Diff between normal RDMS and BW RDMS

[Former Member]

Hi all,

Please let me know if there is any difference between normal RDMS and BW RDMS?

Thanks and Regards

Satish

[S0004647611]

Hi,

indeed as Twan states, the engine is the same. But the character of the system on top is completely different. Never seen a bulk load insert operation in R/3 loading 50 milj. recs in 20 minutes.. This results mainly in different tuning, IO setup and parametrics for the database. This is the most common error that happens to Basis guys installing a BW: configuring it as a R/3 instance.. Furthermore tablespace needs more attention due to the peaks in loading/deleting mass data.

For BW there are separate DB configuration advices compared to R/3 in sap notes. Search in component BW-SYS-DB-"your DBMS"; like notes for Oracle.

Kind regards, Patrick Rieken

[Former Member]

The underying data store is a relational database. BW runs on Oracle, DB2, SQL Server, and others. I believe Oracle has between 2/3 and 3/4 of the installations currently.

As Patrick mentions, BW is a data warehouse rather than an OLTP system that processes transactions like the R3 system does.

A major differnce however is that the bulk of BW querying is done against an OLAP cube. Since the queries actually run against an underlying relational DB, this is sometimes referred to as ROLAP. This is compared to say, Hyperion or Cognos, that have their own proprietary multi-dimension datastores (known as MOLAP). While some querying is done against "flat" tables (ODS), the power of BW is it's ability to support slice and dice analytical querying using an OLAP multi-dimensional cube. The InfoCube, as SAP calls it, uses a star schema design, and SAP refer to their design as an "extended star schema".

When a user submits a query, a conventional SQL query is run against the database and the results of that query are transferred to an OLAP processor that supports the slice and dice analysis.

It starts to get more confusing as Oracle also has it's own MOLAP data store, but SAP does not use it. If you run your BW on Microsoft SQL Server, the data can then be transfered to MS's MOLAP datastore for analysis.

Simple question, but a not so simple answer I'm afraid.

[Former Member]

If you mean with RDMS: 'Relational Data Management System' then there are no differences. In fact BW runs on the same basis software as SAP R/3 (and also APO, CRM, SEM, MDM, etc). In fact, the latest R/3 release (ECC5) comes with integrated BW. Hence they must be using the same basis system.