text: CREATE TABLE memos (
    id integer PRIMARY KEY,
    tag varchar(256),
    content text
  );
  
  CREATE INDEX grnindex ON memos
    USING pgroonga (id pgroonga.int4_ops,
                    content pgroonga.text_full_text_search_ops);
  
  INSERT INTO memos VALUES (1, 'pgsql', 'PostgreSQL is a RDBMS.');
  INSERT INTO memos VALUES (2, 'groonga', 'Groonga is fast full text search engine.');
  INSERT INTO memos VALUES (3, 'pgsql', 'PGroonga is a PostgreSQL extension that uses Groonga.');
  UPDATE memos SET tag = 'groonga'
   WHERE id = 3;
  
  SET enable_seqscan = off;
  SET enable_indexscan = on;
  SET enable_bitmapscan = off;
  
  SELECT id, content, pgroonga.score(memos)
    FROM memos
   WHERE content @@ 'PGroonga OR Groonga';
  
  DROP TABLE memos;
  