CREATE TABLE subscriptions (
  user_id int NOT NULL,
  subscription_type text NOT NULL,
  started date NOT NULL,
  expires date NOT NULL,
  PRIMARY KEY (user_id, subscription_type)
);

> SELECT country, city, department, count(*) FROM HR GROUP BY ROLLUP (country, city, department) ORDER BY 1, 2, 3;

> SELECT country, city, department, count(*) FROM HR GROUP BY CUBE (country, city, department) ORDER BY 1, 2, 3;

> SELECT country, city, department, count(*) FROM HR GROUP BY GROUPING SETS
  ((country, city, department), (country, city), (country), (), (department), 
  (country, department)) ORDER BY 1, 2, 3;

> CREATE TABLE logins (tx timestamp, ip_adress, ...);
> CREATE TABLE logins_201509 (CHECK (tx >= '2015-09-01' AND tx < '2015-10-01')) INHERITS (logins);
> CREATE TABLE logins_201510 (CHECK (tx >= '2015-10-01' AND tx < '2015-11-01')) INHERITS (logins);

SELECT avg(preis) FROM article TABLESAMPLE  SYSTEM(1);

pg_rewind -D /usr/local/pgsql/data --source-server='host=db2 dbname  =postgres'

test=> select citx, country from HR; \
  ERROR: column "citx" does not exist \
  LINE 1: select citx, country from HR; \
  HINT: Perhaps you meant to reference the column "HR"."city".