Database Schema

users

Column name	data type	details
id	integer	not null, primary key
username	string	not null, indexed, unique
full_name	string	not null
email	string	not null, indexed, unique
password_digest	string	not null
session_token	string	not null, indexed, unique

• index on username, unique: true
• index on email, unique: true
• index on session_token, unique: true
• has_many comments
• has_many authored_likes
• has_many images
• has_many in_follows, foreign_key: followee_id - followers table
• has_many out_follows, foreign_key: follower_id - followers table
• has_many followers(as a followee through in_follows - followers table
• has_many following(as a follower through out_follows - followers table
• has_many sent_messages, foreign_key: senders - messages table
• has_many received_messages, foreign_key: recipient - messages table

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images

Column name	data type	details
id	integer	not null, primary key
author_id	integer	not null, indexed, foreign key
image_url	string	not null
caption	text

• index on user_id
• has_many comments
• has_many likes
• has_many hashtags
• belongs_to author, foreign_key: author_id - users table

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comments

Column name	data type	details
id	integer	not null, primary key
author_id	integer	not null, indexed
image_id	integer	not null, indexed
body	text	not null

• indexed on user_id
• indexed on image_id
• belongs_to author, foreign_key: author_id - users table
• belongs_to image, foreign_key: image_id - images table

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likes

Column name	data type	details
id	integer	not null, primary key
user_id	integer	not null, indexed
image_id	integer	not null, indexed

• indexed on user_id
• indexed on image_id
• belongs_to author, foreign_key: user_id - users table
• belongs_to image, foreign_key: image_id - images table

---

followers

Column name	data type	details
id	integer	not null, primary key
followee_id	integer	not null, indexed
follower_id	integer	not null, indexed

• indexed on followee_id
• indexed on follower_id
• belongs_to followee, foreign_key: followee_id - users table
• belongs_to follower, foreign_key: follower_id - users table

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direct_message

Column name	data type	details
id	integer	not null, primary key
sender_id	integer	not null, indexed
recipient_id	integer	not null, indexed
body	text	not null

• indexed on sender_id
• indexed on recipient_id
• belongs_to sender, foreign_key: sender_id - users table
• belongs_to recipient, foreign_key: recipient_id - users table

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hashtags

Column name	data type	details
id	integer	not null, primary key
name	string	not null, indexed
image_id	integer	not null, indexed

• indexed on name
• indexed on image_id
• belongs_to image, foreign_key: image_id - images table