What is Memcached?
Memcached is a simple, high-speed, in-memory storage system that temporarily holds data so that applications can retrieve it quickly instead of repeatedly asking a database for the same information.
Let's break it down
- Simple: Easy to set up and use; you don’t need a lot of configuration.
- High-speed: Stores data in RAM, which is much faster than reading from a hard drive or even a SSD.
- In-memory: All data lives only in the computer’s memory while the program runs; it’s not saved permanently.
- Temporarily holds data: It keeps copies of data for a short time (seconds to minutes) and discards them when they’re no longer needed.
- Applications retrieve it quickly: Programs ask Memcached for data first; if it’s there, they get it instantly instead of doing a slower database query.
Why does it matter?
Because it can dramatically speed up web sites and apps, reduce the load on databases, and lower hosting costs-all by serving frequently-used information in a flash.
Where is it used?
- E-commerce sites: Caching product listings and price data so shoppers see pages instantly.
- Social media platforms: Storing user session info and recent activity feeds for fast access.
- News websites: Caching the latest headlines and article snippets to handle traffic spikes.
- API services: Holding results of expensive calculations or external API calls to avoid repeating them.
Good things about it
- Extremely fast read/write performance.
- Very lightweight; runs on modest hardware.
- Language-agnostic: works with PHP, Python, Ruby, Java, etc.
- Easy to scale horizontally by adding more Memcached servers.
- Reduces database queries, saving bandwidth and CPU.
Not-so-good things
- Data is volatile: a server restart or crash wipes everything.
- Limited to simple key-value storage; no complex queries or relationships.
- Requires careful key management to avoid collisions and stale data.
- Not ideal for storing large objects; RAM is expensive compared to disk storage.