Redis: Get Key Where Value in Python (Detailed Guide w/ Code Examples)

Use Case(s)

Often, you'd want to retrieve keys based on their corresponding values in Redis. This is useful when you are storing data in key-value pairs and need to query via values.

Code Examples

In Redis, there isn't a direct command to get a key by its value. But we can create a workaround in python using the scan_iter function.

Example 1:

import redis

r = redis.Redis()

# Let's assume that we're looking for keys that have the value '100'
search_value = '100'

for key in r.scan_iter():
    if r.get(key).decode('utf-8') == search_value:
        print(f'Key: {key.decode('utf-8')}')

In this example, we connect to Redis, iterate over all keys and print the keys where the value equals our search_value.

Best Practices

While querying keys based on values might be necessary at times, it's not ideal because Redis doesn't support this functionality natively. It's often recommended to design your data in such a way that you don't need to do this kind of operation, which can be expensive and slow.

Common Mistakes

One common mistake is to try to use this method on large databases. The method above requires iterating through every key in the database, so it can be very slow on large databases.

FAQs

Q: Why is there no native command in Redis to get a key by value?

A: Redis is not designed to be queried by value. It's a key-value store, meaning it's optimized for retrieving values based on keys.