ForEachCosmosPartition.cs

using Microsoft.Azure.Documents;
using Microsoft.Azure.Documents.Client;
using Microsoft.Azure.Documents.Linq;
using Newtonsoft.Json.Linq;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;

namespace CosmosPartitionIteration
{
    class Program
    {
        static string key = "your_master_cosmos_key==";
        static string db_acct = "your_cosmos_account_name";
        static string db_id = "your_database_name";
        static string container_id = "your_container_name";
        static string cosmos_url = $"https://{db_acct}.documents.azure.com:443/";

        static async Task Main(string[] args)
        {
            long totalDocumentCount = 0L;

            List<string> partitionKeyRanges = await GetPartitionKeyRangesWithDocumentClient();

            Console.WriteLine($"number of partitions: {partitionKeyRanges}");

            var cosmosUri = UriFactory.CreateDocumentCollectionUri(db_id, container_id);

            string sql = "SELECT VALUE COUNT(1) FROM c";

            foreach (var range in partitionKeyRanges)
            {
                //restrict query to a partition
                FeedOptions feedOptions = new FeedOptions { PartitionKeyRangeId = range, EnableCrossPartitionQuery = false };

                using (var documentClient = new DocumentClient(new Uri(cosmos_url), key)) //typically a static shared instance
                using (var qry = documentClient.CreateDocumentQuery(cosmosUri, sql, feedOptions).AsDocumentQuery())
                {
                    while (qry.HasMoreResults)
                    {
                        var batch = await qry.ExecuteNextAsync();
                        Console.WriteLine($"Request Charge for range {range}: {batch.RequestCharge}");
                        var count = batch.ToList().First();
                        totalDocumentCount += Convert.ToInt64(count);
                    }
                }
            }

            Console.WriteLine($"Total documents = {totalDocumentCount}");
            Console.ReadKey();
        }

        /// <summary>
        /// Creates a list of partition ids in a cosmos database
        /// </summary>
        /// <returns></returns>
        static async Task<List<string>> GetPartitionKeyRangesWithDocumentClient()
        {
            Uri partitionKeyRangesUri = UriFactory.CreatePartitionKeyRangesUri(db_id, container_id);
            FeedResponse<PartitionKeyRange> response = null;
            List<string> ids = new List<string>();
            using (DocumentClient documentClient = new DocumentClient(new Uri(cosmos_url), key))
            {
                do
                {
                    response = await documentClient.ReadPartitionKeyRangeFeedAsync(partitionKeyRangesUri, new FeedOptions { MaxItemCount = 1000 });
                    foreach (var item in response)
                    {
                        ids.Add(item.Id);
                    }
                }
                while (!string.IsNullOrEmpty(response.ResponseContinuation));
            }
            return ids;
        }
}