RE: get hit ration

2003-06-05 Thread Niall Litchfield 
Title: Message



A 
library cache hit means that when parsing a statement the object definition 
is already found in the cached data dictionary (likely it has been recently 
used). A library cache miss means that it aint there. 
 
Now if 
you can explain to your line of business boss why you would wish to improve the 
ratio of one to the other by allocating some memory that could be used for 
something else to the library cache (located in the shared pool), then go right 
ahead. 
 
On the 
other hand you might have a real performance problem (my report runs for 1.5 
hours and it only used to run for 3 minutes),  these sorts of problems 
generally have a different underlying cause than finding objects in memory 
rather than on disk, 80 % of the time or thereabouts its the sql, 10% or there 
abouts its the data. 
 

Niall 

  
  -Original Message-From: [EMAIL PROTECTED] 
  [mailto:[EMAIL PROTECTED] On Behalf Of AKSent: 03 June 2003 
  17:35To: Multiple recipients of list ORACLE-LSubject: 
  get hit ration
  found that gethitratio in v$librarycahce is very 
  low for indexes. what does it mean ? is there any way to improve this 
  .
   
  thanks,
  -ak

Re: get hit ration

2003-06-04 Thread Mogens Nørgaard 




Keep reading the same stuff from the indexes in a useless loop. That should
improve it. Or use Connor McDonald's script on oracledba.co.uk to get any
hitrate you like.

Seriously, hitratios don't mean a thing. Long story. Don't worry.

AK wrote:
  
  
 
  
 

  found that gethitratio in v$librarycahce
is very  low for indexes. what does it mean ? is there any way to improve
this  .
 
   
 
  thanks,
 
  -ak