[ic] howto do if file exists

[John Young]

Mike replied:

> Quoting Stefan Hornburg (Racke) (racke@linuxia.de):
> 
>> On Thu, 17 Apr 2003 12:20:38 -0400
>> Mike Heins <mike@perusion.com> wrote:
>> 
>> > Quoting Nicholas Cook (ncook@gryphon.net):
>>
>> > > I hadn't thought about using apache. I'll try that approach because
>> > > I am talking about 20,000+ images.
> 
>> > Warning -- Apache can't repeal the laws of physics either. It still
>> > has to do directory lookups just like IC does.
>> > 
>> > You will be much happier if you hash your directories (like IC does
>> > with the session directory) and keep maximum entries down to a
>> > thousand or less.
>>
>> Using a filesystem suited for this should be an option as well, right ?
> 
> 
> Which one would you suggest? I am not aware of any mainstream Linux
> B-tree (or such) filesystems....


I'm assuming Racke was speaking of ReiserFS.  From their website:
http://www.reiserfs.org/

     ReiserFS is based on fast balanced trees. Balanced trees are more
     robust in their performance, and are a more sophisticated algorithmic
     foundation for a filesystem. When we started our project, there was a
     consensus in the industry that balanced trees were too slow for
     filesystem usage patterns. We proved that if you just do them right
     they are better.  We have fewer worst case performance scenarios than
     other filesystems and generally better overall performance. If you
     put 100,000 files in one directory, we think its fine; many other
     filesystems try to tell you that you are wrong to want to do it.

Hans Reiser and others have quite a bit of techinical information available
at that site.

Of course, benchmarking would be required to *really* know how it compares
(if anyone wants to build the same system twice, just with different 
filesystems).

John Young