Node Redis: Get All Keys Starting With (Detailed Guide w/ Code Examples)

Use Case(s)

Getting all keys starting with a certain prefix can be useful when you want to operate on a subset of data stored in Redis. For instance, if your application uses prefixes to categorize data (e.g., "user:" for user-related data, "session:" for session data), you might need to fetch all keys related to a particular category.

Code Examples

Example 1: The following script uses the KEYS command to get all keys starting with 'user:' in a Redis database.

const redis = require('redis');
const client = redis.createClient();

client.keys('user:*', function(err, keys) {
  if (err) return console.log(err);
  for(var i = 0, len = keys.length; i < len; i++) {
    console.log(keys[i]);
  }
});

In this example, the pattern 'user:*' is used with the keys command to find all keys that start with 'user:'. The matching keys are then logged to the console.

Best Practices

While the KEYS command can be very useful, it should be used with caution in a production environment as it may adversely affect performance due to its O(N) time complexity. A better approach would be to maintain an index of keys or use the SCAN command which provides a cursor-based iterator that divides the work among multiple calls.

Common Mistakes

A common mistake is not considering the impact of the KEYS command on performance, particularly for large data sets. It's a blocking operation that can potentially stall your Redis server if you have many keys.

FAQs

Q: Can I use the KEYS command in a production environment? A: While it's technically possible, it's not recommended due to the potential performance impact. Consider using SCAN instead.