Redis is an in-memory, persistent, key-value store that supports more than strings. MongoDB doesn't have in-memory and key-value attributes while Memcached doesn't have persistence or support for more than strings. Redis, by contrast, doesn't have support for larger-than-memory datasets and it's not multithreaded.
This is illustrated in a new document outlining the top 5 performance metrics you should look out for if you decide to use Redis, which is a pretty hot data store right now.
The top 5 metrics, which are explained in more detail if you click the PDF link (no registration), include:
- Memory usage: used_memory
- Number of commands processed: total_commands_processed
- Fragmentation Ratio