Question on query

[resting]

Given that I have many documents of the following structure:

{
  "_id" : ObjectId("519c643bc76110cb6e794782"),
  "item" : "1",
  "packets" : { 
    "0" : "0",
    "1" : "0",
     "2" : "1",
    ...
  }
}

How do I query for all documents with packets > 3 (irregardless of key value) for example?

Thanks.

[Tyler Brock]

Create a field that keeps a count of the number of packets.

Then query for { packets_size: { $gt: 3 } }

-Tyler

[Rob Moore]

How do I query for all documents with packets > 3 (irregardless of key value) for example?

If you can't or don't want to maintain a separate field then you can also use something like:

  db.collection.find( { "packets.3" : { "$exists" : true } } )

This assumes that all of the elements in the "packets" document are sequentially numbered and have no gaps... 

This trick would also work if "packets" was an array.

Rob.

[resting]

Hi Tyler,

I wasn't clear previously, here's the structure of the packets again with explanation

"packets" : {

   "0" : "0",

   "1" : "0",

    "2" : "1",

   ...

}

"0" : "0" means at interval 0, there are 0 packets  

"2" : "1" means at interval 2, there was 1 packet

So the key is the interval, and value is already the packet size. 

The objective is to locate the document (so I know which item it belongs to), with a packet size that was greater than x (any integer value), irregardless of which interval it was.

Thanks.

[Rob Moore]

Ah! Looking at the wrong side of the tuples.

Are all of the intervals always filled in for the range [0, N] for some N?  If so then (its ugly but) you can enumerate all of the fields in the query within an $or.  For N = 4:

    db.collection.find( { $or : [ 'packets.0' : { '$gt' : 3 },  'packets.1' : { '$gt' : 3 },  'packets.2' : { '$gt' : 3 }, 'packets.3' : { '$gt' : 3 }, 'packets.4' : { '$gt' : 3 } ] } )

Have you considered changing 'packets' to an array of integers where  the position is the interval and the value is the number of packets? e.g.,

"packets" : [

   0,

   0,

   1,

   ...

]

If you did that then a query like this would work:

   db.collection.find( { 'packets' : { '$gt'  : 3 } } )

Rob.