Entity limits

Output.txt

Size: 1048488 (1048576 - 1048488 = 88)... success!
Size: 1048489 (1048576 - 1048489 = 87)... Bad Request

Program.cs

using System;
using System.Threading.Tasks;
using Microsoft.WindowsAzure.Storage;
using Microsoft.WindowsAzure.Storage.Table;

namespace EntityLimits
{
    class Program
    {
        static async Task Main()
        {
            var connectionString = "DefaultEndpointsProtocol=https;AccountName=account;AccountKey=key;EndpointSuffix=core.windows.net";
            var account = CloudStorageAccount.Parse(connectionString);
            var client = account.CreateCloudTableClient();
            var table = client.GetTableReference("test");

            await TryAsync(table, offset: 0);
            await TryAsync(table, offset: -1);
        }

        private static async Task TryAsync(CloudTable table, int offset)
        {
            const int MaxEntitySize = 1024 * 1024; // 1 MB
            const int MaxBinarySize = 64 * 1024; // 64 KiB

            var dynamicEntity = new DynamicTableEntity
            {
                PartitionKey = "D1",
                RowKey = "R1",
                Properties =
                {
                    { "A", new EntityProperty(new byte[MaxBinarySize]) },
                    { "B", new EntityProperty(new byte[MaxBinarySize]) },
                    { "C", new EntityProperty(new byte[MaxBinarySize]) },
                    { "D", new EntityProperty(new byte[MaxBinarySize]) },
                    { "E", new EntityProperty(new byte[MaxBinarySize]) },
                    { "F", new EntityProperty(new byte[MaxBinarySize]) },
                    { "G", new EntityProperty(new byte[MaxBinarySize]) },
                    { "H", new EntityProperty(new byte[MaxBinarySize]) },
                    { "I", new EntityProperty(new byte[MaxBinarySize]) },
                    { "J", new EntityProperty(new byte[MaxBinarySize]) },
                    { "K", new EntityProperty(new byte[MaxBinarySize]) },
                    { "L", new EntityProperty(new byte[MaxBinarySize]) },
                    { "M", new EntityProperty(new byte[MaxBinarySize]) },
                    { "N", new EntityProperty(new byte[MaxBinarySize]) },
                    { "O", new EntityProperty(new byte[MaxBinarySize]) },
                    { "P", new EntityProperty(new byte[65212 - offset]) },
                }
            };

            try
            {
                var entitySize = GetEntitySize(dynamicEntity);
                Console.Write($"Size: {entitySize} ({MaxEntitySize} - {entitySize} = {MaxEntitySize - entitySize})... ");
                await table.ExecuteAsync(TableOperation.InsertOrReplace(dynamicEntity));
                Console.WriteLine("success!");
            }
            catch (StorageException ex)
            {
                Console.WriteLine(ex.Message);
            }
        }

        /// <summary>
        /// Source: https://docs.microsoft.com/en-us/archive/blogs/avkashchauhan/how-the-size-of-an-entity-is-caclulated-in-windows-azure-table-storage
        /// </summary>
        private static int GetEntitySize(DynamicTableEntity entity)
        {
            var size = 4 + (entity.PartitionKey.Length + entity.RowKey.Length) * 2;

            foreach (var property in entity.Properties)
            {
                size += GetEntityPropertySize(property.Key, property.Value);
            }

            // size += GetEntityPropertySize("ETag", new EntityProperty("W/\"datetime'2021-01-10T06%3A11%3A51.4183681Z'\""));
            // size += GetEntityPropertySize("ETag", new EntityProperty("'2021-01-10T06%3A11%3A51.4183681Z'"));

            return size;
        }

        private static int GetEntityPropertySize(string name, EntityProperty value)
        {
            var size = 8 + name.Length * 2;

            switch (value.PropertyType)
            {
                case EdmType.String:
                    size += value.StringValue.Length * 2 + 4;
                    break;
                case EdmType.Binary:
                    size += value.BinaryValue.Length + 4;
                    break;
                default:
                    throw new NotImplementedException();
            }

            return size;
        }
    }
}