What is Caching Data

Caching data to reduce expensive or frequent database queries, it's common to cache the following data types or structures:

1. Lookup Tables / Reference Data

• Country lists, currency codes, language options, etc.

• Usually small, rarely change.

• Cached as: Map / Object / Dictionary

2. User Sessions / Auth Tokens

• User-specific session or authentication information.

• Cached as: Key-Value Pairs, e.g., {userId: sessionInfo}

3. Frequently Accessed Business Data

• Product catalogs, user profiles, configuration settings, etc.

• Cached as: JSON Objects, Lists, or Serialized Records

4. Query Results

• The result of complex or expensive SQL queries.

• Cached as: Serialized Result Sets, e.g., JSON or binary formats

5. Computed/Derived Data

• Aggregated metrics, scores, or statistics.

• Cached as: Numbers, Objects, or Strings

6. HTML Fragments / Page Chunks

• Rendered UI elements like menus, sidebars, etc.

• Cached as: Strings

7. API Responses

• Cached third-party API responses to avoid redundant calls.

• Cached as: JSON/XML Strings or Deserialized Objects

Common Caching Tools

• In-memory: Redis, Memcached, Ehcache

• Client-side: Browser localStorage/sessionStorage

• Application-level: Guava Cache (Java), @Cacheable (Spring), Angular/React state services

For a toy store website, caching can dramatically improve performance and reduce database load. Here's a breakdown of what you can cache and where it might be best cached:

1. Product Catalog

What to cache:

• Toy listings, categories, filters

• Product details (name, price, description, image URL)

Where to cache:

• In-memory (e.g., Redis, in-app memory) for fast access

• Browser cache for static content like images

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🧸 2. Category and Filter Data

What to cache:

• List of categories (e.g., Age 0-3, Educational, Dolls)

• Available brands, age ranges, price brackets

Where to cache:

• Application-level cache (e.g., in-memory or Redis)

• CDN/static file for rarely changing filters

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👤 3. User Session and Cart

What to cache:

• User login session, preferences

• Shopping cart data

Where to cache:

• Server-side session cache (e.g., Redis)

• Local storage or cookies on the client for carts

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💰 4. Promotions and Pricing Rules

What to cache:

• Discount rules, active coupon codes, seasonal offers

Where to cache:

• In-memory with short TTL (Time To Live)

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🌐 5. Frequently Accessed Pages

What to cache:

• Homepage layout (banners, top products)

• Bestsellers, new arrivals, etc.

Where to cache:

• HTML fragment cache or full-page cache (e.g., Varnish, NGINX)

• CDN for static parts

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🧾 6. Order Status and History (per user)

What to cache:

• Recently placed orders, shipping status

Where to cache:

• Short-lived cache for recently viewed orders

• Could be cached in Redis with keys like orders:userId

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⚠️ Cache with care:

• Inventory/stock levels can be cached, but with short TTL (or use a hybrid cache+DB approach) to avoid overselling.

• Personalized recommendations can be cached per user or user segment.