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Practical limit for the number of databases in mongodb

Is there any practical limit to the number of databases in mongodb? I was having serious problems when I went through 120 databases. Simple things like:

> show dbs
Mon Feb 10 16:35:32 DBClientCursor::init call() failed
Mon Feb 10 16:35:32 query failed : admin.$cmd { listDatabases: 1.0 } to: 127.0.0.1:27017
Mon Feb 10 16:35:32 Error: error doing query: failed src/mongo/shell/collection.js:155
Mon Feb 10 16:35:32 trying reconnect to 127.0.0.1:27017
Mon Feb 10 16:35:32 reconnect 127.0.0.1:27017 failed couldn't connect to server 127.0.0.1:27017
>
Mon Feb 10 16:36:01 trying reconnect to 127.0.0.1:27017
Mon Feb 10 16:36:01 reconnect 127.0.0.1:27017 failed couldn't connect to server 127.0.0.1:27017
>
Mon Feb 10 16:37:01 trying reconnect to 127.0.0.1:27017
Mon Feb 10 16:37:01 reconnect 127.0.0.1:27017 ok

and

> getMemInfo()
{ "virtual" : 32, "resident" : 7 }
Mon Feb 10 16:39:00 DBClientCursor::init call() failed
Mon Feb 10 16:39:00 query failed : admin.$cmd { replSetGetStatus: 1.0, forShell: 1.0 } to: 127.0.0.1:27017
> shell
Mon Feb 10 16:39:38 ReferenceError: shell is not defined (shell):1
Mon Feb 10 16:39:38 trying reconnect to 127.0.0.1:27017
Mon Feb 10 16:39:38 reconnect 127.0.0.1:27017 ok

However, the log file remained cryptic

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1 answer

What version of mongodb are you using on which host? Here is a test on CenOS 6.5, mongodb 2.2 x86_64 directly from EPEL

Here is an example python script that creates 1000 databases

from pymongo import MongoClient  

mc = MongoClient()
for i in range(5000):
    print i
    mc['db%s'%(i)].test.insert({"test":True})

output:

...snip...
506
Traceback (most recent call last):
  File "overload_mongo.py", line 6, in <module>
    mc['db%s'%(i)].test.insert({"test":True})
  File "/usr/lib64/python2.6/site-packages/pymongo/collection.py", line 357, in insert
    continue_on_error, self.__uuid_subtype), safe)
  File "/usr/lib64/python2.6/site-packages/pymongo/mongo_client.py", line 929, in _send_message
    raise AutoReconnect(str(e))
pymongo.errors.AutoReconnect: [Errno 104] Connection reset by peer

Here he is, looking at the magazine

ERROR: Uncaught std::exception: boost::filesystem::basic_directory_iterator constructor: Too many open files: "/index/bauman/db/_tmp/esort.1392056635.506/", terminating

Good ole too many problems with open files

If you are on an enterprise Linux platform, you can delete this file in /etc/security/limits.d/mongodb.conf and start a new session

mongodb        hard    nofile          99999
mongodb        soft    nofile          99999
mongodb        hard    nproc          99999
mongodb        soft    nproc          99999

I do not know how to achieve a similar result in windows.

"" , MongoDB , , -, .

,

python overload_mongo.py


...snip...
995
996 
997
998
999

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