Star Query Indexes

From: Mike Rushton <mike_at_mrush.demon.co.uk>
Date: 1996/11/02
Message-ID: <327b6579.28920154@news.demon.co.uk>#1/1

I am a little puzzled at how to implement indexes on a table which is the central table in a Data Mart with approximately 10 associated dimension tables.

I am using Oracle 7.3.2.1.0 and the documentation states that

"The cost-based optimizer intelligently searches for potential star queries based on two criteria.

1. One table is significantly larger than any other table in the query
2. The larger table contains a concatenated index"

Is the second of the criteria suggesting a single index on all ten dimension key fields? If so what if you query the table using only five of the keys, the index may be useless.

What is the normal method for indexing a Data Mart fact table? Separate indexes for each dimension key?

Please help my confusion

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Mike Rushton | "A greate many open minds mike_at_mrush.demon.co.uk | should be closed for repairs"

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Received on Sat Nov 02 1996 - 00:00:00 CST