July 2006
Intermediate to advanced
378 pages
9h 38m
English
book
Mastering Data Warehouse Aggregates: Solutions for Star Schema Performance
by Christopher Adamson
Content preview from Mastering Data Warehouse Aggregates: Solutions for Star Schema Performance
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
6.6. Materialized Views and Materialized Query Tables
Back-end database technologies, such as Oracle's materialized views and DB2's materialized query tables, are frequently used to implement aggregate navigation functionality. As discussed in Chapter 4, these technologies can also be used to build and maintain the aggregates.
These capabilities eliminate the need to design an ETL process for the construction of the aggregate tables. As discussed in Chapter 5, it is necessary only to define the aggregate, properly establish the rules that govern when the aggregate will participate in query rewrite, and set up an automated call to the database to refresh the aggregate after base table loads have completed.
While the RDBMS will handle most of the remaining additional work, there are cases where a tweak to the base schema can go a long way toward optimizing performance and keeping down the size of the aggregate table.
6.6.1. Defining Attributes for Aggregate Dimensions
Oracle and IBM provide the capability to define aggregates that partially summarize a dimension, without the need to construct the aggregate dimension table itself. Both products enable this capability by allowing the developer to define hierarchies that exist within the dimension. As discussed in Chapter 4, this is done in Oracle via the declaration of a dimension. In DB2, this is done by establishing a cube view.
Each level of a hierarchy must include a defining attribute or set of attributes. The hierarchy may ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.