Server & Connection

Server and connection commands for managing the Redis protocol connection, authentication, and server information.

Commands

Command	Syntax	Description
PING	PING [message]	Test connection, returns PONG or echoes message
ECHO	ECHO message	Echo the given message
INFO	INFO [section]	Get server information and statistics
SELECT	SELECT db	Select database (0-15)
DBSIZE	DBSIZE	Return number of keys in current database
FLUSHDB	FLUSHDB	Delete all keys in current database
QUIT	QUIT	Close the connection
AUTH	AUTH password	Authenticate with password
COMMAND	COMMAND	List all supported commands
CONFIG	CONFIG GET/SET option	Get or set configuration

Examples

Connection Testing

# Simple ping
127.0.0.1:6379> PING
PONG

# Ping with message
127.0.0.1:6379> PING "hello"
"hello"

# Echo message
127.0.0.1:6379> ECHO "testing"
"testing"

Database Selection

# Redlite supports databases 0-15 (like Redis)
127.0.0.1:6379> SELECT 0
OK

127.0.0.1:6379> SET key1 "in db 0"
OK

127.0.0.1:6379> SELECT 1
OK

127.0.0.1:6379> SET key1 "in db 1"
OK

127.0.0.1:6379> GET key1
"in db 1"

127.0.0.1:6379> SELECT 0
OK

127.0.0.1:6379> GET key1
"in db 0"

Database Statistics

# Count keys in current database
127.0.0.1:6379> DBSIZE
(integer) 42

# Clear current database
127.0.0.1:6379> FLUSHDB
OK

127.0.0.1:6379> DBSIZE
(integer) 0

Server Information

127.0.0.1:6379> INFO
# Server
redis_version:7.0.0
redlite_version:0.1.0
os:darwin
arch:aarch64

# Clients
connected_clients:1

# Memory
used_memory:1048576
used_memory_human:1.00M

# Stats
total_connections_received:5
total_commands_processed:100

# Keyspace
db0:keys=42,expires=5

Authentication

# Start server with password
$ redlite --db mydata.db --password mysecret

# Client must authenticate
127.0.0.1:6379> GET key
(error) NOAUTH Authentication required

127.0.0.1:6379> AUTH mysecret
OK

127.0.0.1:6379> GET key
"value"

Configuration

# Get configuration values
127.0.0.1:6379> CONFIG GET maxmemory
1) "maxmemory"
2) "0"

127.0.0.1:6379> CONFIG GET maxmemory-policy
1) "maxmemory-policy"
2) "noeviction"

# Set configuration
127.0.0.1:6379> CONFIG SET maxmemory 104857600
OK

127.0.0.1:6379> CONFIG SET maxmemory-policy allkeys-lru
OK

# Get disk limit
127.0.0.1:6379> CONFIG GET maxdisk
1) "maxdisk"
2) "0"

List Supported Commands

127.0.0.1:6379> COMMAND
1) "GET"
2) "SET"
3) "DEL"
4) "MGET"
5) "MSET"
... (200+ commands)

Configuration Options

Option	Description	Default
maxmemory	Maximum memory in bytes (0 = unlimited)	0
maxmemory-policy	Eviction policy when limit reached	noeviction
maxdisk	Maximum disk size in bytes (0 = unlimited)	0
persist-access-tracking	Persist LRU/LFU tracking to disk	auto
access-flush-interval	Tracking flush interval in ms	300000

Eviction Policies

Policy	Description
noeviction	Return error when memory limit reached
allkeys-lru	Evict least recently used keys
allkeys-lfu	Evict least frequently used keys
allkeys-random	Evict random keys
volatile-lru	Evict LRU keys with TTL set
volatile-lfu	Evict LFU keys with TTL set
volatile-ttl	Evict keys with shortest TTL
volatile-random	Evict random keys with TTL set

Library Mode (Rust)

use redlite::Db;

// Open database (equivalent to connecting)
let db = Db::open("mydata.db")?;

// Select database (0-15)
db.select(1)?;

// Get database size
let count = db.dbsize()?;

// Clear database
db.flushdb()?;

// Configuration
db.set_max_memory(100 * 1024 * 1024);  // 100MB
db.set_eviction_policy(EvictionPolicy::AllKeysLru);

CLI Options

# Start server with options
redlite --db mydata.db \
        --host 127.0.0.1 \
        --port 6379 \
        --password mysecret \
        --max-memory 100mb \
        --max-disk 1gb

Option	Description
--db	Database file path
--host	Bind address (default: 127.0.0.1)
--port	Port number (default: 6379)
--password	Require authentication
--max-memory	Memory limit for eviction
--max-disk	Disk limit for eviction

Use Cases

Health Check

# Simple liveness check
PING

# With custom message for identification
PING "worker-1"

Multi-Tenant Isolation

# Each tenant gets a separate database
SELECT 0  # Tenant A
SET user:1 "Alice"

SELECT 1  # Tenant B
SET user:1 "Bob"

# Data is isolated
SELECT 0
GET user:1  # "Alice"

Development Reset

# Clear all test data
SELECT 15  # Use db 15 for tests
FLUSHDB
# Run tests...