[DOCS-773] include question about preallocation in storage FAQ Created: 19/Nov/12  Updated: 30/Oct/23  Resolved: 23/Sep/14

Status: Closed
Project: Documentation
Component/s: manual
Affects Version/s: None
Fix Version/s: Server_Docs_20231030

Type: Improvement Priority: Trivial - P5
Reporter: auto Assignee: Unassigned
Resolution: Done Votes: 0
Labels: collector-298ba4e7, newwriter
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified
Environment:

Windows Server 2008, MongoDB 2.2.1

Location: http://docs.mongodb.org/manual/reference/sql-comparison/
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.64 Safari/537.11
Referrer: http://www.mongodb.org/display/DOCS/SQL+to+Mongo+Mapping+Chart
Screen Resolution: 1920 x 1080


Participants:
Days since reply: 11 years, 13 weeks, 2 days ago

 Description   

hello, I use MongoDB 2.2.1 and it uses a lot of disk space. about 5-6 times more than it was on mssql. and you can explain it?

Reporter: Bezhan Pkhovelishvili
E-mail: bejo@singular.ge



 Comments   
Comment by auto [ 19/Nov/12 ]

Author:

{u'date': u'2012-11-19T14:42:17Z', u'email': u'samk@10gen.com', u'name': u'Sam Kleinman'}

Message: DOCS-773: including link from SQL charts to FAQ
Branch: master
https://github.com/mongodb/docs/commit/028ed1733241bdbb3eeae064fc18a1f699a0fe41

Comment by Sam Kleinman (Inactive) [ 19/Nov/12 ]

There are a lot of reasons that might explain this kind of behavior, but the most significant explanation is that MongoDB per-allocates disk space for databases upon creation to facilitate responsive write performance. See the output of the database statistics <http://docs.mongodb.org/manual/reference/database-statistics/>, for a start.

Beyond this, you might find better luck addressing the question to the MongoDB user group <http://groups.google.com/group/mongodb-user>, and providing more information about your usage pattern:

  • the amount of data,
  • your data model, including document structure collection and database organization, and
  • your document update pattern, (e.g. do you update documents after inserting them, and how?)

I hope this helps.

To help resolve this issue in the future, I will include a link to the FAQ in the SQL mapping chart, and add some notes to the storage FAQ about disk use and preallocation. <http://docs.mongodb.org/manual/faq/storage/>

Regards,
sam

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