# regular

Published articles for regular.

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## New things for regular expressions in PostgreSQL (pg\_tre and pg\_re2)

DevFeed: [New things for regular expressions in PostgreSQL (pg\_tre and pg\_re2)](<https://devfeed.tech/articles/new-things-for-regular-expressions-in-postgresql-pg-tre-and-pg-re2-33694.md>)

Original publisher: [Read original article](<https://www.depesz.com/2026/08/25/new-things-for-regular-expressions-in-postgresql-pg_tre-and-pg_re2/>)

Author: depesz

Published: 2026-08-25T18:41:53Z

Content type: tutorial

Language: en

Sources: [select \* from depesz;](<https://devfeed.tech/sources/select-from-depesz.md>)

Topics: [PostgreSQL](<https://devfeed.tech/topics/postgresql.md>), [Databases](<https://devfeed.tech/topics/databases.md>), [test](<https://devfeed.tech/topics/test.md>)

Tags: [expression](<https://devfeed.tech/tags/expression.md>), [extension](<https://devfeed.tech/tags/extension.md>), [extensions](<https://devfeed.tech/tags/extensions.md>), [pg-re2](<https://devfeed.tech/tags/pg-re2.md>), [pg-tre](<https://devfeed.tech/tags/pg-tre.md>), [postgresql](<https://devfeed.tech/tags/postgresql.md>), [re2](<https://devfeed.tech/tags/re2.md>), [regexp](<https://devfeed.tech/tags/regexp.md>), [regular](<https://devfeed.tech/tags/regular.md>), [regular-expressions](<https://devfeed.tech/tags/regular-expressions.md>), [test-data](<https://devfeed.tech/tags/test-data.md>), [uncategorized](<https://devfeed.tech/tags/uncategorized.md>)

### AI overview

This article compares PostgreSQL regular-expression approaches using pg_tre and pg_re2 against built-in matching and pg_trgm. Tests on a large table of query plans find that pg_tre is slower than pg_trgm for exact substring searches but supports fuzzy matching, while pg_re2 performs faster than the tested built-in scan. The author notes that both extensions have limitations and rough edges.

### Source excerpt

Well, truth be told these are not all that new (couple of months), but I finally have gotten around to research it. So, let's see what's what. For starters I need some test data. Luckily, I have explain.depesz.com DB... Extracted all plans to side table, with this structure: =$ \d all_plans Table "public.all_plans" Column | ... Continue reading "New things for regular expressions in PostgreSQL (pg_tre and pg_re2)"

## Nix Weekly Recap: 2024-06-09

DevFeed: [Nix Weekly Recap: 2024-06-09](<https://devfeed.tech/articles/nix-weekly-recap-2024-06-09-34722.md>)

Original publisher: [Read original article](<https://nixpkgs.news/archive/2024-06-09/>)

Published: 2024-06-09T00:00:00Z

Content type: news

Language: en

Sources: [nixpkgs.news](<https://devfeed.tech/sources/nixpkgs-news.md>)

Topics: [Nix](<https://devfeed.tech/topics/nix.md>), [releases](<https://devfeed.tech/topics/releases.md>), [Package manager](<https://devfeed.tech/topics/package-manager.md>)

Tags: [community](<https://devfeed.tech/tags/community.md>), [news](<https://devfeed.tech/tags/news.md>), [packages](<https://devfeed.tech/tags/packages.md>), [recap](<https://devfeed.tech/tags/recap.md>), [regular](<https://devfeed.tech/tags/regular.md>), [tools](<https://devfeed.tech/tags/tools.md>), [weekly](<https://devfeed.tech/tags/weekly.md>)

### AI overview

The June 9, 2024 Nix weekly recap covers a retrospective meeting for the NixOS 24.05 release, a call for social media support on the Marketing team, Brioche package manager news, security fixes, and new packages added to Nixpkgs.

### Source excerpt

NixOS 24.05 retrospective, marketing team call for social media support, and the introduction of Brioche.

## Effective Kotlin Item 48: Consider using object declarations

DevFeed: [Effective Kotlin Item 48: Consider using object declarations](<https://devfeed.tech/articles/effective-kotlin-item-48-consider-using-object-declarations-39286.md>)

Original publisher: [Read original article](<https://kt.academy/article/ek-object-declarations>)

Published: 2023-11-06T00:00:00Z

Content type: tutorial

Language: en

Sources: [Kt. Academy](<https://devfeed.tech/sources/kt-academy.md>)

Topics: [Kotlin](<https://devfeed.tech/topics/kotlin.md>), [object](<https://devfeed.tech/topics/object.md>), [classes](<https://devfeed.tech/topics/classes.md>), [Kotlin programming](<https://devfeed.tech/topics/kotlin-programming.md>)

Tags: [classes](<https://devfeed.tech/tags/classes.md>), [consider](<https://devfeed.tech/tags/consider.md>), [effective](<https://devfeed.tech/tags/effective.md>), [instead](<https://devfeed.tech/tags/instead.md>), [kotlin](<https://devfeed.tech/tags/kotlin.md>), [object](<https://devfeed.tech/tags/object.md>), [regular](<https://devfeed.tech/tags/regular.md>), [using](<https://devfeed.tech/tags/using.md>), [workshop-learning-programming](<https://devfeed.tech/tags/workshop-learning-programming.md>)

### AI overview

This tutorial explains when to use Kotlin object declarations instead of regular classes, including the covariant Nothing object pattern for generic types.

### Source excerpt

Why we should use object declarations instead of regular classes.

## PostgreSQL Data Types: Text Processing

DevFeed: [PostgreSQL Data Types: Text Processing](<https://devfeed.tech/articles/postgresql-data-types-text-processing-34594.md>)

Original publisher: [Read original article](<https://tapoueh.org/blog/2018/04/postgresql-data-types-text-processing/>)

Author: Dimitri Fontaine PostgreSQL Major Contributor; Author

Published: 2018-04-11T21:15:42Z

Content type: tutorial

Language: en

Sources: [Dimitri Fontaine](<https://devfeed.tech/sources/dimitri-fontaine.md>)

Topics: [PostgreSQL](<https://devfeed.tech/topics/postgresql.md>), [Regular expression](<https://devfeed.tech/topics/regular-expression.md>), [pattern matching](<https://devfeed.tech/topics/pattern-matching.md>), [CSV](<https://devfeed.tech/topics/csv.md>)

Tags: [csv](<https://devfeed.tech/tags/csv.md>), [dataset](<https://devfeed.tech/tags/dataset.md>), [functions](<https://devfeed.tech/tags/functions.md>), [pattern-matching](<https://devfeed.tech/tags/pattern-matching.md>), [postgresql](<https://devfeed.tech/tags/postgresql.md>), [processing](<https://devfeed.tech/tags/processing.md>), [regexp](<https://devfeed.tech/tags/regexp.md>), [regular](<https://devfeed.tech/tags/regular.md>), [text](<https://devfeed.tech/tags/text.md>)

### AI overview

This tutorial introduces PostgreSQL text-processing functions and operators, including string functions, aggregates, regular expressions, and regexp_split_to_table(). It also discusses text and varchar data types and demonstrates processing comma-separated and hierarchical values in a CSV dataset.

### Source excerpt

Continuing our series of PostgreSQL Data Types today we're going to introduce some of the PostgreSQL text processing functions. There's a very rich set of PostgreSQL functions to process text -- you can find them all in the string functions and operators documentation chapter -- with functions such as overlay(), substring(), position() or trim(). Or aggregates such as string_agg(). There are also regular expression functions, including the very powerful regexp_split_to_table(). In this article we see practical example putting them in practice.

## A Spectral Analysis of Moore Graphs

DevFeed: [A Spectral Analysis of Moore Graphs](<https://devfeed.tech/articles/a-spectral-analysis-of-moore-graphs-40406.md>)

Original publisher: [Read original article](<https://www.jeremykun.com/2016/11/03/a-spectral-analysis-of-moore-graphs/>)

Published: 2016-11-03T08:00:14Z

Content type: tutorial

Language: en

Sources: [Jeremy Kun](<https://devfeed.tech/sources/jeremy-kun.md>)

Topics: [Graphs](<https://devfeed.tech/topics/graphs.md>)

Tags: [adjacency-matrix](<https://devfeed.tech/tags/adjacency-matrix.md>), [eigenvalues](<https://devfeed.tech/tags/eigenvalues.md>), [eigenvectors](<https://devfeed.tech/tags/eigenvectors.md>), [graph](<https://devfeed.tech/tags/graph.md>), [graphs](<https://devfeed.tech/tags/graphs.md>), [math](<https://devfeed.tech/tags/math.md>), [matrix](<https://devfeed.tech/tags/matrix.md>), [moore-graph](<https://devfeed.tech/tags/moore-graph.md>), [orthogonality](<https://devfeed.tech/tags/orthogonality.md>), [regular](<https://devfeed.tech/tags/regular.md>), [spectral-graph-theory](<https://devfeed.tech/tags/spectral-graph-theory.md>), [trace](<https://devfeed.tech/tags/trace.md>), [vertex](<https://devfeed.tech/tags/vertex.md>)

### AI overview

This mathematical article analyzes Moore graphs of girth 5 using the eigenvalues of their adjacency matrices. It derives the minimum vertex count and shows that the degree must be one of 3, 7, or 57.

### Source excerpt

For fixed integers $ r > 0$, and odd $ g$, a Moore graph is an $ r$-regular graph of girth $ g$ which has the minimum number of vertices $ n$ among all such graphs with the same regularity and girth. (Recall, A the girth of a graph is the length of its shortest cycle, and it's regular if all its vertices have the same degree) Problem (Hoffman-Singleton): Find a useful constraint on the relationship between $ n$ and $ r$ for Moore graphs of girth $ 5$ and degree $ r$.