Oracle-L: Re: ASSM & buffer busy waits ?

From: Diego Cutrone <diegocutrone_at_yahoo.com.ar>
Date: Wed, 16 Apr 2003 14:39:02 -0800
Message-ID: <F001.00583819.20030416143902@fatcity.com>

2) Is buffer busy waits TOTALLY eliminated when using ASSM ?
Can buffer busy waits wait occur for reasons OTHER than contention for freelists , PCTUSED , PCTFREE ?

DC - Sure it can happen for other reasons. For instance if one session is reading a buffer from disk and another one wants to access this buffer , it'll have to wait. This is computed as BBW p3=130. I have seen many instances with this kind of BBW type.

Another reason I can think about is when you have a right-hand index (when it gets inserted at the same block all the time).Many sessions would want the same block in XCUR mode, and only one can have it at one time.

I haven't really tested the effect of ASSM in the BBW you have mentioned, but I'll try them in short.

Please correct me if I'm wrong.

greetings
Diego Cutrone

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