Thanks for the question, kartheek.
Asked: November 16, 2016 - 5:01 am UTC
Last updated: November 18, 2016 - 4:14 am UTC
Version: 11g r2
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You Asked
1.how the same blocks are copy/exist(while update transactions) in database block buffer and redolog buffer
2.which one (DBBC and RLB) is first got activated
and Connor said...
They are different things totally. It works like this (I'll leave out anything about 'undo' blocks to keep things simple).
- I read a block into the buffer cache from disk. The block says
EMPLOYEE 10
NAME CONNOR
SALARY 1000
- I want to change that block
- We write the "instructions" on how to change that block to the redo, eg
"Set Salary to 1200"
- Now I can make the block look like this:
EMPLOYEE 10
NAME CONNOR
SALARY 1200
So the database block is a view of the *data*, a redo log is view of *instructions* to change the data.
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