Re: Many files in a single directory

[Kaz Kylheku <[EMAIL PROTECTED]>]

> Hello!
> 
> I'd like to know if there's any problem having like 15,000 (fifteen
> thousand) directories in one single directory.

There are some potential performance problems, particularly with programs
like ls.

> I know that the "ls" command would take lots of time to show the results.
> But besides that, is there any reason to avoid doing this?
 
> Is ext2 a nice guy?  ;-)

I believe that ext2 is a decent filesystem; however, it handles directory
searching using a linear algorithm. Each search for a name through that
15000 element directory will be executed as a naive linear search.

It's better if you structure the data into sub-directories. For example,
if the names are alphabetic, you might want to introduce additional 
hierarchy which divides the names into 26 buckets according to the leading
letter; or possibly two-letter buckets.

You have to watch subdirectories; each new subdirectory causes the link count
of the parent directory to go up by one, because each subdirectory has an
entry called ``..'' (dot dot) which is a hard link to the parent. Some systems
have an upper limit of 32767 on link counts. I don't know off the top of
my head whether the link count in ext2 is a 16 or 32 bit number or whether
it's signed or unsigned.

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