Why would you want to force a physical read?
One thing you could do is define your db_block_buffers very low and that
would mean most of your sql statements would be physical reads. Performance
would go down the tubes.
Jim
"Dan Bikle" <dbikle_at_rahul.net> wrote in message
news:a73fmv$ncc$1_at_samba.rahul.net...
> Hello,
>
> I just ran the query displayed below:
>
> 00:02:13 SQL> SELECT name, value from v$sysstat where name like '%physical
read%';
>
> NAME
VALUE
> ---------------------------------------------------------------- ---------
-
> physical reads
184055010
> physical reads direct
116919057
> physical reads direct (lob)
0
>
> 00:04:20 SQL>
>
> I'd like to have more control over direct physical reads on my DB when I
> run SQL statements.
>
> I do get a small amount of control when I use DIRECT=Y with the export
utility.
>
> Also, when I use sql loader I only need to add the key value pair:
> DIRECT=Y to force a direct physical write.
>
> I looked through available hints in the 8i SQL Reference and no hints
> caught my eye. The NOCACHE keyword in the ALTER TABLE syntax looks
promising
> but their description dampens my hopes:
>
> "For data that is not accessed frequently, this clause indicates that
> the blocks retrieved for this table are placed at the least recently
> used end of the LRU list in the buffer cache when a full table scan
> is performed."
>
> Perhaps I should just make sure that my tables' statistics are up to date
> and then I should rely upon the kernel to to direct physical reads when
> it sees fit.
>
> Let me know if you have any syntax demo which will cause a direct physical
read.
>
> Thanks,
> -Dan
> ---------------------------------------------------------------------
> Daniel B. Bikle/Independent Oracle Consultant
> bikle_at_bikle.com | 650/941-6276 | P.O. BOX AG LOS ALTOS CA 94023
> http://www.bikle.com
> ---------------------------------------------------------------------
>
>
Received on Sun Mar 17 2002 - 19:35:37 CST
