Oracle7 Server Administrator's Guide
Guidelines for Managing Tablespaces
Before working with tablespaces of an Oracle7 database, consider the guidelines in the following sections:
Using Multiple Tablespaces
Using multiple tablespaces allows you more flexibility in performing database operations. For example, when a database has multiple tablespaces, you can perform the following tasks:
- Separate user data from data dictionary data.
- Separate one application's data from another's.
- Store different tablespaces' datafiles on separate disk drives to reduce I/O contention.
- Separate rollback segment data from user data, preventing a single disk failure from causing permanent loss of data.
- Take individual tablespaces offline while others remain online.
- Reserve a tablespace for a particular type of database use, such as high update activity, read-only activity, or temporary segment storage.
- Back up individual tablespaces.
Some operating systems set a limit on the number of files that can be simultaneously open; these limits can affect the number of tablespaces that can be simultaneously online. To avoid exceeding your operating system's limit, plan your tablespaces efficiently. Create only enough tablespaces to fill your needs, and create these tablespaces with as few files as possible. If you need to increase the size of a tablespace, add one or two large datafiles, or create datafiles with the autoextend option set on, rather than many small datafiles.
Review your data in light of these advantages and decide how many tablespaces you will need for your database design.
Specifying Tablespace Storage Parameters
When you create a new tablespace, you can specify default storage parameters for objects that will be created in the tablespace. Storage parameters specified when an object is created override the default storage parameters of the tablespace containing the object. However, if you do not specify storage parameters when creating an object, the object's segment automatically uses the default storage parameters for the tablespace.
Set the default storage parameters for a tablespace to account for the size of a typical object that the tablespace will contain (you estimate this size). You can specify different storage parameters for an unusual or exceptional object when creating that object.
Note: If you do not specify the default storage parameters for a new tablespace, the default storage parameters of Oracle7 become the tablespace's default storage parameters.
See Also: For information about estimating the sizes of objects, see Chapters 9 through 16.
Assigning Tablespace Quotas to Users
Grant users who will be creating tables, clusters, snapshots, indexes, and other objects, the privilege to create the object and a quota (space allowance or limit) in the tablespace intended to hold the object's segment. The security administrator is responsible for granting the required privileges to create objects to database users and for assigning tablespace quotas, as necessary, to database users.
See Also: To learn more about assigning tablespace quotas to database users, see ![[*]](jump.gif)
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