Data can exist in many different places. Instead of moving data to a single database, the BI Server can access multiple databases simultaneously to answer a single query, regardless of whether the databases are from different vendors or what version of database software each runs under.
When the BI Server accesses heterogeneous databases, it handles automatically
- database operations such as
- and required transformation, such as:
- data type casting
- or applying multiple complex functions.
The BI server can access a large of data sources included XML.
This capability is also called:
- Federated Query
- Multi-Database Access
- Cross-Database Join
- one Excel used to store the quota
- an other Oracle where the datawarhouse is located
DWH and OLTP reconciled
A datawarehouse is never completely up-to-date because an extraction is performed periodically.
OBIEE is able to :
- perform a query against your OLTP application system to retrieve the data from the last extraction
- perform a query against the DWH system
- and to merge the two query in on result