Relational Database Models Oracle Tips  by Burleson Consulting

High Performance Data Warehousing

Introduction of the Relational Model

* Declarative data access--Queries are issued with SQL, and database navigation is hidden from the programmers. When compared to navigational languages such as CODASYL DML, in which the programmer was required to know the details of the access paths, relational access is handled with an SQL optimizer, which takes care of all navigation on behalf of the user. Relational data access is a state space approach, whereby the user specifies the boolean conditions for the retrieval, and the system returns the data that meets the selection criteria in the SQL statement.

* Simple conceptual framework--The relational database is very easy to describe, and even naive users can understand the concept of rows, columns, and tables. The complex network diagrams used to describe the structures of network and hierarchical databases are not needed to describe a relational database.

* Referential integrity (RI)--Because business rules are not enforced with pointers, relational databases allow for the control of business rules with constraints. These RI rules are used to ensure that one-to-many and many-to-many relationships are enforced within relational tables. Referential integrity is most useful when loading a data warehouse. RI is only checked when a row is added, updated, or deleted, so RI is of no importance during the period where the data warehouse is serving queries. (See Figure 1.9.)

---

This is an excerpt from "High Performance Data Warehousing", copyright 1997.

If you like Oracle tuning, you may enjoy the book Oracle Tuning: The Definitive Reference , with over 900 pages of BC's favorite tuning tips & scripts.  You can buy it directly from the publisher and save 30%, and get instant access to the code depot of Oracle tuning scripts.