We’re moving along nicely into the process of designing and building a data warehouse. If you’ve been reading all the way through to here, you’ll recall how we’ve introduced the Warehouse Builder software (how to install it along with the Oracle Database), looked at its architecture, and covered a short overview of the analysis and design phases for implementing a data warehouse project. We’ve defined our data sources and imported the metadata for them. We’ve designed our target structure into which we’ll load the data. Congratulations for having read this far — don’t give up now because we’re not done yet. We still have to get data from our sources into our target. We will do that by:
• Designing mappings in OWB.
• Deploying the mappings to the database.
• Running the mappings.
This topic will expose ETL (Extract, Transform, and Load) for the first time in this topic. ETL is the first step in building the mappings from source to target. We have sources and targets defined and now we need to do the following:
• Work on extracting the data from our sources
• Perform any transformations on that data (to clean it up or modify it)
• Load it into our target data warehouse structure
We will accomplish this by designing mappings in OWB. Mappings are visual representations of the flow of data from source to target and the operations that need to be performed on the data. However, before we can do that, we need to be familiar with what OWB offers us so that we can make best use of it.
With this in mind, we’ll spend this topic looking at ETL in general and the Warehouse Builder features that support designing our ETL operations in particular. In the next topic, we’ll actually design our mappings in OWB.
