Tuesday, October 28, 2008

How to Flush your database caches

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Flushing the SGA memory areas, Shared Pool and Buffer Cache, it's an uncommon task, however, it gets useful when you're doing some tests and want to override the memory and go direct to disk, or when you have shared pool issues (here is a workaround, however I encourage you to find the root cause).

Shared Pool flush
This is the only sentence you have to know for releases 9i and up...
alter system flush shared_pool

Buffer Cache flush
For Oracle 9i I didn't know how to do this, fortunately found it today on Rahat Agivetova's blog
alter session set events = 'immediate trace name flush_cache';

I've tested it and does the job well...

And for Oracle 10g and up, the syntaxis is as follows:
alter system flush buffer_cache;

But you already knew that, isn't it? ...well, this was a "snack" post until Friday's follow up to Index Dynamics, which I may anticipate interesting results...

Thanks for reading... and for your comments, too!

You have UNDO space issues?: please read Who is using your UNDO space? Improved Script"
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