Positive vs. Negative Cache in System Design
Below are differences between positive and negative caching:
|
Aspect |
Positive Cache |
Negative Cache |
|---|---|---|
|
Definition |
Positive cache stores successful results of requests. |
Negative cache stores the results of failed or unsuccessful requests. |
|
Purpose |
It aims to speed up repeated access to the same successful results. |
It aims to prevent repeated attempts of operations known to fail. |
|
Response Time |
Positive cache reduces the time to fetch successful data by serving it from the cache. |
Negative cache reduces the time to respond to failed requests by using cached errors. |
|
Resource Utilization |
It helps in conserving resources by avoiding repeated data fetching or processing. |
It saves resources by avoiding redundant processing of known failures. |
|
Data Stored |
Successful data responses or results are stored. |
Error messages or failure responses are stored. |
|
Use Cases |
Commonly used for frequently accessed data like user profiles, product details. |
Commonly used for handling errors in DNS lookups, API calls, or database queries. |
|
Impact on Performance |
It improves system performance by reducing load on servers for repeated successful requests. |
It enhances system performance by preventing repetitive processing of failed requests. |
|
Implementation Complexity |
Generally easier to implement as it deals with expected successful responses. |
Can be more complex as it requires handling and identifying various failure conditions. |
|
Expiration Policies |
Often has longer TTLs because successful data is more stable. |
Typically has shorter TTLs due to the transient nature of errors and failures. |
|
Examples |
Caching a successful API response or a webpage. |
Caching a DNS lookup failure or a database query error. |
|
Cache Miss Handling |
On a cache miss, the system fetches the data from the primary source and caches it. |
On a cache miss, the system processes the request and caches the error if it fails again. |
|
User Experience |
Improves user experience by providing faster access to frequently requested data. |
Enhances user experience by quickly returning known errors and preventing repeated failures. |
Negative Caching – System Design
Negative caching refers to storing failed results or errors to avoid redundant requests. It plays a major role in enhancing system performance by preventing repeated processing of known failures. By caching these negative responses, systems save resources and improve response times. Unlike positive caching, which stores successful results, negative caching focuses on handling errors efficiently. This technique is beneficial in environments with frequent lookup failures, like DNS queries and database searches.
Important Topics for Negative Caching in System Design
- What is Negative Caching?
- Importance of Negative Caching in System Performance
- Positive vs. Negative Cache in System Design
- How Negative Caching Works
- Benefits of Negative Caching
- Mechanics of Negative Caching
- Negative Caching Implementations
- Challenges of Negative Caching
- Best practices for Negative Caching
- Real-World Examples of Negative Caching