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Editorial Team
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Asked: 2026-06-11T13:48:14+00:00

We have an interesting challenge. We have to control access to data that reside

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We have an interesting challenge. We have to control access to data that reside in “bins”. There will be, potentially, hundreds of thousands of “bins”. Access to each bin is controlled individually but the restrictions can, and probably will, overlap. We are thinking of assigning each bin a position in a bitmask (1,2,3,4, etc..).

Then when a user logs into the system, we look at his security attributes and determine which bins he’s allowed to see. With that info we construct a bitmask for this user where the “set” bits correspond to the identifier of the bins he’s allowed to see. So if he can see bins 1, 3 and 4, his bit mask would be 1101.

So when a user searches the data, we can look at the bin index of the returned row and see if that bit is set on his bitmask. If his bitmask has that bit set we let him see that row. We are planning for the bitmask to be stored as a BigInteger in Java.

My question is: Assuming the index number doesn’t get bigger that Integer.MAX_INT, is a BigInteger bitmask going to scale for hundreds of thousands of bit positions? Would it take forever to run BigInteger.isBitSet(n) where n could be huge (e.g. 874,837)? Would it take forever to create such a BigInteger?

And secondly: If you have an alternative approach, I’d love to hear it.

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1 Answer

  1. Editorial Team

    BigInteger should be fast if you don’t change it often.

    A more obvious choice would be BitSet which is designed for this sort of thing. For looking up bits, I suspect the performance is similar. For creating/modifying it would be more efficient to use a BitSet.

    Note: PaulG has commented the difference is “impressive” and BitSet is faster.

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