Re: IO function metric.

"Mladen Gogala" <gogala.mladen_at_gmail.com> wrote in message news:giqolp$fn6$2_at_solani.org...
> Oracle 11g has a table called V$IOFUNCMETRIC which is a typical
> metric table, like the set that was introduced in 10g. What confuses
> me are 2 things:
> 1) SQL> select function_name from V$IOFUNCMETRIC;
>
> FUNCTION_NAME
> ------------------
> Recovery
> Direct Writes
> Smart Scan
> Others
> ARCH
> DBWR
> XDB
> Streams AQ
> Buffer Cache Reads
> Direct Reads
> Data Pump
> LGWR
> RMAN
>
> 13 rows selected.
>
> What the heck is "smart scan"? It's neither a buffer cache read nor
> a direct read since both functions are defined separately.
>
> 2) 1 select SMALL_READ_MBPS,SMALL_READ_IOPS
> 2 from V$IOFUNCMETRIC
> 3* where FUNCTION_NAME='LGWR'
> SQL> /
>
>
> SMALL_READ_MBPS SMALL_READ_IOPS
> --------------- ---------------
> .016650017 1.83150183
>
> Elapsed: 00:00:00.05
>
>
> LGWR is READING? What is log writer reading? Log writer is not supposed
> to be reading anything. Why is LGWR doing reads? I consider it to be
> cheating. Does anybody have any information as to what is LGWR reading?
> Kevin Closson's explanation from this article http://tinyurl.com/yr37pw
> obviously does not cover this case.
>
> --
> Mladen Gogala
> http://mgogala.freehostia.com

I believe smart scan is for the new Exadata storage. (see http://kevinclosson.wordpress.com/exadata-posts/) Jim Received on Tue Dec 23 2008 - 10:10:16 CST