You can use the physical database diagram to identify tables that are most likely to be
involved in transactions. You should also be able to identify which tables are commonly used
together during a data entry or query operation. You can use this information to effectively plan
the distribution of these tables (and their indexes) across the available physical devices to reduce
the amount of I/O contention encountered.
In data warehousing applications, the physical database diagram should show the aggregations
and materialized views accessed by user queries. Although they contain derived data, they are
critical components of the data access path and must be documented.
Space Requirements
The space requirements deliverable should show the initial space requirements for each database
table and index. The recommendations for the proper size of tables, clusters, and indexes are shown
in the ???Sizing Database Objects??? section later in this chapter.
Tuning Goals for Queries and Transaction Processing
Changes to the application design may have significant impact on the application??™s performance.
Application design choices may also directly affect your ability to tune the application. Because
application design has such a great effect on the DBA??™s ability to tune its performance, the DBA
must be involved in the design process.
You must identify the performance goals of a system before it goes into production. The role
of expectation in perception cannot be overemphasized.
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