The Redis HINCRBYFLOAT command increments the field in the hash at the specified key by a floating point number. We specify how much we want the field to increment by when we call the command.

Syntax

The syntax goes like this:

HINCRBYFLOAT key field increment

Example

Here’s an example to demonstrate:

HINCRBYFLOAT player points 2.57

Result:

"2.57"

The command returns a bulk string reply with the value of the field after the operation has taken place.

If the key doesn’t exist, it’s created with the field set to 0, and then incremented by the specified amount. In my case, the key didn’t exist, and so it was created and incremented as specified.

Non-Existent Fields

If the key exists, but the field doesn’t, the field is created, set to 0, and then incremented by the specified amount:

HINCRBYFLOAT player credit 51.50

Result:

"51.5"

We can use a command such as HGETALL to check the key’s fields and their respective values:

HGETALL player

Result:

1) "points"
2) "1.34"
3) "credit"
4) "51.5"

Negative Values

We can also use a negative value to decrement the field:

HINCRBYFLOAT player points -1.23

Result:

"1.34"

Passing the Wrong Number of Arguments

Passing the wrong number of arguments results in an error:

HINCRBYFLOAT player points 10 credit 5

Result:

(error) ERR wrong number of arguments for 'hincrbyfloat' command