valkey-hashes - Man Page

Hashes are record types structured as collections of field-value pairs. You can use hashes to represent basic objects and to store groupings of counters, among other things.

127.0.0.1:6379> HSET bike:1 model Deimos brand Ergonom type 'Enduro bikes' price 4972
(integer) 4
127.0.0.1:6379> HGET bike:1 model
"Deimos"
127.0.0.1:6379> HGET bike:1 price
"4972"
127.0.0.1:6379> HGETALL bike:1
1) "model"
2) "Deimos"
3) "brand"
4) "Ergonom"
5) "type"
6) "Enduro bikes"
7) "price"
8) "4972"

While hashes are handy to represent objects, actually the number of fields you can put inside a hash has no practical limits (other than available memory), so you can use hashes in many different ways inside your application.

The command HSET sets multiple fields of the hash, while HGET retrieves a single field. HMGET is similar to HGET but returns an array of values:

127.0.0.1:6379> HMGET bike:1 model price no-such-field
1) "Deimos"
2) "4972"
3) (nil)

There are commands that are able to perform operations on individual fields as well, like HINCRBY:

127.0.0.1:6379> HINCRBY bike:1 price 100
(integer) 5072
127.0.0.1:6379> HINCRBY bike:1 price -100
(integer) 4972

You can find the full list of hash commands in the documentation\c .

It is worth noting that small hashes (i.e., a few elements with small values) are encoded in special way in memory that make them very memory efficient.

• Store counters for the number of times bike:1 has been ridden, has crashed, or has changed owners:

  127.0.0.1:6379> HINCRBY bike:1:stats rides 1
  (integer) 1
  127.0.0.1:6379> HINCRBY bike:1:stats rides 1
  (integer) 2
  127.0.0.1:6379> HINCRBY bike:1:stats rides 1
  (integer) 3
  127.0.0.1:6379> HINCRBY bike:1:stats crashes 1
  (integer) 1
  127.0.0.1:6379> HINCRBY bike:1:stats owners 1
  (integer) 1
  127.0.0.1:6379> HGET bike:1:stats rides
  "3"
  127.0.0.1:6379> HMGET bike:1:stats owners crashes
  1) "1"
  2) "1"

valkey-data-types(7), valkey-introduction(7), valkey-strings(7).