# regexp

Published articles for regexp.

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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)"

## PostgreSQL Data Types

DevFeed: [PostgreSQL Data Types](<https://devfeed.tech/articles/postgresql-data-types-34598.md>)

Original publisher: [Read original article](<https://tapoueh.org/blog/2018/05/postgresql-data-types/>)

Author: Dimitri Fontaine PostgreSQL Major Contributor; Author

Published: 2018-05-24T12:47:05Z

Content type: article

Language: en

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

Topics: [PostgreSQL](<https://devfeed.tech/topics/postgresql.md>), [data type](<https://devfeed.tech/topics/data-type.md>), [JOIN](<https://devfeed.tech/topics/join.md>), [Query (disambiguation)](<https://devfeed.tech/topics/query.md>), [Regular expression](<https://devfeed.tech/topics/regular-expression.md>)

Tags: [data-type](<https://devfeed.tech/tags/data-type.md>), [documentation](<https://devfeed.tech/tags/documentation.md>), [join](<https://devfeed.tech/tags/join.md>), [postgresql](<https://devfeed.tech/tags/postgresql.md>), [query](<https://devfeed.tech/tags/query.md>), [regexp](<https://devfeed.tech/tags/regexp.md>), [reporting](<https://devfeed.tech/tags/reporting.md>)

### AI overview

A recap of a series on PostgreSQL data types, covering how types provide input validation, expected behaviors, and processing functions. It reviews examples involving booleans, text encoding and processing, date and time values, and network address types.

### Source excerpt

Today it's time to conclude our series of PostgreSQL Data Types articles with a recap. The series cover lots of core PostgreSQL data types and shows how to benefit from the PostgreSQL concept of a data type: more than input validation, a PostgreSQL data type also implements expected behaviors and processing functions. This allows an application developer to rely on PostgreSQL for more complex queries, having the processing happen where the data is, for instance when implementing advanced JOIN operations, then retrieving only the data set that is interesting for the application.

## 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.

## Regular Expressions and Grouping Sets

DevFeed: [Regular Expressions and Grouping Sets](<https://devfeed.tech/articles/regular-expressions-and-grouping-sets-34563.md>)

Original publisher: [Read original article](<https://tapoueh.org/blog/2017/08/regular-expressions-and-grouping-sets/>)

Author: Dimitri Fontaine PostgreSQL Major Contributor; Author

Published: 2017-08-14T14:37:53Z

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>), [SQL](<https://devfeed.tech/topics/sql.md>), [data-processing](<https://devfeed.tech/topics/data-processing.md>), [Open Data](<https://devfeed.tech/topics/open-data.md>), [Structured-data](<https://devfeed.tech/topics/structured-data.md>), [CSV](<https://devfeed.tech/topics/csv.md>), [elt](<https://devfeed.tech/topics/elt.md>), [etl](<https://devfeed.tech/topics/etl.md>)

Tags: [array](<https://devfeed.tech/tags/array.md>), [csv](<https://devfeed.tech/tags/csv.md>), [data-processing](<https://devfeed.tech/tags/data-processing.md>), [elt](<https://devfeed.tech/tags/elt.md>), [etl](<https://devfeed.tech/tags/etl.md>), [functions](<https://devfeed.tech/tags/functions.md>), [postgresql](<https://devfeed.tech/tags/postgresql.md>), [regexp](<https://devfeed.tech/tags/regexp.md>), [regular-expressions](<https://devfeed.tech/tags/regular-expressions.md>), [sql](<https://devfeed.tech/tags/sql.md>), [table](<https://devfeed.tech/tags/table.md>)

### AI overview

A PostgreSQL tutorial showing how to split hierarchical, comma-separated values from a messy column with regular-expression functions, normalize the results, and analyze category distributions with grouping sets, CUBE, and ROLLUP. It also contrasts ETL with ELT.

### Source excerpt

There's a very rich set of PostgreSQL functions to process text, you can find them all at the String Functions and Operators documentation chapter, with functions such as overlay, substring, position or trim. Or aggregates such as string_agg. And then regular expression functions, including the very powerful regexp_split_to_table.

## tor: generowanie milszej nazwy dla hidden service

DevFeed: [tor: generowanie milszej nazwy dla hidden service](<https://devfeed.tech/articles/tor-generowanie-milszej-nazwy-dla-hidden-service-27581.md>)

Original publisher: [Read original article](<https://gagor.pro/2013/09/tor-generowanie-milszej-nazwy-dla-hidden-service/>)

Author: Tom

Published: 2013-09-09T00:00:00Z

Content type: tutorial

Language: pl

Sources: [Tomasz Gągor](<https://devfeed.tech/sources/tomasz-gagor.md>)

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

Tags: [regexp](<https://devfeed.tech/tags/regexp.md>), [tor](<https://devfeed.tech/tags/tor.md>)

### AI overview

The author describes exposing a website through a Tor hidden service and finding Shallot, which generates hidden-service names until one matches a specified regular expression.

### Source excerpt

Chcąc pobawić się tor'em postanowiłem udostępnić jedna z moich stron z wykorzystaniem mechanizmu hidden service. Nie spodobał mi się jedynie sposób generowania nazw, które były mało opisowe - ale najwidoczniej nie mnie jednemu, bo szybko namierzyłem Shallot external link , który generuje kolejne nazwy aż trafi na pasującą do zadanego regexp'a.

## Regexp performances and Finite Automata

DevFeed: [Regexp performances and Finite Automata](<https://devfeed.tech/articles/regexp-performances-and-finite-automata-34389.md>)

Original publisher: [Read original article](<https://tapoueh.org/blog/2010/09/regexp-performances-and-finite-automata/>)

Author: Dimitri Fontaine PostgreSQL Major Contributor; Author

Published: 2010-09-26T19:00:00Z

Content type: article

Language: en

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

Topics: [Automaton](<https://devfeed.tech/topics/automaton.md>), [Regular expression](<https://devfeed.tech/topics/regular-expression.md>), [Parser](<https://devfeed.tech/topics/parser.md>), [PostgreSQL](<https://devfeed.tech/topics/postgresql.md>), [Perl](<https://devfeed.tech/topics/perl.md>), [Ruby](<https://devfeed.tech/topics/ruby.md>), [Emacs](<https://devfeed.tech/topics/emacs.md>)

Tags: [dfa](<https://devfeed.tech/tags/dfa.md>), [emacs-lisp](<https://devfeed.tech/tags/emacs-lisp.md>), [perl](<https://devfeed.tech/tags/perl.md>), [postgresql](<https://devfeed.tech/tags/postgresql.md>), [regexp](<https://devfeed.tech/tags/regexp.md>), [regular-expressions](<https://devfeed.tech/tags/regular-expressions.md>), [ruby](<https://devfeed.tech/tags/ruby.md>)

### AI overview

This article examines regular-expression performance through the lens of finite automata, contrasting NFA and DFA-based implementation techniques. It also discusses PostgreSQL's regular-expression implementation and the author's preference for using awk in some file-searching situations.

### Source excerpt

The major reason why I dislike perl so much, and ruby too, and the thing I'd want different in the Emacs Lisp API so far is how they set developers mind into using regexp. You know the quote, don't you? Some people, when confronted with a problem, think "I know, I'll use regular expressions." Now they have two problems. That said, some situations require the use of regexp -- or are so much simpler to solve using them than the maintenance hell you're building here ain't that big a drag. The given expressiveness is hard to match with any other solution, to the point I sometime use them in my code (well I use rx to lower the burden sometime, just see this example).