azure-cosmosdbazure-cosmosdb-mongoapidatabase-view

Is it possible to use MongoDB Views with Azure CosmosDB?


I tried to create a view via Robo3T. The command executes successfully, but the view is always empty, no matter how I specify the aggregation pipeline for the view. Example:

db.createView("testView","originCollection", [{
    $project : {
        _id: 1
    } 
}])

Does CosmosDB even support views for MongoDB?


Edit: As Kevin Smith asked in comments db.testView.stats() returns:

{
    "_t" : "CollStatsResponse",
    "ok" : 1,
    "ns" : "myDb.testView",
    "count" : 0.0,
    "size" : 0,
    "avgObjSize" : 0,
    "numExtents" : 0,
    "lastExtentSize" : 0,
    "paddingFactor" : 0,
    "systemFlags" : 0,
    "userFlags" : 0,
    "totalIndexSize" : 0,
    "indexSizes" : {
        "indexSizes" : {}
    }
}

Solution

  • From the details that you have given, it looks like it's treating the view as just another collection and nothing is happening when you create a view (I've seen this with other commands it just continues without any errors).

    When you call stats on a view you'd normally end up with the following

    db.testView.stats()
    {
        "ok" : 0,
        "errmsg" : "Namespace test.testView is a view, not a collection",
        "code" : 166,
        "codeName" : "CommandNotSupportedOnView"
    }
    

    Also, looking at the documentation (https://learn.microsoft.com/en-us/azure/cosmos-db/mongodb-feature-support#administration-commands) the Administration Commands don't support createView.