Conceptually, Tom (as always) is right. But Alban's hack help. DROP TABLE foo; CREATE TABLE IF NOT EXISTS foo(ID INTEGER,G1 INTEGER, T1 TEXT, ID2 SERIAL PRIMARY KEY); INSERT INTO foo(ID,G1,T1) VALUES(1,2,'ABC'); INSERT INTO foo(ID,G1,T1) VALUES(1,2,'ABCD'); INSERT INTO foo(ID,G1,T1) VALUES(1,2,'ABDC'); INSERT INTO foo(ID,G1,T1) VALUES(1,2,'DEF'); INSERT INTO foo(ID,G1,T1) VALUES(1,2,'DEFH'); /* A little editing to remove duplicates a to b and b to a */ SELECT foo1.ID, foo1.G1, foo1.T1, levenshtein(foo1.T1, foo2.T1),foo2.T1 FROM foo foo1 INNER JOIN foo foo2 ON (foo2.ID = foo1.ID AND foo2.G1 = foo1.G1) WHERE foo1.ID2<foo2.ID2 GROUP BY foo1.ID, foo1.G1, foo1.T1, levenshtein(foo1.T1, foo2.T1),foo2.T1 HAVING levenshtein(foo1.T1, foo2.T1) <2; RETURNS ID|G1|foo1.T1|foo2.T1 1;2;"ABC";1;"ABCD" 1;2;"ABC";1;"ABDC" 1;2;"ABCD";2;"ABDC" 1;2;"DEF";1;"DEFH" Then it requires a second grouping but as Tom suggested it would be hard to somehow group all similar cases together because then it becomes a clustering problem. With a second grouping we will have 3 records instead of 4, so it is better than the initial case by 25%. -- View this message in context: http://postgresql.1045698.n5.nabble.com/Postgresql-GROUP-BY-SIMILAR-but-not-equal-values-tp5790860p5790876.html Sent from the PostgreSQL - general mailing list archive at Nabble.com. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
