redisのzcountって本番で使って良い悪いがあまり自信がなくて調査
結論として100万件程度のデータ量なら使って問題ない

redis 公式ドキュメントを読む

[ZCOUNT]
(http://redis.shibu.jp/commandreference/sortedsets.html#command-ZCOUNT) について読むと計算量は O(log(N))+O(M)　要素数Mによって線形に計算量が増加。線形に増加は怖いので調査してみた

結果

問題なし！

コード

from __future__ import absolute_import, unicode_literals
import redis
import random

KEY = "SORTED_SET_KEY"

def time(func):
    import functools
    import datetime
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        start = datetime.datetime.today()
        result = func(*args, **kwargs)
        end = datetime.datetime.today()
        return end - start
    return wrapper

def main():
    print "start"

    redis_client = redis.StrictRedis(host='localhost', port=6379, db=0)

    # redis initial data
    redis_client.delete(KEY)

    # set data
    for h in xrange(1, 100):
        for i in xrange(1, 10000):
            player_key = 'player:{}:{}'.format(h, i)
            redis_client.zadd(KEY, random.randint(1, 10000), player_key)

        zscore_time_10000 = zscore_time(redis_client, player_key)
        score = 10
        zcount_time_10000 = zcount_time(redis_client, score)
        print "----- {}times zcount:{}".format(h, redis_client.zcount(KEY, score, 'inf'))
        print "10000times zscore:{}sec, zcount:{}sec".format(zscore_time_10000, zcount_time_10000)

@time
def zscore_time(redis_client, unique_key, count=10000):
    [redis_client.zscore(KEY, unique_key) for x in xrange(count)]

@time
def zcount_time(redis_client, score, count=10000):
    [redis_client.zcount(KEY, score, 'inf') for x in xrange(count)]

main()

実行結果

> python set_redis_data.py 
start
----- 1times zcount:9992
10000times zscore:0:00:00.749579sec, zcount:0:00:00.735492sec
----- 2times zcount:19978
10000times zscore:0:00:00.757828sec, zcount:0:00:00.733708sec
----- 3times zcount:29973
10000times zscore:0:00:00.745015sec, zcount:0:00:00.736602sec
----- 4times zcount:39962
10000times zscore:0:00:00.768604sec, zcount:0:00:00.733056sec
----- 5times zcount:49951
10000times zscore:0:00:00.781331sec, zcount:0:00:00.727951sec
----- 6times zcount:59940
10000times zscore:0:00:00.744400sec, zcount:0:00:00.727242sec
----- 7times zcount:69930
10000times zscore:0:00:00.754257sec, zcount:0:00:00.728895sec
----- 8times zcount:79920
10000times zscore:0:00:00.749809sec, zcount:0:00:00.736275sec
----- 9times zcount:89908
10000times zscore:0:00:00.739206sec, zcount:0:00:00.732444sec
----- 10times zcount:99901
10000times zscore:0:00:00.754966sec, zcount:0:00:00.753912sec
----- 11times zcount:109891
10000times zscore:0:00:00.766370sec, zcount:0:00:00.734423sec
----- 12times zcount:119885
10000times zscore:0:00:00.751999sec, zcount:0:00:00.739062sec
----- 13times zcount:129872
10000times zscore:0:00:00.743560sec, zcount:0:00:00.723789sec
----- 14times zcount:139857
10000times zscore:0:00:00.754542sec, zcount:0:00:00.749401sec
----- 15times zcount:149852
10000times zscore:0:00:00.749797sec, zcount:0:00:00.761494sec
----- 16times zcount:159845
10000times zscore:0:00:00.963314sec, zcount:0:00:00.904765sec
----- 17times zcount:169834
10000times zscore:0:00:00.852251sec, zcount:0:00:00.804572sec
----- 18times zcount:179828
10000times zscore:0:00:00.832594sec, zcount:0:00:00.830622sec
----- 19times zcount:189812
10000times zscore:0:00:00.913706sec, zcount:0:00:01.014552sec
----- 20times zcount:199798
10000times zscore:0:00:00.834342sec, zcount:0:00:00.754801sec
----- 21times zcount:209786
10000times zscore:0:00:00.781016sec, zcount:0:00:00.777940sec
----- 22times zcount:219780
10000times zscore:0:00:00.942493sec, zcount:0:00:00.811952sec
----- 23times zcount:229768
10000times zscore:0:00:00.800323sec, zcount:0:00:00.791843sec
----- 24times zcount:239761
10000times zscore:0:00:00.871959sec, zcount:0:00:00.809339sec
----- 25times zcount:249747
10000times zscore:0:00:00.808262sec, zcount:0:00:00.782781sec
----- 26times zcount:259740
10000times zscore:0:00:00.798491sec, zcount:0:00:00.747983sec
----- 27times zcount:269729
10000times zscore:0:00:00.796869sec, zcount:0:00:00.767065sec
----- 28times zcount:279724
10000times zscore:0:00:00.875296sec, zcount:0:00:00.807199sec
----- 29times zcount:289715
10000times zscore:0:00:00.778267sec, zcount:0:00:00.773806sec
----- 30times zcount:299704
10000times zscore:0:00:00.817535sec, zcount:0:00:00.856725sec
----- 31times zcount:309689
10000times zscore:0:00:00.779981sec, zcount:0:00:00.802634sec
----- 32times zcount:319679
10000times zscore:0:00:00.779044sec, zcount:0:00:00.885543sec
----- 33times zcount:329668
10000times zscore:0:00:00.801946sec, zcount:0:00:00.920779sec
----- 34times zcount:339659
10000times zscore:0:00:00.840763sec, zcount:0:00:00.862033sec
----- 35times zcount:349647
10000times zscore:0:00:00.848629sec, zcount:0:00:00.839048sec
----- 36times zcount:359635
10000times zscore:0:00:00.796536sec, zcount:0:00:00.757579sec
----- 37times zcount:369628
10000times zscore:0:00:00.761311sec, zcount:0:00:00.743290sec
----- 38times zcount:379620
10000times zscore:0:00:00.787605sec, zcount:0:00:00.793797sec
----- 39times zcount:389610
10000times zscore:0:00:00.756282sec, zcount:0:00:00.753933sec
----- 40times zcount:399601
10000times zscore:0:00:00.762800sec, zcount:0:00:00.748836sec
----- 41times zcount:409588
10000times zscore:0:00:00.756001sec, zcount:0:00:00.730211sec
----- 42times zcount:419579
10000times zscore:0:00:00.744252sec, zcount:0:00:00.732069sec
----- 43times zcount:429565
10000times zscore:0:00:00.752527sec, zcount:0:00:00.733024sec
----- 44times zcount:439545
10000times zscore:0:00:00.742493sec, zcount:0:00:00.729422sec
----- 45times zcount:449538
10000times zscore:0:00:00.754651sec, zcount:0:00:00.731426sec
----- 46times zcount:459530
10000times zscore:0:00:00.751480sec, zcount:0:00:00.751284sec
----- 47times zcount:469518
10000times zscore:0:00:00.848265sec, zcount:0:00:00.810607sec
----- 48times zcount:479504
10000times zscore:0:00:00.765747sec, zcount:0:00:00.739687sec
----- 49times zcount:489496
10000times zscore:0:00:00.752537sec, zcount:0:00:00.736055sec
----- 50times zcount:499486
10000times zscore:0:00:00.765538sec, zcount:0:00:00.728143sec
----- 51times zcount:509477
10000times zscore:0:00:00.748288sec, zcount:0:00:00.725538sec
----- 52times zcount:519468
10000times zscore:0:00:00.742314sec, zcount:0:00:00.741281sec
----- 53times zcount:529456
10000times zscore:0:00:00.782913sec, zcount:0:00:00.744661sec
----- 54times zcount:539448
10000times zscore:0:00:00.758629sec, zcount:0:00:00.764310sec
----- 55times zcount:549439
10000times zscore:0:00:00.743581sec, zcount:0:00:00.729405sec
----- 56times zcount:559430
10000times zscore:0:00:00.752376sec, zcount:0:00:00.738607sec
----- 57times zcount:569419
10000times zscore:0:00:00.770094sec, zcount:0:00:00.745846sec
----- 58times zcount:579408
10000times zscore:0:00:00.745116sec, zcount:0:00:00.736532sec
----- 59times zcount:589397
10000times zscore:0:00:00.747376sec, zcount:0:00:00.772593sec
----- 60times zcount:599386
10000times zscore:0:00:00.838002sec, zcount:0:00:00.740173sec
----- 61times zcount:609379
10000times zscore:0:00:00.749521sec, zcount:0:00:00.728057sec
----- 62times zcount:619375
10000times zscore:0:00:00.749353sec, zcount:0:00:00.729088sec
----- 63times zcount:629359
10000times zscore:0:00:00.768890sec, zcount:0:00:00.753640sec
----- 64times zcount:639350
10000times zscore:0:00:00.746590sec, zcount:0:00:00.728816sec
----- 65times zcount:649343
10000times zscore:0:00:00.739419sec, zcount:0:00:00.742850sec
----- 66times zcount:659335
10000times zscore:0:00:00.866874sec, zcount:0:00:00.773135sec
----- 67times zcount:669329
10000times zscore:0:00:00.766303sec, zcount:0:00:00.751412sec
----- 68times zcount:679319
10000times zscore:0:00:00.774909sec, zcount:0:00:00.731371sec
----- 69times zcount:689309
10000times zscore:0:00:00.753021sec, zcount:0:00:00.738191sec
----- 70times zcount:699298
10000times zscore:0:00:00.738990sec, zcount:0:00:00.723266sec
----- 71times zcount:709287
10000times zscore:0:00:00.887564sec, zcount:0:00:00.871255sec
----- 72times zcount:719281
10000times zscore:0:00:00.774284sec, zcount:0:00:00.780908sec
----- 73times zcount:729272
10000times zscore:0:00:00.779932sec, zcount:0:00:00.827605sec
----- 74times zcount:739263
10000times zscore:0:00:00.768705sec, zcount:0:00:00.734963sec
----- 75times zcount:749252
10000times zscore:0:00:00.776220sec, zcount:0:00:00.897861sec
----- 76times zcount:759246
10000times zscore:0:00:01.110917sec, zcount:0:00:00.730362sec
----- 77times zcount:769235
10000times zscore:0:00:00.751864sec, zcount:0:00:00.736097sec
----- 78times zcount:779224
10000times zscore:0:00:00.932775sec, zcount:0:00:00.823374sec
----- 79times zcount:789206
10000times zscore:0:00:00.790337sec, zcount:0:00:00.836322sec
----- 80times zcount:799188
10000times zscore:0:00:00.820177sec, zcount:0:00:00.771782sec
----- 81times zcount:809177
10000times zscore:0:00:00.760560sec, zcount:0:00:00.738159sec
----- 82times zcount:819170
10000times zscore:0:00:00.823681sec, zcount:0:00:00.793130sec
----- 83times zcount:829159
10000times zscore:0:00:00.792423sec, zcount:0:00:00.778726sec
----- 84times zcount:839149
10000times zscore:0:00:00.849077sec, zcount:0:00:00.786689sec
----- 85times zcount:849133
10000times zscore:0:00:00.821718sec, zcount:0:00:00.743985sec
----- 86times zcount:859119
10000times zscore:0:00:00.752505sec, zcount:0:00:00.752729sec
----- 87times zcount:869106
10000times zscore:0:00:00.804886sec, zcount:0:00:00.801518sec
----- 88times zcount:879095
10000times zscore:0:00:00.830245sec, zcount:0:00:00.745599sec
----- 89times zcount:889085
10000times zscore:0:00:00.812706sec, zcount:0:00:00.800208sec
----- 90times zcount:899072
10000times zscore:0:00:00.827639sec, zcount:0:00:00.911494sec
----- 91times zcount:909064
10000times zscore:0:00:00.819233sec, zcount:0:00:00.772907sec
----- 92times zcount:919055
10000times zscore:0:00:00.766537sec, zcount:0:00:00.778436sec
----- 93times zcount:929043
10000times zscore:0:00:00.805694sec, zcount:0:00:00.846116sec
----- 94times zcount:939033
10000times zscore:0:00:00.845019sec, zcount:0:00:00.832113sec
----- 95times zcount:949024
10000times zscore:0:00:00.773874sec, zcount:0:00:00.766136sec
----- 96times zcount:959013
10000times zscore:0:00:00.785367sec, zcount:0:00:00.774693sec
----- 97times zcount:969002
10000times zscore:0:00:00.828814sec, zcount:0:00:00.910054sec
----- 98times zcount:978993
10000times zscore:0:00:00.855522sec, zcount:0:00:00.855757sec
----- 99times zcount:988978
10000times zscore:0:00:00.855399sec, zcount:0:00:00.804692sec