ER/Studio - Embarcadero Technologies Product Documentation

USING ER/STUDIO > DEVELOPING THE PHYSICAL MODEL
Planning for and Predicting Database Growth
In order to ensure optimal database performance, it is important that you assess your storage needs and plan
accordingly. This section will help you to do this and is comprised of the following topics:
• Planning for Table and Index Storage
• Predicting Table Growth
Planning for Table and Index Storage
Planning the storage of tables and indexes is best done during the physical design stage in order to improve
performance and to streamline data administration tasks. When planning physical storage, carefully consider both the
placement and size of tables and indexes. The performance of almost all database applications is I/O bound. To
improve I/O throughput, physically separate tables that are frequently joined together. Also, separate tables from their
indexes. The objective is to have the database read or write data in parallel as much as possible.
Two key concerns of every database administrator are free space management and data fragmentation. If you do not
properly plan for the volume and growth of your tables and indexes, these two administrative issues could severely
impact system availability and performance. Therefore, when designing the physical model, consider the initial extent
size and logical partition size.It
As a starting point, estimate the size of each table and its indexes based on a projected row count. The Capacity
Planning tool helps project the size of the databases given certain growth parameters. For databases that let you
specify initial extent sizes, such as Oracle, set the initial extent size to the estimated size in order to avoid data
fragmentation as the table grows. By keeping tables within a single extent, data access times decreases and table
reorganization can be determined.
Once you have determined the placement and sizes of the tables and indexes in your database, estimate the total size
requirements of the database in order to avoid running out of free space for the database.
Predicting Table Growth
Capacity planning metrics can be recorded for each table so that proper sizing can be done before the table is
implemented in a database.
The Capacity Planning tab of the Table Editor helps predict change using metrics such as table row count, table
growth rate, growth type, growth period and table maximum size.
1 In the Data Model Explorer, double-click a table in the physical model.
2 Click and then complete the Capacity Planning tab.
TIP: Change the column Avg. Width and Percent Null values to more accurately predict the table
growth.
The growth predictions you make in the Table Editor display in the Capacity Planning utility and can be edited
there.
EMBARCADERO TECHNOLOGIES > ER/STUDIO® 8.0.3 USER GUIDE 218