How to organise a many to many relationship in MongoDB

Posted by Gareth Elms on Stack Overflow See other posts from Stack Overflow or by Gareth Elms
Published on 2011-01-29T22:35:08Z Indexed on 2011/01/29 23:26 UTC
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Filed under:

mongodb

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many-to-many

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relational-database

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document-database

I have two tables/collections; Users and Groups. A user can be a member of any number of groups and a user can also be an owner of any number of groups. In a relational database I'd probably have a third table called UserGroups with a UserID column, a GroupID column and an IsOwner column.

I'm using MongoDB and I'm sure there is a different approach for this kind of relationship in a document database. Should I embed the list of groups and groups-as-owner inside the Users table as two arrays of ObjectIDs? Should I also store the list of members and owners in the Groups table as two arrays, effectively mirroring the relationship causing a duplication of relationship information?

Or is a bridging UserGroups table a legitimate concept in document databases for many to many relationships?

Thanks

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