Re: Table size

The size estimate for a complete database has to include more than just the data; it must include the overhead necessary to support SYSTEM, SYSAUX, TEMP, and UNDO. The TEMP and UNDO tablespaces can require a lot of space depending on how the application works, activity levels, and how far back in time it is desired to be able to flashback a query.

The size estimate for the database then has to be then more than doubled to support Oracle's recommendation for a flashback database area (10g), if you plan to use this feature.

You can make the estimates without building a database if you have a decent idea of the amount of data, number of tables, and number of indexes. There have been numerous posts in the past on how to estimate the size of a table. The big problem is that development often has no idea how big the application is going to be!

Note that the total space consumed by indexes has a tendency in the OLTP world to just about equal the total space consumed by tables as applications grow in number of tables. In another environment I have the data is 3/4 the size of the indexes (part OLTP and part SPC system).

HTH -- Mark D Powell -- Received on Wed Jun 01 2005 - 09:52:53 CDT