In which storage does the oracle query table appear?

Oracle tables may appear in the following storage: Data files: store table data and indexes. Temporary table space: stores temporary data. Rollback segment: stores changes in transactions. Undo segment: stores changes from undo operations. Persistence table pool: caches table data to improve performance. InnoDB tablespace: Stores table data in the InnoDB storage engine. External tables: Connect to external data sources and access data through SQL.

#In which storages do Oracle tables appear?

Oracle tables may appear in the following types of storage:

• Data file: The core storage area of the Oracle database, containing table data and index.
• Temporary table space: Used to store temporary data, such as the results of sorting, aggregation, and join operations.
• Rollback segment: Used to store changes made during transaction processing to support rollback and recovery.
• Undo segment: Similar to the rollback segment, it is used to store the changes made by the cancellation operation.
• Persistence table pool: Optimize the performance of frequently accessed tables by caching table data into shared memory.
• InnoDB Table Space: When using the InnoDB storage engine, table data is stored in a table space.
• External Tables: Allows Oracle to connect to external data sources, such as files or a Hadoop data lake. These tables reside in external storage but are accessible through SQL queries.

Detailed description:

• Data files: Each data file corresponds to a specific table space. When the table is created, the data is allocated into data files.
• Temporary table space: Temporary table space allocates a separate area for each session to store temporary data. This data will be cleared when the session ends.
• Rollback segment: Each database has one or more rollback segments. When the transaction commits, the changes are written to the rollback segment. If a rollback is required, these changes can be used to restore the database to its pre-commit state.
• Undo segment: The undo segment is similar to the rollback segment, but is used to cancel operations. For example, if a user accidentally deletes a row, they can use the undo segment to restore the row.
• Persistence table pool: The persistence table pool caches table data into shared memory. When a table is accessed, Oracle will first check whether the data exists in the cache. If present, the data is retrieved from the cache, resulting in faster access.
• InnoDB Table Space: In the InnoDB storage engine, table data is stored in table spaces. Each tablespace can contain multiple tables.
• External Tables: External tables allow Oracle to connect to external data sources, such as files or a Hadoop data lake. The data itself is stored in external storage, but can be accessed via SQL queries, just as the seolah data resides in an Oracle database.

The above is the detailed content of In which storage does the oracle query table appear?. For more information, please follow other related articles on the PHP Chinese website!