[GitHub] [incubator-kvrocks] kinoute opened a new issue, #1402: `scan` and `scan_iter` stuck to first iteration

[via GitHub]

kinoute opened a new issue, #1402:
URL: https://github.com/apache/incubator-kvrocks/issues/1402

   ### Search before asking
   
   - [X] I had searched in the 
[issues](https://github.com/apache/incubator-kvrocks/issues) and found no 
similar issues.
   
   
   ### Version
   
   2.3.0
   
   ### Minimal reproduce step
   
   1. Start Kvrocks Docker container:
   
   `docker run -it -p 6666:6666 apache/kvrocks`
   
   2. Populate the database with 200k keys with Python 3.9.13 and the forked 
version of Redis-py available here : https://github.com/hashlookup/redis-py
   
   ```bash
   pip install git+https://github.com/hashlookup/redis-py@master
   ```
   
   ```python3
   import redis
   
   REDIS = redis.Redis(
       host='0.0.0.0',
       port=6666,
       password='',
       db=0,
       )
   
   # Populate Kvrocks with 200 keys
   pipe = REDIS.pipeline()
   
   for i in range(200_000):
       pipe.set(f'dba_{i}', 1)
   
   pipe.execute()
   
   # Test "scan_iter"
   for key in scan_iter('dba_*'):
       print(key)
   
   
   # Test "scan"
   cursor = '0'
   
   while True:
       cursor, keys = REDIS.scan(
           cursor=cursor,
           match='dba_*',
       )
       for key in keys:
           print(key)
   
       if not keys:
           break
   
   ### What did you expect to see?
   
   I expected both commands to iterate through every `dba_*` key.
   
   ### What did you see instead?
   
   Instead, both commands are stuck on the first iteration of default size (10) 
and keep printing the same batch of keys every time.
   
   Exemple with `scan_iter`:
   
   
   ```
   b'dba_0'
   b'dba_1'
   b'dba_10'
   b'dba_100'
   b'dba_1000'
   b'dba_10000'
   b'dba_100000'
   b'dba_100001'
   b'dba_100002'
   b'dba_100003'
   b'dba_100004'
   b'dba_100005'
   b'dba_100006'
   b'dba_100007'
   b'dba_100008'
   b'dba_100009'
   b'dba_10001'
   b'dba_100010'
   b'dba_100011'
   b'dba_100012'
   b'dba_1'
   b'dba_10'
   b'dba_100'
   b'dba_1000'
   b'dba_10000'
   b'dba_100000'
   b'dba_100001'
   b'dba_100002'
   b'dba_100003'
   b'dba_100004'
   b'dba_100005'
   b'dba_100006'
   b'dba_100007'
   b'dba_100008'
   b'dba_100009'
   b'dba_10001'
   b'dba_100010'
   b'dba_100011'
   b'dba_100012'
   b'dba_100013'
   b'dba_1'
   b'dba_10'
   b'dba_100'
   b'dba_1000'
   b'dba_10000'
   b'dba_100000'
   b'dba_100001'
   b'dba_100002'
   b'dba_100003'
   b'dba_100004'
   b'dba_100005'
   b'dba_100006'
   b'dba_100007'
   b'dba_100008'
   b'dba_100009'
   b'dba_10001'
   b'dba_100010'
   b'dba_100011'
   b'dba_100012'
   b'dba_100013'
   ```
   
   etc.
   
   ### Anything Else?
   
   While being inefficient, `keys` doesn't suffer from this problem and return 
every key matching the pattern:
   
   ```python3
   len(REDIS.keys('dba_*'))
   
   200000
   ```
   
   ### Are you willing to submit a PR?
   
   - [ ] I'm willing to submit a PR!


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