HMGET command in Redis is commonly used when there's a need to retrieve multiple field values from a hash stored at a specific key. In the context of Python, Redis'
HMGET is often used in applications that require high-speed access to structured data like user profiles, stateful data, or cached web pages.
Let's say we have a hash representing a User, with fields like "name", "email", and "age". You can use
HMGET to fetch multiple fields at once.
Here's an example using the redis-py library:
hmget method takes the key of the hash and the field names you want to retrieve. It returns a list of values corresponding to the given field names.
HMGETwill return a
Nonevalue for that field.
HMGETinstead of multiple
HGETcommands if you need to get multiple fields from a hash. It reduces the number of round-trip times between your application and Redis server.
HMGETon non-hash keys: If the key exists in the database but its associated value is not a hash, an error will be returned.
Nonevalues in the return list: If a field does not exist in the hash,
Nonefor that field.
Q: Can I use HMGET to get all fields from a hash?
HMGET requires you to specify the fields you want to retrieve. If you want to get all fields and their values, use
Q: What if the specified key does not exist in Redis?
A: If the key does not exist,
HMGET simply returns
None values for all requested fields.