Oracle Warehouse Horizontal Partitioning Oracle Tips by Burleson Consulting

The Data Warehouse Development Life Cycle

Oracle Features for the Data Warehouse

Read-only tablespaces in the real world

For a production Oracle data warehouse it is very important to develop a method for determining when the data becomes permanent. For example, a large data warehouse may store historical data for the past decade, but the last 18 month’s worth of data are subject to updates as the data status changes within the OLTP database. In Figure 8.14 we assume that our fact tables have been horizontally partitioned, that is, a very long table with rows going back ten years in time will be separated into tables that govern a smaller period of time.

Figure 8.14 - Horizontal partitioning of an Oracle warehouse

Here we see that the main fact table has been logically partitioned into ten horizontal partitions, and only the most recent section of the table (fact_97) is subject to update. The other partitions for the fact table are static and will never change. For details of using horizontal table partitioning with Oracle tables, see Chapter 4, Oracle Data Warehouse Design. For details on automatic table and index partitioning with Oracle8, see Chapter 14, Oracle8 for the Warehouse.

We should also note that each chunk of the fact table has been segregated into its own tablespace, such that there are ten independent tablespaces for each table. We should also note that this is a rolling strategy. As fact_96 ages into the static category, the Oracle DBA will reorganize this table chunk to tightly pack it into a static tablespace. This is achieved by calculating the precise amount of storage for the table, and using Oracle export-import utility to offload the data and pack it into the new chunk . The index for each chunk also reside in its own tablespace, and this is also packed into its new, static tablespace.

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This is an excerpt from "High Performance Data Warehousing", copyright 1997.

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