Re: db_file_multiblock_read_count and 10g
From: (wrong string) 조동욱 <ukja.dion_at_gmail.com>
Date: Mon, 26 Jan 2009 08:42:45 +0900
Message-ID: <43c2e3d60901251542u5fe50b69p3026a8dbba251798_at_mail.gmail.com>
>
>
> 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.
Dion Cho - Oracle Performance Storyteller
Date: Mon, 26 Jan 2009 08:42:45 +0900
Message-ID: <43c2e3d60901251542u5fe50b69p3026a8dbba251798_at_mail.gmail.com>
>
>
> 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)).
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 11.1.0.6 show quite different _db_file_exec_read_count.
In 10.2.0.1 : _db_file_exec_read_count = 5 In 11.1.0.6 : _db_file_exec_read_count = 128
It seems quite dependent on Oracle version, not just on OS and/or storage settings.
Dion Cho - Oracle Performance Storyteller
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-- http://www.freelists.org/webpage/oracle-lReceived on Sun Jan 25 2009 - 17:42:45 CST