Estimating Database Size

You can estimate the size of a database for all the tables in the model or for only selected tables throughout the model.

Basis of Calculation

You obtain an estimate based on the following elements:


  • Estimated number of records in tables

  • Columns in each table

  • Indexes in the model

  • Tablespaces in the model

  • Database storage options

Estimation depends on parameters like DBMS type, physical options, column data types, indexes and keys. The estimation formula used in this feature proceeds from the DBMS documentation.

Note:

You indicate a number of records in each table in your model.

Columns

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


  • Size of fixed length data types

  • Average size of variable length data types

Indexes

The estimate of the database size includes all indexes including primary key indexes, foreign key indexes, alternate key indexes and database-specific indexes such as IQ join indexes.

Note:

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 Size

The size of a tablespace associated with a table is estimated 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 Creating an Index.

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.

Parent topic: Generating a Database from a PDM

Created October 7, 2009. Send feedback on this help topic to Sybase Technical Publications: pubs@sybase.com