Re: [Firebird-devel] MaxFileSystemCache (was Re: FB 2.1 64bit and memory usage ??)

[Alexandre B. S. <ib...@th...>]

Adriano dos Santos Fernandes wrote:
> Vlad Horsun escreveu:
>   
>>> This is big problem with FS cache disabled...
>>>     
>>>       
>>     I.e. you disabled it explicitly for some database ? 
>>   
>>     
> Incread buffer to 65536.
>
>   
>>  
>>   
>>     
>>> Imagine all users disconnect from application in the end of day and 
>>> reconect again in the another day.
>>>     
>>>       
>>     Do you think OS will retain FS cache over the night ? ;) It must be not 
>> a very busy server ;) 
>>   
>>     
> If there is no activity in the server, I expect the OS to not loose the 
> cache for nothing.
>
>   
>>   
>>     
>>> Just for example, I have a query that runs in 250 seconds when database 
>>> is not cached, and 3 seconds when it is cached (i.e., run it again even 
>>> if I close the server).
>>>     
>>>       
>>     And what ? 
>>
>>     This feature :
>>
>> a) disabled by default. To enable it you must set page buffers for some (or 
>>     all) database more than 65536 (not a very common value, isn't is ?) or 
>>     set MaxFileSystemCache to some small value (less than 2048, by default). 
>>
>> b) If you decide to use it - you must understand what you do
>>
>>     I'll write short guide how and when to use it
>>     
> I know this is as designed, but is not good.
>
> Also, imagine admin put database in exclusive mode for some task then 
> disconnect after make it online again.
>
> This really limit the usage of the new feature.
>
>
> Adriano
>   

I got your point.. But I think it's worth... How much time will be 
needed to FB fill in the cache ? 10 minutes ? (I believe even less).

When a non cached database start to work the first queries will be slow, 
but I think in very few time the most used data will be in cache again.

see you !

-- 
Alexandre Benson Smith
Development
THOR Software e Comercial Ltda
Santo Andre - Sao Paulo - Brazil
www.thorsoftware.com.br