ER/Studio - Embarcadero Technologies Product Documentation

USING ER/STUDIO > DEVELOPING THE PHYSICAL MODEL
Create a TableSpace
1 In the Data Model Explorer, expand the Physical Main Model, right-click the Tablespaces node, and then click
New Tablespace.
2 Complete the Tablespaces Wizard and then click Finish to create the alias.
TIP: Once you have created the tablespace, you can edit it by right-clicking the tablespace you want
to change, and then selecting Edit Tablespace.
The following describe options that require additional explanation. The options available depend on the database
platform selected.
NOTE: Many of the table space parameters are also used when defining table storage. For information
on defining storage parameters not described here, see Defining Table Storage.
Name & Type page/tab
• Choose the type of data to store in the tablespace:
• Regular: Choose for all data types except for temporary tables.
• Long: Choose for long or LOB tables columns, or for structured type columns or index data. The table space
must be a DMS table space.
• Temporary: Choose if you want to store temporary data. A database must have at least one temporary table
space to store temporary tables and another that allows the declaration of temporary tables.
Name page/tab
• Do you want space management to be performed through the dictionary or locally in the tablespace?
Specify how extents should be managed.
• Dictionary Managed: Relies on SQL dictionary tables to track space utilization. Adding an extent to a table
requires the database manager to find free space, mark it as non-free and potentially causes rollback
segments to extend. These operations may jeopardize database performance because they cannot be
performed simultaneously. However, dictionary managed tablespaces are very flexible, different objects
sharing the same tablespace can have different extent sizes.
• Locally Managed: Eliminates the problem of tablespace fragmentation, and potential bottlenecks associated
with the data dictionary. The database manager maintains a bitmap of free and used blocks, or sets of blocks.
Locally managed tablespaces can be used for temporary tablespaces and can often sustain high
extent-allocation and deallocation activities. If a table is created with the wrong extent size, causing tablespace
fragmentation, this type of tablespace management can enforce extent uniformity at the tablespace level.
• Disable logging when schema/data is modified: If selected, disables logging when schema or data is
modified.
• Place tablespace offline after creation: If selected, places tablespace offline after creation.
• AutoAllocate Extents: If selected, Oracle automatically assigns and allocates appropriately sized extents
depending on the objects in the tablespace.
• Uniform Extent Size: If selected, extent sizes are managed at the tablespace level, not at the object level. The
extent size is specified when the tablespace is created and all the extents for objects created in the tablespace
will be the same.The uniform extent size cannot be overridden when a schema object, such as a table or an
index, is created. This option may eliminate fragmentation.
Datafile page/tab
• Defined Datafiles: Double-click the Size or Unit fields to edit them. Click Add only when you need to define
another datafile.
EMBARCADERO TECHNOLOGIES > ER/STUDIO® 8.0.3 USER GUIDE 207