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Aucbvax.4731 fa.unix-wizards utzoo!decvax!ucbvax!unix-wizards Tue Oct 27 20:40:44 1981 group membership and protection >From decvax!duke!bcw@Berkeley Tue Oct 27 19:54:35 1981 It seems to me that it is reasonable for one user to belong to multiple groups; we have a locally-written data management system which uses a similar scheme and have found it to be reasonably close to what we need for solving problems with multi-user access.

This scheme is not as "overhead-bound" as some of the contributors seem to think. It is quite easy to keep a small table in memory for each user keeping the n most recently used groups. Since access tends to be fairly localized, this gives reasonable performance if n is even as small as 3 (at least in our environment; although it is possible that there exist places which might have a problem). If this number isn't sufficient it is easy to increase it to, say, 10 or any higher number to obtain reasonable access time.

Also, since the list is kept sorted in memory, you usually get a hit within the first or second group and aren't doing an unbounded search through the list.

If anyone sees any problems with this scheme I would be interested to hear about them.

Bruce Wright (Duke)

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