Types of Standby Databases

 Types of Standby Databases:

=======================


Physical Standby

Logical Standby

Snapshot Standby

Active data guard


1.PHYSICAL STANDBY:

1.Physical Standby is the exact block-for-block copy of the primary database.

2.Physical standby database synchronized with the primary database through the application of redo data received from the primary database.

3.It can be used concurrently for data protection and reporting.   

4.Physical standby database will be mounted stage while recovery is processed.

5.It can be opened as read-only mode

6.Active standby database is available for reading mode, enabling recovery at the backend. 


Physical standby database benefits:

1.An identical physical copy of the primary database.

2.Disaster recovery and high availability.

3.High Data protection.

4.Reduction in primary database workload.

5.Performance can be Faster.


2.LOGICAL STANDBY:

1.A logical standby database does not have to match the schema structure of the source database.

2.Logical standby tables can be open for SQL queries (read-only), and all other standby tables can be open for updates.

3.The primary database logs can be converted as SQL then the SQL statements can be applied into the logical standby database.

4.The logical standby database can have different unique Database IDs.

5.A logical standby database can have additional materialized views and indexes added for faster performance



Logical Standby Database Benefits:

1.Simultaneous use for reporting, summations, and queries.

2.Efficient use of standby hardware resources.

3.Reduction in primary database workload.

4.Some limitations on the use of certain data types



3.SNAPSHOT STANDBY:

1.The snapshot standby database is and fully update standby database.

2.A snapshot standby database receives and archives redo data from a primary database but are not applied.

3.Redo data received from the primary database is applied when a snapshot standby database is converted back into a physical standby database,

4.This database can be used for updates but these updates are discarded before the snapshot database is converted back into a physical standby database


Snapshot Standby Database benefits:

1.Temporary snapshot of the primary database.

2.fully updatable stand-alone database.

3.As this is in READ and WRITE mode, any kind of testing or changes can be done,


4.ACTIVE DATA GUARD:

Standby DB will be in OPEN mode

Normal user transactions can also continue on standby

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