Oracle Database Snapshots Tutorial345

Introduction

Snapshot is a point-in-time copy of a database. It is a read-only database that can be used for various purposes, such as reporting, testing, and data recovery. Snapshots are created quickly and efficiently, and they do not consume any additional storage space. This makes them an ideal way to create a copy of a database without affecting the performance of the original database.

Creating a Snapshot

To create a snapshot, you can use the following syntax:```
CREATE SNAPSHOT ON AS OF TIMESTAMP ;
```

For example, to create a snapshot named my_snapshot on the my_database database as of the current timestamp, you would use the following command:```
CREATE SNAPSHOT my_snapshot ON my_database AS OF TIMESTAMP SYSDATE;
```

Using a Snapshot

Once a snapshot has been created, you can use it to perform various operations, such as:* Queries: You can run queries against a snapshot to retrieve data as of the snapshot timestamp.
* Reports: You can create reports based on data from a snapshot.
* Testing: You can use a snapshot to test changes to your database without affecting the original database.
* Data recovery: You can use a snapshot to recover data that was lost or corrupted.

Managing Snapshots

Once you have created a snapshot, you can manage it using the following commands:* ALTER SNAPSHOT: You can use the ALTER SNAPSHOT command to rename a snapshot or change its retention period.
* DROP SNAPSHOT: You can use the DROP SNAPSHOT command to delete a snapshot.

Example

The following example shows how to create and use a snapshot:```
-- Create a snapshot named my_snapshot on the my_database database
CREATE SNAPSHOT my_snapshot ON my_database AS OF TIMESTAMP SYSDATE;
-- Query the snapshot to retrieve data as of the snapshot timestamp
SELECT * FROM my_table@my_snapshot;
-- Drop the snapshot
DROP SNAPSHOT my_snapshot;
```

Conclusion

Snapshots are a powerful feature that can be used for a variety of purposes. They are easy to create and manage, and they do not consume any additional storage space. This makes them an ideal way to create a copy of a database without affecting the performance of the original database.

2024-12-09

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