Re: speed questions

Steve Rentz wrote:
>
> We have a 50 gig database in Oracle 7.1 (currently testing 7.3). Raw
> data consists of about 15 gig. We have the data denormalized to avoid
> joins. The amount of time it takes to get results from queries we feel
> is unacceptable (3 hours for an average query, 8 hours for anything
> complex). The database consists of 3 main tables (customers - 13 million
> records, orders - 27 million records, items - 80 million records). We
> are wondering if going to a star schema would improve performance? Any
> recommendations would be appreciated.

In the past, it has seemed to me that denormalization has rarely been of much benefit. We have a small system that has one table with 40+ columns and only 20,000 rows that requires substantial more time to produce simple queries and updates than a NORMALIZED system consisting of 66 tables of which 1 table alone requires 100+ Meg of actual data storage (this is smaller than its actual database size).

The keys here are normalization, indexing and TUNE YOUR QUERIES. You also need to use EXPLAIN PLAN to verify that your queries are using your indexes.

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David M. Taulbee
TRW Vehicle Safety Systems
dtaulbee_at_po.michsb.trw.com