Re: script for buffer hit ratio ??

Hi.

 In my opinion they made a couple of mistakes :

1. Instead of using 37 ( opens of replaced files ) it must be 73 ( physical writes ).
2. They should change WHERE clause accordingly.

 HTH. Michael.

In article <7uq12g$2kv$1_at_nnrp1.deja.com>,   Ed Stevens <Ed.Stevens_at_nmm.nissan-usa.com> wrote:
> I’m seeking some help understanding a PL*SQL script for determining
> buffer hit ratios. I picked up the script from Oracle Magazine’s “Tip
> and Code Archive.” Specifically, it is “listing 6” located at
> http://www.oracle.com/oramag/code/cod46dba.html. As published there,
> the section of code dealing with buffer hit ratio has two blocks of
> code, one of which is commented out. When I run the code as
published,
> the buffer hit ratio is reported as a negative number in the
> thousands. This made no sense to me, so I uncommented the other block
> of code and ran it, getting number that made sense. After closely
> analyzing the two methods, I find that the one that was originally
> commented out is essentially saying
>
> buffer hit ratio = 1 – physical_reads / (db_block_gets +
> consistent_gets)
>
> While the originally active code is saying
>
> buffer hit ratio = ((opens_of_replaced_files + db_block_gets) –
> consistent_gets) / (opens_of_replaced_files + db_block_gets))
>
> Does anyone have any comments on the use or meaning of either of these
> pieces of code?
>
> TIA
>
> - Ed Stevens
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
>

Sent via Deja.com http://www.deja.com/
Before you buy. Received on Fri Oct 22 1999 - 17:38:56 CDT