Re: [pgadmin-hackers] Declarative partitioning in pgAdmin4

   Taking average of two columns is just an example/representation of expression, there is no use case of that. As I am also in learning phase. Below are some use case that I can think of:

• Partitions based on first letter of their username
  

  CREATE TABLE users (
      id             serial not null,
      username       text not null,
      password       text,
      created_on     timestamptz not null,
      last_logged_on timestamptz not null
  )PARTITION BY RANGE ( lower( left( username, 1 ) ) );
  CREATE TABLE users_0
      partition of users (id, primary key (id), unique (username))
      for values from ('a') to ('g');
  CREATE TABLE users_1
      partition of users (id, primary key (id), unique (username))
      for values from ('g') to (unbounded);

•  Partition based on country's sale for each month of an year.

CREATE TABLE public.sales

(

    country text NOT NULL,

    sales bigint NOT NULL,

    saledate date

) PARTITION BY RANGE (country, (extract (YEAR FROM saledate)), (extract(MONTH FROM saledate)))

CREATE TABLE public.sale_usa_2017_jan PARTITION OF sales

    FOR VALUES FROM ('usa', 2017, 01) TO ('usa', 2017, 02);

CREATE TABLE public.sale_india_2017_jan PARTITION OF sales

    FOR VALUES FROM ('india', 2017, 01) TO ('india', 2017, 02);

CREATE TABLE public.sale_uk_2017_jan PARTITION OF sales

    FOR VALUES FROM ('uk', 2017, 01) TO ('uk', 2017, 02);

INSERT INTO sales VALUES ('india', 10000, '2017-1-15');

INSERT INTO sales VALUES ('uk', 20000, '2017-1-08');

INSERT INTO sales VALUES ('usa', 30000, '2017-1-10');

   Apart from above there may be N number of use cases that depends on specific requirement of user.