Buffer cache LRU

From: Taral Desai <taral.desai_at_gmail.com>
Date: Sun, 3 Jan 2010 01:52:50 -0600
Message-ID: <2b0cd5cd1001022352y1979c7e4mcb0c25c7cb87183c_at_mail.gmail.com>

Hi All,

Few Doubts regarding oracle buffer cache. Here is the documentation link from 11g R2.


Which Says

<http://download.oracle.com/docs/cd/E11882_01/server.112/e10713/memory.htm#i12483> "The database uses a sophisticated algorithm to make buffer access efficient. Pointers to dirty and nondirty buffers exist on the same least recently used (LRU) list, which has a hot end and cold end. A cold buffer is one that has not been recently used. A hot buffer is frequently accessed and has been recently used."

Now, i was under impression that there is a different LRU which is LRUW for write list but this says LRU maintains both cold, dirty, free, hot all pointers.

Can someone please explain this and also i had few question

  1. How to you find that particular buffer in hot, cold or dirty ?
  2. How to find buffer is in which list LRU or LRUW ?

To find this do we need SGA dump and if yes where to find this information.


Thanks & Regards,
Taral Desai
Samuel Goldwyn<http://www.brainyquote.com/quotes/authors/s/samuel_goldwyn.html>
- "I'm willing to admit that I may not always be right, but I am never

Received on Sun Jan 03 2010 - 01:52:50 CST

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