go/example/cluster-mget

KV Cluster MGET Example

This example demonstrates how to use the KV Cluster client with the MGET command to retrieve multiple keys efficiently.

Overview

The example shows:

• Creating a KV Cluster client
• Setting 10 keys with individual SET commands
• Retrieving all 10 keys in a single operation using MGET
• Validating that the retrieved values match the expected values
• Cleaning up by deleting the test keys

Prerequisites

You need a running KV Cluster. The example expects cluster nodes at:

• localhost:7000
• localhost:7001
• localhost:7002

Setting up a KV Cluster (using Docker)

If you don't have a KV Cluster running, you can use the docker-compose setup from the repository root:

# From the go-kv repository root
docker compose --profile cluster up -d

This will start a KV Cluster with nodes on ports 16600-16605.

If using the docker-compose cluster, update the Addrs in main.go to:

Addrs: []string{
    "localhost:16600",
    "localhost:16601",
    "localhost:16602",
},

Running the Example

go run main.go

Expected Output

✓ Connected to KV cluster

=== Setting 10 keys ===
✓ SET key0 = value0
✓ SET key1 = value1
✓ SET key2 = value2
✓ SET key3 = value3
✓ SET key4 = value4
✓ SET key5 = value5
✓ SET key6 = value6
✓ SET key7 = value7
✓ SET key8 = value8
✓ SET key9 = value9

=== Retrieving keys with MGET ===

=== Validating MGET results ===
✓ key0: value0
✓ key1: value1
✓ key2: value2
✓ key3: value3
✓ key4: value4
✓ key5: value5
✓ key6: value6
✓ key7: value7
✓ key8: value8
✓ key9: value9

=== Summary ===
✓ All values retrieved successfully and match expected values!

=== Cleaning up ===
✓ Cleanup complete

Key Concepts

MGET Command

MGET (Multiple GET) is a KV command that retrieves the values of multiple keys in a single operation. This is more efficient than executing multiple individual GET commands.

Syntax:

result, err := rdb.MGet(ctx, key1, key2, key3, ...).Result()

Returns:

• A slice of interface{} values
• Each value corresponds to a key in the same order
• nil is returned for keys that don't exist

Cluster Client

The ClusterClient automatically handles:

• Distributing keys across cluster nodes based on hash slots
• Following cluster redirects
• Maintaining connections to all cluster nodes
• Retrying operations on cluster topology changes

For MGET operations in a cluster, the client may need to split the request across multiple nodes if the keys map to different hash slots.

Code Highlights

// Create cluster client
rdb := kv.NewClusterClient(&kv.ClusterOptions{
    Addrs: []string{
        "localhost:7000",
        "localhost:7001",
        "localhost:7002",
    },
})

// Set individual keys
for i := 0; i < 10; i++ {
    err := rdb.Set(ctx, fmt.Sprintf("key%d", i), fmt.Sprintf("value%d", i), 0).Err()
    // handle error
}

// Retrieve all keys with MGET
result, err := rdb.MGet(ctx, keys...).Result()

// Validate results
for i, val := range result {
    actualValue, ok := val.(string)
    // validate actualValue matches expected
}

Learn More

• KV MGET Documentation
• KV Cluster Specification
• go-kv Documentation