I have a large array that contains sets of integers.

array[0]="1,100,105,1003";
array[1]="42,314,2718,30302";
etc...
[download]

I would like to save RAM with a more efficient representation of these sets. Here are a few facts about the numbers:

• The numbers do not repeat
• The numbers represent an index into another array
• I can reorder the data if I really need to
• Some numbers are much more common than others
• I don't care much about how long it takes to compress the data
• I would like to decompress the data relatively quickly
• In some cases there are thousands of entries per row, other cases only one.

The best answer might be to just use a database. I was thinking about a RAM-based solution in an attempt to get blazing speed in a mod_perl application. It would be nice if I could look up and decode about 100 of these rows in 0.05 seconds or so.

I would also like to be able to load these numbers into RAM relatively quickly, so I would like a data structure that can be stored and restored with Storable or some other quick method.

I am looking for ideas, pointers to algorithms, modules, or code. It seems like a fairly fundamental area of computer science, but I don't know what this area is called.

Thanks!

It should work perfectly the first time! - toma

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