Master Redis: Essential Commands for Data Management and Persistence

Redis Restart and Cache Clearing

After a Redis restart the data remains because Redis uses persistence (RDB and optionally AOF). To log in use redis-cli -h IP -p port and clear all data with flushall.

Basic Key Operations

Set a key: set keyname "value". Retrieve with get keyname. Delete with del keyname. Example: set test 123.

Database Selection

Switch databases with select 7 or select 10. List keys in the current DB using keys *. The default DB is 0; return to it with select 0.

Numeric Increment

Increase a numeric key value by 1 using incr keyname (or incrby keyname increment).

Serialization

Serialize a key’s value with dump keyname. Deserialization is performed by Redis when loading data.

Key Expiration

Set expiration in seconds: expire keyname 10. Set expiration by Unix timestamp: expireat keyname 1639116230. Set expiration in milliseconds: pexpire keyname 2000. Set expiration by millisecond timestamp: pexpireat keyname 1639116950000. Remove expiration with persist keyname.

Checking Expiration

Get remaining time to live in seconds with ttl keyname and in milliseconds with pttl keyname. Return values: -1 (no expiration), -2 (key does not exist), positive integer (remaining time).

Key Existence and Pattern Search

Check if a key exists: exists keyname (returns 1 if exists, 0 otherwise). Find keys matching a pattern with keys test*. List all keys with keys *.

Moving Keys Between Databases

Move a key to another DB with move keyname db-index. Returns 1 on success, 0 if the target DB already has a key with the same name or the source key does not exist.

Random Key Retrieval

Get a random key from the current DB using randomkey. Returns nil (or null on Windows) if the DB is empty.

Renaming Keys

Rename a key with rename oldkey newkey. If newkey already exists it will be overwritten. Use renamenx oldkey newkey to rename only when newkey does not exist.

Number of Databases

Redis typically provides 16 databases. Check the configuration file ( /etc/redis/redis.conf) or run config get databases after logging in.