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Posted by Surfer! on 07/08/06 13:24
In message <jQFrg.79662$eN2.70498@fe67.usenetserver.com>, David T.
Ashley <dta@e3ft.com> writes
>"Richard Levasseur" <richardlev@gmail.com> wrote in message
>news:1152322021.658752.74530@b28g2000cwb.googlegroups.com...
>> Another option would be to name the file after the primary key, or
>> other unique index, of the table.
>
>The reason for the prime moduli directory scheme is that Unix directory
>operations become inefficient beyond a few hundred entries in a directory.
Indeed, AFAIK it starts at the beginning of the directory and searches
sequentially until it finds a hit.. There is no structure of any kind,
unlike the old System 10 / System 25 computers, where the directories
were tree structures and so much more efficient for large numbers of
files.
However there are schemes that people find easier to understand... For
example, Demon's home directory for a user 'picture' will be similar to
/home/p/i/c/picture. What makes it a good scheme IMHO is that the path
can be derived from the user's name..
At present I don't have enough images anywhere for this to be a problem
but I would adopt a similar approach:
$IMGPATH/0 holds images 0 to 99
$IMGPATH/1 holds images 100 to 199
and so on.
So, the database doesn't even need to hold the full path to the file -
the code can easily derive it from $IMGPATH and the file name. Moving
$IMGPATH doesn't involve altering the database contents, and (obviously
I hope) the code to derive the path would be a function or class so that
if you ever re-organise the structure there is only one place to have to
change the code.
--
Surfer!
Email to: ramwater at uk2 dot net
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