create table users (
  id int, -- Will overflow at 2.1 billion
  email varchar(255), -- Unnecessary length limit
  created_at timestamp, -- Missing timezone info
  is_active varchar(5), -- String for boolean
  price varchar(20) -- String for numeric
);

create table users (
  id bigint generated always as identity primary key, -- 9 quintillion max
  email text, -- No artificial limit, same performance as varchar
  created_at timestamptz, -- Always store timezone-aware timestamps
  is_active boolean default true, -- 1 byte vs variable string length
  price numeric(10,2) -- Exact decimal arithmetic
);

-- IDs: use bigint, not int (future-proofing)
-- Strings: use text, not varchar(n) unless constraint needed
-- Time: use timestamptz, not timestamp
-- Money: use numeric, not float (precision matters)
-- Enums: use text with check constraint or create enum type