System requirements

Functional:

• Allow tagging -> normalize tags
• Allow searchability
• Provide tag suggestions

Non-Functional:

• Scalable -> Multiple tags on multiple items could grow quickly
• Prioritize Consistency
• Available but prioritize consistency -> because even if its available but tags are inaccurate, it would be considered as unavailable

API design

External Endpoints:

POST:

• addTag/:tag/:item

GET:

• retrieveTag/:tag
• tagRecommendation/:currentPartialTag

High-level design

• User tags item, can add multiple tags -> POST request to addTag/:tag/:item
• User can search tags on items -> GET request to retrieveTag/:tag
• Elastic search will make searches efficient to retrieve items with tag
• Tag recommendation -> GET request to tagRecommendation/:currentPartialTag
• Elastic search will make searches efficient to retrieve existing tags

Shard ElasticSearchDB by user ID to scale horizontally

Normalize tags by using only lower case in serverside logic before adding to Elastic Search DB

Detailed component design

Provide Tag Suggestion

-> option 1: Grab all tags and client-side can implement partial search system

-> option 2: Client side implements debouncing method, send request to serverside to get suggested tags

Database design

Use Elastic Search DB to find items more quickly (NoSQL) to search by tag

Index by tag and item name

{

UserID: 123,

items: {

item1ID: {itemName: itemName, tags: []},

item2ID: {itemName: itemName, tags: []},

}

}

MySQL for User Table:

• UserID
• First Name
• Last Name