Re: Daramtically improve BCHR with a single statement

So, if I coerce the developers into writing better code that does less logical IO, and the BCHR goes down, I should then investigate and fix the problem? ;)

Jared

On Monday 13 January 2003 08:09, Yechiel Adar wrote:
> Hello All
>
> I saw that piece of code a few times and still think that even if you can
> bump up the BCHR it has it's place. How can you tell that you need more
> space in the buffer pool? Bad BCHR is an indication that you need to check
> this. It is also an indication that you do a lot of FTS or missing an index
> and you SQL reads too many blocks.
>
> Use the BCHR as an indication. When it goes down it is time to check.
>
> Yechiel Adar
> Mehish
> ----- Original Message -----
> To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> Sent: Monday, January 13, 2003 5:08 AM
>
> > To add an example of what Anjo, Morgens and everyone else is talking
>
> about,
>
> > here is a perfect illustration of why focusing on BCHR is like
> > concentrating intensely on how fast your tyres rotate in a Tour de
> > France, instead of looking of where you are going (probably a lot more
> > useful). Another example:
> > If I raced (100M sprint) against Maurice Green, and he went off in the
> > wrong direction, despite the fact that he is so much faster than me (duh
>
> !)
>
> > , I could lightly jog (as if I have anything else to offer) the 100M in
>
> the
>
> > right direction and beat him. Well, focusing on BCHR alone is like going
>
> at
>
> > full tilt with no direction.
> > Also, I have realized that cars have been around for > 100 years now, so
> > why exactly would I want to sprint again ? :-)
> >
> > Check out this example:
> >
> > run any number of scripts to look at BCHR. Then run the following
>
> anonymous
>
> > PL/SQL block:
> >
> > declare
> > jackass number;
> > begin
> > for jackass in 1..10000000 loop
> > execute immediate 'select count (*) from solvit.solvit_lic ' ; --
> > replace this table with any single row table you like.
> > end loop;
> > end;
> > /
> >
> > Check your BCHR again. Wow, amazing ! How much better your BCHR looks
> > now. This must be magic. If you would like to purchase other such tools,
> > please feel free to drop me a line, I could also sell you a large
> > iceberg, which would end your personal water restriction problems.
> >
> > Another advantage to the above code is that it eliminates idle capacity
> > from my CPU's (I paid for the thing, it should be put to work, right ? )
>
> as
>
> > my laptop has been at 100% CPU utilization for the last 8 minutes as I
> > let this piece of crap run before I killed it (Oracle 9 on XP with 512 MB
> > RAM [SGA 120 MB], with a bunch of other starved stuff running
> > concurrently).
> >
> > Reduction of logical I/O : Now THERE is the holy grail worth pursuing ! I
> > am sure we could have a VERY interesting discussion on that one !
> >
> > Feel free to use the above example to prove for once and for all that
> > concetration on tuning BCHR alone is a fruitless exercise.
> >
> > Regards :
> >
> > Ferenc Mantfeld
> >
> > -----Original Message-----
> > From: Rachel Carmichael [SMTP:wisernet100_at_yahoo.com]
> > Sent: Monday, January 13, 2003 11:24 AM
> > To: Multiple recipients of list ORACLE-L
> > Subject: Re: BCHR Tuning
> >
> > and those people "sell a tuning tool".... hm, I hadn't noticed any
> > selling going on here. Or perhaps it's been subliminal?
> >
> > --- Jared Still <jkstill_at_cybcon.com> wrote:
> > > On Friday 10 January 2003 14:48, Mogens Norgaard wrote:
> > > > Obviously, we don't know what we're talking about. I can see
> > >
> > > there's a
> > >
> > > > presentation by Rich Niemich at IOUG-A where he'll address all
> > >
> > > those
> > >
> > > > idiots who are saying you should ignore the Cash Hit Ratio (and who
> > >
> > > are
> > >
> > > > all just after making big money on their products - I loved that
> > >
> > > one).
> > >
> > > > > Or modify the set up of these tools to take action when BCHR
> > >
> > > falls......
> > >
> > >
> > > Here's the session info:
> > >
> > > Date: Mon, Apr 28, 2003 @ 11:45 AM - 12:15 PM
> > > Venue: Southern Hemisphere 2, Walt Disney World
> > > Dolphin, Lake Buena Vista, FL
> > >
> > > Abstract: Lately, there has been a big push to ignore your
> > > hit ratio with claims that it is meaningless. This shallow
> > > minded view (usually by people who sell a tuning tool) ignores
> > > why people look at hit ratios and what they are looking for.
> > > This quick tip talk will show you what to look for and why.
> > > You will definitely know when, where & why to look at your
> > > hit ratio in the future.
> > >
> > > Show you why your hit ratio matters. How to analyze the
> > > hit ratio. Fallacies by those who want to sell you products
> > > and tools instead.
> > >
> > >
> > > Shallow Minded ?!
> > >
> > > Jared
> > > --
> > > Please see the official ORACLE-L FAQ: http://www.orafaq.net
> > > --
> > > Author: Jared Still
> > > INET: jkstill_at_cybcon.com
> > >
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> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.net
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> > Author: Rachel Carmichael
> > INET: wisernet100_at_yahoo.com
> >
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Jared Still
  INET: jkstill_at_cybcon.com

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