As a result, you can picture the
new level as being an index within the index. The additional level in the index increases the
negative effect of the index on data load rates. You will not see this impact until after the index is
split. Applications that work acceptably for the first week or two in production only to suddenly
falter after the data volume reaches critical levels do not support the business needs. In testing,
there is no substitute for production data loaded at production rates while the tables already
contain a substantial amount of data.
Test with Many Concurrent Users
Testing with a single user does not reflect the expected production usage of most database
applications. You must be able to determine if concurrent users will encounter deadlocks, data
consistency issues, or performance problems. For example, suppose an application module uses
a work table during its processing. Rows are inserted into the table, manipulated, and then queried.
A separate application module does similar processing??”and uses the same table. When executed
at the same time, the two processes attempt to use each other??™s data. Unless you are testing with
multiple users executing multiple application functions simultaneously, you may not discover this
problem and the business data errors it will generate.
Testing with many concurrent users will also help to identify areas in the application where
users frequently use undo segments to complete their queries, thus impacting performance.
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