
Fractal Tree to create fast, snapshottable, massively scalable databases - jgrodziski
https://github.com/datacrypt-project/hitchhiker-tree
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sctb
Previous discussion:
[https://news.ycombinator.com/item?id=12229906](https://news.ycombinator.com/item?id=12229906)

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jbapple
I don't understand the difference between this data structure [0] and buffered
B-trees, as described in "Lower Bounds for External Memory Dictionaries", by
Gerth Stølting Brodal and Rolf Fagerberg [1], or in "On External Memory Graph
Traversal" by Adam L. Buchsbaum, Michael Goldwasser, Suresh
Venkatasubramanian, and Jeffery R. Westbrook [2]. Granted, this adds in path-
copying, but I'm not sure what new innovation this has that merits the
description "Hitchhiker trees are a newly invented (by @dgrnbrg)
datastructure".

0: [https://github.com/datacrypt-project/hitchhiker-
tree/blob/ma...](https://github.com/datacrypt-project/hitchhiker-
tree/blob/master/doc/hitchhiker.adoc)

1: [http://www.cs.au.dk/~gerth/papers/alcomft-
tr-03-75.pdf](http://www.cs.au.dk/~gerth/papers/alcomft-tr-03-75.pdf)

2:
[http://euler.slu.edu/~goldwasser/publications/SODA2000.pdf](http://euler.slu.edu/~goldwasser/publications/SODA2000.pdf)

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jacquesm
Maybe add 'in clojure' to the title?

~~~
rlefebvre
I am always surprised how people care about the language of implementation so
much. The data structure is interesting by itself. Why should we care what
this is built with?

~~~
jacquesm
Because that may mean that it is not usable for you. Not everybody is
interested in the theory of things, and once you implement you tie things down
to a specific ecosystem.

Adding 'in clojure' does not detract from the info already in the title but
makes it more informative. This particular implementation is also quite
dependent (as far as I can see) on bits and pieces that clojure supplies
natively but that may be hard to implement in other languages.

