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Choosing a Good Hash Function, Part 1
Author’s note: Hello, reader! I’m Colin, a new data scientist on the team. This is the first in a series of posts in which I will be describing my efforts to characterize various hash functions for use...
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Choosing a Good Hash Function, Part 2
Author’s note: Part two of a series in which I investigate the performance of a menagerie of hash functions on our data. In today’s episode the analysis begins in earnest with an investigation of...
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Choosing a Good Hash Function, Part 3
Author’s note: Part three of a series studying hash functions. My last post identified a few candidate algorithms that are subjected to further scrutiny here today. The Story So Far The simplest...
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K-Minimum Values: Sketching Error, Hash Functions, and You
Introduction “All known efficient cardinality estimators rely on randomization, which is ensured by the use of hash functions.” –Flajolet, et al Recalling the KMV algorithm Matt presented in his last...
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HyperLogLog++: Google’s Take On Engineering HLL
Matt Abrams recently pointed me to Google’s excellent paper “HyperLogLog in Practice: Algorithmic Engineering of a State of The Art Cardinality Estimation Algorithm” [UPDATE: changed the link to the...
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Open Source Release: postgresql-hll
We’re happy to announce the first open-source release of AK’s PostgreSQL extension for building and manipulating HyperLogLog data structures in SQL, postgresql-hll. We are releasing this code under the...
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Open Source Release: js-murmur3-128
As you can imagine from of all of our blog posts about hashing that we hash a lot of things. While the various hashing algorithms may be well-defined, the devil is always in the details especially when...
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Hitting the Books: EADS Summer School on Hashing
Rob, Matt, and I just wrapped up our trip to Copenhagen for the EADS Summer School on Hashing at the University of Copenhagen and it was a blast! The lineup of speakers was, simply put, unbeatable:...
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