title: How do I read a single item from CosmosDb using Microsoft.Azure.Cosmos v3.9.1
body: <p>I'm using CosmosDB for the first time, and I am attempting to read a single document by id, according to this documentation:</p>
  
  <p><a href="https://docs.microsoft.com/en-us/dotnet/api/microsoft.azure.cosmos.container.readitemasync?view=azure-dotnet" rel="nofollow noreferrer">https://docs.microsoft.com/en-us/dotnet/api/microsoft.azure.cosmos.container.readitemasync?view=azure-dotnet</a></p>
  
  <p>According to this documentation, my container object should have a <code>ReadItemAsync</code> method that I can use to find and read a single item. However, when I import the "Microsoft.Azure.Cosmos" nuget package to my project and attempt to use this code snippet, there is no function on the container for <code>ReadItemAsync</code>. Here is a snippet of my code:</p>
  
  <pre><code>    using Microsoft.Azure.Cosmos;
          ...
      var databaseId = "{databaseId}";
      var containerId = "{containerId}";
      var client = new CosmosClient(model.IndexDatabaseUri, model.IndexDatabasePrimaryKey);
      var database = client.GetDatabase(databaseId);
      var container = database.GetContainer(containerId);
      var call = container... // NO ReadItemAsync HERE
  </code></pre>
  
  <p>I do see <strong>these</strong> functions on the container: </p>
  
  <pre><code>    GetItemLinqQueryable
      GetItemQueryIterator
      GetItemQueryStreamIterator
  </code></pre>
  
  <p>From the looks of it, I could probably create a query iterator with a custom <code>SELECT</code> statement, and retrieve the first item in the iterator. But that seems overkill for what I am wanting to do. I will always only want a single item in this instance. Why is there no <code>ReadItemAsync</code> method here, when it shows in the documentation that there should be one? And, if the "Iterator" is the new, preferred method, are there any performance considerations in using QueryIterator vs retrieving a single document? This function will be run millions of times over the span of one day.</p>
  
  <p>p.s. - I am using the "Microsoft.Azure.Cosmos" nuget package v3.9.1</p>