Home » RDBMS Server » Performance Tuning » buffer cache hit ratio reduces to -3
buffer cache hit ratio reduces to -3 [message #64873] Mon, 23 February 2004 19:28 Go to next message
kamal matta
Messages: 8
Registered: April 2003
Junior Member
hi,

i have a linux high end server with oracle 9i. database has got only 300 to 400 mb data not more than that. but queries are working very slow, and buffer cache hit ration shows -3 in toad which expects me to increase the db_block_buffers.

what is u ppl's opinion.

thanks

km

 

 
Re: buffer cache hit ratio reduces to -3 [message #64875 is a reply to message #64873] Tue, 24 February 2004 00:15 Go to previous messageGo to next message
Daljit Singh
Messages: 290
Registered: October 2003
Location: Texas
Senior Member
Hi,

Very first i want to say u that this is not enough info to take any solid step to improve performance. U just tell us abt ur current db buffer size and instead of believing on TOAD output use :
select (1-( a.value/(b.value+c.value)))*100
from v$sysstat a, v$sysstat b, v$sysstat c
where
a.name ='physical reads' and
b.name ='db block gets' and
c.name ='consistent gets'

to find out the hit ratio.

Moreover as per u, u have very limited data in ur DB so i dont think u have u increase ur DB buffer just let us know abt the amount of concurrent transactions that happens on ur DB.

Check ur DB is analayzed or not? And proper indexes are there or not? These two are the major areas of increasing the speed of queries.

Just chek all this and revert back with more information.

Daljit Singh.
Re: buffer cache hit ratio reduces to -3 [message #64880 is a reply to message #64875] Tue, 24 February 2004 21:48 Go to previous messageGo to next message
kamal matta
Messages: 8
Registered: April 2003
Junior Member
d/daljit,
thanks for reply. i checked the db_buffer_blocks and as per the init file its value is zero. i checked on another 9i installation too, its 0 on that too. pl tell me will increasing this will help in query results. if yes then pl tell me how its value shoudl be planned ?
thanks
km
Re: buffer cache hit ratio reduces to -3 [message #64882 is a reply to message #64875] Tue, 24 February 2004 22:57 Go to previous message
kamal matta
Messages: 8
Registered: April 2003
Junior Member
i think in 9i db_buffer_size parameter is changed to db_cache_size ? actually i was confused as i am using both 7.3 and 9i. so its value is 117440512

km
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