 how can increase buffer hit ratio [message #182564] |
Mon, 17 July 2006 01:00  |
abs_amit
Messages: 59
Registered: January 2006
Location: delhi
|
Member |
|
|
Hi all,
How can I increase buffer cache hit ratio
Statistics are:
Total System Global Area 4294967296 bytes
Fixed Size 1313192 bytes
Variable Size 515634776 bytes
Database Buffers 3774873600 bytes
Redo Buffers 3145728 bytes
Total Database size is : 158 GB
Cache Hit Ratio % Ratio
--------------- ----------
.136982839 13.7
|
|
|
|
| Re: how can increase buffer hit ratio [message #182586 is a reply to message #182564] |
Mon, 17 July 2006 03:14  |
JRowbottom
Messages: 5933
Registered: June 2006
Location: Sunny North Yorkshire, ho...
|
Senior Member |
|
|
Why do you want to increase the buffer cache hit ratio?
Have you identified a performance problem with your database for which you believe that increasing this figure is the solution, or have you read somwhere that thi figure needs to be high for your database to be performing well.
If it the latter, then I@m afraid you have been misled somewhat.
If your system is a data warehouse, this ratio will generally be low.
If your system is one where you frequently access a large range of records, rather than just adding new ones, then this ratio will be generally be low.
If your system is very badly written and does lots ofelects inside cursor loops, then this can make the hit ratio quite high - indeed, it is possible to write a utility to raise the BCHR to any value you want it to be.
Now, a low BCHR can be an indication that you have a problem, and fixing that problem can raise the BCHR, but a high BCHR in and of itself says nothing about the performance of your Db.
Have a look at this AskTom thread and most of the rest of that site.
[Updated on: Mon, 17 July 2006 08:18] Report message to a moderator |
|
|
|
| Re: how can increase buffer hit ratio [message #182623 is a reply to message #182564] |
Mon, 17 July 2006 06:59 |
 |
Mahesh Rajendran
Messages: 10707
Registered: March 2002
Location: oracleDocoVille
|
Senior Member
Account Moderator |
|
|
The OP has asked the same question before
http://www.orafaq.com/forum/m/179261/42800/#msg_179261
and was answered.
If the OP is looking into a particular response, may be he/she could just post it here and we can provide the same.
As JRowbottom has nicely put,
>>Now, a low BCHR can be an indication that you have a problem,
>>and fixing that problem can raise the BCHR, but a high BCHR
>>in and of itself says nothing about the performance of your Db.
BCHR does mean something. But working to increase BCHR leads nowhere.
|
|
|
|
] 
Blog
Search
Help
Members
Register
Login
Home
