Re: db_file_multiblock_read_count and 10g
Date: Sun, 25 Jan 2009 16:38:01 -0800
On Sun, Jan 25, 2009 at 3:42 PM, Á¶µ¿¿í <ukja.dion_at_gmail.com> wrote:
>> IIRC _db_file_exec_read_count=8 and
>> _db_file_optimizer_read_count=((max I/O size)/DB_BLOCK_SIZE)), so
>> usually 1MB I/O size.
> I think you mean _db_file_optimizer_read_count=8 and
> _db_file_exec_read_count = ((max I/O size)/DB_BLOCK_SIZE)).
I did. Caught a bit of dyslexia for a moment.
> This is a reasonable assumption, but I'm not sure how Oracle determines the
> maximum I/O size. On my laptop, Oracle 10.2.0.1 and 22.214.171.124 show quite
> different _db_file_exec_read_count.
> In 10.2.0.1 : _db_file_exec_read_count = 5
> In 126.96.36.199 : _db_file_exec_read_count = 128
> It seems quite dependent on Oracle version, not just on OS and/or storage
Going from memory and not looking at the code, I think the db cache size and number of processes also influence it, and I don't recall if this changed between releases or not.
I'll research this a bit more next week if I have free time.
-- Regards, Greg Rahn http://structureddata.org -- http://www.freelists.org/webpage/oracle-lReceived on Sun Jan 25 2009 - 18:38:01 CST