PostgreSQL Database Tables 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 comments
• has_many votes

questions

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

• author_id references users
• parent_question_id references questions
• index on author_id
• index on parent_question_id
• belongs_to author
• has_many answers
• has_many comments
• has_many votes

answers

column name	data type	details
id	integer	not null, primary key
body	text	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 author
• belongs_to question
• has_many comments
• has_many votes

comments

column name	data type	details
id	integer	not null, primary key
body	text	not null
commenter_id	integer	not null, indexed, foreign key
question_id	integer	not null, indexed, foreign key
answer_id	integer	not null, indexed, foreign key
parent_comment_id	integer	indexed, foreign key
created_at	datetime	not null
updated_at	datetime	not null

• commenter_id references users
• question_id references questions
• answer_id references answers
• parent_comment_id references comments
• index on commenter_id
• belongs_to question
• belongs_to answer
• belongs_to comment
• has_many comments

votes

column name	data type	details
id	integer	not null, primary key
voter_id	integer	not null, indexed, foreign key
question_id	integer	not null, indexed, foreign key
answer_id	integer	not null, indexed, foreign key
vote	boolean	not null
created_at	datetime	not null
updated_at	datetime	not null

• voter_id references users
• question_id references questions
• answer_id references answers
• vote is true for an upvote and false for a downvote
• index on [:voter_id, :question_id, :answer_id], unique: true
• belongs_to user
• belongs_to question
• belongs_to answer