Of course it dropped dramatically. That's because you are no longer doing 99% of the buffer gets that you were wasting to begin with.
If it drops my resource use and increases my performanc, I'd love to have a BCHR of 1%. (I know that's extreme, but wouldn't it be cool..?) F> Here's an excellent real life example of why BCHR is not a good tuning F> metric and you should focus on reducing I/Os. F> A simple fix for a query and here is the resulting email to the client, who F> understands that BCHR is not good. A little techie humor... F> I have good news and I have bad news. F> The good news is that the elapsed query time and total I/Os for the latest F> iteration dropped significantly. Old -->> 1:42 min 2,715,659 i/os (15,925 physical) New -->> 22 seconds 3318 i/os (2861) F> However, the bad news is that the Buffer Cache Hit Ratio dropped F> dramatically! Old -->> 99.36% New -->> 13.77% F> So, I have undone all the changes I made and will begin looking at other F> methods to improve performance! -rje -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Robert Eskridge INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
