Re: Expert Cache

Hi Alexei

This is interesting - how does this relate to QWCCHGTN API? Everything there 
seems related to database objects - *CALC is equivalent to tuning type 3, 
correct? And *FIXED to type 0 - with user control in between? And in that 
documentation it is speaking of the "locality of reference".

But is this expert cache, then, or something different?

Thanks
Vern

-------------- Original message -------------- 
From: Alexei Pytel <pytel@xxxxxxxxxx> 

Of course, this has the best effect when file access is basically 
consistent, because it affects all IO requests, not table by table. 

Expert cache works object by object. It tries to recognize the pattern of 
access to each object 
and optimize paging activity for that object. 

Leaving it *FIXED uses a 4KB request size no matter what is going on. 

Each object has a default transfer size, which is not necessarily 4KB. 
This is what it falls back to when Expert cache is off. 
For example, QUSCRTUS API (Create user space) allows to set the transfer 
size. 
Look for optional parameter group 3. 

http://publib.boulder.ibm.com/infocenter/iseries/v5r4/topic/apis/quscrtus.htm 


Alexei Pytel 
always speaking for myself 


"We have all reasons to assume that our assumptions are not unreasonable." 
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