HLEN for field count in Redis

Introduction

HLEN helps you find out how many fields are inside a hash. It tells you the size of the hash.

You want to know how many details are stored about a user in a profile hash.

You need to check if a hash has any data before processing it.

You want to count the number of settings saved in a configuration hash.

You want to monitor how many items are stored in a hash for debugging.

You want to limit the number of fields in a hash and check if it is reached.

Syntax

Redis

HLEN key

key is the name of the hash you want to check.

The command returns an integer showing the number of fields in the hash.

Examples

Returns the number of fields in the hash named user:1000.

Redis

HLEN user:1000

Returns how many settings are stored in the config:app hash.

Redis

HLEN config:app

Sample Program

This example creates a hash user:1 with three fields: name, age, and city. Then it uses HLEN to count how many fields are in that hash.

Redis

HMSET user:1 name "Alice" age "30" city "Paris"
HLEN user:1

Important Notes

If the key does not exist, HLEN returns 0.

Only fields directly inside the hash are counted, not nested data.

Summary

HLEN counts the number of fields in a hash.

It helps check the size or presence of data in a hash.

Returns 0 if the hash does not exist.