All 7 Hashes in Redis questions
More in Hashes in Redis
What is a Redis hash, and how do you create one to store a simple object with multiple fields? How do you retrieve a single field or all fields from a Redis hash? How do you atomically increment a numeric field within a Redis hash? How do you check if a specific field exists within a hash, and how do you delete just one field without affecting the rest of the hash? How would you decide between storing an object as a single JSON string versus as a native Redis hash, considering both memory usage and access patterns? How does the internal listpack encoding for small hashes affect memory usage, and at what point does Redis switch to a different, less compact encoding?
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How do you retrieve only the field names or only the values from a Redis hash, without needing both together?

Intermediate

Answer

You use HKEYS to retrieve just the list of field names currently stored in a hash, and HVALS to retrieve just the list of corresponding values, which can be useful when you only need one or the other rather than the complete set of field value pairs that HGETALL would return.
HKEYS user:100
HVALS user:100
Real-world example A data export tool uses HKEYS to first discover what fields exist across different user hashes with varying schemas, before deciding which specific fields to actually extract and include in its export.

Common follow-ups: Is there a performance difference between HKEYS, HVALS, and HGETALL?;How do you get just the count of fields in a hash without retrieving the data itself?

Data Types;Redis CLI & Basic Commands
All 7 Hashes in Redis questions