What is the INSTANCES modifier of the PARALLEL clause?

Hey all,

I'm looking to implement parallelism for our largest tables in 10.1.0.5.0 on AIX in order to more fully utilize our SAN. While continuing testing with various parameters, I've been seeing that there is an INSTANCES qualifier of the PARALLEL clause in the ALTER TABLE statement.

>From experiment, it appears to affect whether or not parallelism is used for
certain queries (I think there was just a thread here about that, but regarding the DEGREE qualifier). The kicker is that I can't find any documentation on INSTANCES.

Docs on tahiti.oracle.com do not mention it in the 10.1, 10.2, or even the 11.1 version for the ALTER TABLE command, and a search for "parallel instances" is nearly futile with the number of unrelated hits on "instance[s]".

Anyone have any pointers on this? Thanks! Rich

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