what type of data should be kept in redis

Redis is an in-memory data structure store that can be used as a database, cache, and message broker. It is designed for scenarios that require fast access to data and can handle a variety of data structures such as strings, hashes, lists, sets, and more. Here's a detailed overview of what data to put in Redis and its persistence capabilities:

Data to Put in Redis

1. Caching Frequently Accessed Data:

   • Web Session Data: Store user session data to speed up authentication processes.
   • API Responses: Cache API responses to reduce load on backend services and improve response times.
   • Page Fragments: Cache parts of web pages that do not change frequently.

2. Transient Data:

   • Rate Limiting Counters: Track the number of requests from users or IP addresses to implement rate limiting.
   • Temporary Data: Store temporary data such as one-time tokens or short-lived data that doesn’t need to persist long-term.

3. Pub/Sub Messaging:

   • Use Redis for real-time messaging applications where you need to send messages between different parts of your application.

4. Real-Time Analytics and Metrics:

   • Counters and Statistics: Track real-time metrics, such as page views, user actions, and other counters.
   • Event Logging: Store real-time event logs for quick access and monitoring.

5. Leaderboards and Rankings:

   • Gaming Applications: Maintain real-time leaderboards and rankings for players.
   • Voting Systems: Track votes or scores in applications that require real-time updates.

6. Geospatial Data:

   • Store and query geospatial data for applications that need to handle location-based data.

7. Data Structures:

   • Lists: Manage queues or stacks for task processing.
   • Sets: Handle collections of unique items, such as tags or categories.
   • Hashes: Store objects or dictionaries for fast access to individual fields.

Persistence in Redis

Redis primarily operates in-memory, but it does provide mechanisms for persisting data to disk, ensuring that data can survive restarts and crashes. Redis offers two main persistence options:

1. RDB (Redis Database Backup):

   • Snapshotting: Redis creates point-in-time snapshots of your dataset at specified intervals. This is done by saving the dataset to an RDB file.
   • Configuration: You can configure Redis to save snapshots at different intervals (e.g., every 5 minutes if there have been at least 100 writes).

   save 900 1
   save 300 10
   save 60 10000
   

   • Pros: Compact storage, fast startup times.
   • Cons: Potential data loss between snapshots if Redis crashes.

2. AOF (Append-Only File):

   • Append-Only Log: Redis logs every write operation received in an append-only file. This file can be rewritten in the background to optimize its size.
   • Configuration: You can configure Redis to flush the AOF to disk at different intervals (e.g., every write, every second, or no automatic flush).

   appendonly yes
   appendfilename "appendonly.aof"
   appendfsync everysec
   

   • Pros: More durable than RDB, less data loss (up to the last second).
   • Cons: Larger file sizes, slower startup times compared to RDB.

3. Hybrid Approach:

   • Using Both RDB and AOF: You can configure Redis to use both RDB and AOF to balance between performance and durability. This provides the benefit of quick snapshots and detailed write logs.

   save 900 1
   save 300 10
   save 60 10000
   appendonly yes
   appendfilename "appendonly.aof"
   appendfsync everysec