column name	data type	details
id	integer	not null, primary key
display_name	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

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

• index on author_id
• author_id references users

column name	data type	details
id	integer	not null, primary key
body	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

• index on author_id
• author_id references users
• index on question_id
• question_id references questions

column name	data type	details
id	integer	not null, primary key
voter_id	integer	not null
votable_type	string	not null, indexed
votable_id	integer	not null, indexed
vote_type	integer	not null

• votes represents a polymorphic association, whereby question and answers can both be upvoted

column name	data type	details
id	integer	not null, primary key
user_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

• index on user_id
• user_id references users
• index on question_id
• question_id references questions

`