How to fix CROSSSLOT Keys in request don't hash to the same slot in Redis

# Connect to any Redis Cluster node
redis-cli -c -h <host> -p <port>

# Check slot for individual keys
CLUSTER KEYSLOT user:123:profile
CLUSTER KEYSLOT user:123:sessions
CLUSTER KEYSLOT session:456:data

# Example output:
# (integer) 650
# (integer) 8734
# (integer) 200

# Without hash tags – different slots
CLUSTER KEYSLOT user:123:profile    # slot 7592
CLUSTER KEYSLOT user:123:sessions   # slot 10411

# With hash tags – same slot
CLUSTER KEYSLOT user:{123}:profile   # slot 3300 (based on '123')
CLUSTER KEYSLOT user:{123}:sessions  # slot 3300 (based on '123')

// Instead of (will cause CROSSSLOT)
const keys = ['user:123:profile', 'user:123:sessions'];
redis.mget(...keys);

// Use hash tags (all hash to same slot)
const keys = ['user:{123}:profile', 'user:{123}:sessions'];
redis.mget(...keys);  // Works!

// Without hash tags – fails with CROSSSLOT
redis.multi()
  .get('user:123:name')
  .get('session:456:token')
  .exec();

// With hash tags – all keys in same slot
redis.multi()
  .get('user:{123}:name')
  .get('session:{123}:token')
  .exec();

// Instead of MGET that fails with CROSSSLOT
redis.mget('key1', 'key2', 'key3');  // Fails if keys in different slots

// Use individual GET calls
const values = await Promise.all([
  redis.get('key1'),
  redis.get('key2'),
  redis.get('key3')
]);

# Instead of DEL key1 key2 key3 (fails if in different slots)
DEL key1
DEL key2
DEL key3

const redis = require('ioredis');
const cluster = new redis.Cluster([...nodes]);

// Get multiple values efficiently by grouping by slot
const keys = ['user:{1}:name', 'user:{1}:email', 'user:{2}:name', 'user:{2}:email'];

// Group by hash tag (all user:{1} keys go together)
const groupedBySlot = groupByHashTag(keys);
const results = {};

for (const [tag, keyGroup] of Object.entries(groupedBySlot)) {
  const values = await cluster.mget(...keyGroup);
  results[tag] = values;
}

// ioredis example – automatically handles cluster routing
const Redis = require('ioredis');
const cluster = new Redis.Cluster([
  { host: '127.0.0.1', port: 7000 },
  { host: '127.0.0.1', port: 7001 },
]);

// Use hash tags for multi-key commands
await cluster.mget('user:{1}:name', 'user:{1}:email');

# redis-py-cluster example
from rediscluster import RedisCluster

startup_nodes = [
    {'host': '127.0.0.1', 'port': 7000},
    {'host': '127.0.0.1', 'port': 7001},
]
rc = RedisCluster(startup_nodes=startup_nodes, decode_responses=True)

# Use hash tags
rc.mget('user:{1}:name', 'user:{1}:email')