Multiple concurrent "REFRESH MATERIALIZED VIEW": how to manage?
It looks like you want to refresh the materialized views whenever the data in the tables change. If you do that with materialized views, it will take a long time, and updates will block each other and queries.

Maybe you can build your own &ldquo;on commit refresh&rdquo; materialized views as tables.

A simple example:

Instead of

CREATE MATERIALIZED VIEW sum_eumel AS
SELECT eumel_category,
       sum(eumel_data) AS eumel_sum
FROM eumel
GROUP BY eumel_category;


you could do this:

BEGIN;

CREATE TABLE sum_eumel (
   eumel_category text NOT NULL PRIMARY KEY,
   eumel_sum bigint NOT NULL DEFAULT 0
);

CREATE FUNCTION eumel_trigger() RETURNS trigger
   LANGUAGE plpgsql AS
$$BEGIN
   IF TG_OP IN ('UPDATE', 'DELETE') THEN
      /*
       * Will leave rows with value 0 after the last
       * row for a category has been deleted.
       */
      UPDATE sum_eumel
      SET eumel_sum = eumel_sum - OLD.eumel_data
      WHERE eumel_category = OLD.eumel_category;
   END IF;

   IF TG_OP IN ('INSERT', 'UPDATE') THEN
      INSERT INTO sum_eumel (eumel_category, eumel_sum)
      VALUES (NEW.eumel_category, NEW.eumel_data)
      ON CONFLICT TO UPDATE
      SET eumel_sum = sum_eumel.eumel_sum + EXCLUDED.eumel_data
   END IF;

   IF TG_OP = 'TRUNCATE' THEN
      TRUNCATE sum_eumel;
      RETURN NULL;
   END IF;

   IF TG_OP = 'DELETE' THEN
      RETURN OLD;
   ELSE
      RETURN NEW;
   END IF;
END;$$;

CREATE TRIGGER eumel_dml_trig
   AFTER INSERT OR UPDATE OR DELETE ON eumel
   FOR EACH ROW EXECUTE PROCEDURE eumel_trigger();

CREATE TRIGGER eumel_truncate_trig
   AFTER TRUNCATE ON eumel
   FOR EACH STATEMENT EXECUTE PROCEDURE eumel_trigger();

INSERT INTO sum_eumel
SELECT eumel_category,
       sum(eumel_data) AS eumel_sum
FROM eumel
GROUP BY eumel_category;

COMMIT;