Standby Database : A standby database is a transactionally consistent copy of the primary database.
There are 3 types of standby setup:
1. Physical standby
2. Logical standby
3. Snapshot standby
PHYSICAL STANDBY:
A physical standby database is an exact, block-for-block copy of a primary database. A physical standby is maintained as an exact copy through a process called REDO APPLY, in which redo data received from a primary database is continuously applied to a physical standby database using the database recovery mechanisms. So it will be always in sync with primary.
This Standby database can be opened in read only mode( knows as ACTIVE DATA GUARD), for reporting purpose. Most of the corporations use physical standby for dataguard configuration.
LOGICAL STANDBY:
The logical standby database is kept synchronized with the primary database through SQL APPLY, which transforms the data in the redo received from the primary database into SQL statements and then executes the SQL statements on the standby database. So it contains same logical information as that of production , but physical structure of data can be different.
SNAPSHOT STANDBY:
A snapshot standby database is a fully update-able standby database that is created by converting a physical standby database into a snapshot standby database. During this setup though it will receive logs from primary,But those redo won’t be applied to snapshot standby. Redo data received from the primary database is applied when a snapshot standby database is converted back into a physical standby database, after discarding all local updates to the snapshot standby database.
It provides an exact replica of a production database for development and testing purposes, while maintaining data protection at all times.
There are 3 types of standby setup:
1. Physical standby
2. Logical standby
3. Snapshot standby
PHYSICAL STANDBY:
A physical standby database is an exact, block-for-block copy of a primary database. A physical standby is maintained as an exact copy through a process called REDO APPLY, in which redo data received from a primary database is continuously applied to a physical standby database using the database recovery mechanisms. So it will be always in sync with primary.
This Standby database can be opened in read only mode( knows as ACTIVE DATA GUARD), for reporting purpose. Most of the corporations use physical standby for dataguard configuration.
LOGICAL STANDBY:
The logical standby database is kept synchronized with the primary database through SQL APPLY, which transforms the data in the redo received from the primary database into SQL statements and then executes the SQL statements on the standby database. So it contains same logical information as that of production , but physical structure of data can be different.
SNAPSHOT STANDBY:
A snapshot standby database is a fully update-able standby database that is created by converting a physical standby database into a snapshot standby database. During this setup though it will receive logs from primary,But those redo won’t be applied to snapshot standby. Redo data received from the primary database is applied when a snapshot standby database is converted back into a physical standby database, after discarding all local updates to the snapshot standby database.
It provides an exact replica of a production database for development and testing purposes, while maintaining data protection at all times.
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