by Burleson Consulting
The Data Warehouse Development Life Cycle
Distributed Oracle Data Warehouses
Warehouse Table Partitioning And Distributed Oracle
In data warehouses that allow cross-database access, a very common
method of distribution uses horizontal partitioning. For example,
customer service organizations commonly allow their remote sites to
maintain customer information while maintaining a
location-transparent access mode to every customer, regardless of
their physical location. Horizontal partitioning is achieved by
taking a subset of each remote site's customer table and populating
a master look-up table that is accessible from any node in the
distributed data warehouse, as shown in Figure 9.10.
Figure 9.10 Horizontal data partitioning.
In a Unix-based distributed data warehouse, the CRON utility can be
used to schedule a periodic refresh of a master table. CRON is a
time-dependent task activation utility that starts tasks at
predetermined dates and times. An SQL script automatically extracts
customer_name from the remote site and repopulates the master
customer table, leaving the customer details at the remote site. The
Oracle SQL might look like this:
/* Delete remote rows in the master table... */
DELETE FROM customer@master
SEE CODE DEPOT FOR FULL SCRIPT;
This is an excerpt from "High Performance
Data Warehousing", copyright 1997.
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