What is the difference between a logical and physical standby database?
January 25th, 2006 By Fahd Mirza
And what are the harms of not using data guard when implementing a standby database?
2 Responses to “What is the difference between a logical and physical standby database?”
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January 28th, 2006 at 1:08 pm
The difference between physical and logical standby is in the way the changes from the primary are applied. Both created as an exact image of the primary database. Both receive redo logs from the primary database. The difference is that a physical standby is mounted (but not open) and applies the received redo logs just as in the case of media failure recovery. A logical standby reconstructs SQL statements from the received redo logs and executes them. A logical standby is (must be) opened and can with some limitations be used for reporting or other purposes. A physical standby is mounted and generally cannot be used for any other purposes. You can however switch temporarily to read-only mode and query it but synchronization with the primary will be paused until you return to the recovery mode. In 10g Rel. 2 you can also open it read-write and then flashback to its original state
Vadim Bobrov
Oracle Performance Tools
http://www.fourthelephant.com
January 29th, 2006 at 11:00 pm
Got it, thanks a lot.