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 = off;
  SET enable_indexscan = on;
  SET enable_bitmapscan = off;
  \pset format unaligned
  EXPLAIN (COSTS OFF)
  SELECT id, title, content, pgroonga_score(tableoid, ctid)
    FROM memos
   WHERE ARRAY[title, content] &@
         ('PostgreSQL',
          NULL,
          NULL,
          'pgrn_index')::pgroonga_full_text_search_condition_with_scorers
  \g |sed -r -e "s/('.+'|ROW.+)::pgroonga/pgroonga/g"
  QUERY PLAN
  Index Scan using pgrn_index on memos
    Index Cond: (ARRAY[title, content] &@ pgroonga_full_text_search_condition_with_scorers)
  (2 rows)
  \pset format aligned
  SELECT id, title, content, pgroonga_score(tableoid, ctid)
    FROM memos
   WHERE ARRAY[title, content] &@
         ('PostgreSQL',
          NULL,
          NULL,
          'pgrn_index')::pgroonga_full_text_search_condition_with_scorers;
   id |   title    |                        content                        | pgroonga_score 
  ----+------------+-------------------------------------------------------+----------------
    1 | PostgreSQL | PostgreSQL is a RDBMS.                                |              2
    3 | PGroonga   | PGroonga is a PostgreSQL extension that uses Groonga. |              1
  (2 rows)
  
  DROP TABLE memos;
  