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WarehouseArchitect - User's Guide

Part 3 WarehouseArchitect Model

Chapter 22: Database Creation and Modification

Computing database size

Computing database size

• Entire database (global model)
• Part of the database (submodel)

Basis of calculationYou compute database size based on the following:

• Estimated number of records in tables
• Number of columns in each table
• Number of indexes in the database
• Number of tablespaces in the database
• Database storage options

Records in tables You must indicate an estimated number of records in each table in your global model or submodel.

ColumnsThe estimated database size for a column is based on the following:

• Length of fixed length data types
• Average size of variable length data types
• Default values for data types that do not have values defined for data type length

IndexesYou compute database size for all indexes including primary key indexes, foreign key indexes, and alternate key indexes.

Generation parameters determine the indexes that are used to compute database size. You need verify which generation parameters are selected before you compute database size.

Automatic index constraints The automatic indexing of keys is DBMS specific. If the target database supports the automatic indexing of keys, the resulting database size estimation includes these indexes.

Tablespace sizeThe estimated size of a tablespace associated with a table is computed by default, and is displayed as a total of the following:

• All tables in the tablespace
• All indexes in the tablespace

For more information on how to associate a tablespace with an index or table, see the section Defining tablespace and storage.

Storage options

Data storage options are DBMS specific. You define data storage options supported by the target database. These are included in the estimate of database size.

Indicating the number of records in a table

Before you compute database size, you indicate the number of records in each table that you generate.

• To indicate the number of records in a table:
  1. Select Dictionary-->List of Tables.

     The List of Tables dialog box appears.

     

  2. Select one or more tables in the list.

  3. Type an estimated number of records in the Number box.

  4. Click OK.

Indicating average data type length

You can indicate the estimated average data type length for variable length data types. This average length value is then used instead of the maximum data type length when you compute database size.

• To indicate average data type length:
  1. Select Dictionary-->List of Tables.

     The List of Tables dialog box appears.

  2. Select a table name.

  3. Click the Fill button.

     The Fill Parameters dialog box appears.

     

  4. Select a column that uses a variable length data type.

  5. In the Average Length textbox, type an average length.

  6. Click OK.

     You return to the List of Tables.

  7. Click OK.

Computing database size of a global model

You can compute database size based on all objects in the global model or a selection of objects in the global model (submodel).

• To compute database size of a global model:
  1. Select Database-->Compute Database Size.

     A message window displays the estimated database size.

     

  2. Click OK.

Computing database size of a submodel

You can compute database size based on all objects in a submodel.

• To compute database size of a submodel:
  1. From the submodel, select Database-->Compute Database Size.

  2. Select Compute the Current Submodel.

     

  3. Click OK.

     A message window displays the estimated database size.

     

  4. Click OK.