text: CREATE TABLE memos (
    id integer,
    title text,
    content text
  );
  
  INSERT INTO memos VALUES (1, 'PostgreSQL', 'PostgreSQL is a RDBMS.');
  INSERT INTO memos VALUES (2, 'Groonga', 'Groonga is fast full text search engine.');
  INSERT INTO memos VALUES (3, 'PGroonga', 'PGroonga is a PostgreSQL extension that uses Groonga.');
  
  CREATE INDEX pgrn_index ON memos
   USING pgroonga ((ARRAY[title, content])
                   pgroonga_text_array_full_text_search_ops_v2);
  
  SET enable_seqscan = on;
  SET enable_indexscan = off;
  SET enable_bitmapscan = off;
  
  \pset format unaligned
  EXPLAIN (COSTS OFF)
  SELECT id, title, content, pgroonga_score(tableoid, ctid)
    FROM memos
   WHERE ARRAY[title, content] &@~
         ('Groonga OR search OR fast OR RDBMS -PGroonga',
          ARRAY[5, 2],
          ARRAY[
            'scorer_tf_idf($index)',
            'scorer_tf_at_most($index, 0.25)'
          ],
          'pgrn_index')::pgroonga_full_text_search_condition_with_scorers
  \g |sed -r -e "s/('.+'|ROW.+)::pgroonga/pgroonga/g"
  \pset format aligned
  
  SELECT id, title, content, pgroonga_score(tableoid, ctid)
    FROM memos
   WHERE ARRAY[title, content] &@~
         ('Groonga OR search OR fast OR RDBMS -PGroonga',
          ARRAY[5, 2],
          ARRAY[
            'scorer_tf_idf($index)',
            'scorer_tf_at_most($index, 0.25)'
          ],
          'pgrn_index')::pgroonga_full_text_search_condition_with_scorers;
  
  DROP TABLE memos;
  