Estimating Database Size

You can estimate the size of a database for all or some of the tables and other objects in your model. You can estimate the initial size of the database or project its growth over a number of years.

The estimate is based on the following elements:

Estimated number of records in tables - Specify the number of rows (and their annual projected growth rate) in a table in the Number and Row growth rate fields on the General tab of its property sheet (see Table Properties).
Table columns and their sizes - Specify the average size for variable length columns in the Average length field on the Detail tab of its property sheet (see Column Properties). If you do not specify an average length for variable length columns, then the maximum length is used. It is particularly important to specify an average length for strings or long binary data types, as a Binary Long OBject (BLOB), such as a picture, can represent the largest portion of the space actually taken by a table.

Note: To specify values for multiple tables or columns, select Model > Tables or Model > Columns. If you do not see the appropriate property column, then add it using the Customize Columns and Filter tool.
Indexes in the model - including primary, alternate, and foreign key indexes (if supported) and database-specific indexes such as IQ join indexes.
Tablespaces in the model - the size of a tablespace is estimated as a total of all the tables and all the indexes in the tablespace.
DBMS and its storage options.

Note: The default estimation algorithms can be overridden in the DBMS definition file (see Customizing and Extending PowerDesigner > DBMS Definition Files > Profile Category > Modifying the Estimate Database Size Mechanism).

Select Database > Estimate Database Size to open the Database Size Estimation dialog.
Select the tables for which you want to estimate the size.
[optional] Click the Options tab and specify the number of years of growth that you want to include in your estimate. By default, only the initial size of the database is calculated, without allowing for any growth.

Click OK to begin the estimation.

Size estimates are generated to both the Result List and Output windows. The Database Size tab of the Result List provides a list of objects which can be double-clicked to open their property sheets, while the Database Size tab of the Output window prints a textual list of objects with sizes and a total for the database:

Estimate of the size of the Database "Project Management"...

    Number       Estimated size   Object
----------   ------------------   ----------------------------
 1,000,000           136,224 KB   Table 'Customer'
                                    Index 'Primary' (4,880 KB)
     1,000                48 KB   Table 'Division'
    10,000               696 KB   Table 'Employee'
                                    Index 'Primary' (48 KB)
     5,000               312 KB   Table 'Material'
    10,000                96 KB   Table 'Member'
    10,000               392 KB   Table 'Participate'
    10,000               640 KB   Table 'Project'
                                    Index 'Primary' (48 KB)
    10,000               464 KB   Table 'Task'
     1,000                80 KB   Table 'Team'
    10,000                96 KB   Table 'Used'
----------   ------------------   ----------------------------
                     139,048 KB   Total estimated space

Database size estimation completed.
The number of records was not defined for 1 table(s).

A warning is given if any tables in the model do not have a number of a records defined.