I read that MongoDB has a 4MB limit per document. Am I wrong?

Question

MongoDB

It is especially not clear if it is recommended to de-normalize the data - for example, to store comments to the comment ...
comment:{Id:..., Text: ..., comments: []}
This will hit the limit and the pipe ...

Answer 1

In version 2.2, the size of a single document has been increased to 16M. Although, as many above said, GridFS will allow you to store files of any size. Even those that exceed the size of one physical computer in the cluster.

Answer 2

To bypass the restriction, there is GridFS, it seems :)

Answer 3

mongo has another more interesting limitation www.mongodb.org/display/DOCS/Using+a+Large+Number+of+Collections
it worries me more than 4mb per write

Answer 4

This is configurable.

Answer 5

It seems to me that the problem is somewhat contrived, because a comment on a comment can be stored flat with a foreign key. For data larger than 4mb there is GridFS.

Answer 6

This is how many comments to write for 4 mb. Even on 32-bit machines, the total database size is limited to 2 GB, once started.
GridFS is still for binaries, I don't think it's the best solution.
In extreme cases, you can specify in the application the maximum amount of comments stored in one document and, when it is reached, open a new one with DBRef (foreign key) to the main one.

Answer 7

1) For text data - 4MB is a lot, all binary data will go to GridFS
2) In version 1.7 this can be configured
3) If you still go beyond 4MB, then it is solved by changing the database structure - for the example above, we make a collection of comments "flat" with links. See www.mongodb.org/display/DOCS/Trees+in+MongoDB vansickle, Today at 23:07 for more details on tree data options in Mongo