Question: When to use Memcached vs Redis?

Answer

Memcached and Redis are both in-memory data stores, but they have some differences in terms of functionality and implementation. Choosing between them for a particular use case can depend on factors like data complexity, read/write operations, and scalability requirements. Here are some guidelines to consider:

1. Data Complexity:

   1. For simple key-value pairs, Memcached is often a good choice because it has a smaller memory footprint and faster performance.
   2. For more complex data types (e.g., lists, sets, hashes) and more advanced data manipulation capabilities, Redis offers better support.

2. Read/Write Operations:

   1. Memcached excels at handling high volumes of reads and writes, making it a great option for caching frequently accessed data.
   2. Redis is better suited for write-heavy workloads or situations where data must be persisted beyond just caching.

3. Scalability:

   1. Both Memcached and Redis are horizontally scalable, which means you can add nodes to the cluster as needed to handle increasing traffic.
   2. However, Memcached may be easier to scale due to its simpler architecture, while Redis offers more advanced features like data replication and clustering.

Here are some code examples to illustrate the basic usage of both Memcached and Redis:

# Memcached Python Example
import memcache

mc = memcache.Client(['127.0.0.1:11211'], debug=0)
mc.set("key", "value")
print(mc.get("key"))

# Redis Python Example
import redis

r = redis.Redis(host='localhost', port=6379, db=0)
r.set('key', 'value')
print(r.get('key'))

In summary, choose Memcached if you need a lightweight, fast, and easy-to-scale caching solution that can handle high read/write loads. Choose Redis for more advanced data structures, write-heavy workloads or situations where data must be persisted beyond just caching.