redis not connected with django-redis

Question

i have set a query set in my cache as :

cache.set('person',Lecture_Detail.objects.all())

in my views:

from django.core.cahe import cache
t3=datetime.datetime.now()
list(Lecture_Detail.objects.all())
t5 = datetime.datetime.now()
print "time before",(t5 - t3)
g = cache.get('person')
t4 = datetime.datetime.now()
print "time after",(t4 - t5)
g = cache.get('person')
t6 = datetime.datetime.now()
print "time after",t6-t4
g = cache.get('person')
t7 = datetime.datetime.now()
print "time after",t7-t6

when i exexute this its output is:

time before 0:00:00.014256
time after 0:00:01.366022
time after 0:00:01.552436
time after 0:00:01.433049

so i think that my redis is not connected with django-redis . my settings are:

CACHES = {
    "default": {
        "BACKEND": "redis_cache.RedisCache",
        "LOCATION": "redis://127.0.0.1:6379:1",
        "OPTIONS": {
            "CLIENT_CLASS": "redis_cache.client.DefaultClient",
        }
    }
}

so plz me suggest me something .. thanx in advance..

Where do you run your Redis instance? Same server or somewhere else? Is queryset loaded all att once or is it lazy? (That is: does it fetch all rows or does it only fetch rows as you read them?). How large of a difference is it? You can edit your question to include answers to these questions. — Emil Vikström
– Emil Vikström, Commented Sep 21, 2015 at 11:04

sinitsynsv · Accepted Answer · 2015-09-21 11:35:59Z

5

When you write queryset=Lecture_Detail.objects.all() database sql query is not yet executed. When the query is executed:

iteration
slicing
Pickling/Caching
repr()
len()
list()
bool()

Read more about this here: When QuerySets are evaluated. So in your example database query would be executed on line cache.set('person',queryset)

You can test by change line from queryset=Lecture_Detail.objects.all() to list(queryset=Lecture_Detail.objects.all())

edited Sep 21, 2015 at 11:35

answered Sep 21, 2015 at 11:17

sinitsynsv

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4 Comments

Sumit Singh Over a year ago

as you have suggest me now i'm applying following operation on both condition (after getting data from database and from cache) : t1=datetime.datetime.now() g = Lecture_Detail.objects.all() name = g.filter(lecture_name = 'Chemistry') length = len(name) t2=datetime.datetime.now() bt still time difference is very much its about : "without cache 0:00:00.903429 with cache 0:00:02.490702 " so please suggest me something..

sinitsynsv Over a year ago

How many records in the table? How many records after filtering?

Sumit Singh Over a year ago

101006 records are in table and 50000 afer filtering

sinitsynsv Over a year ago

I tried myself, but I used filesystem caching, and got similar results: without cache 0:00:00.246513 and wich cache 0:00:00.666614

Sumit Singh · Accepted Answer · 2015-09-28 10:20:55Z

0

Actually my mistake was that i was using django cache instead of using redis cache .... to use redis we have to do something like this :

first set data from your python shell or view as:

import redis
r=redis.StrictRedis()
r.set('person',Lecture_Detail.objects.all())

to get data from redis cache:

import redis

r=redis.StrictRedis()
t3=datetime.datetime.now()
list(Lecture_Detail.objects.all())
t5 = datetime.datetime.now()
print "time before",(t5 - t3)
g = r.get('person')
t4 = datetime.datetime.now()
print "time after",(t4 - t5)

and now the time difference is just unbelieveable

answered Sep 28, 2015 at 10:20

Sumit Singh

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