Dictionaries and PostgreSQL FTS. Part 2

This is the second part of the topic about using Ispell and Hunspell dictionaries within PostgreSQL. In this topic I want to give some information about FLAG and AF parameters of Hunspell and about a patch which helps PostgreSQL to load dictionaries with this parameters.

Dictionaries and PostgreSQL FTS

Introduction

There are some text search operator in PostgreSQL: LIKE (~~), ILIKE (~~*), ~, ~* and SIMILAR TO. But they have important disadvantage - they do not provide linguistic support. For example, you will not find the string "great abilities", if you will execute the following query:

CREATE TABLE table1 (col1 varchar);
INSERT INTO table1 VALUES ('great abilities');
SELECT col1 FROM table1 WHERE col1 LIKE '%ability%';

To avoid this drawback use tsvector and tsquery data types. These data types consist of lexemes. Moreover tsvector can store a position and a rank of lexemes.