Oracle Essentials [Electronic resources] : Oracle Database 10g, 3rd Edition نسخه متنی

9.5 Managing the Data Warehouse

Once
you've built a data warehouse topology, you could
deploy multiple Oracle databases to implement the data warehouse and
its data marts. Enterprise-wide warehouses are more common on Unix
servers and are beginning to appear on clustered (RAC) Linux
platforms. Smaller data marts are common on Windows and Linux. Many
organizations are increasingly consolidating data marts and
enterprise data warehouses on the more scalable platforms.

Oracle Enterprise Manager provides a common
GUI for managing these multiple instances regardless of the
underlying operating system. EM is browser-based with a multiuser
repository for tracking and managing the Oracle instances. (EM is
discussed in much more detail in Chapter 5.)

In warehousing, in addition to basic management, ongoing tuning for
performance is crucial. Enterprise Manager 10g
supports many of the automated diagnostics and tuning features in
Oracle Database 10g.

Within the largest warehouses and
data marts, you may want to manage or maintain availability to some
of the data even as other parts of the database are moved offline.
Oracle's Partitioning option enables data partitions
based on business value ranges (such as date) or discrete values for
administrative flexibility, while enhancing query performance through
the cost-based optimizer's ability to eliminate
access to non-relevant partitions. As an example,
"rolling window" administrative
operations are used to add new data and remove old data based on
ranges of time. A new partition can be added, loaded, and indexed in
parallel, and optionally removed, all without impacting access to
existing data.

Range
partitioning first became available as an Oracle8 option. Hash
partitioning was added to the Oracle8i
Partitioning option enabling the spread of data evenly based on a
hash algorithm for performance. Hashing may be used within range
partitions (composite partitioning) to increase the performance of
queries while still maintaining the manageability offered by range
partitioning. Oracle9i introduced
"List"
partitioningpartitions based on discrete values such as
geographies. A composite partitioning type of Range-List, such that
you can partition by dates within geographies, first appeared in
Oracle9i Release 2.