mget

Get the values of multiple keys

Description

Returns the values of all specified keys. For every key that does not hold a string value or does not exist, the special value null is returned.

Syntax

// Using array
redis.mget<TData extends unknown[]>(keys: string[]): Promise<TData>

// Using rest parameters
redis.mget<TData extends unknown[]>(...keys: string[]): Promise<TData>

Parameters

keys · string[] | ...string[] · required

The keys to retrieve. Can be passed as an array or as individual arguments

Type Parameters

TData · type · default: "(string | null)[]"

An array type representing the expected types of the returned values. Each element can be a specific type or null if the key doesn’t exist.

Returns

values · TData

An array of values at the specified keys. For keys that don’t exist, null is returned at that position.

Examples

Basic Usage

import { Redis } from '@upstash/redis';

const redis = new Redis({
  url: 'https://your-redis-url.upstash.io',
  token: 'your-token'
});

// Set multiple values
await redis.set('key1', 'value1');
await redis.set('key2', 'value2');
await redis.set('key3', 'value3');

// Get multiple values using array
const values = await redis.mget(['key1', 'key2', 'key3']);
console.log(values); // ["value1", "value2", "value3"]

Using Rest Parameters

// Get multiple values using rest parameters
const values = await redis.mget('key1', 'key2', 'key3');
console.log(values); // ["value1", "value2", "value3"]

Handling Non-Existent Keys

await redis.set('exists1', 'value1');
await redis.set('exists2', 'value2');

// Mix of existing and non-existent keys
const values = await redis.mget(['exists1', 'nonexistent', 'exists2']);
console.log(values); // ["value1", null, "value2"]

Fetching User Data

// Store user data
await redis.set('user:1:name', 'Alice');
await redis.set('user:1:email', '[e-mail]');
await redis.set('user:1:age', '30');

// Fetch all user data at once
const [name, email, age] = await redis.mget(
  'user:1:name',
  'user:1:email',
  'user:1:age'
);

console.log({ name, email, age });
// { name: "Alice", email: "[e-mail]", age: "30" }

Batch Fetching with Type Safety

interface UserData {
  name: string;
  email: string;
  role: string;
}

// Store user data as JSON
const user1 = { name: 'Alice', email: '[e-mail]', role: 'admin' };
const user2 = { name: 'Bob', email: '[e-mail]', role: 'user' };

await redis.set('user:1', user1);
await redis.set('user:2', user2);

// Fetch multiple users
const users = await redis.mget<(UserData | null)[]>('user:1', 'user:2', 'user:3');
console.log(users);
// [
//   { name: "Alice", email: "[e-mail]", role: "admin" },
//   { name: "Bob", email: "[e-mail]", role: "user" },
//   null
// ]

Configuration Settings

// Store configuration values
await redis.set('config:api_url', 'https://api.example.com');
await redis.set('config:timeout', '5000');
await redis.set('config:max_retries', '3');

// Fetch all config at once
const [apiUrl, timeout, maxRetries] = await redis.mget(
  'config:api_url',
  'config:timeout',
  'config:max_retries'
);

const config = {
  apiUrl,
  timeout: timeout ? parseInt(timeout) : 3000,
  maxRetries: maxRetries ? parseInt(maxRetries) : 3
};

console.log(config);

Dynamic Key Fetching

// Generate keys dynamically
const userIds = ['123', '456', '789'];
const keys = userIds.map(id => `user:${id}:score`);

// Set some scores
await redis.set('user:123:score', '100');
await redis.set('user:456:score', '85');
// user:789:score doesn't exist

// Fetch all scores
const scores = await redis.mget(keys);
console.log(scores); // ["100", "85", null]

// Filter out null values
const validScores = scores.filter((score): score is string => score !== null);
console.log(validScores); // ["100", "85"]

Cache Warming

// Warm up cache with multiple keys
async function warmCache(productIds: string[]) {
  const keys = productIds.map(id => `product:${id}`);
  const products = await redis.mget(keys);
  
  // Find missing products
  const missingIndices = products
    .map((p, i) => p === null ? i : -1)
    .filter(i => i !== -1);
  
  if (missingIndices.length > 0) {
    console.log(`Cache miss for products: ${missingIndices.map(i => productIds[i])}`);
    // Fetch from database and populate cache
  }
  
  return products;
}

const productData = await warmCache(['p1', 'p2', 'p3']);

Performance Considerations

• MGET is more efficient than multiple GET commands because it reduces network round trips
• For fetching many keys, MGET significantly reduces latency compared to sequential GET calls
• The command has O(N) time complexity where N is the number of keys to retrieve

Notes

• The order of values in the result matches the order of keys in the request
• Non-existent keys return null at their respective positions
• This is an atomic operation
• MGET is significantly faster than multiple GET commands due to reduced network overhead

Related Commands

• get - Get the value of a single key
• mset - Set multiple keys to multiple values

Redis Documentation

For more information, see the Redis MGET documentation.