Deleting Redis Cache in Golang (Detailed Guide w/ Code Examples)

Use Case(s)

For web applications, cached data can become outdated or irrelevant over time. In these cases, it is necessary to delete specific keys from the Redis cache. This operation is common during updates to database records that are also stored in cache, or when a session expires and related user data needs to be purged from cache.

Code Examples

To handle such scenarios in Go, we typically use the go-redis library:

Example 1: Deleting a single key

package main

import (
	"github.com/go-redis/redis/v8"
	"context"
)

func main() {
	ctx := context.Background()
	rdb := redis.NewClient(&redis.Options{
		Addr:     "localhost:6379",
	})

	err := rdb.Del(ctx, "key1").Err()
	if err != nil {
		panic(err)
	}
	println("Deleted key1")
}

In this code piece, we create a connection to a local Redis instance, then delete the key 'key1' from cache.

Example 2: Deleting multiple keys

package main

import (
	"github.com/go-redis/redis/v8"
	"context"
)

func main() {
	ctx := context.Background()
	rdb := redis.NewClient(&redis.Options{
		Addr:     "localhost:6379",
	})

	err := rdb.Del(ctx, "key1", "key2", "key3").Err()
	if err != nil {
		panic(err)
	}
	println("Deleted keys")
}

In this example, we delete multiple keys ('key1', 'key2', 'key3') at once.

Best Practices

Always handle the error returned by Del() to make sure the operation was successful. If the key doesn't exist, Redis will return 0, not an error, so don't rely solely on error handling to check the existence of a key.

Common Mistakes

Not checking if a key exists before trying to delete it can lead to confusion: Redis won't throw an error if you try to delete a non-existent key, it just returns 0. Thus, if you want to confirm whether a deletion was successful or if a key was already missing, you need to manually check the key's existence beforehand.

FAQs

Q: What happens if I try to delete a key that does not exist? A: Redis won't return an error, but rather a zero, indicating no keys were deleted.

Q: Can I delete multiple keys at once? A: Yes, the Del() function accepts multiple keys as arguments.