I have some information I am storing which is unique based on UserIDs. The problem is that the IDs are not sequential (and in fact range from 50,000ish to 120,000ish with approx 2000 unique values. My obvious first thought was to use these IDs in an array. However, then there is the problem of dealing with all of the IDs which are not assigned a value within the array. (This could be a large issue, as I need to create an n x n array to store a metric comparing each ID to every other ID) 
@Social[$id_1][$id_2]

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The second thought was to use a Hash with the ID as the key. Obviously, for the hash I would only be using the number of entries that I have IDs. 
%Social{$id_1}{id_2}

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Are there downsides for using a hash I am not considering? Or should I be looking at a different data structure? Thanks. -dm

Code tags added by GrandFather

In reply to Array vs. Hash by Anonymous Monk

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