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fuzzy: Fuzzy String Matching and Phonetics in SQLite

Fuzzy-matching helpers:

  • Measure distance between two strings.
  • Compute phonetic string code.
  • Transliterate a string.

Adapted from libstrcmp by Ross Bayer and spellfix.c by D. Richard Hipp.

If you want a ready-to-use mechanism to search a large vocabulary for close matches, see the spellfix extension.

String Distances

Measure distance between two strings:

  • dlevenshtein(x, y) - Damerau-Levenshtein distance,
  • edit_distance(x, y) - Spellcheck edit distance,
  • hamming(x, y) - Hamming distance,
  • jaro_winkler(x, y) - Jaro-Winkler distance,
  • levenshtein(x, y) - Levenshtein distance,
  • osa_distance(x, y) - Optimal String Alignment distance.
sqlite> select dlevenshtein('awesome', 'aewsme');
2

sqlite> select edit_distance('awesome', 'aewsme');
215

sqlite> select hamming('awesome', 'aewsome');
2

sqlite> select jaro_winkler('awesome', 'aewsme');
0.907

sqlite> select levenshtein('awesome', 'aewsme');
3

sqlite> select osa_distance('awesome', 'aewsme');
3

Only ASCII strings are supported.

Phonetic Codes

Compute phonetic string code:

  • caverphone(x) - Caverphone code,
  • phonetic_hash(x) - Spellcheck phonetic code,
  • soundex(x) - Soundex code,
  • rsoundex(x) - Refined Soundex code.
sqlite> select caverphone('awesome');
AWSM111111

sqlite> select phonetic_hash('awesome');
ABACAMA

sqlite> select soundex('awesome');
A250

sqlite> select rsoundex('awesome');
A03080

Only ASCII strings are supported.

Transliteration

Transliteration converts the input string from UTF-8 into pure ASCII by converting all non-ASCII characters to some combination of characters in the ASCII subset.

Distance and phonetics functions are ASCII-only, so to work with Unicode string one should transliterate it first.

sqlite> select translit('привет');
privet

Installation and Usage

SQLite command-line interface:

sqlite> .load ./fuzzy
sqlite> select soundex('hello');

See How to Install an Extension for usage with IDE, Python, etc.

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