Redis only using 1 key in database

Question

I have setup Redis as a caching mechanism on my server with a Wordpress site. Basically on each request I check if a cache of the page exists and then I show the cache.

I'm using Predis (https://github.com/nrk/predis) as an interface to the redis database.

When I get the info from the usage of Redis however, I only see 1 key used in the system:

used_memory:103810376
used_memory_human:99.00M
used_memory_rss:106680320
used_memory_peak:222011768
used_memory_peak_human:211.73M
mem_fragmentation_ratio:1.03
mem_allocator:jemalloc-2.2.5
loading:0
aof_enabled:0
changes_since_last_save:8
bgsave_in_progress:0
last_save_time:1396168319
bgrewriteaof_in_progress:0
total_connections_received:726918
total_commands_processed:1240245
expired_keys:22
evicted_keys:0
keyspace_hits:1158841
keyspace_misses:699
pubsub_channels:0
pubsub_patterns:0
latest_fork_usec:21712
vm_enabled:0
role:master
db0:keys=1,expires=0

How could this be? I expect to see more keys listed, as each cached copy of the html of a page should have it's own key?

What am I missing here?

Answer 1

Without looking at the technical implementation, it could be several things.

1) The pages didn't get a hit, so they are not in the cache

2) The keys expired already

3) The mechanism uses for example a HSET , where you can have N key/values registered under 1 main key. You can check this by using the TYPE redis command on the single key you've got.