Fuzzy scoping in Rails with PostgreSQL

When you want to filter records in a model where a string column roughly matches a given term, you can use PostgreSQL’s trigram similarity search.

Writing a fuzzy query in Rails

CopyUser.where("similarity(name, ?) > 0.3", "John")

This finds all users where the name is similar to "John" with a similarity score above 0.3.

You can tune the threshold:

• Closer to 1.0 = stricter match
• Closer to 0.0 = looser match

Ordering by best match

CopyUser
  .where("similarity(name, ?) > 0.3", "John")
  .order(Arel.sql("similarity(name, 'John') DESC"))

Indexing

See Trigram indexing as an alternative to PostgreSQL fulltext search.