Re: Oracle slowed down

From: Bob Jones <email_at_me.not>
Date: Fri, 21 Apr 2006 02:33:53 GMT
Message-ID: <lwX1g.4480$Lm5.2796@newssvr12.news.prodigy.com>

"DA Morgan" <damorgan_at_psoug.org> wrote in message news:1145557619.596258_at_yasure.drizzle.com...

> Bob Jones wrote:
>> "DA Morgan" <damorgan_at_psoug.org> wrote in message 
>> news:1145489802.204935_at_yasure.drizzle.com...
>>> Bob Jones wrote:
>>>> "Poh Tien Lye" <pohtl_at_singnet.com.sg> wrote in message 
>>>> news:e25jd2$anb$1_at_reader01.singnet.com.sg...

>>>>> Hi,

>>>>>

>>>>> Recently, I found that my Oracle database (8.1.7.4) on Windows NT
>>>>> service
>>>>> pack 6
>>>>> response time has increased significantly. I did a check and found the
>>>>> buffer chache hit ratio
>>>>> was down to less than 0.20. However, the ratio does not improve even
>>>>> when I
>>>>> increase the
>>>>> db_buffer from 17MB to 38MB. The ratio still drop to 0.20 after 8 hrs
>>>>> of
>>>>> operation.

>>>> Are you sure the hit ratio is calculated correctly? That is very low. 
>>>> How much data are you dealing with? 38MB is still too small for an 
>>>> average database.
>>> High? Low? What's the difference. Hit ratios have been proven 
>>> irrelevant.
>>
>> Irrelevant to performance? I have not yet seen that prove.
>
> 1. Read books by Tom Kyte
> 2. Read books by Jonathan Lewis
> 3. Read the archives of this usenet group specifically looking for posts 
> by Richard Foote and Howard Rogers (as well as Jonathan Lewis).
> 4. Hit ratios have been dead, buried, and fossilized for some years now.
> -- 

Do I really need to read that many books just to get one reason why hit ratios are irrelevant? I remember having a conversation with a couple of those guys about this. The auguments they presented were less than convincing.

May I aslo suggest reading Oracle's official performance tuning books? Received on Thu Apr 20 2006 - 21:33:53 CDT