Data Elixir

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Data Elixir is a weekly newsletter with curated data science picks from around the web. Subscribe at dataelixir.com and follow us here for selections between issues. Covering machine learning, data visualization, analytics, and strategy.

Indexes speed up reads but slow writes. The real insight: indexes only help when you're returning <15-20% of rows. Beyond that, sequential scans win. Space and memory costs matter too. btree indexes often exceed table size.

Introduction to PostgreSQL Indexes

Who’s this for Basics How data is stored in disk How indexes speedup access to data Costs associated with indexes Disk Space Write operations Query planner Memory usage Types of Indexes Btree Hash…

dlt.github.io

What if a model’s prediction was literally an eigenvalue? This post kicks off a thoughtful series exploring spectrum-based models as a middle ground between linear models and neural nets, with interpretability and robustness baked in. A fun, slightly off-the-beaten-path ML read.

Behold the power of the spectrum!

Eigenvalues as neurons: represent nonlinear models as the k-th eigenvalue of a learned symmetric matrix pencil. Explore monotonicity/convexity properties and train simple spectral models.

alexshtf.github.io

Data To Art is a new curated gallery transforming datasets into visual storytelling. Latest addition: Alisa Singer's Environmental Graphiti turns climate science into vibrant data-driven art. The line between science and abstraction is thinner than you think.

Data to Art

A curated gallery celebrating data visualization as art. Discover innovative artworks from international artists who transform data into emotionally compelling visual experiences.

data-to-art.com

ClickHouse solved Advent of Code 2025 puzzles using single ClickHouse queries. No UDFs, no temp tables, no preprocessing. Just pure SQL doing things SQL probably shouldn't do. Impressive and slightly cursed in the best way.

Solving the "Impossible" in ClickHouse: Advent of Code 2025

At ClickHouse, we don't like the word "impossible." We believe that with the right tools, everything is a data problem. To prove it, we decided to complete the 2025 Advent of Code unconventionally:…

clickhouse.com

Your browser can run Python (Pyodide), execute OCR on PDFs, crop videos, and call LLM APIs—all without uploading anything to a server. The localStorage + CORS pattern makes surprisingly powerful tools possible with zero backend infrastructure.

Useful patterns for building HTML tools

I’ve started using the term HTML tools to refer to HTML applications that I’ve been building which combine HTML, JavaScript, and CSS in a single file and use them to …

simonwillison.net

Haskell for data science? dataHaskell adds dataframes, NSE-style column operations, and compiler optimizations that turn chained operations into single-pass computations. Immutability + strong types + functional composition might be the combo we've been missing. jcarroll.com.au/2025/12/05/h...

Haskell IS a Great Language for Data Science

I’ve been learning Haskell for a few years now and I am really liking a lot of the features, not least the strong typing and functional approach. I thought it was lacking some of the things I missed…

jcarroll.com.au

Learning SQL is like learning a foreign language: you need to read more variations than you'll actually write. Learn disciplined canonical syntax for your own queries, but understand the messy dialects others use.

A modern guide to SQL JOINs

There are many SQL JOINs guides and tutorials, but this one takes a different approach. We try to avoid misleading wording and imagery, and we structure the material in a different way. The goal of…

kb.databasedesignbook.com

Sometimes the best polars pattern is knowing when to exit the DataFrame. partitionby() splits data into a dict of frames, letting you process with list comprehensions. Cleaner than forcing everything through mapgroups() when further wrangling isn't needed.

Python Rgonomics: User-defined functions in polars | Emily Riederer

Polars provides a consistent API for conducting transformations against a DataFrame. But what do you do when you need to apply a user-defined function beyond the native API? This post surveys the…

emilyriederer.com

I curated some readings for class on "data tensions" and the list felt worth sharing. Come on a tour of datasets, books, the web, and AI with me... We'll start with this piece on the Google Books project: the hopes, dreams, disasters, and aftermath of building a public library on the internet. 1/n

Torching the Modern-Day Library of Alexandria

“Somewhere at Google there is a database containing 25 million books and nobody is allowed to read them.”

theatlantic.com