All 7 Hashes in Redis questions
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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 retrieve only the field names or only the values from a Redis hash, without needing both together? 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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Redis › Hashes in Redis

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?

Intermediate

Answer

You use HEXISTS to check whether a specific field is present in a hash, returning a simple true or false style result, and HDEL to remove one or more specific fields from a hash, leaving the remaining fields completely untouched.
HEXISTS user:100 phoneNumber
HDEL user:100 temporaryFlag
Real-world example A user profile system checks whether an optional phone number field exists before displaying it, and removes a temporary flag field from a user's hash once it is no longer needed, without affecting any other stored profile data.

Common follow-ups: What happens if you call HDEL on the last remaining field in a hash?;Can you delete multiple fields at once with a single HDEL call?

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