Tooling & Monitoring

redis-cli is more than a REPL

redis-cli ships with a rich set of diagnostic flags that go well beyond typing commands. Knowing these tools means you can identify slow queries, memory hogs, and connection problems without any extra software.

INFO — server statistics at a glance

INFO returns a large block of key-value statistics grouped by section. Call a specific section to reduce noise:

127.0.0.1:6379> INFO server
# Server
redis_version:7.2.4
redis_mode:standalone
os:Linux 5.15.0 x86_64
...

127.0.0.1:6379> INFO memory
# Memory
used_memory_human:1.02M
used_memory_peak_human:1.03M
...

127.0.0.1:6379> INFO stats
# Stats
total_commands_processed:1024
instantaneous_ops_per_sec:12
...

INFO server
INFO memory
INFO keyspace

SLOWLOG — find slow commands

Redis records commands that exceed a configurable threshold (default 10 ms). SLOWLOG GET N returns the N most recent slow entries with timestamp, duration, and full command:

127.0.0.1:6379> SLOWLOG GET 5
1) 1) (integer) 3
   2) (integer) 1700000000
   3) (integer) 15420
   4) 1) "KEYS"
      2) "*"
   5) "127.0.0.1:54321"
   6) ""

Reset the log with SLOWLOG RESET. Adjust the threshold with:

127.0.0.1:6379> CONFIG SET slowlog-log-slower-than 5000
OK

SLOWLOG GET 5
SLOWLOG LEN
SLOWLOG RESET

—bigkeys — find memory-hungry keys

Run from your shell (not the REPL) to scan the entire keyspace and report the largest key per type:

redis-cli --bigkeys

Sample output:

-------- summary -------
Biggest string found 'session:heavy' has 512000 bytes
Biggest list   found 'log:events' has 1048576 items
Biggest hash   found 'user:profile:1' has 312 fields

This uses SCAN internally so it does not block the server.

—scan and —pattern — iterate the keyspace

# List all keys matching a pattern (uses SCAN internally, non-blocking)
redis-cli --scan --pattern "session:*"

# Count matching keys
redis-cli --scan --pattern "cache:*" | wc -l

—latency — measure round-trip time

redis-cli --latency
redis-cli --latency-history   # sample every 15 seconds
redis-cli --latency-dist      # ASCII histogram

These ping Redis in a loop and display min/max/avg latency. Use them to detect network jitter or a suddenly slow server.

MONITOR — real-time command stream

MONITOR streams every command processed by the server in real time:

127.0.0.1:6379> MONITOR
OK
1700000001.123456 [0 127.0.0.1:54322] "SET" "foo" "bar"
1700000001.124000 [0 127.0.0.1:54322] "GET" "foo"

It is invaluable for debugging what an application is actually sending. Press Ctrl+C to stop.

CLIENT LIST — inspect connections

CLIENT LIST shows every connected client with its id, address, database, command, and memory usage:

127.0.0.1:6379> CLIENT LIST
id=5 addr=127.0.0.1:54321 laddr=127.0.0.1:6379 fd=8 name= age=0 idle=0 flags=N db=0 cmd=client|list ...

Kill a stale connection with CLIENT KILL id 5.

CLIENT LIST
CLIENT GETNAME
CLIENT INFO

RedisInsight — GUI for Redis

RedisInsight is the official free GUI from Redis Ltd. It provides a visual keyspace browser, slow-log viewer, memory profiler, and a built-in CLI. Download it from redis.io/insight and point it at any Redis instance — local or remote.