.rehash

[dsimcha]

Rehash is nice, in my experience, for the specific but common usage case of
dumping tons of data into an AA, and then using it for lots of read-only access
after it's been built.  Hash collisions greatly hurt the performance of AAs.
Rehash basically increases the hash space if necessary, to lessen hash collisions
at the price of slightly more memory usage and some upfront processing time.  This
happens anyway occasionally as your AA gets larger, but calling .rehash makes it
happen explicitly.