require 'pstore'
db = PStore.new("/tmp/foo")
db.transaction do
p db.roots
ary = db["root"] = [1,2,3,4]
ary[1] = [1,1.5]
end
1000.times do
db["root"][0] += 1
p db["root"][0]
db.transaction(true) do
p db["root"]