Buffer cache LRU
- From: Taral Desai <taral.desai@xxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Sun, 3 Jan 2010 01:52:50 -0600
Hi All,
Few Doubts regarding oracle buffer cache. Here is the documentation link
from 11g R2.
http://download.oracle.com/docs/cd/E11882_01/server.112/e10713/memory.htm#i12483
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
wrong."
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