Redis values set from Python are not reflecting in redis client

Question

I have installed redis on my OS X, and trying to set and get some values in Redis from Python 3.5 client. I have the Redis server on (through command redis-server) and the redis-client on as well (opened through the command redis-cli). This is what I am trying on Python:

import redis
r = redis.StrictRedis()
r.set("foo", "bar")
r.get("foo")

This prints bar as expected. However, if I go to my redis-client prompt and try get foo, it returns nil. In the same way, if I set a value in the redis-client itself, like set boo too, calling get boo in the client returns too as expected, however, in my Python client if I run r.get(boo), I get None.

Funny thing is, they are synced between their own instances. So if I open another Python command prompt and type r.get("foo"), it returns bar. In the same way, if I open another redis-cli instance and type get boo, I get too. It is only that the values between Python client and Redis client are not syncing. I even tried to enforce a bgsave from Python client after setting the value there, and it did trigger a save in the window where redis-server is running, but the values do not reflect in the redis-cli window even after that.

They were working perfectly fine until some days back, this has started happening sometime recently.

Any idea how to fix this?

You are obviously not connecting to the same redis-server from the clis and python code... — Itamar Haber
– Itamar Haber, Commented Nov 21, 2018 at 16:44
I guessed as much, but cannot understand how to connect both to the same instance, and why did this start to happen suddenly! — NedStarkOfWinterfell
– NedStarkOfWinterfell, Commented Nov 21, 2018 at 17:34

felipecgonc · Accepted Answer · 2018-11-21 16:45:32Z

1

It seems to me that you are accessing (setting/getting values) through different dbs in your redis-cli and your redis-py instance. redis servers can have multiple key-value stores (or "tables") completely isolated from one another. These are referred throughout the documentation as db, and are uniquely identified by integers.

If you are instancing redis-py exactly as in your code snippet, with:

import redis
r = redis.StrictRedis()

Then you are using the constructor's default value for db, which is 0. (See documentation)

If the values differ between the Python implementation and redis-cli, then most likely your command line client is running on a different dbthan 0. You can check which db you are working on with the command CLIENT LIST, which will return your current database id.

To switch to the same database as the Python implementation, just run on your redis-cli:

SELECT 0

(See documentation)

Or, alternatively, you can call your redis-py constructor with the desired db parameter:

r = redis.StrictRedis(db=3) # 3 is an example value for your redis-cli's working db

answered Nov 21, 2018 at 16:45

felipecgonc

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6 Comments

NedStarkOfWinterfell Over a year ago

Thanks. I instantiated it with db value as 3 in Python, and set it to so in Redis as well: SELECT 3. Output: 127.0.0.1:6379[3]> get foo (nil)

felipecgonc Over a year ago

@SexyBeast your redis-py database value was definitely set to 0, whereas you don't know which database your redis-cli was using, so you can't expect to be able to get the same value with 100% certainty. Try running SELECT 0 and then GET foo in your redis-cli

NedStarkOfWinterfell Over a year ago

That's what I said, I tried setting it to 3 in both, then ran the commands. Still not reflecting..

felipecgonc Over a year ago

@SexyBeast but did you also run SET foo bar (in any one of the clients) after setting both databases to 3?

NedStarkOfWinterfell Over a year ago

Yes. Did that. And still not reflecting! :(

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