hset() for redis in python

Question

I have next question: I use the `hset()` procedure for Redis Server in python. This procedure is described here. ok, now I couldn't understand the parameter `value`... From one hand it should be a number 0 or 1, anyway I could use also other numbers for this parameter (and I also find examples in net with other values). For example I define next def: ``` def setHashKeyValue(key, value, number): assert (key != None), "Please, get a key" #assert (number == 0 or number ==1), "Please enter 0 or 1" redis_server.hset(key, value, number); ``` And got right output with the next parameters: ``` setHashKeyValue('5', 'test ok for key 5', 1) setHashKeyValue('6', 'test ok for key 6', 1) ``` On the other hand, I would like to define some loop for time measuring, so I define next def: ``` def loopKeyValues(number): timeUse = [] for x in range(number): start = time.time() setHashKeyValue(x, x**2, 1) end = time. time() timeUse.append(end-start) plt.plot(timeUse) plt.ylabel("time") plt.show() return ti…

Accepted Answer

The value parameter is just the key of your hash object entry.

Hash objects are like Python dictionaries. They provide associative arrays. When you write:

```
redis_server.hset(key, value, number)
```

it means the hash object "key" will be added/set with an entry "value"/"number". In Python, you would write:

```
key[value] = number
```

You got an error because in Redis the objects are typed. Once you have stored a string at a given key, Redis cannot consider anymore this object is a hash object: so the operations associated to a hash object will not work for this key.

In other words, if you have:

```
SET 10 100
```

then you cannot do:

```
HSET 10 100 1
```

However you could do:

```
DEL 10
HSET 10 100 1
```

I would suggest to use the redis-cli program to experiment with Redis before using Python scripts.

hset() for redis in python

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