PostgreSQL full-text search with arrays

In Postgres 9.6 array_to_tsvector was added.

If you are dealing with same table you can write it something like this.

CREATE FUNCTION tsv_trigger() RETURNS trigger AS $$
  begin
    IF (TG_OP = 'INSERT') OR old.array_column <> new.array_column THEN
     new.tsv := array_to_tsvector( new.array_column);
    END IF;
   return new;
end
$$ LANGUAGE plpgsql;

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

If you are dealing with two tables than you need to write update

CREATE FUNCTION cross_tables_tsv_trigger() RETURNS trigger AS $$
  begin
    IF (TG_OP = 'INSERT') OR old.array_column <> new.array_column THEN
     UPDATE search_table st
     SET tsv = array_to_tsvector( new.array_column )
     WHERE st.id = new.searchable_record_id
    END IF;
   # you can't return NULL because you'll break the chain 
   return new; 
end
$$ LANGUAGE plpgsql;

Pay attention that it will differ from default to_tsvector( array_to_string() ) combination.

It goes without position numbers, and lowercase normalization so you can get a unexpected results.