Chapter 13 - Data loading

Abstract

This chapter examines the loading of data into an Oracle Database data warehouse. . Data loading for a data warehouse is essentially the process by which data is loaded into that data warehouse. There are various ways in which the loading process can be made to perform better. It focuses on the performance aspects of what is effectively a three-step process, and sometimes even a four-step process, including extraction, transportation, transformation, and loading processes. Data can be extracted from a source database using a number of methods. The most basic is simply dumping data into flat text files. There are external tables, transportable tablespaces, and the export utility, including Data Pump technology. Transportation is the process of moving data from source (OLTP) database to target (data warehouse) database. Loading data into a data warehouse is very likely to be a two-step process: loading followed by transformation processing. Loading simply plugs data into a data warehouse. Transformation changes loaded-data into a form that the data warehouse can understand. The chapter also discusses transportation methods, because some methods are better and faster than others and there are some very specific and highly efficient transportation methods specific to Oracle Database.