docker run --name some-postgres -e POSTGRES_PASSWORD=mysecretpassword -d study/postgresql-zetasketch

docker run --name some-postgres -e POSTGRES_PASSWORD=mysecretpassword -d study/postgresql-zetasketch

docker exec -it some-postgres psql -U postgres

postgres=# SELECT HLL_COUNT.MERGE(respondents_hll) AS num_respondents, flavor
FROM (
  SELECT
    HLL_COUNT.INIT(respondent) AS respondents_hll,
    flavor,
    country
  FROM (
    SELECT * FROM (
      VALUES (1, 'Vanilla', 'CH'),
             (1, 'Chocolate', 'CH'),
             (2, 'Chocolate', 'US'),
             (2, 'Strawberry', 'US')) AS t(respondent, flavor, country)) as foo
  GROUP BY flavor, country) as bar
GROUP BY flavor;

$ git clone https://github.com/tada/pljava.git
$ cd pljava
$ git checkout tags/V1_5_5
$ mvn -Pwnosign clean install
$ cd ..