CODEWITHSUNDEEP
mongodbdatabasenosql
Just a coder
Just a coder

Reputation: 16730

Am i correctly using indexes for this mongoDB?

So i need some advice as to what i'm doing incorrectly.

My database is setup up exactly like a file system consisting of folders and files. It begins with a folder, but can have a relatively infinite number of subfolders and or files.

{
   "name":"folder1",
   "uniqueID":"zzz0",
   "subcontents": [ {"name":"subfolder1", "uniqueID":"zzz1"}, 
                    {"name":"subfile1", "uniqueID":"zzz2"}, 
                    {"name":"subfile2", "uniqueID":"zzz3"}, 
                    {"name":"subfolder2", "subcontents": [...etc...], "uniqueID":"zzz4"}, 
                  ] 
}

Each folder/file document have a uniqueID so that I can reference to it (seen above zzz#). My question is, can I make a mongoDB query to pull out only a single document?

Like say for example db.fileSystemCollection.find({"uniqueID":"zzz4"}) and it would give me the following result? Do i have to use indexes to do this? I've been trying but the query returns empty every time.

intended result ---> {"name":"subfolder2", "subcontents": [...etc...], "uniqueID":"zzz4"}

[EDIT] Based on the responses below, I will consider an XML database instead on mongoDB. The json structure cant be rearranged to work with MongoDB (too much data).

Upvotes: 0

Views: 91

Answers (2)

Alex Komyagin
Alex Komyagin

Reputation: 121

Short answer is no, as it's stated by Chris.

Your embedded representation of a tree is really good for intuitive understanding (and implementation as well). But if you want to allow effective searches on your tree using indices in MongoDB, you might consider another ways for tree storage. A bunch of ways is listed at http://docs.mongodb.org/manual/tutorial/model-tree-structures/

Please keep in mind that every representation has its own pros and cons depending on your access patterns.

Since for filesystem-like structure it's likely to have the ability to find all the sub contents of a given folder, you may use child references pattern for this:

{
   "name":"folder1",
   "uniqueID":"zzz0",
   "subcontents": [ "zzz1", 
                    "zzz2", 
                    "zzz3", 
                    "zzz4" 
                  ] 
}

{
  "name":"subfolder1", 
  "uniqueID":"zzz1"
}

...

Upvotes: 3

Chris Heald
Chris Heald

Reputation: 62648

No; searching for {uniqueID: "zzz4"} will only get you documents whose top-level uniqueID matches.

What you probably want is to maintain an array on the document which lists all the unique IDs in that tree. So your document would be:

{
   "name":"folder1",
   "uniqueID":"zzz0",
   "idList": ["zzz0", "zzz1", "zzz2", "zzz3", "zzz4"],
   "subcontents": [ {"name":"subfolder1", "uniqueID":"zzz1"},
                    {"name":"subfile1", "uniqueID":"zzz2"},
                    {"name":"subfile2", "uniqueID":"zzz3"},
                    {"name":"subfolder2", "subcontents": [...etc...], "uniqueID":"zzz4"},
                  ]
}

Then you can index that:

db.fileSystemCollection.ensureIndex({"idList": 1})

Then you can find on it:

db.fileSystemCollection.find({"idList": "zzz4})

That'll return you those documents.

As an aside, if you're trying to store files in Mongo, have you looked at GridFS?

Upvotes: 1

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