You can gain tablespace by deleting incidents, as Oracle overwrites the deleted data when new incidents come in. However, deleting incidents will not work if your tablespace is already full. For more information, see Why doesn't the database shrink after incidents are deleted? However, you can take a tablespace offline to make data inaccessible to users when you update and maintain the applications.
In case of some errors such as hardware failures, Oracle automatically takes an online tablespace offline. Any attempt to access data in offline tablespace will result in an error. The read-only tablespaces allow Oracle to avoid performing backup and recovery of large, static parts of a database. You can bring a tablespace online only in the database in which it was created because the necessary data dictionary information is maintained in the SYSTEM tablespace of that database. An offline tablespace cannot be read or edited by any utility other than Oracle.
Thus, tablespaces cannot be transferred from database to database transfer of Oracle data can be achieved with tools described in Oracle7 Server Utilities. Oracle automatically changes a tablespace from online to offline when certain errors are encountered for example, when the database writer process, DBWR, fails in several attempts to write to a datafile of the tablespace.
Users trying to access tables in the tablespace with the problem receive an error. Using Tablespaces for Special Procedures By using multiple tablespaces to separate different types of data, the database administrator can also take specific tablespaces offline for certain procedures, while other tablespaces remain online and the information in them is still available for use. However, special circumstances can occur when tablespaces are taken offline. For example, if two tablespaces are used to separate table data from index data, the following is true: If the tablespace containing the indexes is offline, queries can still access table data because queries do not require an index to access the table data.
If the tablespace containing the tables is offline, the table data in the database is not accessible because the tables are required to access the data. In summary, if Oracle determines that it has enough information in the online tablespaces to execute a statement, it will do so.
If it needs data in an offline tablespace, then it causes the statement to fail. Read-Only Tablespaces The primary purpose of read-only tablespaces is to eliminate the need to perform backup and recovery of large, static portions of a database. Note : Because you can only bring a tablespace online in the database in which it was created, read-only tablespaces are not meant to satisfy archiving or data publishing requirements.
Whenever you create a new tablespace, it is always created as read-write. Read-only tablespaces cannot be modified. Therefore, they do not need repeated backup. Also, should you need to recover your database, you do not need to recover any read-only tablespaces, because they could not have been modified.
You can drop items, such as tables and indexes, from a read-only tablespace, just as you can drop items from an offline tablespace. However, you cannot create or alter objects in a read-only tablespace. Read-Only vs. Online or Offline Making a tablespace read-only does not change its offline or online status. Offline datafiles cannot be accessed. Bringing a datafile in a read-only tablespace online makes the file readable.
The file cannot be written to unless its associated tablespace is returned to the read-write state. This tablespace is automatically created at database creation. Oracle Database uses it to manage the database.
It contains the data dictionary, which is the central set of tables and views used as a read-only reference for a particular database. It also contains various tables and views that contain administrative information about the database. These are all contained in the SYS schema, and can be accessed only by the SYS user or other administrative users with the required privilege. Every database using Oracle Database 10 g release 1 For more information, see Oracle Database Administrator's Guide.
This tablespace stores temporary data generated when processing SQL statements. For example, this tablespace would be used for query sorting.
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