Comments on: Ruby 1.9 Internals: Ordered Hash

By: Tokyo Cabinet: Beyond Key-Value Store - igvita.com

Tokyo Cabinet: Beyond Key-Value Store - igvita.com — Sun, 08 Nov 2009 18:44:52 +0000

[...] us to do prefix and range matching on a key, as well as, traverse the entries in order. (Think Ruby 1.9 ordered hash). Let’s look at some [...]

By: Ruby Algorithms: Sorting, Trie & Heaps - igvita.com

Ruby Algorithms: Sorting, Trie & Heaps - igvita.com — Thu, 26 Mar 2009 16:03:07 +0000

[...] are definitely worth exploring for educational value. For those who are curious, take a look at Red-Black Trees and Bloomfilters as [...]

By: Ilya Grigorik

Ilya Grigorik — Sun, 08 Feb 2009 16:35:27 +0000

Trans, do you know if there is a 1.9 port of facets underway, or any plans for one?

By: trans

trans — Sat, 07 Feb 2009 14:02:58 +0000

Nice write-up. Concise and informative. Thanks.

I’ll note that eventually Facets Dictionary will take advantage of 1.9’s ordered hash. Dictionary brings one additional feature to the table, it can keep the dataset in any order, not just insertion order.

By: Ilya Grigorik

Ilya Grigorik — Thu, 05 Feb 2009 23:36:44 +0000

Josh, I think as Radarek pointed out, I may have unnecessarily put too much emphasis on the speed aspect. In reality, the relative overhead is very low - the speed comment is probably more on the pedantic side.

By: josh susser

josh susser — Thu, 05 Feb 2009 17:58:10 +0000

Thanks for this post. I’ve been wondering for a while how ordering was implemented in the 1.9 hashes. It’s clear there has to be *some* cost in both space and speed. I don’t know if it’s always going to be worth the cost, but it looks like it’s probably livable. I wonder how hard it would be to support also having an unordered hash that doesn’t maintain order information so it’s as fast and small as the old implementation.

By: Christian Romney

Christian Romney — Thu, 05 Feb 2009 17:17:02 +0000

I love ordered hash. When you don’t care about the order, it doesn’t hurt you (performance impact seems negligible). When you do care about the order, it’s awesome not to have to call sort_by and work with an array of arrays.

By: Michael Tsai - Blog - Ordered Hashes in Ruby 1.9

Michael Tsai - Blog - Ordered Hashes in Ruby 1.9 — Thu, 05 Feb 2009 15:58:44 +0000

[...] Ruby 1.9, hash tables preserve insertion order by maintaining a doubly-linked list. This seems like a dubious feature. It only accords with the [...]

By: sgwong

sgwong — Thu, 05 Feb 2009 13:34:28 +0000

Ordered Hash is a good thing, I have a lot of time where a want to create a Hash but fail to do so because I can’t keep the item ordered.

By: gnufied

gnufied — Thu, 05 Feb 2009 12:05:37 +0000

There is another project:

http://github.com/kanwei/algorithms/tree/master

Which was developed as Google summer of code. It includes pure ruby and C implementation of various algorithms.