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DB cache filled up, any solution???? [message #309855] Sat, 29 March 2008 05:52 Go to next message
ahmed.nsa
Messages: 12
Registered: March 2008
Location: bangalore
Junior Member
Hi all,

I hv read one book regarding Database buffer cache, but I hv doubt in that so please anyone can overcome the problem and give me the exact solution?

question:
let my database instance is manipulating a large volume of transaction and requeires more space in the database buffer cache,. what happens if the database buffer cache filled up before transaction completed???

the solution in the book has been given like this that, "if db cache filled up, the uncommitted datas from the cache are written to datafiles"!
please let me know the exact answer!!!
Re: DB cache filled up, any solution???? [message #309886 is a reply to message #309855] Sat, 29 March 2008 10:55 Go to previous messageGo to next message
Michel Cadot
Messages: 64103
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
The sentence is correct.
Blocks are writen to files when space is needed and in some other cases.

The best book to know how Oracle works is Database Concepts

Regards
Michel
Re: DB cache filled up, any solution???? [message #309894 is a reply to message #309855] Sat, 29 March 2008 12:26 Go to previous messageGo to next message
varu123
Messages: 754
Registered: October 2007
Senior Member
Quote:
the solution in the book has been given like this that, "if db cache filled up, the uncommitted datas from the cache are written to datafiles"!


How would DBWR know whether the data is committed or not?
With commit ,data is written to logfiles.
How the author is so sure that it is uncommitted data and not committed?

[Updated on: Sat, 29 March 2008 12:51] by Moderator

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Re: DB cache filled up, any solution???? [message #309895 is a reply to message #309894] Sat, 29 March 2008 12:55 Go to previous message
Michel Cadot
Messages: 64103
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
Quote:
How would DBWR know whether the data is committed or not?


I think (I hope) the author means committed and even uncommitted blocks are written.

Quote:
With commit ,data is written to logfiles.

No, "data" (actually changes) are written to log files (actually log buffer) all along the transactions. At commit time only commit marker is written and log buffer is flushed to log file.

Regards
Michel
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