Den 2011-06-10 11:11 skrev Pavel Cisar såhär:
>> MaxFileSystemCache is intended for use with SuperServer, where really
>> big FB cache on top of file system cache could be counter productive.
>> Classic and SuperClassic work with very small FB cache (to conserve
>> memory and lower IPC traffic to synchronize them between FB
>> processes/threads).
Pavel told about MaxFileSystemCache setting which controls if Firebird
will use file system cache or not. This setting was introduced in v2.1 as
FileSystemCacheThreshold and renamed in v2.5 into MaxFileSystemCache.
> On the other hand, I experienced undesirable file system cache growth
> for a web app with essentially a single connection with a Classic server
> set to default page buffers (75?).
>
> I hade to make OS API calls to limit the file system cache.
>
> This is with a ~50 Gbyte database with two tables containing 150 million
> records each and 50-100 other (smaller) tables. Especially on unindexed
> queries on those large tables, the file system cache tended to grow too
> large, causing performance degradation.
>
> So, what I'm saying is that MaxFileSystemCache may be useful for classic
> as well, in some situations. I haven't tried it though. Still on 2.1.
And you speak about FileSystemCacheSize setting which was introduced
in v2.5 and allows to limit size of file system cache. This is system-wide
setting and it is fully independent of Firebird's usage of file system cache.
Regards,
Vlad
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