Golang: Deleting Redis Keys by Prefix (Detailed Guide w/ Code Examples)

Use Case(s)

In Golang applications that utilize Redis as a key-value store, it might be necessary to delete keys based on a certain prefix. This can be used for data cleanup processes or when related keys need to be removed at once.

Code Examples

The following example shows how to use the Scan function with a specified prefix and then remove the matching keys. Please install the go-redis/redis package before running this code.

package main

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

func main() {
  rdb := redis.NewClient(&redis.Options{
    Addr:     "localhost:6379",
    Password: "", // no password set
    DB:       0,  // use default DB
  })

  ctx := context.Background()
  var cursor uint64
  var n int
  for {
    var keys []string
    var err error

    keys, cursor, err = rdb.Scan(ctx, cursor, "myprefix*", 10).Result()
    if err != nil {
      panic(err)
    }

    for _, key := range keys {
      fmt.Println("deleting key: ", key)
      rdb.Del(ctx, key)
    }

    if cursor == 0 {
      break
    }
  }
  fmt.Printf("Deleted %d keys\n", n)
}

This code connects to a local Redis instance, then it scans keys that match the prefix myprefix. Matching keys are then deleted using Del function.

Best Practices

• Make sure to limit the number of keys per Scan operation to avoid blocking the server for long periods.
• Always handle the errors returned by the Scan and Del functions.

Common Mistakes

• A common mistake is to use the KEYS command followed by DEL in production environments. KEYS can block the server when used against large databases, prefer SCAN instead.

FAQs

Q: Can I delete keys with multiple different prefixes at once? A: No, you need to run separate Scan and Del operations for each prefix.

Q: What happens if there are no keys matching the prefix? A: The Scan function will simply return an empty list, and no keys will be deleted.