NYCPHP Meetup

[Steve Manes]

At 03:39 PM 12/23/2002 -0500, Michael J Lee wrote:
>What would be the best way to store the images in the database?  Links to
>the images?  Can you store the actual images? (I'm guessing that would not
>be recommended . . )

I would never store images in a database.  For one thing, they can't be 
locally cached.  For another it precludes the use of a dedicated image 
server, or at least complicates it.  For another, it takes a lot more 
bandwidth to pull something from a database than it does from a 
filesystem.  And if the application should ever grow to the scale where 
edge delivery is desirable...

You could store the paths in the database but if you have a lot of images 
you have to be careful about overloading directories.  Typically, 
hand-rolled photo archives are based on a bunch of categorized 
directories.  For instance, you might have thousands of photos in the "NYC" 
category and only a handful of snapshots of Boise.  As those directories 
grow, search times slow and maintenance becomes more problematic.

A better solution which tends to balance out a directory tree better is 
create a two or three tiered directory structure based on an MD5 hash of 
the image's name or image id:

     $IMAGE_DIR = "/images";
     $hash  = md5($image_name);
     $relative_path = sprintf("%s/%s/%s/%s", $IMAGE_DIR,
         substr($hash, 0, 2), substr($hash, 2, 2), $image_name);

This creates a pseudo-random distribution of directories.  Run through this 
function, the image "slobbering_dog.jpg" would produce this directory 
hierarchy:

/images/fe/24/slobbering_dog.jpg

Then you only need to store the image's name, or numeric id, in the 
database (along with a category id probably).  If you have millions of 
images, I'd probably increase those node names to three characters.  We 
use  this at CCI too, BTW.