5.7 Mixed Access Methods

5.7 Mixed Access Methods

No single access method will work best for all tables. Access depends too much on the current data and the current queries made against it to generalize. The MARIS project at Grady Hospital in Atlanta, Georgia, under Henry Camp used a unique self-adjusting access method to get around this problem. This system was a medical research statistical database used by doctors. It would track the queries being made against its files and analyze them. Then during downtime, it would pick the best access method from a set of about a dozen options and reorganize the files. Users never saw this, but they would notice that response time was better after letting the system rest.

This is one of the great strengths of SQL: a change in the database access method does not invalidate all the code that has already been written. But it is also a problem because we become like the detached mathematician in that classic joke: we tend to shove the mere details of performance onto our engineer and physicist, in the form of the database administrator. We should worry about them, too, because that is where our next meal is coming from.

< Previous Excerpt Next Excerpt >

Purchase This Book

Joe Celko's Data and Databases: Concepts in Practice

TABLE OF CONTENTS

5.7 Mixed Access Methods

Contact Preferences

This is embarrasing...

Customize Your GlobalSpec Experience

Select Your Free Newsletters

Industry Newsletters

Select Your Free Product Alerts

This is embarrasing...