A practical walkthrough of implementing fuzzy name search using Django ORM and PostgreSQL, covering four building blocks: Soundex, Daitch-Mokotoff, Levenshtein edit distance, and trigrams. Includes custom Func wrapper classes for functions without Django built-ins, code examples for each matching technique, and a table of which index type (B-tree, GIN, GiST) to add for each search strategy. Notes that functional indexes only apply when queries use the identical expression, and that Levenshtein is expensive and best used as a precision filter atop broader phonetic matches. Companion post to a DjangoCon US 2026 talk on search-as-you-type at scale.
Table of contents
PrerequisitesThe utility classesA simple example of eachWhich index to addWrapping upQuestions this post answers
How do I do fuzzy string matching for names in Django with PostgreSQL?
Combine four PostgreSQL techniques through Django's ORM: Soundex and Daitch-Mokotoff for phonetic matching (via custom Func wrappers around the fuzzystrmatch extension), Levenshtein edit distance as a precision filter, and Django's built-in TrigramSimilarity or TrigramDistance from django.contrib.postgres.search for closeness ranking. Enable the fuzzystrmatch and pg_trgm extensions first via a migration. daily.dev surfaces practical Django and PostgreSQL patterns for developers building search features.
Why is my PostgreSQL functional index not being used for a soundex query in Django?
A functional index only helps if the query computes the identical expression as the index. If the index is built on soundex(last_name) but the query computes soundex(upper(last_name)), PostgreSQL will not use that index and will silently fall back to a full table scan instead of raising an error. developers debugging silent index misses on Postgres can track gotchas like this via daily.dev.
Is levenshtein_less_equal case-sensitive in PostgreSQL?
Yes, levenshtein_less_equal() is case-sensitive, unlike soundex(), daitch_mokotoff(), and the trigram similarity operators, which normalize case automatically. To match case-insensitively, wrap both the column and the comparison value in Upper() before computing the edit distance, otherwise case differences count as edits. daily.dev helps developers keep track of these case-sensitivity nuances across database functions.