Daniel Lemire ranks in the top 2% of scientists worldwide according to the Stanford University/Elsevier’s 2025 ranking. He is also editor of the journal Software: Practice and Experience, a long-established (1971) journal where many crucial results were published (e.g., articles by Knuth and Bentley). Daniel Lemire’s blog is one of the top 50 most popular blogs on Hacker News, the standard tech news aggregation site. He wrote several books. He serves on the program committees of leading computer science conferences.

You can find his software in the major Web browsers, in Git, in the standard libraries of major programming languages, and so forth. In February 2019, he was ranked in second position among the most popular developers on GitHub and most popular in C++ (ahead of Microsoft, Google and Facebook). He is among the 0.0006% most followed programmers in the world on GitHub; GitHub has over 100 million developers.

In 2020 and 2021, Daniel Lemire was co-chair of the NSERC computer science committee. He received the University of Quebec’s 2020 Award of Excellence for Achievement in Research (all fields) for his work on the acceleration of JSON parsing. He was admitted twice to the circle of excellence of the University of Quebec.

Software

“Most Computer Science professors are not good programmers. There are exceptions, like Daniel Lemire, but they are rare.” (Casey Muratori)

I take the production of software seriously. You can find most of my software on GitHub.

Some noteworthy contributions:

• The Ada library might be the fastest URL parser in the world. Ada has improved the performance of the popular JavaScript environment Node.js: Since Node.js 18, a new URL parser dependency was added to Node.js — Ada. This addition bumped the Node.js performance when parsing URLs to a new level. Some results could reach up to an improvement of 400%. As a regular user, you may not use it directly. But if you use an HTTP server then it’s very likely to be affected by this performance improvement. (State of Node.js Performance 2023) Our parsing library was also adopted by Cloudflare: It delivers a significantly faster implementation of not only URL but URLPattern and makes even more improvements on spec compliance. It is also part of Redpanda, Zoom, Telegram, and other important systems. The library has advanced features such as support for URLPattern.
• simdutf: Unicode operations several times faster than conventional functions.
• fast_float: parse floating-point numbers four times faster than conventional functions (strtod).
• simdjson: the first JSON parser to run at speeds of gigabytes per second with full validation using a single core on a commodity processor. The simdjson library is used by Facebook, by Shopify, by Intel, by Microsoft, by Apache Doris and by several other important systems such as Node.js. The results of this work are used to speed up the Blink HTML engine which powers the Google Chrome and Microsoft Edge browsers as well as the WebKit engine which powers the Safari browser. The parsing JSON strategy was adopted by the Bun JavaScript engine at Anthropic in 2026.
• Roaring bitmaps have been widely adopted: Google Procella (YouTube’s database engine), Apache Lucene, Solr, Elasticsearch, Metamarkets’ Druid, Apache Spark, Apache Hive, Apache Tez, Apache CarbonData, Netflix Atlas, LinkedIn Pinot, Pilosa, Microsoft Visual Studio Team Services (VSTS), eBay’s Apache Kylin, and so forth. Companies like Quantcast and Seek have chosen Roaring bitmaps for their performance needs. When Uber switched to Apache Pinot and its Roaring indexes, it saved 2 million dollars per year in infrastructure cost, and improved by a factor of three the page load delay.
• JavaFastPFOR and FastPFor have been included in Terrier, Apache Parquet, Apache Lucene, and Apache NiFi.
• EWAHBoolArray and JavaEWAH have been included in Git (i.e., GitHub), jGit, Apache Hive, and so forth. JavaEWAH is part of standard Linux distributions like Ubuntu and Red Hat. GitHub engineers wrote several articles on their application of EWAH bitmaps to accelerate the processing of code archives. The Git documentation covers the EWAH format.

Some of my blog posts led to improvements in widely used software.

• My blog post Accelerating PHP hashing by "unoptimizing" it led to an optimization of the PHP hash function (starting with PHP 7.4).
• My blog post A fast alternative to the modulo reduction describes a technique used by TensorFlow, by Facebook RocksDB, by Google netstack and by the Bitcoin core.
• My blog post Computing the number of digits of an integer even faster has helped optimize Oracle TruffleRuby and Microsoft .NET.
• My blog post Visiting all values in an array exactly once in random order is quoted in the source code of the Swift compiler.
• Techniques to measure memory-level parallelism developed on my blog have been adopted by tech journalists at sites such as anandtech.com.
• My blog post Fastest way to compute the greatest common divisor motivated a substantial improvement to the LLVM std::gcd function.
• In 2025, we multiplied the base64 encoding speed in the popular OpenSSL library for AVX2 capable processors by three to four times.

Some of our research articles have also had notable impacts.

• Our accelerated number parser from the article Number Parsing at a Gigabyte per Second has been adopted by the C#, Go and Rust programming languages, Apache Arrow, Yandex ClickHouse, Microsoft LightGBM, FasterXML’s Jackson and other major projects where it multiplied the number-parsing speed. The Go 1.16 release notes state that “ParseFloat now uses the Eisel-Lemire algorithm, improving performance by up to a factor of 2. This can also speed up decoding textual formats like encoding/json.” The Rust 1.55 release notes state that the “standard library’s implementation of float parsing has been updated to use the Eisel-Lemire algorithm, which brings both speed improvements and improved correctness”. It is part of the LLVM libc standard library. It has also been adopted by Microsoft in C# as of .NET7. It is part of the standard C++ library under Linux (as of GCC 12). It is part of the standard Mojo library. The Google Abseil library also adopted our approach. It is also part of WebKit, the engine of Safari, Apple’s web browser. It was also adopted by Chromium, the engine behind Google Chrome and Microsoft Edge. The popular in-memory database engine Redis also adopted our approach which improved the tail latency by 30% in some cases. It is also part of MySQL, Boost JSON, Blender, etc.
• Our StreamVByte compression algorithm from the article Stream VByte: Faster Byte-Oriented Integer Compression is used by Facebook Thrift, StarRocks and RedisLabs’ RediSearch.
• The algorithm described in my article Fast Random Integer Generation in an Interval was adopted to accelerate random number generation
  • by the standard C++ Linux library (GNU libstdc++) to accelerate the std::uniform_int_distribution function (as of GNU GCC 11),
  • by the Microsoft standard C++ library,
  • by Apache Commons,
  • by the Linux kernel,
  • by the FreeBSD libc library,
  • by Google’s Abseil C++ Common Libraries,
  • by the Swift standard library,
  • by the Go language,
  • by the Julia language,
  • by the C# runtime,
  • by the Zig language,
  • and by Numpy (Python).
• The algorithm described in our article Faster Base64 Encoding and Decoding using AVX2 Instructions is used within PHP (as of version 7.4) and in the C# standard library. The algorithm described in our article Base64 encoding and decoding at almost the speed of a memory copy is used within OpenJDK (Java) to accelerate java/util/Base64, in the C# standard library, in the Mojo standard library and in the Safari browser. OpenSSL’s base64 encoder relies on our work.
• The algorithm described in our paper Faster Population Counts using AVX2 Instructions is used by the Windows Terminal.
• The algorithm described in our article Faster Remainder by Direct Computation: Applications to Compilers and Software Libraries is used

• within the C# standard library to accelerate the Dictionary class and to accelerate virtual function calls.
• Our innovative approach is also used within the Go runtime: it reportedly made several Go programs run 1.5% faster.
• It is also used in the unordered map Boost implementation where it contributes to the high performance.

• The algorithm described in our article Validating UTF-8 In Less Than One Instruction Per Byte is used by the PHP interpreter, in Oracle GraalVM and Google Fuchsia, and in many important systems. Our C++ library simdutf which contains this algorithm as well as many others is part of major systems such as Node.js, Bun and WebKit (the web engine behind Safari). The adoption of the simdutf library by the popular Node.js JavaScript runtime led to a significant performance gain: Decoding and Encoding becomes considerably faster than in Node.js 18. With the addition of simdutf for UTF-8 parsing the observed benchmark, results improved by 364% (an extremely impressive leap) when decoding in comparison to Node.js 16. (State of Node.js Performance 2023) It is also part of the Mojo programming language runtime library where it made UTF-8 validation 10 times faster.
• The GitHub search team has identified my work as fundamental to their own.
• The article On-demand JSON: A better way to parse documents? was the most read article of the last 5 years at Software: Practice and Experience (2024).
• The algorithm from the article Batched Ranged Random Integer Generation has been adopted by Microsoft in their standard C++ library. The net result is a multiplication by a factor of five of the function std::shuffle.

Recent Publications

You can find my work on arXiv, on Google Scholar, on DBLP, on the ACM Portal, on R Libre and elsewhere.

• Jaël Champagne Gareau, Daniel Lemire
  Converting an Integer to a Decimal String in Under Two Nanoseconds
  Software: Practice and Experience (to appear)

  Details PDF (arXiv) Code

• Jaël Champagne Gareau, Daniel Lemire
  Converting Binary Floating-Point Numbers to Shortest Decimal Strings: An Experimental Review
  Software: Practice and Experience 56 (4), 2026

  Details PDF Code

• Robert Clausecker, Daniel Lemire, Florian Schintke
  Faster Positional-Population Counts for AVX2, AVX-512, and ASIMD
  Concurrency and Computation: Practice and Experience 37 (27-28), 2025

  Details PDF (arXiv) Code

• Daniel Lemire
  Scanning HTML at Tens of Gigabytes per Second on ARM Processors
  Software: Practice and Experience 55 (7), 2025

  Details PDF (arXiv) Code

• Jeroen Koekkoek, Daniel Lemire
  Parsing Millions of DNS Records per Second
  Software: Practice and Experience 55 (4), 2025

  Details PDF (arXiv) Code

• Nevin Brackett-Rozinsky, Daniel Lemire
  Batched Ranged Random Integer Generation
  Software: Practice and Experience 55 (1), 2025

  Details PDF (arXiv) Code

• John Keiser, Daniel Lemire
  On-Demand JSON: A Better Way to Parse Documents?
  Software: Practice and Experience 54 (6), 2024

  Details PDF (arXiv) Code

• Yagiz Nizipli, Daniel Lemire
  Parsing Millions of URLs per Second
  Software: Practice and Experience 54 (5), 2024

  Details PDF (arXiv) Code

• Daniel Lemire
  Exact Short Products From Truncated Multipliers
  Computer Journal 67 (4), 2024

  Details PDF (arXiv) Code

• Robert Clausecker, Daniel Lemire
  Transcoding Unicode Characters with AVX-512 Instructions
  Software: Practice and Experience 53 (12), 2023.

  Details PDF (arXiv) Code

• Noble Mushtak, Daniel Lemire
  Fast Number Parsing Without Fallback
  Software: Practice and Experience 53 (7), 2023

  Details PDF (arXiv)

• Thomas Mueller Graf, Daniel Lemire
  Binary Fuse Filters: Fast and Smaller Than Xor Filters
  Journal of Experimental Algorithmics 27, 2022

  Details PDF (arXiv) Code

• Daniel Lemire, Wojciech Muła
  Transcoding Billions of Unicode Characters per Second with SIMD Instructions
  Software: Practice and Experience 52 (2), 2022

  Details PDF (arXiv) Code

• Daniel Lemire
  Unicode at Gigabytes per Second
  SPIRE 2021: String Processing and Information Retrieval

  Details PDF (arXiv) Code

• Daniel Lemire, Colin Bartlett, Owen Kaser
  Integer Division by Constants: Optimal Bounds
  Heliyon 7 (6), 2021

  Details PDF (arXiv)

• Marcus D. R. Klarqvist, Wojciech Muła, Daniel Lemire
  Efficient Computation of Positional Population Counts Using SIMD Instructions
  Concurrency and Computation: Practice and Experience 33 (17), 2021

  Details PDF (arXiv) Code

• Daniel Lemire
  Number Parsing at a Gigabyte per Second
  Software: Practice and Experience 51 (8), 2021

  Details PDF (arXiv) Code

• John Keiser, Daniel Lemire
  Validating UTF-8 In Less Than One Instruction Per Byte
  Software: Practice and Experience 51 (5), 2021

  Details PDF (arXiv) Code

• Thomas Mueller Graf, Daniel Lemire
  Xor Filters: Faster and Smaller Than Bloom and Cuckoo Filters
  Journal of Experimental Algorithmics 25 (1), 2020

  Details PDF (arXiv) Code

• Wojciech Muła, Daniel Lemire
  Base64 encoding and decoding at almost the speed of a memory copy
  Software: Practice and Experience 50 (2), 2020

  Details PDF (arXiv) Code

• Geoff Langdale, Daniel Lemire
  Parsing Gigabytes of JSON per Second
  VLDB Journal 28 (6), 2019

  Details PDF (arXiv) Code

• Daniel Lemire
  Fast Random Integer Generation in an Interval
  ACM Transactions on Modeling and Computer Simulation 29 (1), 2019

  Details PDF (arXiv) Video Code

• Daniel Lemire, Owen Kaser, Nathan Kurz
  Faster Remainder by Direct Computation: Applications to Compilers and Software Libraries
  Software: Practice and Experience 49 (6), 2019

  Details PDF (arXiv) Code

• Daniel Lemire, Melissa E. O’Neill
  Xorshift1024*, Xorshift1024+, Xorshift128+ and Xoroshiro128+ Fail Statistical Tests for Linearity
  Computational and Applied Mathematics 350, 2019

  Details PDF (arXiv) Code

• Wojciech Muła, Daniel Lemire
  Faster Base64 Encoding and Decoding using AVX2 Instructions
  ACM Transactions on the Web 12 (3), 2018

  Details PDF (arXiv) Code

• Daniel Lemire, Owen Kaser, Nathan Kurz, Luca Deri, Chris O’Hara, François Saint-Jacques, Gregory Ssi-Yan-Kai
  Roaring Bitmaps: Implementation of an Optimized Software Library
  Software: Practice and Experience 48 (4), 2018

  Details PDF (arXiv) Code

• Edmon Begoli, Jesús Camacho Rodríguez, Julian Hyde, Michael J. Mior, Daniel Lemire
  Apache Calcite: A Foundational Framework for Optimized Query Processing Over Heterogeneous Data Sources
  SIGMOD'18, 2018

  Details PDF (arXiv) Code

• Wojciech Muła, Nathan Kurz, Daniel Lemire
  Faster Population Counts Using AVX2 Instructions
  Computer Journal 61 (1), 2018

  Details PDF (arXiv) Code

• Antonio Badia, Daniel Lemire
  On Desirable Semantics of Functional Dependencies over Databases with Incomplete Information
  Fundamenta Informaticae 158 (4), 2018

  Details PDF (arXiv)

• Daniel Lemire, Nathan Kurz, Christoph Rupp
  Stream VByte: Faster Byte-Oriented Integer Compression
  Information Processing Letters 130, 2018

  Details PDF (arXiv) Code

• Daniel Lemire, Christoph Rupp
  Efficient Integer-Key Compression in a Key-Value Store using SIMD Instructions
  Information Systems 66, 2017

  Details PDF (arXiv) Code

• Dmytro Ivanchykhin, Sergey Ignatchenko, Daniel Lemire
  Regular and almost universal hashing: an efficient implementation
  Software: Practice and Experience 47 (10), 2017

  Details PDF (arXiv) Code

• Samy Chambi, Daniel Lemire, Owen Kaser, Robert Godin
  Better bitmap performance with Roaring bitmaps
  Software: Practice and Experience 46 (5), 2016

  Details PDF (arXiv) Slides Code Project

• Owen Kaser, Daniel Lemire
  Compressed bitmap indexes: beyond unions and intersections
  Software: Practice and Experience 46 (2), 2016

  Details PDF (arXiv) Code

• Daniel Lemire, Gregory Ssi-Yan-Kai, Owen Kaser
  Consistently faster and smaller compressed bitmaps with Roaring
  Software: Practice and Experience 46 (11), 2016

  Details PDF (arXiv) Slides Code Project

• Daniel Lemire, Owen Kaser
  Faster 64-bit universal hashing using carry-less multiplications
  Journal of Cryptographic Engineering 6(3), 2016

  Details PDF (arXiv) Code

• Daniel Lemire, Leonid Boytsov, Nathan Kurz
  SIMD Compression and the Intersection of Sorted Integers
  Software: Practice and Experience 46 (6), 2016

  Details PDF (arXiv) Slides Code

• Wayne Xin Zhao, Xudong Zhang, Daniel Lemire, Dongdong Shan, Jian-Yun Nie, Hongfei Yan, Ji-Rong Wen
  A General SIMD-based Approach to Accelerating Compression Algorithms
  ACM Transactions on Information Systems 33 (3), 2015

  Details PDF (arXiv)

• Adina Crainiceanu, Daniel Lemire
  Bloofi: Multidimensional Bloom Filters
  Information Systems 54, 2015

  Details PDF (arXiv) Code

• Daniel Lemire, Leonid Boytsov
  Decoding billions of integers per second through vectorization
  Software: Practice & Experience 45 (1), 2015

  Details PDF (arXiv) Slides Code

• Antonio Badia, Daniel Lemire
  Functional dependencies with null markers
  Computer Journal 58 (5), 2015

  Details PDF (arXiv)

• Xiaodan Zhu, Peter Turney, Daniel Lemire, Andre Vellino
  Measuring academic influence: Not all citations are equal
  Journal of the Association for Information Science and Technology 66 (2), 2015

  Details PDF (arXiv) Dataset

• Jeff Plaisance, Nathan Kurz, Daniel Lemire
  Vectorized VByte Decoding
  International Symposium on Web Algorithms 2015, 2015

  Details PDF (arXiv) Slides Code

• Owen Kaser, Daniel Lemire
  Strongly universal string hashing is fast
  Computer Journal 57 (11), 2014

  Details PDF (arXiv) Code

• Hazel Webb, Owen Kaser, Daniel Lemire
  Diamond Dicing
  Data & Knowledge Engineering 86, 2013

  Details PDF (arXiv)

• Daniel Lemire, Owen Kaser, Eduardo Gutarra
  Reordering Rows for Better Compression: Beyond the Lexicographic Order
  ACM Transactions on Database Systems 37 (3), 2012

  Details PDF (arXiv) Slides Code Code Code

• Daniel Lemire
  The universality of iterated hashing over variable-length strings
  Discrete Applied Mathematics 160 (4-5), 2012

  Details PDF (arXiv)

• Zoltán Prekopcsák, Daniel Lemire
  Time Series Classification by Class-Specific Mahalanobis Distances
  Advances in Data Analysis and Classification 6 (3), 2012

  Details PDF (arXiv)

• Antonio Badia, Daniel Lemire
  A Call to Arms: Revisiting Database Design
  SIGMOD Record 40 (3), 2011

  Details PDF (arXiv)

• Daniel Lemire, Andre Vellino
  Extracting, Transforming and Archiving Scientific Data
  In VLDL 2011, Berlin, Germany, 2011

  Details PDF (arXiv)

• Daniel Lemire, Owen Kaser
  Reordering Columns for Smaller Indexes
  Information Sciences 181 (12), 2011

  Details PDF (arXiv)

• Daniel Lemire, Owen Kaser
  Recursive n-gram hashing is pairwise independent, at best
  Computer Speech & Language 24 (4), pages 698-710, 2010

  Details PDF (arXiv) Code

• Daniel Lemire, Owen Kaser, Kamel Aouiche
  Sorting improves word-aligned bitmap indexes
  Data & Knowledge Engineering 69 (1), 2010

  Details PDF (arXiv) Code

• Daniel Lemire, Martin Brooks, Yuhong Yan
  An Optimal Linear Time Algorithm for Quasi-Monotonic Segmentation
  International Journal of Computer Mathematics 86 (7), 2009

  Details PDF (arXiv) Code

• Daniel Lemire
  Faster retrieval with a two-pass dynamic-time-warping lower bound
  Pattern recognition 42 (9), 2009

  Details PDF (arXiv) Code

• Daniel Lemire, Owen Kaser
  Hierarchical Bin Buffering: Online Local Moments for Dynamic External Memory Arrays
  ACM Transactions on Algorithms 4(1): 14 (2008)

  Details PDF (arXiv) Code

• Owen Kaser, Daniel Lemire, Kamel Aouiche
  Histogram-Aware Sorting for Enhanced Word-Aligned Compression in Bitmap Indexes
  DOLAP 2008

  Details PDF (arXiv) Code

• Hazel Webb, Owen Kaser, Daniel Lemire
  Pruning Attribute Values From Data Cubes with Diamond Dicing
  IDEAS 2008

  Details PDF (arXiv)

• Daniel Lemire
  A Better Alternative to Piecewise Linear Time Series Segmentation
  SIAM Data Mining 2007

  Details PDF (arXiv) Code

• Kamel Aouiche, Daniel Lemire
  A Comparison of Five Probabilistic View-Size Estimation Techniques in OLAP
  DOLAP 2007, pp. 17-24, 2007

  Details PDF (arXiv) Slides Code

• Dan Kucerovsky, Daniel Lemire
  Monotonicity Analysis over Chains and Curves
  In Curves and Surfaces 2006, Saint-Malo, France, 2007

  Details PDF (arXiv)

• Owen Kaser, Daniel Lemire
  Removing Manually-Generated Boilerplate from Electronic Texts: Experiments with Project Gutenberg e-Books
  CASCON 2007

  Details PDF (arXiv) Code

• Owen Kaser, Daniel Lemire
  Tag-Cloud Drawing: Algorithms for Cloud Visualization
  Tagging and Metadata for Social Information Organization (WWW 2007)

  Details PDF (arXiv) Slides Code Dataset

• Owen Kaser, Daniel Lemire
  Attribute Value Reordering For Efficient Hybrid OLAP
  Information Sciences 176 (16) 2006

  Details PDF (arXiv)

• Daniel Lemire
  Streaming Maximum-Minimum Filter Using No More than Three Comparisons per Element
  Nordic Journal of Computing 13 (4), pages 328-339, 2006

  Details PDF (arXiv) Code Code

• Daniel Lemire, Harold Boley, Sean McGrath, Marcel Ball
  Collaborative filtering and inference rules for context‐aware learning object recommendation
  Interactive Technology and Smart Education 2 (3), 2005

  Details PDF

• Daniel Lemire
  Scale and Translation Invariant Collaborative Filtering Systems
  Information Retrieval 8 (1), 2005

  Details PDF

• Daniel Lemire, Anna Maclachlan
  Slope One Predictors for Online Rating-Based Collaborative Filtering
  In SIAM Data Mining (SDM 2005), Newport Beach, California, April 21-23, 2005

  Details PDF (arXiv)

• Daniel Lemire
  A family of 4-point dyadic high resolution subdivision schemes
  In Curves and Surfaces 2002, Saint-Malo, France, 2003

  Details PDF Code

• Serge Dubuc, Daniel Lemire, Jean-Louis Merrien
  Fourier analysis of 2-point Hermite interpolatory subdivision schemes
  Journal of Fourier Analysis and Applications 7 (5), 2001

  Details PDF

• Daniel Lemire, Chantal Pharand, Jean-Claude Rajaonah, Benoît Dubé, A.-Robert LeBlanc
  Wavelet time entropy, T wave morphology and myocardial ischemia
  IEEE Transactions on Biomedical Engineering 47 (7), 2000

  Details PDF

• Gilles Deslauriers, Serge Dubuc, Daniel Lemire
  Une famille d'ondelettes biorthogonales sur l'intervalle obtenue par un schéma d'interpolation itérative
  Annales des Sciences Mathématiques du Québec 23 (1), 1999

  Details PDF

Talks

More Talks

I regularly give industrial talks; they are often well received. My QCon San Francisco 2019 talk was outlined as a “best voted” talk with 98% of the audience giving it thumbs up; this is much higher than the average.

• SIMD-Accelerated Data Processing

  Sat, May 9, 2026, SIMD-Accelerated Data Processing

• C++26 Reflection for JSON Serialization - A Practical Journey

  Fri, Sep 19, 2025, CppCon 2025

• Ada: Parsing Millions of URLs per Second

  Sat, Nov 11, 2023, NodeConf EU 2023

• Binary Fuse Filters: Fast and Tiny Immutable Filters

  Fri, Jun 16, 2023, Invited talk at the Filter Workshop, Workshop held in conjunction with SPAA 2023 (June 16, 2023 - Orlando, USA)

• Accurate and efficient software microbenchmarks

  Sat, Feb 25, 2023, Invited talk at the SIGPLAN BID 2023, Benchmarking in the Data Center: Expanding to the Cloud, Workshop held in conjunction with PPoPP 2023: Principles and Practice of Parallel Programming 2023 (February 25, 2023 - Montreal, Canada)

• Unicode at gigabytes per second

  Fri, Oct 1, 2021, Invited talk at SPIRE 2021, 28th International Symposium on String Processing and Information Retrieval (October 4-6th, 2021 - Lille, France)

• Parsing numbers at a gigabyte per second

  Wed, May 12, 2021, MIT Fast Code Seminar

• Floating-point Number Parsing with Perfect Accuracy at GB/s

  Wed, Oct 7, 2020, Go Systems

• Data Engineering at the Speed of Your Disk

  Tue, Jun 16, 2020, Performance Summit III (Facebook)

• Parsing JSON Really Quickly: Lessons Learned

  Mon, Oct 7, 2019, QCon San Francisco 2019

Projects

Laboratory

We are lucky to have a fully equipped laboratory with a dedicated technician. We have a server farm that has been used worldwide for experiments in software performance (e.g., by researchers such as Agner Fog). We also have several powerful workstations and beautiful white boards!

Teaching

I teach primarily in French and online since 2004.

Undergraduate courses:

• INF 1220 - Introduction à la programmation
• INF 2007 - Programmation avancée
• INF 2020 - Programmation d’applications avec Python : des jeux au Web
• INF 6450 - Gestion de l’information avec XML
• INF 4450 - Programmation orientée-données
• INF 6460 - Recherche et filtrage d’informations
• INF 9004 - Informatique des entrepôts de données

Graduate courses:

• INF 6104 - Recherche d’informations et Web
• INF 6107 - Web social
• INF 6408 - Informatique de l’analyse multidimensionnelle
• INF 9010 - Analyse syntaxique et théorie des langages
• INF 9011 - Optimisation et performance en programmation

Students

Marina

verret

Some recent graduates:

• Hana Hbaieb, Application de la réalité mixte pour améliorer l’efficacité de la compréhension de la conception architecturale (M.Sc., 2026);
• Antoine Tohme, Analyse approfondie des techniques de hacking éthique (M.Sc., 2025);
• Fatma Miladi, Agents conversationnels pédagogiques basés sur l’IA générative pour améliorer l’apprentissage en ligne (supervised with Valéry Psyché, Ph.D., 2025);
• Nicolas Mathon, Évaluation d’Apache Ozone et de son intégration du protocole de consensus RAFT avec la librairie Apache Ratis afin d’obtenir un système distribué fiable et cohérent (M.Sc., 2024);
• François Lewis, Pertinence de l’ajout d’une composante sérieuse personnalisée à un jeu vidéo dédié à la rééducation en lecture d’élèves ayant des difficultés (Ph.D., 2024);
• Jean Philippe Dionne, Générateur de textes aléatoires automatiquement lemmatisés (M.Sc., 2024, Governor’s General Gold Medal);
• Ernso Decelien (M.Sc., 2024);
• Zakia Chaibeddra (Alexander-Graham-Bell scholarship) (M.Sc., 2023);
• Pierre Marie Ntang, Visualiser pour comprendre : application à la programmation vectorielle (Ph.D., 2023);
• Blandine Courcot, Suivi et modélisation du potentiel hydrique du sol dans un contexte de stress climatique (M.Sc., 2023, Governor’s General Gold Medal);
• Roger Guévin-Kamena, Réglage fin par ensemble convergent de divers modèles transformers pour l’analyse du sentiment (M.Sc., 2023);
• Gary Germeil, La crédibilité du comportement d’un personnage non-joueur dans un jeu de type cartes à collectionner (Ph.D., 2022);
• Marina Lopez, Proposition d’une plateforme de gestion des données de recherche et son adoption par les chercheurs en environnement et informatique dans le contexte de la recherche en foresterie au Québec (M.Sc., 2022);
• Jean-François Grenier, GitHub and Blog, Segmentation sémantique par réseaux neuronaux des espèces indésirables dans la culture du bleuet sauvage (M.Sc., 2022);
• Nicolas Boulet-Lavoie (M.Sc., 2022);
• Carl Verret, Analyse d’un nouvel algorithme et conception d’une librairie en C# permettant la conversion des nombres décimaux en nombres à virgule flottante (M.Sc., 2022, Governor’s General Gold Medal);
• Carine Croteau, GitHub Recherche et analyse de solutions performantes pour le traitement de fichiers JSON dans un langage de haut niveau (M.Sc., 2020) (Computer Science Professor at cégep de Victoriaville);
• Achille Alain Kamdem Djoko (M.Sc., 2020) (developer at Bell Canada)
• Hakim Berraki (M.Sc., 2020) (Solution Designer at Société de transport de Montréal);
• Abdelkader Kaddour Brahim (M.Sc., 2020);
• Zeeshan Ahmed, Preserving Consumer DNA Privacy For Finding Relatives In A Malicious Two Party Computation (M.Sc., 2020) (Data Engineer at Four Eyes Financial);
• Tarek Khei, Établir les correspondances entre les artéfacts d’un système d’information (Ph.D., 2020) (Director of AI and Software at Iristel);
• Xueping Dai, Caractérisation du bruit électromagnétique dans les tunnels miniers profonds et application de la méthode de débruitage (Ph.D., 2019);
• Massamba Fall (M.Sc., 2018) (Senior Analyst at Promutuel);
• Erick Aokou Koffi, Approche systémique de la conscience de la situation pour la réduction des erreurs de décision en environnement complexe : cas des projets informatiques (Ph.D., 2018) (Data Architect at Metro);
• Badis Merdaoui, Simulation probabilistique d’acquisition des langues secondes (Ph.D., 2018) (IT Architect at Saputo);
• Maxime Boisvert (M.Sc., 2017) (Production Engineering Manager at Shopify);
• Shany Carle (M.Sc., 2017) (Computer Science Professor at cégep de Victoriaville);
• Joseph Tumusenge (M.Sc., 2016);
• Samy Chambi, Les index bitmap compressés (Ph.D., 2016, with Robert Godin) (Software Engineer at Collective-i);
• Jing Li, Full Solution Indexing and Efficient Compressed Graph Representation for Web Service Composition (Ph.D., 2016, with Yuhong Yan);
• Claude Corriolan (M.Sc., 2016);
• Ikhtear Sharif (M.Sc. 2013) (Security Technical Specialist at IBM), Performance evaluation of fast integer compression techniques;
• Hazel Webb (Ph.D., 2010, with Owen Kaser) (Instructor at UNB);
• Eduardo Gutarra (M.Sc. 2012) (Senior Associate at JPMorgan Chase), Multi-column Bitmap Indexing;
• Steven Keith (M.Sc. 2006) (Application Architect at Innovatia Inc.), Efficient Storage Methods for a Literary Data Warehouse.

ntang

Some alumni:

• Luis Garcia Vargas
• Shira Smith is an engineer at Discord in California.
• Dara Aghamirkarimi teaches Computer Science at LaSalle College.
• Geneviève Lefebvre (died of cancer during her master’s)

Current Ph.D. students:

• Guy Jobin (supervised with Dragos Vieru)
• Khargou Jalal
• Sofiane Faïdi
• Faten Slama
• William Ouedraogo
• Jean-Vincent Bogui
• Aubrey Trask
• Ali Lienaux

Current M.Sc. students:

• Isaac Hurtubise
• Juan Hernandez
• Nicolas Irep
• Emna Ben Hamouda
• Aaron Rivera
• Khalid Bouraki
• Yan Levasseur

Recent postdocs:

• Jaël Champagne-Gareau (2025–2027)

Recent research assistants (undergraduate):

• Nick Nuon, Summer 2023 and 2024, recipient of an NSERC Undergraduate Student Research Award.
• Nicolas Boyer, Summer 2021 and 2022, recipient of an NSERC Undergraduate Student Research Award.
• David Favreau, Fall 2021.
• Yoann Le Rouzic, Summer 2020. GitHub
• Io Andes Daza-Dillon, Summer 2019, recipient of an NSERC Undergraduate Student Research Award. Io is consultant at Savoir-faire Linux. GitHub
• Jérémie Piotte, Fall 2018 and 2019, recipient of an NSERC Undergraduate Student Research Award. Jérémie is Senior Manager (Machine Learning Engineering) at Unity Technologies. GitHub
• Niko Girardelli, Winter 2018. GitHub

Recent research guests:

• Robert Clausecker

Mentoring

• Homma Kazutaka, Google Summer of Code, Summer 2018 (co-mentor with Harlan Haskins at Apple)

News

More Posts

Services

I am editor of the Software: Practice and Experience journal (Wiley) since 2021. This journal was founded in 1971 and it published many central results in computer science.

Prior to the 2020 events, I was the organizer of an ongoing series of workshops open to the public: the technolab workshops and the tribalab workshops. In 2019, I was the chair of EDA 2019 (Business Intelligence & Big Data) held in October at Montpellier, France. In 2018, I was recognized by the journal Software: Practice and Experience as a distinguished referee for my “insightful, careful, constructive and timely reviews”. In June 2018, I participated in the Dagstuhl Seminar 18251: Database Architectures for Modern Hardware. I was an associate editor of the computer science section of the Heliyon journal (Elsevier) from 2015 to 2020.

I recently served on the following program committees:

• CIKM 2026: 34th ACM International Conference on Information and Knowledge (November 7-11, 2026 in Rome Italy) – Senior Member
• ECMLPKDD 2026: European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (September 7-11, 2026 in Naples Italy)
• WSDM 2026: The Nineteenth International Conference on Web Search and Data Mining (March 10-14, 2026, in Boise, Idaho, USA) – Senior Member
• CIKM 2025: 33rd ACM International Conference on Information and Knowledge (October 21-25, 2025 in Boise, Idaho) – Senior Member
• BIGDACI 2025: 10th International Conference on Big Data Analytics, Data Mining and Computational Intelligence (23-25 July 2025 in Lisbon, Portugal)
• SIGIR 2025: The 48th International ACM SIGIR Conference on Research and Development in Information Retrieval (13-18 July 2025 in Padua, Italy)
• ECMLPKDD 2025: European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (15-19 September 2025, in Oporto, Portugal)
• WSDM 2025: The Eighteenth International Conference on Web Search and Data Mining (March 10-14, 2025, in Hannover, Germany) – Senior Member
• ECMLPKDD 2024: European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (September 9-13, 2023, in Vilnius, Lithuania)
• SIGIR 2024: The 47th International ACM SIGIR Conference on Research and Development in Information Retrieval (Washington D.C., USA, 14-18 July, 2024).
• ECMLPKDD 2023: European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (September 18-22, 2023, in Turin, Italy)
• SIGKDD 2023: 29th SIGKDD Conference on Knowledge Discovery and Data Mining (Long Beach, California, August 6 2023)
• SIGIR 2023: The 46th International ACM SIGIR Conference on Research and Development in Information Retrieval (Taiwan, July 23rd to 27th, 2023).
• EDA 2022: 18e journées EDA Business Intelligence and Big Data (Clermont-Ferrand, France, October 27-28 2022)
• SIGIR 2022: The 45th International ACM SIGIR Conference on Research and Development in Information Retrieval (Madrid, Spain, July 11-15, 2022)
• DOLAP 2022: 24th International Workshop on Design, Optimization, Languages and Analytical Processing of Big Data
• WSDM 2022 15th ACM International WSDM Conference (Phoenix, AZ, USA, Feb. 2nd to March 4th, 2022)
• ASD 2021: 13th edition of the Conference on Advances in the Science of Data (Blida, Algeria, 24-25 October 2021)
• CIKM 2021: 30th ACM International Conference on Information and Knowledge (Gold Coast, Queensland, Australia, 1-5 November 2021)
• ECML/PKDD 21: European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (Bilbao, Spain, 13-17 September)
• EDA 2021: 17e journées EDA Business Intelligence and Big Data (1-2 July 2021)
• SIGKDD 2021: 27th International Conference on Knowledge Discovery and Data Mining (Singapore, Aug 14-18, 2021)
• SIGIR 2021: 44th International ACM SIGIR Conference on Research and Development in Information Retrieval
• DOLAP 2021: 23rd International Workshop On Design, Optimization, Languages and Analytical Processing of Big Data
• WSDM 2021: 14th ACM International WSDM Conference (Jerusalem, Israel, March 8-12, 2021)
• EDML20: Second Workshop on Evaluation and Experimental Design
• RecSys 2020: 14th ACM Recommender Systems Conference (Rio de Janeiro, Brazil)
• BBIGAP'2020: Second International Workshop for Business Intelligence & Big Data Applications
• ECML-PKDD 2020: European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (Area Chair)
• CIKM 2020: 29th ACM International Conference on Information and Knowledge
• DaWak 2020: 22nd International Conference on Big Data Analytics and Knowledge Discovery
• SIGIR 2020: 43rd International ACM SIGIR Conference on Research and Development in Information Retrieval
• DOLAP 2020: 22nd International Workshop On Design, Optimization, Languages and Analytical Processing of Big Data
• ADBIS 2020: 24th European Conference on Advances in Databases and Information Systems (August 25-28: Lyon, France)
• CIKM 2019: 28th ACM International Conference on Information and Knowledge Management (Nov 3-7, 2019: Beijing, China)
• RecSys 2019: 13th ACM Recommender Systems Conference (September 2019; Copenhagen, Denmark)
• BBigAP 2019: 1st International Workshop on BI & Big Data applications, In conjunction with the 23rd European Conference on Advances in Databases and Information Systems (ADBIS 2019) (September 8, 2019; Bled, Slovenia)
• DOLAP 2019 - 21st International Workshop On Design, Optimization, Languages and Analytical Processing of Big Data (March 26, 2019; Lisbon, Portugal)
• CIKM 2018 - Twenty-Seventh ACM International Conference on Information and Knowledge Management (October 22-26, 2018; Turin, Italy)
• ASD 2018 - 12th edition of the Conference on Advances of Decisional Systems : Big data & Applications (May 2018; Marrakech, Morocco)
• WABiD* 2018 - 1st International Workshop on Advances on Big Data Management, Analytics and Security (September 2018; Budapest, Hungary)
• RecSys 2018 - 12th ACM Recommender Systems Conference (October 2018; Vancouver, Canada)
• WWW 2018 - Twenty-seventh International WWW Conference (April 23-27 2018; Lyon, France)
• DOLAP 2018 - 20th International Workshop On Design, Optimization, Languages and Analytical Processing of Big Data (March 26–29, 2018; Vienna, Austria)
• CIKM 2017 - Twenty-Sixth ACM International Conference on Information and Knowledge Management (November 6-10, 2017; Singapore)
• SPIRE 2017 - 24th International Symposium on String Processing and Information Retrieval (September 26-29, 2017; Palermo, Italy)

I was an external referee for the following Ph.D. students:

• Azim Afroozeh at Vrije Universiteit Amsterdam (2026) – supervised by Peter Boncz.
• Lockman Saleh at UQAM (2025) - supervised by Hafedh Mili and Mounir Boukadoum.
• Jaël Champagne Gareau at UQAM (2024) - supervised by Éric Beaudry.
• Nathan Maurice at la Sorbonne, France (2024) - supervised by Lionel Lacassagne.
• Nigel Medforth at Simon Fraser University (2022) - supervised by Robert Cameron.
• Luca Versari at Pisa University (2021) - supervised by Roberto Grossi.
• Kareem El Gebaly at Waterloo University (2018) - supervised by Jimmy Lin, Lukasz Golab and Ashraf Aboulnaga.
• Mohammed Shaaban at Université Pierre et Marie Curie (2017) - supervised by Patrick Garda.
• Mehdi Boukhechba at UQAC (2016) - supervised by Abdenour Bouzouane and Charles Gouin-Vallerand.
• Hicham Assoudi at UQAM (2016) - supervised by Hakim Lounis.
• Khaled Dehdouh at Lyon 2 (2015) - supervised by Omar Boussaid.
• Martin Leginus at Aalborg University (2015) - supervised by Peter Dolog.
• Ahmad Taleb at Université Concordia (2011) - supervised by Todd Eavis.

I was an external referee for the following M.Sc. students:

• Benjamin Lapointe-Pinel from UQAR, Canada (2024) - supervised by Steven Pigeon.

In 2020, I was one of two external reviewers for the M.Sc. in computer science program assessment at UQAC.

I served as a committee member for several funding bodies:

• FRQNT: review committee 03F (theoretical computer science) since 2007.
• FRQNT: review committee 309 (team projects in computer science) since 2006.
• NSERC: Research Tools and Instruments Grants Program (2012-2015)
• NSERC: Computer Science Evaluation Group (EG 1507) for the Discovery Grants Program, comité 1507 (2018-2021), co-chair in 2019-2020 and 2020-2021.
• NSERC: Program Fit Advisor for Discovery Horizons (2022)

In 2022, I was a member of the university sub-committee on engineering and information technologies, within the committee on the implementation of the measures of the Quebec government’s Operation Manpower.

Books

English

Mastering Programming: From Testing to Performance in Go

French

Java pas à pas

Programmation avec Python: des jeux au Web

La science des données: Théorie et applications avec R et Python

Maîtriser la programmation: Des tests à la performance en Go

Curriculum vitae

• Resume (1 page, PDF)
• English c.v. (PDF)
• French c.v. (PDF)

Media

Articles and interviews

• Algorithmes et réseaux sociaux, CHOI FM 93 (Radio X), 9 February 2026.
• Des milliards pour les éoliennes au Québec: pourquoi et pour qui?, Libre Média, 15 September 2025.
• Pour un Québec prospère et une approche équilibrée en environnement, Libre Média, June 3 2025.
• Trump, nouvel alibi des Libéraux pour gouverner par la peur, Libre Média, April 2 2025.
• On SIMD, cache and CPU internals with the expert Daniel Lemire!, Game Engineering Podcast, February 21 2025.
• Avenir de la science (entrevue), Libre Média, February 18 2025.
• Les géants du numérique raffolent des algorithmes de ce prof québécois, Journal de Montréal, October 19 2024.
• Artificial Intelligence Is the Crisis We Need, Communications of the ACM (blog), June 6 2024.
• The Service of Dissent, Brownstone Institute, May 3 2024.
• Les universités de Québec ont « l’oreille tendue » vers la recherche sur l’IA, Radio-Canada, April 23 2024.
• L’intelligence artificielle à l’Université TÉLUQ, Téléjournal ICI Québec, April 23 2024.
• Un robot conversationnel dans certains cours de la TÉLUQ comme outil d’aide pédagogique, Journal de Québec, February 28 2024.
• Making Parsing I/O Bound with Daniel Lemire, Software Unscripted, August 17 2023.
• ¿Supone ChatGPT el fin de los programadores? "Los hará más eficientes en lugar de reemplazarlos", El País, June 9 2023.
• ChatGPT is Not a Technological Singularity, Communications of the ACM (blog), June 5 2023. (One of the most read ACM posts of 2023.)
• Identité numérique: Une solution, mille interrogations, La Presse, November 21st 2022.
• Liberté académique: l’Université Laval doit s’excuser et réparer ses torts, letter in Le Soleil, 15 août 2022.
• L’identité numérique: quels enjeux et quels risques?, letter in Le Journal de Montréal, June 10th 2022.
• Ajouter sa brique à l’édifice de Microsoft, Radio-Canada (Moteur de recherche), May 6th 2022.
• Microsoft utilise le mémoire universitaire d’un étudiant pour améliorer ses fonctionnalités, Figaro, March 11th 2022.
• Microsoft va utiliser les travaux d’un étudiant à la maîtrise, Les Affaires, March 9th 2022.
• Qu’attendez-vous pour adopter le «no-code»?, Les Affaires, January 31st 2022.
• Protéger et promouvoir les libertés académiques pour tous, opinion letter in Le Soleil (newspaper), September 25th 2021.
• Quebec parliamentary commission on academic freedom (CTV News), short clip, August 24th 2021.
• TwitterSpaces with Daniel Lemire (interview), Denis Bakhalov, May 3rd 2021.
• Memorandum addressed to the independent scientific and technical commission on the recognition of academic freedom in the university environment, June 2021 (English at the end).
• Frontiers of Performance with Daniel Lemire (interview), Corecursive, December 1st 2020.
• The research paper should NOT be the final product (interview), A.I. Socratic Circles, March 3 2020.
• Optimizations in C++ Compilers by Godbolt (quotes my blog). Communications of the ACM, February 2020.
• Des serveurs informatiques plus rapides et moins énergivores (interview), Les années lumières, Radio-Canada, December 13th 2019.
• Des langues découpées en bits pour comparer leur efficacité (interview), Les années lumières, Radio-Canada, September 15th 2019.
• L’intelligence artificielle pour rendre les logiciels plus rapides (magazine article on Daniel Lemire’s work), Québec Science, March 28th 2019.
• Défendre la liberté académique, opinion letter in Le Soleil, January 29th 2019.
• Open Source Powers Supercomputing by Shein (quotes my views). Communications of the ACM, February 2018.

Click on the picture for a high resolution version.

D. Lemire’s picture

D. Lemire’s picture

Consulting

I have worked as a consultant since 1998. As a consultant, I built custom mission-critical software, I have solved deep performance issues, I have offered specialized training sessions, I designed novel algorithms. I love working with industry on important problems. I offer the following commercial services.

• Conferences. I am happy to speak to your team about recent advances in software or other relevant topics. My conferences are well received. My rates vary from 5,000ドル to 15,000ドル per engagement, depending on the duration, format (virtual or in person), and travel expenses, which are generally covered separately.
• Training. I provide exclusive and high-quality advanced training for your team. For corporate training sessions in software engineering, my rates are between 3,000ドル and 5,000ドル per day, depending on customization, duration (half-day or full day), and the number of participants.
• Consultation. If you have specific problems in your company, I will be happy to come and help you. My consulting fees are 400ドル per hour, with additional fees for travel. When possible, I prefer to offer flat fee services (e.g., 5,000ドル).
• Sponsored open-source software. Some of my open-source work has been sponsored by private companies and developed according to their needs. Sponsorships for open-source projects can be structured in monthly levels (for example, 100ドル for bronze, 500ドル for gold) or in one-time contributions for specific features, ranging from 1,000ドル to 10,000ドル or more, depending on the scope. I encourage businesses to sponsor me on GitHub especially if they benefit from my work. The top sponsorship tiers on GitHub are meant for businesses and come with specific benefits.

Contact

• [email protected]
• University of Quebec (TELUQ), 5800 Saint-Denis, Office 1105, Montreal (Quebec) H2S 3L5 Canada
• email for appointment