PostgreSQL create index and full-text search query

create_index.sql

UPDATE tus SET text1_tsvector = to_tsvector(COALESCE(lang1_psql, 'simple')::regconfig, COALESCE(text1, ''));
UPDATE tus SET text2_tsvector = to_tsvector(COALESCE(lang2_psql, 'simple')::regconfig, COALESCE(text2, ''));

/* CREATE INDEX text1_tsvector_idx ON tus USING gin(text1_tsvector);
CREATE INDEX text2_tsvector_idx ON tus USING gin(text2_tsvector); */
CREATE INDEX text_tsvector_idx ON tus USING gin(text1_tsvector, text2_tsvector);

CREATE FUNCTION text_tsvector_update() RETURNS TRIGGER AS $$
BEGIN
  IF TG_OP = 'INSERT' THEN
      NEW.text1_tsvector = to_tsvector(COALESCE(NEW.lang1_psql, 'simple')::regconfig, COALESCE(NEW.text1, ''));
      NEW.text2_tsvector = to_tsvector(COALESCE(NEW.lang2_psql, 'simple')::regconfig, COALESCE(NEW.text2, ''));
  END IF;
  IF TG_OP = 'UPDATE' THEN
      IF NEW.text1 <> OLD.text1 THEN
          NEW.text1_tsvector = to_tsvector(COALESCE(NEW.lang1_psql, 'simple')::regconfig, COALESCE(NEW.text1, ''));
      END IF;
      IF NEW.text2 <> OLD.text2 THEN
          NEW.text2_tsvector = to_tsvector(COALESCE(NEW.lang2_psql, 'simple')::regconfig, COALESCE(NEW.text2, ''));
      END IF;
  END IF;
  RETURN NEW;
END
$$ LANGUAGE 'plpgsql';

CREATE TRIGGER tsvectorupdate BEFORE INSERT OR UPDATE ON tus
FOR EACH ROW EXECUTE PROCEDURE text_tsvector_update();

query.sql

WITH cache AS (SELECT plainto_tsquery(COALESCE(:lang1_psql, 'simple')::regconfig, :query) AS tsquery)
SELECT id, lang1, lang2,
    CASE lang1
        WHEN :lang1 THEN ts_headline(COALESCE(:lang1_psql, 'simple')::regconfig, text1, (SELECT tsquery FROM cache), 'StartSel = <***, StopSel = ***>')
        WHEN :lang2 THEN text1
    END AS text1,
    CASE lang1
        WHEN :lang1 THEN text2
        WHEN :lang2 THEN ts_headline(COALESCE(:lang1_psql, 'simple')::regconfig, text2, (SELECT tsquery FROM cache), 'StartSel = <***, StopSel = ***>')
    END AS text2,
    topic, tm_id
FROM (
    SELECT "tus".id, lang1, lang2, text1, text2, topic, tm_id,
        CASE "tus".lang1
            WHEN :lang1 THEN ts_rank_cd(text1_tsvector, (SELECT tsquery FROM cache))
            WHEN :lang2 THEN ts_rank_cd(text2_tsvector, (SELECT tsquery FROM cache))
        END AS rank
    FROM "tus"
    WHERE ("tus".lang1 = :lang1 AND "tus".lang2 = :lang2 AND text1_tsvector @@ (SELECT tsquery FROM cache) AND length(text1) < length(:query) + :add_length)
    OR ("tus".lang1 = :lang2 AND "tus".lang2 = :lang1 AND text2_tsvector @@ (SELECT tsquery FROM cache) AND length(text2) < length(:query) + :add_length)
    ORDER BY rank DESC
    LIMIT :limit OFFSET :offset
) AS foo;