Implementation of durability by Oracle deserves some discussion.
The term REDO is may be fine but now days there exists a better term:
Write-ahead logging. Three words tell the essence: write to log ahead of
modifications.
Obviously for some reasons (a few of them can be named actually) oracle
implemented the commit command using Write-after logging. One wonders what
about rollback ? For me, Rollback seems to be fine even with write-after
logic.
---------------------------------------------------------------------------------
Please consider the environment before printing this e-mail
----- Forwarded by Laimutis Nedzinskas/VBankas on 2011.08.24 12:45 -----
From: Laimutis Nedzinskas/VBankas
To: jonathan@xxxxxxxxxxxxxxxxxx
Cc: "Oracle L" <oracle-l@xxxxxxxxxxxxx>,
oracle-l-bounce@xxxxxxxxxxxxx
Date: 2011.08.24 12:37
Subject: Re: ACID
http://en.wikipedia.org/wiki/ACID
There is one property which has very special comments about it:
" Isolation ...
This property of ACID is often relaxed (i.e. partly respected) because of
the huge speed decrease this type of concurrency management implies.
...
In reality, many alternatives are used due to speed concerns, but none of
them guarantees the same reliability. "
Could not be said better.
---------------------------------------------------------------------------------
Please consider the environment before printing this e-mail
From: "Jonathan Lewis" <jonathan@xxxxxxxxxxxxxxxxxx>
To: "Oracle L" <oracle-l@xxxxxxxxxxxxx>
Date: 2011.08.23 11:54
Subject: ACID
So who knows the meaning of ACID (not the Timothy Leary kind) ?
http://tonyhasler.wordpress.com/2011/08/22/why-is-acid-important/
http://jonathanlewis.wordpress.com/2011/08/19/redo-2/
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
--
//www.freelists.org/webpage/oracle-l
--
//www.freelists.org/webpage/oracle-l
