Re: Logical IO

  • From: Yong Huang <yong321@xxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Thu, 19 Nov 2009 09:50:13 -0800 (PST)

> that the only way to find the current mode read is either use 
> event 10046 (when the blocks are not already cached) or check 
> x$bh for increase in touch count (class 4 for segment header, 
> verify with file and block number). There's no event to trace 
> CU read.

I posted that before I read Fuyuncat's posting at

http://www.hellodba.com/Doc/logic_io_secret_FTS_1.html

It looks like setting _trace_pin_time to non-zero unambiguously 
pinpoints the buffers read in current mode. Excellent!

BTW, for the benefit of others, the meanings of some of the 
logical I/O functions Fuyuncat used are explained at
http://www.jlcomp.demon.co.uk/buffer_usage.html

Yong Huang


      
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