Acronyms

Definitions

ETL

Extract, Transform, and Load: The process of taking data from a source system into a warehouse.

SQL

Structured Query Language: The basic language that databases such as Oracle and SQL Server understand. SQL is used to create data, create database objects such as tables, and to query data.

Performance Data

I use this term to describe any data which helps to speed up reporting performance. This includes creating aggregate tables, for example the Tournament Fact table. It also includes the use of subsets of data, partitioning of tables, and indexing.

Star Transformation

A special feature of Oracle databases is their ability to maximize the performance of a query that uses a star design table layout. Oracle can build a more efficient query than usual due to the fact that it knows all Dimensions join to the Fact table.

Hints

Hints are used to help an Oracle database to query the tables in the most efficient manner. This could include telling Oracle to use particular join methods or indexes.

Exadata

An Oracle machine that increases performance of the Oracle database by bringing together the storage, processing, and database operating system into one box.

Cubes

A cube is a special way of organizing data so that it can be queried extremely quickly. Data is often aggregated in cubes so that numbers are available to the user without the database having to do any calculations.

Slowly Changing Dimensions

A dimension record, for example a player, does not normally change once it has been created. However, if a player married and then changed their last name, the warehouse designer needs to decide how this is reflected in the Dimension table. If you create a new record based upon the player's new details then you have created a Slowly Changing Dimension table.

Indexes

Indexes are used to help a database access data more quickly than simply by looking at the data itself.

Hierarchies

Records in a table can often have a parent:child relationship which develop into a hierarchy of levels. For example, in the Date table, we have Date, which has a parent of Month, which has a parent of Year. The hierarchy is then:

Year | Month | Date