text: CREATE TABLE memos (
    id integer,
    content varchar(256)
  );
  
  INSERT INTO memos VALUES (1, 'PostgreSQL is a RDBMS.');
  INSERT INTO memos VALUES (2, 'Groonga is fast full text search engine.');
  INSERT INTO memos VALUES (3, 'PGroonga is a PostgreSQL extension that uses Groonga.');
  
  CREATE INDEX grnindex ON memos
   USING pgroonga (content pgroonga.varchar_full_text_search_ops_v2);
  
  SET enable_seqscan = off;
  SET enable_indexscan = on;
  SET enable_bitmapscan = off;
  
  SELECT id, content
    FROM memos
   WHERE content &` 'content @ "rdbms" || content @ "engine"';
  
  DROP TABLE memos;
  