similarity

I need to create a ranking of similar strings in a table. I have the following table create table names ( name character varying(255) ); Currently, I'm using pg_trgm module which offers the similarity function, but I have an efficiency problem. I created an index like the Postgres manual suggests : CREATE INDEX trgm_idx ON names USING gist (name gist_trgm_ops); and I'm executing the following query: select (similarity(n1.name, n2.name)) as sim, n1.name, n2.name from names n1, names n2 where n1.name != n2.name and similarity(n1.name, n2.name) > .8 order by sim desc; The query works, but is

I'm looking for a way to compare a string with an array of strings. Doing an exact search is quite easy of course, but I want my program to tolerate spelling mistakes, missing parts of the string and so on. Is there some kind of framework which can perform such a search? I'm having something in mind that the search algorithm will return a few results order by the percentage of match or something like this. You could use the Levenshtein Distance algorithm . "The Levenshtein distance between two strings is defined as the minimum number of edits needed to transform one string into the other, with

if i have two strings in mysql: @a="Welcome to Stack Overflow" @b=" Hello to stack overflow"; is there a way to get the similarity percentage between those two string using MYSQL? here for example 3 words are similar and thus the similarity should be something like: count(similar words between @a and @b) / (count(@a)+count(@b) - count(intersection)) and thus the result is 3/(4 + 4 - 3)= 0.6 any idea is highly appreciated! Alaa you can use this function (cop^H^H^Hadapted from http://www.artfulsoftware.com/infotree/queries.php#552 ): CREATE FUNCTION `levenshtein`( s1 text, s2 text) RETURNS int