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

Use Case(s)

In Node.js applications, you may need to fetch all keys from a Redis database. This is often used for debugging purposes or when you need to analyze or manipulate all data.

## Code Examples

1. Using KEYS * command:
   ```
   const redis = require('redis');
   const client = redis.createClient();

client.keys('*', (err, keys) => {
if (err) return console.log(err);

for(let i = 0; i < keys.length; i++) {
console.log(keys[i]);
}
});
```
In this example, KEYS * command is used to fetch all the keys from Redis. The returned keys are then logged to the console.

2. Using SCAN command for large databases:
   ```
   const redis = require('redis');
   const client = redis.createClient();
   let cursor = '0';

function scan() {
client.scan(cursor, 'MATCH', '*', 'COUNT', '100', function(err, reply) {
if(err) throw err;

cursor = reply[0];
reply[1].forEach(function(key, i) {
console.log(key);
});

if(cursor === '0') {
return console.log('Scan complete');
} else {
return scan();
}
});
}

scan();
```
For larger databases, it's better to use SCAN as KEYS * may end up blocking the server while it fetches all keys. In this example, SCAN is used in a loop until all keys are fetched and logged.

Best Practices

• Avoid using KEYS * command in a production environment as it might affect performance. Instead, use SCAN as it's more efficient and doesn't block the server.

Common Mistakes

• Using KEYS * on large databases can lead to performance issues. It's best to use SCAN for such cases.

FAQs

• Q: Can I filter keys when fetching them from Redis?
  A: Yes, both KEYS and SCAN commands accept a pattern that can be used to filter keys.