Oracle Tips  by Burleson Consulting

The Data Warehouse Development Life Cycle

Parallelism And Oracle Data Warehousing
Parallel Processing
To speed up the replication of two tables, a Unix shell script directs CPU-A to begin the copy of Table A as a background task. The script then directs CPU-B to issue a remote mount to Table B, making Table B addressable as if it were a local disk to CPU-B. The script then issues a copy of Table B, and the tables are copied simultaneously, reducing the overall processing time (see Figure 7.4).

Figure 7.4 Linear versus parallel processing.

Of course, the overall elapsed time will not be half of the time required for a linear process--the remote mount still requires the database on CPU-A to manage the I/O against Table B. The benefit lies in having the second processor (CPU-B) handle all of the processing for the unload of Table B.

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This is an excerpt from "High Performance Data Warehousing". To learn more about Oracle, try "Oracle Tuning: The Definitive Reference", by Donald K. Burleson.  You can buy it direct from the publisher at 30% off here:
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