HGET

HGET is a command in the Redis in-memory data structure store. It retrieves the value associated with a given field inside a hash that is stored at a specified key. If the key does not exist or the field is not present, the command returns a nil value.

Syntax: HGET key field. The command returns the string value stored for the specified field within the hash identified by key. If the key exists but is not a hash, Redis returns a type error indicating the wrong kind of value.

Example: To set a field and then retrieve it, you might use HSET user:1001 name "Ada"; HGET user:1001 name would return "Ada". If you ask for a non-existent field, HGET returns nil.

Notes and related commands: HGET is often used with a hash data model to store related attributes under a single key. If you need multiple fields at once, HMGET retrieves several fields in one call. Other related commands include HGETALL (returns all fields and values), HEXISTS (checks for the existence of a field), HDEL (deletes a field), HLEN (returns the number of fields), HKEYS and HVALS (returning keys and values, respectively).

Performance and data model: HGET operates in O(1) time for a single field. Hashes are a memory-efficient way to group related field-value pairs under a single key, making HGET a fast and common operation for accessing individual attributes in a hash.