Re: parallel query

My Name wrote in message <383B2E4C.837CD020_at_earthlink.net>...

>Can you tell me what does Parallel query mean?

Parallel Query (PQ) processes are used to run queries (usually full table scans) in parallel. Let's say you need to process 10 million rows with a full table scan, and calculate some kind of aggregation. Using 10 PQ processes, each PQ would processes 1 million rows. All 10 PQ's run in parallel (simultaneously). This can very significant performance increases if you are using PQ correctly, have a powerful enough platform, structure the queries correctly, have up to date statistics and so on.

>and how can I tell if my database is using parallel query?

It is an add-on product (requiring additional licensing) that needs to be installed. Look in table v$option to see what is installed.

If you have it installed you need to configure PQ processes for your Oracle instance, specifying the min and max number of PQ processes in the INIT.ORA config file.

After configuring your instance, you need to configure the tables for PQ use - see the PARALLEL clause of the CREATE and ALTER TABLE statements. Or you can use hints instead in queries to try and force PQ use.

regards,
Billy Received on Tue Nov 23 1999 - 23:52:43 CST