I know the directory page is designed to faster read using binary search,
since the records of one page is unordered(in physical).
With the purpose of binary search, we also can do it in the same page:
1) When you do first search in a page, we overwrite the page with the
ordered list(because one page is 16KB or others, but it’s very small, and
close to the disk transfer block in modern)
2) The second time you search it you can do binary search internal this
page, so do not need the page directory.
Why not it?
"The great artist is the simplifier."--- *Vincent Van Gogh*