The most important aspect of any database is the data it contains. However, the data within a database doesn't always stay there—it often needs to be migrated in some way. Data migration involves the movement of a database's data to another location—out to the filesystem, in from the filesystem, or between databases. Let's consider an example. Data warehouses often take large amounts of data from mainframe systems as input to serve in a mid-tier data store. The process of reading that data, perhaps stored in an external flat file and inserting it into another database is data migration. The Oracle database includes a number of methods and tools for migrating data. In this chapter, we'll examine the process of data migration and the native tools we can use to accomplish it.
In this chapter, we shall:
Examine external loading methodologies
Use SQL*Loader to input data
Understand the Data Pump architecture
Use Data Pump to migrate data