I can think of are the following:
Judgment to heavy use language, ex tables to heavy, database deduplication, file name deduplication,
Some people say: one billion url ex table does not fit! !
And binary tree may be thought to 1,000,000,000 url, becomes a unit to minimize tree, and then to re-table ex
Re-thinking ex tables can also be used to make maximum use of memory tree!
(Ps: of course you want to spend a lot of time and effort)!