Oracle DBA - Data Modeling

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Oracle Tip: Understand the difference between star and snowflake schemas in OLAP

At the core of data warehouse applications and OLAP (online analytical processing) is a specialized schema that relaxes the rules of Third Normal Form RDBMS schemas in favor of faster analysis and processing of large amounts of data. It's important to understand the difference between these kinds of schemas during application design or migration, rather than later when schema changes are more costly.

Oracle Varray and Nested Table Performance

Oracle offers a variety of data structures to help create robust database systems. Oracle supports the full use of binary large objects (BLOB), nested tables, non–first-normal-form table structures (VARRAY tables), and object-oriented table structures. It even treats flat data files as if they were tables within the Oracle database.

Oracle/PLSQL: Indexes

An index is a performance-tuning method of allowing faster retrieval of records. An index creates an entry for each value that appears in the indexed columns. By default, Oracle creates B-tree indexes.

Relationships Should NOT Be Natural!

As designers, we all learn early how to implement relationships using a relational database management system (RDBMS). We establish the connection by carrying the same data value in both of the tables. To put the two rows together, we simply join where the data values match up. We then cement that relationship with primary keys and foreign keys. What column should we use to do this? A big temptation is to use data that occurs "naturally"—data values that everyone knows and understands—but maybe that's not such a good idea. Using naturally occurring data can have some negative impacts on performance. I'll describe those problems in this article.

Reverse Engineering a Data Model

This article shows you how to use the Oracle Data Dictionary to obtain: Table definitions Constraints Indexes Views

PowerDesigner 7.5

The industry's first design tool with an enterprise-class repository that simplifies UML object modeling and data modeling - including Java and XML This next generation modeling tool combines the functionality of Sybase's leading database design product with powerful UML-based object modeling.

ER-Diagrammer

The Entity Relationship Diagrammer shows the tables and their relations with one another in strict accordance with the IDEF1X standard. On the one hand, the ER Diagrammer is used to generate an ER diagram from the existing database. On the other hand, it is possible to generate data models of a smaller size, using the ER Diagrammer and Hora, another tool of the KeepTool 4 - family. You define the tables and the relations between the tables with Hora, and use the ER Diagrammer to get a graphic impression of your data model. For such design work you will very much appreciate the functions add column, rename column and drop column.

ER/Studio

ER/Studio is a data modeling application for logical and physical database design and construction. Its powerful, multi-level design environment addresses the everyday needs of database administrators, developers and data architects who build and maintain large, complex database applications.

ERwin

ERwin is a rich set of design techniques and unique iterative approach provide exceptional productivity for implementing transactional systems and data warehouses across the enterprise.

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