Re: db file multiblock read count
From: Tanel Poder <tanel_at_tanelpoder.com>
Date: Thu, 28 Jan 2021 11:39:59 -0500
Message-ID: <CAMHX9JKxfTA6my11BOU=7xTP_AU2cLtbwLKnKBCuUBejHR4--A_at_mail.gmail.com>
Date: Thu, 28 Jan 2021 11:39:59 -0500
Message-ID: <CAMHX9JKxfTA6my11BOU=7xTP_AU2cLtbwLKnKBCuUBejHR4--A_at_mail.gmail.com>
One small addition - there used to be a bug when explicitly setting db_file_multiblock_read_count = 0 didn't enable the "self-tuning MBR", but ended up setting the MBRC value to 1 instead (that's no good). So, one had to completely unset the parameter in spfile/init.or, for the auto-selected MBRC to kick in.
MOS Note: Unable To Set Db_file_multiblock_read_count Parameter To Zero (Doc ID 1153666.1)
-- Tanel Poder https://tanelpoder.com/events On Sun, Jan 17, 2021 at 10:40 AM Frits Hoogland <frits.hoogland_at_gmail.com> wrote:Received on Thu Jan 28 2021 - 17:39:59 CET
> I too agree with most previous replies.
>
> At a certain point in time in the past, setting
> db_file_multiblock_read_count to 0 would make it oracle controlled and
> dynamic. However since it’s not documented what it takes into account and
> how it responds to it, I never used this setting, dynamic settings are
> unpredicatable especially if the whole mechanism is undocumented. I just
> read the db_file_multiblock_read_count parameter description in the oracle
> 19 documentation, and any mentioning of it being dynamic is gone, rather it
> says that the default value is ‘maximum I/O size that can be performed
> efficiently’ that is a rather clumsy and non-descriptive formulation.
>
>
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