Data Guard
Physical Standby
disk database structures are identicial on a block for block basis.
Database schema, including indexes are same.
REDO Apply - redo data from the primary is applied to the standby
- Database cannot be open when the Redo is applied
- When you open the DB in Read only mode, the standby received redo but wont apply it.
- Can open temporarily in read/write mode and tehn flashed back to a point in the past to make it standby again
Logical Standby
Physical Organization and structure can be different. Contains same logical information.
SQL Apply - SQL are generated from the redo data of the primary and then executed in standby.
- Target tables (copy of primary) are available only for read only operations.
- You can create indexes, materialized views on these tables.
- Table rows in the primary should be Uniquely Identified.
Primary Key or shortest nonnull unique-constraint index is logged as part of UPDATE
If you do not have then all the columns (except LONG, LOB, RAW) are logged.
All database should run on teh same platform (Same OS/Chipset)
All database should be on same release of Oracle Enterprise Editiion
Data Guard Services
Redo Transport Services - auto transfer of redo from primary to standby
Log Apply Services - Applying redo data either from archive redo log files or online redo log files.
Role Transitions - Changing the standby database to primary standby etc
Physical Standby
disk database structures are identicial on a block for block basis.
Database schema, including indexes are same.
REDO Apply - redo data from the primary is applied to the standby
- Database cannot be open when the Redo is applied
- When you open the DB in Read only mode, the standby received redo but wont apply it.
- Can open temporarily in read/write mode and tehn flashed back to a point in the past to make it standby again
Logical Standby
Physical Organization and structure can be different. Contains same logical information.
SQL Apply - SQL are generated from the redo data of the primary and then executed in standby.
- Target tables (copy of primary) are available only for read only operations.
- You can create indexes, materialized views on these tables.
- Table rows in the primary should be Uniquely Identified.
Primary Key or shortest nonnull unique-constraint index is logged as part of UPDATE
If you do not have then all the columns (except LONG, LOB, RAW) are logged.
All database should run on teh same platform (Same OS/Chipset)
All database should be on same release of Oracle Enterprise Editiion
Data Guard Services
Redo Transport Services - auto transfer of redo from primary to standby
Log Apply Services - Applying redo data either from archive redo log files or online redo log files.
Role Transitions - Changing the standby database to primary standby etc
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