Postgres Database Schema

users

column name	data type	details
id	integer	not null, primary key
username	string	not null, indexed, unique
email	string	not null, indexed, unique
password_digest	string	not null
session_token	string	not null, indexed, unique
created_at	datetime	not null
updated_at	datetime	not null

• index on username, unique: true
• index on email, unique: true
• index on session_token, unique: true
• has_many questions
• has_many answers
• has_many upvotes
• has_many downvotes

questions

column name	data type	details
id	integer	not null, primary key
body	string	not null
code	string	not null
author_id	integer	not null, indexed, foreign key
created_at	datetime	not null
updated_at	datetime	not null

• author_id references users
• index on author_id
• belongs_to user
• has_many answers

answers

column name	data type	details
id	integer	not null, primary key
body	string	not null
code	string	not null
author_id	integer	not null, indexed, foreign key
question_id	integer	not null, indexed, foreign key
created_at	datetime	not null
updated_at	datetime	not null

• author_id references users
• question_id references questions
• index on [:question_id, :author_id], unique: true
• belongs_to question
• belongs_to user
• has_many upvotes
• has_many downvotes

upvotes

column name	data type	details
id	integer	not null, primary key
user_id	integer	not null, indexed, foreign key
answer_id	integer	not null, indexed, foreign key
created_at	datetime	not null
updated_at	datetime	not null

• user_id references users
• answer_id references answers
• index on [:answer_id, :user_id], unique: true
• belongs_to answer
• belongs_to user

downvotes

column name	data type	details
id	integer	not null, primary key
user_id	integer	not null, indexed, foreign key
answer_id	integer	not null, indexed, foreign key
created_at	datetime	not null
updated_at	datetime	not null

• user_id references users
• answer_id references answers
• index on [:answer_id, :user_id], unique: true
• belongs_to answer
• belongs_to user