Group system benchmarks

[Joel Peshkin]

Benchmarks on current schema in the Groups_20020716_Branch....

AMD Duron 950 system hosting both BZ and mysqld

10000 users 500 open groups, 500 closed groups  (i.e.  almost all users are members of 500
of the 1000 defined groups)

Rederivation of group membership happens on the first login by each user after 
a group definition change has occurred,

rederive 1.3 sec wall time each user for membership in 500 groups (60% cpu=perl, 40% cpu=sql)
With only 50 groups this falls to 0.13 sec each

fetching all bugs and then calling CanSeeBug on each.....
500 bugs retrieved by search but only 3 visible --> 2 seconds elapsed wall time
50000 bugs retrieved by search but only 3 visible --> 140 seconds elapsed wall time

Building a join to bug_group_map into the query.....
50000 bugs retrieved by search but only 3 visible --> 10 seconds elapsed wall time

Size of user_group_map for 116 users in 500 groups each = 1.2MB

I think this is scalable enough based on this.  

If anyone can provide some numbers from large BZ sites to plug into this analysis, 
please post them.

-Joel