A database snapshot is a point-in-time image of a database that is taken without affecting the performance of the database. Database snapshots can be used to protect data, to support development and testing, and to provide a read-only view of the database for reporting purposes.
When you create a database snapshot, Oracle Database creates a duplicate of the datafiles, redo logs, and control files of the database. The snapshot is read-only and does not occupy any additional disk space.
You can create a database snapshot by using the CREATE DATABASE SNAPSHOT statement or the ALTER DATABASE SNAPSHOT statement.
The following example creates a database snapshot named “snapshot1” of the “prod” database.
CREATE DATABASE SNAPSHOT snapshot1
FROM DATABASE prod
The following example creates a database snapshot of the “prod” database that is named “snapshot1” and is mounted at the “snapshot1” mount point.
CREATE DATABASE SNAPSHOT snapshot1
FROM DATABASE prod
MOUNT point=’snapshot1′
When you create a database snapshot, you can optionally specify a list of tablespaces to be included in the snapshot. The following example includes the “users” and ” payroll ” tablespaces in the snapshot.
CREATE DATABASE SNAPSHOT snapshot1
INCLUDING tablespaces=’users, payroll’
You can also include specific datafiles in the snapshot. The following example includes the “payroll” datafile in the snapshot.
CREATE DATABASE SNAPSHOT snapshot1
INCLUDING datafiles=’payroll’
You can use the ALTER DATABASE SNAPSHOT statement to add or remove tablespaces and datafiles from a database snapshot.
The following example adds the “admin” tablespace to the “snapshot1” database snapshot.
ALTER DATABASE SNAPSHOT snapshot1
ADD TABLESPACE admin
The following example removes the “payroll” datafile from the “snapshot1” database snapshot.
ALTER DATABASE SNAPSHOT snapshot1
REMOVE DATAFILES=’payroll’
You can use the ALTER DATABASE SNAPSHOT statement to change the name of a database snapshot.
The following example changes the name of the “snapshot1” database snapshot to “snapshot2”.
ALTER DATABASE SNAPSHOT snapshot1
RENAME TO snapshot2
You can use the ALTER DATABASE SNAPSHOT statement to make a database snapshot read-write.
The following example makes the “snapshot1” database snapshot read-write.
ALTER DATABASE SNAPSHOT snapshot1
READ WRITE
You can use the ALTER DATABASE SNAPSHOT statement to disable a database snapshot.
The following example disables the “snapshot1” database snapshot.
ALTER DATABASE SNAPSHOT snapshot1
DISABLE
You can use the DROP DATABASE SNAPSHOT statement to delete a database snapshot.
The following example deletes the “snapshot1” database snapshot.
DROP DATABASE SNAPSHOT snapshot1
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What is snapshot backup in Oracle?
A snapshot backup is a form of incremental backup that copies the data blocks that have changed since the last backup. The advantage of snapshot backups is that they can be taken very quickly and do not require the Oracle database to be shutdown.
The disadvantage of snapshot backups is that they can only be used to restore the data to the same point in time that the snapshot was taken. If data is changed after the snapshot is taken, the changes will not be included in the backup.
What is difference between database snapshot and backup?
A database backup is a copy of the data and structures of a database that is taken at a specific point in time. A database snapshot is a read-only, static view of a database at a specific point in time.
A database backup is a copy of the data and structures of a database that is taken at a specific point in time. A database snapshot is a read-only, static view of a database at a specific point in time.
Database backups are used to restore a database to a previous state, while database snapshots can be used to view the state of a database at a specific point in time.
When you create a database backup, all the data in the database is copied, including the data in the transaction log. This means that a database backup can be used to restore the database to a point in time that is before the backup was taken.
When you create a database snapshot, only the data in the database is copied. This means that a database snapshot can only be used to restore the database to the state that it was in when the snapshot was taken.
A database backup can be used to restore a database to a previous state, while a database snapshot can be used to view the state of a database at a specific point in time.
What is snapshot backup?
In computing, a snapshot backup is a method of backing up data that records the state of a given set of files at a particular point in time. This information can then be used to restore the files to that state at a later date.
Snapshot backups are often used in virtualization, where the state of a virtual machine can be captured and then restored if the virtual machine is ever damaged or lost. In this context, a snapshot is a point-in-time image of a virtual machine that can be used to restore the machine if it is damaged or lost.
Snapshot backups can also be used to restore files that have been accidentally or maliciously deleted. In this case, the snapshot backup would be used to restore the files to their state at the time the snapshot was taken.
What is the use of snapshot in Oracle?
A snapshot is a point-in-time image of a data set. The image is created by taking a “snapshot” of the data set at a particular point in time and freezing the contents of the data set at that point. Snapshots can be used to preserve the state of a data set so that it can be restored to that state at a later time.
Snapshots can also be used to speed up the performance of some Oracle operations. For example, when you query a table that is currently being updated by another process, Oracle can use the snapshot of the table to answer the query more quickly.
Why snapshot is faster than backup?
When it comes to backing up your data, there are two main options: snapshot and backup. Both have their own benefits and drawbacks, but which one is the best for you?
Snapshot is a faster process than backup, and it doesn’t require you to restore your entire system in the event of data loss. Instead, you can simply restore the specific files or folders that you need. This makes it a great option for businesses that need to frequently restore data.
Backup, on the other hand, is a more comprehensive solution that can be used to restore your entire system in the event of data loss. However, it is a slower process and can be more expensive than snapshot.
Ultimately, the best solution for you depends on your individual needs. If you need a fast, simple solution for restoring specific files, then snapshot is the best option. If you need a comprehensive solution that can restore your entire system, then backup is the better option.
What is the difference between snapshot and view?
A snapshot is a point-in-time image of a table or schema, while a view is a query that is stored in the database.
A snapshot is a point-in-time image of a table or schema. When you take a snapshot of a table, the table is frozen as it is at the time the snapshot is taken. You can’t modify the table, and you can’t add or delete rows from the table. You can, however, query the table in the snapshot.
A view is a query that is stored in the database. When you create a view, you specify the SELECT statement that defines the view. The view is then stored in the database and can be queried just like any other table.
Why is snapshot not a backup?
A snapshot is a copy of a virtual machine (VM) or disk at a specific point in time. When you create a snapshot, VM hardware state, configuration, and the data on the disks are all saved.
Snapshots can be used to revert a VM to a previous state, or to duplicate a VM. They can also be used as a safeguard against accidental data loss.
Although snapshots are a convenient way to preserve VM states, they are not a reliable backup solution. Here are some reasons why:
1. Snapshots only capture the state of a VM at a specific point in time. If data on the disks changes after the snapshot is taken, that data will not be included in the snapshot.
2. Snapshots can grow in size over time, depending on how much data changes on the disks. If the disk space allocated to a snapshot is exceeded, the snapshot will be deleted.
3. Snapshots are not always reliable. If a VM crashes or the power is turned off while a snapshot is being taken, the snapshot may not be complete or may be corrupted.
4. Snapshots can be tricky to manage. If you have multiple VMs, each with its own set of snapshots, it can be difficult to keep track of which snapshots are current and which ones need to be deleted.
5. Snapshots can be time-consuming to create and delete.
For these reasons, snapshots should not be relied on as a sole backup solution. However, they can be a helpful addition to a more comprehensive backup strategy.
