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

[Adriano d. S. F. <adr...@uo...>]

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