ensure that the number of partitions does not become too large, a<br />

check is carried out when the contents of the F- fact table are completely deleted<br />

to see whether this fact table has 25 or more partitions. If this is the case, the<br />

table is deleted and created again with one partition only. You can overwrite the<br />

threshold value of 25 <strong>using</strong> the <strong>DB2</strong>_FFACT_DROP_DEL_NUM_PARTS<br />

parameter in Table RSADMIN.<br />

2.3.3 Partitioning of PSA tables<br />

This section is about partitioned PSA tables. Partitioning in principal subdivides<br />

big data clusters into more and smaller ones. The benefits of partitioned PSA<br />

tables are faster loading and also faster deleting data as permanently needed in<br />

volatile tables. Not to expand the number of partitions more than necessary,<br />

there exists the rotating principle of partitioned tables, shown in Figure 2-8.<br />

� Partitioned by logical number PARTNO by default<br />

with <strong>DB2</strong> V8 RSADMIN settings are no longer needed<br />

� Use ABAP report Z_MIGRATE_PSA_TABLES_<strong>DB2</strong> (<strong>SAP</strong> note 986202) <strong>for</strong><br />

migrating from V7 to V8 partitioning<br />

� Standard load with <strong>DB2</strong> V8:<br />

– Data packages are loaded into the current partition<br />

– If the current partition is full, either the next partition becomes current if any exists,<br />

or a new partition is added and becomes the current.<br />

� Fast deletion with ROTATE<br />

– A data package is logical flagged as ´deleted´ first<br />

– The first partition is ROTATEd if all related data packages are flagged as ´deleted´<br />

deleted<br />

deleted<br />

deleted<br />

deleted<br />

Figure 2-8 Partitioning of PSA tables<br />

ROTATE<br />

Part 1 Part 2 Part 3 Part 1<br />

Chapter 2. Overview of <strong>SAP</strong> <strong>BI</strong> and related data 19

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!