如何在MongoDB集合中存储描述文档的元数据？

Question

What is the best way to store metadata that describe a collection in MongoDB?

I have a collection with an arbitrary and changing number of documents within. As I create new documents, I want to assign a new, temporary name (String) based on the number of documents currently in the collection, eg "Doc 1", "Doc 2", ... Since documents could be removed, just doing a count() will not yield a useful result.

One option is to store metadata describing a collection within a different collection, but this seems awkward.

Since Mongo is schema-free, I could keep the collection's metadata within the collection itself, perhaps within a document with the name "metadata". In that case, how would I access that document quickly? Would I need to build an index for "metadata" to get at it immediately, without O(n) search time?

Is there a more standard, or simpler, way than what I described in the previous paragraph? I may end up with more metadata in the future than just a count.

Answer 1

You can check this link https://docs.mongodb.com/v3.0/tutorial/create-an-auto-incrementing-field/ .

According to the link above, my opinion is that just storing those in a colleciton named metadata with the format:

{
    '_id':'collection1'
    'c': 0,
    'other metadata1': 'foo',
    'other metadata2': 'bar'
}

Then you can get those metadata according to the collection name. If you want to add a field to this document, just use $set with update.

Answer 2

What we often do is put settings or metadata or so in a separate, one-document collection .settings. eg. if your data is located in collection 'user', I put the metadata in 'user.settings'