Hashes

Hash commands for storing field-value pairs within a single key.

Commands

Command	Syntax	Description
HSET	HSET key field value [field value ...]	Set field(s)
HGET	HGET key field	Get field value
HMGET	HMGET key field [field ...]	Get multiple field values
HGETALL	HGETALL key	Get all fields and values
HDEL	HDEL key field [field ...]	Delete field(s)
HEXISTS	HEXISTS key field	Check if field exists
HKEYS	HKEYS key	Get all field names
HVALS	HVALS key	Get all values
HLEN	HLEN key	Count fields
HINCRBY	HINCRBY key field increment	Increment field by integer
HINCRBYFLOAT	HINCRBYFLOAT key field increment	Increment field by float
HSETNX	HSETNX key field value	Set field only if not exists

Examples

Basic Operations

# Set single field
127.0.0.1:6379> HSET user:1 name "Alice"
(integer) 1

# Set multiple fields
127.0.0.1:6379> HSET user:1 email "alice@example.com" age "30"
(integer) 2

# Get single field
127.0.0.1:6379> HGET user:1 name
"Alice"

# Get multiple fields
127.0.0.1:6379> HMGET user:1 name email
1) "Alice"
2) "alice@example.com"

# Get all fields and values
127.0.0.1:6379> HGETALL user:1
1) "name"
2) "Alice"
3) "email"
4) "alice@example.com"
5) "age"
6) "30"

Field Management

# Check if field exists
127.0.0.1:6379> HEXISTS user:1 name
(integer) 1
127.0.0.1:6379> HEXISTS user:1 phone
(integer) 0

# Get all field names
127.0.0.1:6379> HKEYS user:1
1) "name"
2) "email"
3) "age"

# Get all values
127.0.0.1:6379> HVALS user:1
1) "Alice"
2) "alice@example.com"
3) "30"

# Count fields
127.0.0.1:6379> HLEN user:1
(integer) 3

# Delete field
127.0.0.1:6379> HDEL user:1 age
(integer) 1

Counters in Hashes

# Increment integer field
127.0.0.1:6379> HSET stats:page views 0
(integer) 1
127.0.0.1:6379> HINCRBY stats:page views 1
(integer) 1
127.0.0.1:6379> HINCRBY stats:page views 10
(integer) 11

# Increment float field
127.0.0.1:6379> HSET product:1 price 9.99
(integer) 1
127.0.0.1:6379> HINCRBYFLOAT product:1 price 0.50
"10.49"

Conditional Set

# Only set if field doesn't exist
127.0.0.1:6379> HSETNX user:1 email "alice@example.com"
(integer) 0  # Field exists, not set
127.0.0.1:6379> HSETNX user:1 phone "555-1234"
(integer) 1  # Field created

Library Mode (Rust)

use redlite::Db;

let db = Db::open("mydata.db")?;

// Set fields
db.hset("user:1", &[("name", b"Alice"), ("email", b"alice@example.com")])?;

// Get single field
let name = db.hget("user:1", "name")?;  // Some(b"Alice".to_vec())

// Get multiple fields
let values = db.hmget("user:1", &["name", "email"])?;

// Get all fields and values
let all = db.hgetall("user:1")?;  // Vec<(String, Vec<u8>)>

// Check existence
let exists = db.hexists("user:1", "name")?;

// Increment
db.hincrby("stats:page", "views", 1)?;

// Delete field
db.hdel("user:1", &["age"])?;

Use Cases

User Profiles

HSET user:1000 username "alice" email "alice@example.com" created_at "2024-01-01"
HGET user:1000 username
HGETALL user:1000

Configuration Storage

HSET config:app debug "false" timeout "30" max_connections "100"
HGET config:app timeout

Object Storage

HSET product:123 name "Widget" price "29.99" stock "50"
HINCRBY product:123 stock -1  # Decrement stock on sale