oracle different table spaces

Oracle database is a relational database system that can use multiple table spaces to store data. Each tablespace is different and has different characteristics and functions. This article will introduce the different table spaces in Oracle and their uses.

1. System table space

The system table space is a table space that comes with the Oracle database by default. It contains all stable parts of system objects such as data dictionaries, control files, log files, shared libraries and internal storage structures required for program execution. These objects are usually created during database installation and cannot be changed. The system tablespace cannot be deleted because deleting the system tablespace will cause the database to crash.

2. User table space

The user table space is where new users are created and space is allocated in the Oracle database. This is the most common type of table space. Each user has his own table space. Users can create tables, indexes and other objects in their own table space, and allocate the space they need. There is at least one tablespace per user, but space can be allocated among multiple tablespaces.

3. Index table space

The index table space is a table space specially used to store indexes. Indexes typically require much less space than tables, so a separate index tablespace can help optimize performance. When creating an index, you can specify which table space the index should belong to. Index table spaces are usually used separately from user table spaces.

4. Temporary table space

Temporary table space is a table space specially used to store temporary tables. Temporary tables can be used when certain queries require extensive sorting or grouping. Temporary table spaces are used to save these temporary tables, usually using a large amount of logical I/O and physical I/O. Using temporary tablespaces also avoids the burden of sorting and grouping large tables on user tablespaces.

5. Rollback table space

Rollback table space is used to manage the rollback operation of transactions. When a transaction needs to be rolled back to a previous state, the data in the rollback tablespace can be used to restore the changed data. A rollback tablespace can be a single tablespace or a combination of multiple tablespaces.

6. Large Object Table Space

The large object table space is a table space used to store large binary objects (LOB). These LOBs can be images, audio, videos or documents, etc., and usually require hundreds of megabytes or several gigabytes of storage space. The large object table space contains two different types of LOBs: BFILE lob and INLINE lob. BFILE lob points to the file system file of the external file system, while INLINE lob is stored in the table space. Large object table spaces are commonly used in multimedia applications, document management systems, and satellite image processing.

In short, Oracle's different table spaces have different functions and uses. Understanding these table spaces will help optimize database performance and better manage the database.

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