Source

BsonSql / BsonSql.Driver / BsonSqlCollection.cs

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using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using BsonSql.Common;
using MongoDB.Bson;
using MongoDB.Bson.Serialization;
using MongoDB.Bson.Serialization.IdGenerators;
using BsonSql.Driver.Configuration;
using BsonSql.Driver.Events;
using BsonSql.Common.Events;
using System.Data.SqlClient;
using System.Data;
using BsonSql.Driver.Builders;
using BsonSql.Driver.Builders.Enums;
using System.Threading.Tasks;
using System.Runtime.Caching;

using log4net;
using log4net.Core;



namespace BsonSql.Driver
{
	public class BsonSqlCollection
	{
        private static ILog _logger = LogManager.GetLogger("BsonSql.Audit");
        private string _logMask;

		private IndexSqlCache _indexCache = null;
		private BsonSqlServer _server;
		private string _domainId;
		private string _name;
        
		private DomainConfiguration _configuration;
        

		private object _sync = new object();
        private bool _logging = false;

		private static Query _findOneById = QueryBuilder.Where(WhereClauseBuilder.CreateBound("BsonDocumentID", Comparison.Equals)).Compile();

		internal BsonSqlCollection(string domainId, string name, BsonSqlServer server, DomainConfiguration configuration)
		{
			_domainId = domainId;
			_name = name;
			_server = server;
			_configuration = configuration;
            _logMask = _domainId + "." + _name;

            if (_logger.IsInfoEnabled)
                _logging = true;

			server.Dispatcher.Add("configuration.changed", new BsonSqlEventHandler<ConfigurationEvent>(ConfigurationChanged));
		}

		public virtual BsonSqlServer Server { get { return _server; } }

		private void ConfigurationChanged(ConfigurationEvent configEvent)
		{
			_indexCache = null;
			_configuration = configEvent.Configuration;
		}

		private CollectionInstance GetConfiguration()
		{
			
			DomainInstance instance = _configuration.GetDomain(_domainId);
			if (instance == null)
				throw new InvalidOperationException("the " + _domainId + " domain no longer exists");

			CollectionInstance collection = instance.GetCollection(_name);
			if (collection == null)
				throw new InvalidOperationException("the " + _name + " collection no longer exists");

			return collection;
		}

		public virtual void EnsureIndex(string name, bool unique, bool clustered, IEnumerable<IndexKey> keys)
		{
			CollectionInstance instance = GetConfiguration();

			
			//ask server to create an instance
			BsonDocument request = new BsonDocument() { 
				{ "DomainId", _domainId }, 
				{"CollectionName", instance.CollectionName} ,
				{ "IndexName", name } ,
				{ "Unique", unique } ,
				{ "Clustered", clustered } 
			};

			List<BsonDocument> keyDocs = new List<BsonDocument>();
			foreach(IndexKey key in keys)
			{
				keyDocs.Add(key.ToBsonDocument());
			}

			request.Set("Keys", new BsonArray(keyDocs));

			bool updated = false;
			BsonDocument response = _server.SubmitRequest("index/create", request, out updated);

			instance = GetConfiguration();
			if(instance.GetIndex(name) == null)
				throw new ApplicationException("server could not create the collection requested...check server");
		}

        public virtual void DropIndex(string name)
        {
            CollectionInstance instance = GetConfiguration();


            //ask server to create an instance
            BsonDocument request = new BsonDocument() { 
				{ "DomainId", _domainId }, 
				{"CollectionName", instance.CollectionName} ,
				{ "IndexName", name } 
			};

           

            bool updated = false;
            BsonDocument response = _server.SubmitRequest("index/drop", request, out updated);

            instance = GetConfiguration();
            
        }
		
		public virtual void Save<TNominalType>(TNominalType document)
		{
			Save(typeof(TNominalType), document, false, null);
		}

		public virtual void Save<TNominalType>(TNominalType document, SqlTransaction transaction)
		{
			Save(typeof(TNominalType), document, false, transaction);
		}

		public virtual void Save(object document)
		{
			Type t = document.GetType();
			Save(t, document, false, null);
		}

		public virtual void Save(object document, SqlTransaction transaction)
		{
			Type t = document.GetType();
			Save(t, document, false, transaction);
		}

		public virtual void Insert<TNominalType>(TNominalType document)
		{
			Insert(typeof(TNominalType), document, null);
		}

		public virtual void Insert<TNominalType>(TNominalType document, SqlTransaction transaction)
		{
			Insert(typeof(TNominalType), document, transaction);
		}

		public virtual void Insert(object document)
		{
			Type t = document.GetType();
			Insert(t, document, null);
		}

		public virtual void Insert(object document, SqlTransaction transaction)
		{
			Type t = document.GetType();
			Insert(t, document, transaction);
		}

		public virtual void Upsert<TNominalType>(TNominalType document)
		{
			Upsert(typeof(TNominalType), document, null);
		}

		public virtual void Upsert<TNominalType>(TNominalType document, SqlTransaction transaction)
		{
			Upsert(typeof(TNominalType), document, transaction);
		}

		public virtual void Upsert(object document)
		{
			Type t = document.GetType();
			Upsert(t, document, null);
		}

		public virtual void Upsert(object document, SqlTransaction transaction)
		{
			Type t = document.GetType();
			Upsert(t, document, transaction);
		}

		//TODO: implement concurrency using the _rowVersion field name if the flag is true
		//make sure that selects have this coming out

		public virtual void Save(Type nominalType, object document, bool checkConcurrency, SqlTransaction transaction)
		{
			//make sure we have a configuration
			CollectionInstance instance = GetConfiguration();

			var serializer = BsonSerializer.LookupSerializer(document.GetType());
			object id;
			Type idNominalType;
			IIdGenerator idGenerator;
			if (serializer.GetDocumentId(document, out id, out idNominalType, out idGenerator))
			{
				if (id == null)
				{
					throw new InvalidOperationException("No Id found");
				}

				if (idGenerator != null && idGenerator.IsEmpty(id))
				{
					if (!(idGenerator is GuidGenerator))
						throw new InvalidOperationException("BsonSqlServer only supports Guid document Ids");

					//this is an insert..we always generate a sequential id for them
					id = SqlIdentifierHelper.GenerateGuid();
					serializer.SetDocumentId(document, id);

					BsonDocument insertDocument = BsonSqlSerializer.SerializeToDocument(document);
					int insertBucket = 0;
					string insertConnectionId = instance.GetConnectionIdForDocument(insertDocument, out insertBucket);

					//save this document
					StringBuilder insertSql = new StringBuilder(1000);
					insertSql.Append( @"INSERT INTO dbo." + _configuration.Prefix + instance.CollectionName + " (BsonDocumentID, BucketID, BsonDocument) VALUES (@BsonDocumentID, @BucketID, @BsonDocument)");

					SqlCommand command = new SqlCommand();
					command.Parameters.Add("@BsonDocumentID", SqlDbType.UniqueIdentifier).Value = id;
					command.Parameters.Add("@BucketID", SqlDbType.SmallInt).Value = insertBucket;
					command.Parameters.Add("@BsonDocument", SqlDbType.Image).Value = insertDocument.ToBson();

                    EvaluateForAutoIncrementer(command, insertSql, instance, insertConnectionId);

					UpdateDocumentIndex(command, insertSql, insertDocument, true);
					ExecuteCommandNonQuery(command, insertConnectionId, transaction, false, insertDocument, instance);
				}
				else
				{
					if(!(id is Guid))
						throw new InvalidOperationException("BsonSqlServer only supports Guid document Ids");

					
					//this is an update
					BsonDocument updateDocument = BsonSqlSerializer.SerializeToDocument(document);
					int updateBucket = 0;
					string updateConnectionId = instance.GetConnectionIdForDocument(updateDocument, out updateBucket);

					

					//save this document
					StringBuilder insertSql = new StringBuilder(1000);
                    insertSql.Append(@"
                       
						UPDATE dbo." + _configuration.Prefix + instance.CollectionName + @" 
						SET BsonDocument = @BsonDocument
						WHERE BsonDocumentID = @BsonDocumentID

						IF @@ROWCOUNT = 0
                            BEGIN
							    INSERT INTO dbo." + _configuration.Prefix + instance.CollectionName + @" (BsonDocumentID, BucketID, BsonDocument) VALUES (@BsonDocumentID, @BucketID, @BsonDocument)");


					SqlCommand command = new SqlCommand();
					command.Parameters.Add("@BsonDocumentID", SqlDbType.UniqueIdentifier).Value = id;
					command.Parameters.Add("@BucketID", SqlDbType.SmallInt).Value = updateBucket;
					command.Parameters.Add("@BsonDocument", SqlDbType.Image).Value = updateDocument.ToBson();

                    EvaluateForAutoIncrementer(command, insertSql, instance, updateConnectionId);

                    insertSql.AppendLine("END");

					UpdateDocumentIndex(command, insertSql, updateDocument, false);
					ExecuteCommandNonQuery(command, updateConnectionId, transaction, false, updateDocument, instance);
				}
			}
			else
			{
				throw new InvalidOperationException("Save can only be used with documents that have an Id");
			}
		}

		public virtual void Insert(Type nominalType, object document, SqlTransaction transaction)
		{
			//make sure we have a configuration
			CollectionInstance instance = GetConfiguration();

			var serializer = BsonSerializer.LookupSerializer(document.GetType());
			object id;
			Type idNominalType;
			IIdGenerator idGenerator;
			if (serializer.GetDocumentId(document, out id, out idNominalType, out idGenerator))
			{
				if (id == null)
				{
					throw new InvalidOperationException("No Id found");
				}

				if (idGenerator != null && idGenerator.IsEmpty(id))
				{
					if (!(idGenerator is GuidGenerator))
						throw new InvalidOperationException("BsonSqlServer only supports Guid document Ids");

					//this is an insert..we always generate a sequential id for them
					id = SqlIdentifierHelper.GenerateGuid();
					serializer.SetDocumentId(document, id);

					
				}
				
				if (!(id is Guid))
					throw new InvalidOperationException("BsonSqlServer only supports Guid document Ids");

				BsonDocument insertDocument = BsonSqlSerializer.SerializeToDocument(document);
				int insertBucket = 0;
				string insertConnectionId = instance.GetConnectionIdForDocument(insertDocument, out insertBucket);

				//save this document
				StringBuilder insertSql = new StringBuilder(1000);
                insertSql.Append(@"INSERT INTO dbo." + _configuration.Prefix + instance.CollectionName + " (BsonDocumentID, BucketID, BsonDocument) VALUES (@BsonDocumentID, @BucketID, @BsonDocument)");

               
				SqlCommand command = new SqlCommand();
				command.Parameters.Add("@BsonDocumentID", SqlDbType.UniqueIdentifier).Value = id;
				command.Parameters.Add("@BucketID", SqlDbType.SmallInt).Value = insertBucket;
				command.Parameters.Add("@BsonDocument", SqlDbType.Image).Value = insertDocument.ToBson();

                EvaluateForAutoIncrementer(command, insertSql, instance, insertConnectionId);

				UpdateDocumentIndex(command, insertSql, insertDocument, true);
				ExecuteCommandNonQuery(command, insertConnectionId, transaction, false, insertDocument, instance);
			}
			else
			{
				throw new InvalidOperationException("Insert can only be used with documents that have an Id");
			}
		}


		public virtual void Upsert(Type nominalType, object document, SqlTransaction transaction)
		{
			//make sure we have a configuration
			CollectionInstance instance = GetConfiguration();

			var serializer = BsonSerializer.LookupSerializer(document.GetType());
			object id;
			Type idNominalType;
			IIdGenerator idGenerator;
			if (serializer.GetDocumentId(document, out id, out idNominalType, out idGenerator))
			{
				if (id == null || (idGenerator != null && idGenerator.IsEmpty(id)))
					throw new InvalidOperationException("No Id found");
				
				if (!(id is Guid))
					throw new InvalidOperationException("BsonSqlServer only supports Guid document Ids");

				//this is an update
				BsonDocument updateDocument = BsonSqlSerializer.SerializeToDocument(document);
				int updateBucket = 0;
				string updateConnectionId = instance.GetConnectionIdForDocument(updateDocument, out updateBucket);

				//TODO: cache this sql...and parameter collection so all we have to do is set the properties

				//save this document
				StringBuilder insertSql = new StringBuilder(1000);
				insertSql.Append (@"
					UPDATE dbo." + _configuration.Prefix + instance.CollectionName + @" 
					SET BsonDocument = @BsonDocument
					WHERE BsonDocumentID = @BsonDocumentID

					IF @@ROWCOUNT = 0
                        BEGIN
						    INSERT INTO dbo." + _configuration.Prefix + instance.CollectionName + " (BsonDocumentID, BucketID, BsonDocument) VALUES (@BsonDocumentID, @BucketID, @BsonDocument)");

				SqlCommand command = new SqlCommand();
				command.Parameters.Add("@BsonDocumentID", SqlDbType.UniqueIdentifier).Value = id;
				command.Parameters.Add("@BucketID", SqlDbType.SmallInt).Value = updateBucket;
				command.Parameters.Add("@BsonDocument", SqlDbType.Image).Value = updateDocument.ToBson();

                EvaluateForAutoIncrementer(command, insertSql, instance, updateConnectionId);

                //put the "END" in place, had to wait until after the other thing is done...
                insertSql.AppendLine("END");

				UpdateDocumentIndex(command, insertSql, updateDocument, false);
				ExecuteCommandNonQuery(command, updateConnectionId, transaction, false, updateDocument, instance);
			}
			else
			{
				throw new InvalidOperationException("Upsert can only be used with documents that have an Id");
			}
		}

        private void EvaluateForAutoIncrementer(SqlCommand command, StringBuilder insertSql, CollectionInstance instance, string connectionId)
        {
            if (!string.IsNullOrEmpty(instance.AutoIncrementer))
            {
                command.Parameters.Add("@AutoIncrementer", SqlDbType.NVarChar).Value = instance.CollectionName;
                command.Parameters.Add("@AutoIncrementerIndex", SqlDbType.BigInt).Value = instance.GetAutoIncrementerIdForConnection(connectionId);

                //spit out the sql
                //that goes between the begin / end following an insert
                // solution from here http://michaeljswart.com/2011/09/mythbusting-concurrent-updateinsert-solutions/
                insertSql.Append(@"           
                                    
                            DECLARE @result bigint
                            SET @result = -1
                            MERGE dbo.BsonSqlCounters WITH (UPDLOCK) as MyTarget
                                USING (SELECT @AutoIncrementer AS CollectionName) as MySource
                                ON MySource.CollectionName = MyTarget.CollectionName
                                WHEN MATCHED 
                                    THEN UPDATE
                                        SET [Counter] += 10000, @result = [Counter]
                                WHEN NOT MATCHED
                                    THEN
                                        INSERT (CollectionName, [Counter])
                                        VALUES (@AutoIncrementer, @AutoIncrementerIndex);
      
                            SELECT @result
                            RETURN
                ");
            }
        }

        private IndexSqlCache GetIndexCache(CollectionInstance instance)
        {
            IndexSqlCache sqlCache = _indexCache;
            if (sqlCache == null)
            {
                sqlCache = new IndexSqlCache();
                IndexInstance[] indexes = instance.Indexes;

                sqlCache.DoNothing = !(indexes != null && indexes.Length > 0);
                Dictionary<string, IndexKey> uniqueList = new Dictionary<string, IndexKey>();
                StringBuilder insertSql = new StringBuilder(500);
                StringBuilder allSql = new StringBuilder(500);
                SqlCommand cmd = new SqlCommand();
                int count = 0;

                if (!sqlCache.DoNothing)
                {
                    foreach (IndexInstance index in indexes)
                    {
                        foreach (IndexKey key in index.Keys)
                        {
                            if (key.FieldName != "_id" && !uniqueList.ContainsKey(key.FieldName))
                            {
                                uniqueList.Add(key.FieldName, key);

                                string parameterName = "@Idx" + count.ToString();
                                sqlCache.ParameterMap[parameterName] = key;
                                SqlDbType sqlType = BsonSqlSerializer.GetSqlTypeForBsonType(key.DataType);
                                if (sqlType == SqlDbType.VarChar && !key.UseVarChar)
                                    sqlType = SqlDbType.NVarChar;

                                cmd.Parameters.Add(parameterName, sqlType);
                                count += 1;
                            }
                        }
                    }
                }

                //build the insert sql
                //and the normal sql
                insertSql.AppendLine();
                insertSql.Append("INSERT INTO dbo." + _configuration.Prefix);
                insertSql.Append(instance.CollectionName);
                insertSql.Append("_I (BsonDocumentID, SchemaVersion");

                StringBuilder insertSql2 = new StringBuilder(500);
                insertSql2.AppendLine();
                insertSql2.Append("VALUES (@IdxDocumentId,@IdxSchemaVersion");

                allSql.AppendLine();
                allSql.Append("UPDATE dbo." + _configuration.Prefix);
                allSql.Append(instance.CollectionName);
                allSql.Append("_I SET SchemaVersion = @IdxSchemaVersion");

                if (!sqlCache.DoNothing)
                {
                    foreach (SqlParameter parameter in cmd.Parameters)
                    {
                        IndexKey parameterKey = sqlCache.ParameterMap[parameter.ParameterName];
                        string columnName = parameterKey.FieldName.Replace(".", "_");

                        insertSql.AppendFormat(",{0}", columnName);
                        insertSql2.AppendFormat(",{0}", parameter.ParameterName);

                        allSql.AppendFormat(",{0} = {1}", columnName, parameter.ParameterName);
                    }
                }

                insertSql.Append(") ");
                insertSql2.Append(") ");
                insertSql.Append(insertSql2.ToString());

                allSql.Append(" WHERE BsonDocumentID = @IdxDocumentId");
                allSql.AppendLine();
                allSql.AppendLine("IF @@ROWCOUNT = 0");
                allSql.Append(insertSql.ToString());

                sqlCache.InsertOnlySql = insertSql.ToString();
                sqlCache.Sql = allSql.ToString();
                sqlCache.Command = cmd;
                sqlCache.UniqueList = uniqueList;

                _indexCache = sqlCache;
            }

            return sqlCache;
        }

		private void UpdateDocumentIndex(SqlCommand command, StringBuilder sql, BsonDocument document, bool insertOnly)
		{
			CollectionInstance instance = GetConfiguration();
            IndexSqlCache sqlCache = GetIndexCache(instance);
			
			//otherwise we need to add some sql here...
			command.Parameters.Add("@IdxDocumentId", SqlDbType.UniqueIdentifier).Value =  document["_id"].AsGuid;
			command.Parameters.Add("@IdxSchemaVersion", SqlDbType.TinyInt).Value = instance.SchemaVersion;

            if (!sqlCache.DoNothing)
			{
				SqlCommand indexCommand = sqlCache.Command;
				foreach (SqlParameter parameter in indexCommand.Parameters)
				{
					SqlParameter commandParameter = command.Parameters.Add(parameter.ParameterName, parameter.SqlDbType);
					commandParameter.Value = DBNull.Value;

					//do we have this in our index 
					IndexKey indexKey = null;
					if (!sqlCache.ParameterMap.TryGetValue(parameter.ParameterName, out indexKey))
						continue;

					List<BsonValue> bsonValues = GetValuesForIndexFieldPopulation(indexKey.FieldName, document);

					if (bsonValues.Count > 0)
					{
						if (bsonValues.Count == 1)
						{
							BsonValue bsonValue = bsonValues[0];
							if (bsonValue.IsBsonArray && indexKey.DataType == BsonType.Array)
							{
								List<string> arrayValues = new List<string>();
								foreach (BsonValue arrayValue in bsonValue.AsBsonArray.Values)
								{
									BsonValue finalValue = arrayValue;
									while (finalValue.IsBsonArray)
									{
										finalValue = finalValue.AsBsonArray[0];
									}

									if (finalValue != null)
										arrayValues.Add(finalValue.RawValue.ToString());
								}

								if (arrayValues.Count == 0)
									commandParameter.Value = string.Empty;
								else
								{
									string valueList = "||" + string.Join("||", arrayValues) + "||";
									if (valueList.Length > indexKey.Length)
										valueList = valueList.Substring(0, indexKey.Length);
									commandParameter.Value = valueList;
								}
							}
							else
							{
								//if we ended up with an array...then get the first value
								while (bsonValue.IsBsonArray)
								{
									bsonValue = bsonValue.AsBsonArray[0];
								}

								switch (bsonValue.BsonType)
								{
									case BsonType.ObjectId:
										commandParameter.Value = bsonValue.AsString;
										break;
									case BsonType.DateTime:
										commandParameter.Value = bsonValue.AsDateTime;
                                        if (commandParameter.Value != null)
                                            commandParameter.Value = ((DateTime)commandParameter.Value).ToUniversalTime(); //bson takes care of this internally, we need to do it for indexes
										break;
									case BsonType.String:
										string bsonString = bsonValue.AsString;
										if (bsonString != null && bsonString.Length > indexKey.Length)
											bsonString = bsonString.Substring(0, indexKey.Length);
										commandParameter.Value = bsonString;
										break;
									default:
										if (bsonValue.IsGuid)
											commandParameter.Value = bsonValue.AsGuid.ToString();
										else
											commandParameter.Value = bsonValue.RawValue;
										break;
								}
							}
						}
						else
						{
							if (indexKey.DataType == BsonType.Array)
							{
								List<string> arrayValues = new List<string>();
								foreach (BsonValue arrayValue in bsonValues)
								{
									BsonValue finalValue = arrayValue;
									while (finalValue.IsBsonArray)
									{
										finalValue = finalValue.AsBsonArray[0];
									}

									if (finalValue != null)
										arrayValues.Add(finalValue.RawValue.ToString());
								}

								if (arrayValues.Count == 0)
									commandParameter.Value = string.Empty;
								else
								{
									string valueList = "||" + string.Join("||", arrayValues) + "||";
									if (valueList.Length > indexKey.Length)
										valueList = valueList.Substring(0, indexKey.Length);
									commandParameter.Value = valueList;
								}
							}
							else
							{
								//take the first one
								BsonValue bsonValue = bsonValues[0];
								while (bsonValue.IsBsonArray)
								{
									bsonValue = bsonValue.AsBsonArray[0];
								}

								switch (bsonValue.BsonType)
								{
									case BsonType.ObjectId:
										commandParameter.Value = bsonValue.AsString;
										break;
									case BsonType.DateTime:
										commandParameter.Value = bsonValue.AsDateTime;
                                        if (commandParameter.Value != null)
                                            commandParameter.Value = ((DateTime)commandParameter.Value).ToUniversalTime(); //bson takes care of this internally, we need to do it for indexes
										break;
									case BsonType.String:
										string bsonString = bsonValue.AsString;
										if (bsonString != null && bsonString.Length > indexKey.Length)
											bsonString = bsonString.Substring(0, indexKey.Length);
										commandParameter.Value = bsonString;
										break;
									default:
										if (bsonValue.IsGuid)
											commandParameter.Value = bsonValue.AsGuid.ToString();
										else
											commandParameter.Value = bsonValue.RawValue;
										break;
								}
							}
						}
					}


				}
			}

			sql.AppendLine();
			sql.Append((insertOnly) ? sqlCache.InsertOnlySql : sqlCache.Sql);
			command.CommandText = sql.ToString();
		}

		private List<BsonValue> GetValuesForIndexFieldPopulation(string fieldNames, BsonDocument source)
		{
			List<BsonValue> values = new List<BsonValue>();
			string[] names = fieldNames.Split('.');
			EvaluateValuesForIndexFieldPopulation(values, names, source);
			return values;
		}

		private void EvaluateValuesForIndexFieldPopulation(List<BsonValue> valueList, string[] elementNames, BsonDocument source)
		{
			if (source.Contains(elementNames[0]))
			{
				BsonElement currentElement = source.GetElement(elementNames[0]);

				if (elementNames.Length > 1)
				{
					if (currentElement.Value.IsBsonDocument)
						EvaluateValuesForIndexFieldPopulation(valueList, new string[] { string.Join(".", elementNames, 1, elementNames.Length - 1) }, currentElement.Value.AsBsonDocument);
					else if (currentElement.Value.IsBsonArray)
					{
						//for each element in the source array we need to see if we have a corresponding
						//element in this array
						
						BsonArray currentArray = currentElement.Value.AsBsonArray;

						for (int i = 0; i < currentArray.Count; i++)
						{
							BsonValue currentValue = currentArray[i];
							
							if (currentValue != null && currentValue.IsBsonDocument)
								EvaluateValuesForIndexFieldPopulation(valueList, new string[] { string.Join(".", elementNames, 1, elementNames.Length - 1) }, currentValue.AsBsonDocument);
						}
					}
				}
				else
				{
					valueList.Add(currentElement.Value);
				}
			}	
		}
		
		private void ExecuteCommandNonQuery(SqlCommand command, string connectionId, SqlTransaction transaction, bool forDelete, BsonDocument current, CollectionInstance instance)
		{
            
			bool startedTransaction = (transaction == null);

			using (SqlConnection conn = new SqlConnection(_configuration.GetServer(connectionId).ConnectionString))
			{
                if (_logging)
                {
                    if (current != null && current.Contains("_id"))
                        MDC.Set("auditKey.BsonID", current["_id"].AsGuid.ToString());

                    MDC.Set("auditKey.Server", conn.DataSource);
                    MDC.Set("auditKey.Db", conn.Database);

                    if (current != null)
                    {
                        foreach (BsonElement e in current)
                        {
                            MDC.Set("audit." + e.Name, e.ToJson());
                        }
                    }
                    _logger.Info(_logMask + ((forDelete) ? "Delete" : "Update"));

                    //have to wipe them out or else another thread gets them and may taint the results
                    MDC.Set("auditKey.BsonID", "");

                    if (current != null)
                    {
                        foreach (BsonElement e in current)
                        {
                            MDC.Set("audit." + e.Name, "");
                        }
                    }
                }

				if (!startedTransaction)
				{
					command.Connection = transaction.Connection;
					command.Transaction = transaction;
				}
				else
				{
					command.Connection = conn;
					conn.Open();
					transaction = conn.BeginTransaction();
					command.Transaction = transaction;
				}


				try
				{
                    //be aggressive about not letting an exception throw everything off
                    if(forDelete || current == null || string.IsNullOrEmpty(instance.AutoIncrementer))
					    command.ExecuteNonQuery();
                    else
                    {
                        //execute a scalar, which will tell us if we just created a new autonumber, at which point we need 
                        object scalarResult = command.ExecuteScalar();
                        
                        if (scalarResult != null) //then we need to save this document again
                        {
                            long result = (long)scalarResult;
                            //set and store the result of the auto incrementer in the document

                            //if the first one, we start at the indexer, otherwise, we are behind by 1 interval (saves a deadlock);
                            if (result == -1)
                                result = instance.GetAutoIncrementerIdForConnection(connectionId);
                            else
                                result += 10000;

                            current.Set(instance.AutoIncrementer, result);
                            Save(current, transaction);
                        }
                    }


					if(startedTransaction)
						transaction.Commit();
				}
				catch
				{
					if (startedTransaction && transaction != null)
						transaction.Rollback();

					throw;
				}
			}

            
		}

		public string GetConnectionStringFromConnectionId(string connectionId)
		{
			return _configuration.GetServer(connectionId).ConnectionString;
		}

		public string GetConnectionStringFromValues(object values)
		{
			if (values == null)
				return null;


			CollectionInstance instance = GetConfiguration();
			int junk = 0;
			string connectionId = null;

			if (values is Dictionary<string, string>)
				connectionId = instance.GetConnectionIdForValues((Dictionary<string, string>)values, out junk);
			else if (values is BsonDocument)
				connectionId = instance.GetConnectionIdForDocument((BsonDocument)values, out junk);
			else
			{
				BsonDocument document = values.ToBsonDocument();
				connectionId = instance.GetConnectionIdForDocument(document, out junk);
			}

			if (connectionId == null)
				return null;
			else
			return _configuration.GetServer(connectionId).ConnectionString;
		}

		

		internal List<TDocument> ExecuteQuery<TDocument>(BsonSqlCursor cursor) where TDocument: class
		{
			Query query = cursor.Query.Compile();
			SqlTransaction transaction = cursor.Transaction;
			string[] fields = cursor.Fields;

			CollectionInstance instance = GetConfiguration();
			CollectionServerInstance[] servers = instance.Servers;

			Type documentType = typeof(TDocument);
			Type joinType = typeof(JoinResult);
			bool returnMultipleDocuments = false;

			StringBuilder sql = new StringBuilder(1000);

			sql.Append("SELECT ");
			if (cursor.Limit > 0)
			{
				sql.Append("TOP ");
				sql.Append(cursor.Limit.ToString());
			}

			sql.Append(" [BD].BsonDocumentID, [BD].BsonDocument, [BD].Version");


			if (query._joins.Count > 0)
			{
				//need to include the three fields from each of the documents if a return type was defined...
				int joinLevel = 1;
				foreach (Join join in query._joins)
				{
					if (join.ReturnType != null)
					{
						string prefix = "[BD" + joinLevel.ToString() + "]";
						sql.Append(", ");
						sql.Append(prefix);
						sql.Append(".BsonDocumentID as BsonDocumentID");
						sql.Append(joinLevel.ToString());
						sql.Append(", ");
						sql.Append(prefix);
						sql.Append(".BsonDocument as BsonDocument");
						sql.Append(joinLevel.ToString());
						sql.Append(", ");
						sql.Append(prefix);
						sql.Append(".Version as Version");
						sql.Append(joinLevel.ToString());
						returnMultipleDocuments = true;

						if (documentType.BaseType != joinType)
							throw new InvalidOperationException("if you are returning multiple documents from a join you must use a JoinResult as your cursor type");
					}
					joinLevel += 1;
				}
			}

			sql.AppendLine();
            sql.Append("FROM dbo." + _configuration.Prefix);
			sql.Append(instance.CollectionName);
			sql.Append("_I [BI]");
			sql.AppendLine();
            sql.Append("INNER JOIN dbo." + _configuration.Prefix);
			sql.Append(instance.CollectionName);
			sql.AppendLine(" [BD] ON ([BD].BsonDocumentID = [BI].BsonDocumentID)");

			sql.AppendLine(GetQueryWhereClause(query));


			sql.AppendLine(query.SqlOrderByClause);

			string finalSql = sql.ToString();

			if (servers.Length == 1)
				return ExecuteQueryAgainstSingleConnection<TDocument>(cursor, servers[0].ConnectionId, query, transaction, instance, fields, finalSql, returnMultipleDocuments);
			else
			{
				int bucketThrowAway = 0;
				string connectionId = instance.GetConnectionIdForValues(query.StringValues, out bucketThrowAway);

				if (transaction != null && connectionId == null)
					throw new InvalidOperationException("can't execute a shard query using a transaction - distributed transactions not supported");

				if (connectionId != null)
					return ExecuteQueryAgainstSingleConnection<TDocument>(cursor, connectionId, query, transaction, instance, fields, finalSql, returnMultipleDocuments);
				else
				{
					List<TDocument> combinedResults = new List<TDocument>();

					//go through all of our servers and execute them
					Parallel.ForEach(servers, server =>
					{
						List<TDocument> singleResults = ExecuteQueryAgainstSingleConnection<TDocument>(cursor, server.ConnectionId, query, transaction, instance, fields, finalSql, returnMultipleDocuments);
						if (singleResults != null && singleResults.Count > 0) 
						{
							lock (combinedResults)
							{
								combinedResults.AddRange(singleResults);
							}
						}
					});

					return combinedResults;
				}
			}
		}

        //looks to see if query has any join clauses, which means it will have use of the dbo.[PREFIX]
        //which only needs to be replaced 1 time. we cache it for 10 minutes so things that are used
        //frequently will be ok, but things that aren't won't stay around forever
        private string GetQueryWhereClause(Query q)
        {
            if(q._joins.Count == 0)
                return q.SqlWhereClause;

            string whereClause = MemoryCache.Default[q.Id] as string;
            if (whereClause == null)
            {
                whereClause = q.SqlWhereClause.Replace("dbo.[PREFIX]", "dbo." + _configuration.Prefix);
                MemoryCache.Default.Set(q.Id, whereClause, new CacheItemPolicy() { SlidingExpiration = TimeSpan.FromMinutes(10) });
            }

            return whereClause;
        }

		private List<TDocument> ExecuteQueryAgainstSingleConnection<TDocument>(BsonSqlCursor cursor, string connectionId, Query query, SqlTransaction transaction, CollectionInstance instance, string[] fields, string sql, bool returnMultipleDocuments) where TDocument : class
		{
			List<TDocument> documents = new List<TDocument>();
			Type documentType = typeof(TDocument);

			using (SqlConnection conn = new SqlConnection(_configuration.GetServer(connectionId).ConnectionString))
			{
                SqlCommand cmd = query.PrepareCommandForExecution(GetIndexCache(instance).UniqueList);
				cmd.CommandText = sql;
                
                if (_logging)
                {
                    MDC.Set("auditKey.Server", conn.DataSource);
                    MDC.Set("auditKey.Db", conn.Database);
                    MDC.Set("audit.Sql", sql);
                    MDC.Set("auditKey.QID", Guid.NewGuid().ToString());

                    if(cmd.Parameters != null)
                    {
                        foreach (SqlParameter p in cmd.Parameters)
                        {
                            if (p.Value != null && p.Value != DBNull.Value)
                            {
                                try { MDC.Set("audit." + p.ParameterName, p.Value.ToString()); }
                                catch { }
                            }
                        }
                    }

                    _logger.Info(_logMask + "Query");
                    
                    
                    MDC.Set("audit.Sql", "");

                    if (cmd.Parameters != null)
                    {
                        foreach (SqlParameter p in cmd.Parameters)
                        {
                            MDC.Set("audit." + p.ParameterName, "");
                        }
                    }
                }

				if (transaction != null)
				{
					cmd.Connection = transaction.Connection;
					cmd.Transaction = transaction;
				}
				else
				{
					cmd.Connection = conn;
					conn.Open();
				}

				
				using (SqlDataReader dr = cmd.ExecuteReader((transaction == null) ? CommandBehavior.CloseConnection : CommandBehavior.Default))
				{
					DbReaderWrapper wrapper = null;
					if(query._joins.Count == 0)
						wrapper = new DbReaderWrapper(dr, "BsonSqlCollection.ExecuteQuery");
					else
						wrapper = new DbReaderWrapper(dr);

                    int logIndex = 0;

					while (dr.Read())
					{
                        int logCount = 0;

						//always get it as a document first
						BsonDocument document = wrapper.GetBsonValue<BsonDocument>("BsonDocument");
						document.Set("_id", wrapper.GetGuid("BsonDocumentID"));

                        if (_logging)
                        {
                            MDC.Set("auditKey.Idx", logIndex++.ToString());
                            MDC.Set("auditKey.BsonID", wrapper.GetGuid("BsonDocumentID").ToString());
                            logCount++;
                        }

						if (fields != null)
						{
							//we arent' grabbing all of the fields
							BsonDocument partial = PrepareFragmentFromFields(document, fields);
							partial.Set("_id", document["_id"]);
							document = partial;
						}

						if (returnMultipleDocuments)
						{

							JoinResult joinResult = JoinResult.Create(documentType);
							joinResult.SetCapacity(query._joins.Count + 1);
							joinResult.SetResult(0, BsonSqlSerializer.Deserialize(joinResult.MainResultType, document, (byte[])wrapper.GetValue("Version")));

							int joinIndex = 1;
							foreach (Join join in query._joins)
							{
								if (join.ReturnType != null)
								{
									string joinSuffix = joinIndex.ToString();
									if (!wrapper.IsDBNull("BsonDocument" + joinSuffix))
									{
										BsonDocument addlDocument = wrapper.GetBsonValue<BsonDocument>("BsonDocument" + joinSuffix);
										addlDocument.Set("_id", wrapper.GetGuid("BsonDocumentID" + joinSuffix));

                                        if (_logging)
                                        {
                                            MDC.Set("auditKey.BsonID" + logCount++.ToString(), addlDocument["_id"].AsGuid.ToString());
                                        }

										joinResult.SetResult(joinIndex, BsonSqlSerializer.Deserialize(join.ReturnType, addlDocument, (byte[])wrapper.GetValue("Version" + joinSuffix)));
									}
								}
								joinIndex += 1;
							}

							documents.Add(joinResult as TDocument);
						}
						else
							//otherwise you return the type
							documents.Add((TDocument)BsonSqlSerializer.Deserialize<TDocument>(document, (byte[])wrapper.GetValue("Version")));

                        if (_logging)
                        {
                            _logger.Info(_logMask + "QueryResult");

                            //clear what we need to
                            MDC.Set("auditKey.BsonID", "");
                            for (int logI = 0; logI < logCount; logI++)
                            {
                                MDC.Set("auditKey.BsonID" + logI.ToString(), "");
                            }
                        }
					}

					dr.Close();

                    if (_logging)
                    {                        
                        MDC.Set("auditKey.QID", "");
                        MDC.Set("auditKey.Idx", "");
                    }
				}
			}

			return documents;
		}


		private int ExecuteCountAgainstSingleConnection(string connectionId, Query query, SqlTransaction transaction, CollectionInstance instance, string sql) 
		{
			int totalCount = 0;

			using (SqlConnection conn = new SqlConnection(_configuration.GetServer(connectionId).ConnectionString))
			{
                SqlCommand cmd = query.PrepareCommandForExecution(GetIndexCache(instance).UniqueList);
				cmd.CommandText = sql;

                if (_logging)
                {
                    MDC.Set("auditKey.Server", conn.DataSource);
                    MDC.Set("auditKey.Db", conn.Database);
                    MDC.Set("audit.Sql", sql);

                    if (cmd.Parameters != null)
                    {
                        foreach (SqlParameter p in cmd.Parameters)
                        {
                            if (p.Value != null && p.Value != DBNull.Value)
                            {
                                try { MDC.Set("audit." + p.ParameterName, p.Value.ToString()); }
                                catch { }
                            }
                        }
                    }

                    _logger.Info(_logMask + "Count");
                    MDC.Set("audit.Sql", "");

                    if (cmd.Parameters != null)
                    {
                        foreach (SqlParameter p in cmd.Parameters)
                        {
                            MDC.Set("audit." + p.ParameterName, "");
                        }
                    }
                }


				if (transaction != null)
				{
					cmd.Connection = transaction.Connection;
					cmd.Transaction = transaction;
				}
				else
				{
					cmd.Connection = conn;
					conn.Open();
				}


				using (SqlDataReader dr = cmd.ExecuteReader((transaction == null) ? CommandBehavior.CloseConnection : CommandBehavior.Default))
				{
					DbReaderWrapper wrapper = new DbReaderWrapper(dr, "BsonSqlCollection.ExecuteCount");
					while (dr.Read())
					{
						totalCount = dr.GetInt32(0);
					}

					dr.Close();
				}
			}

			return totalCount;
		}


		private BsonDocument PrepareFragmentFromFields(BsonDocument source, string[] fields)
		{
			BsonDocument partial = new BsonDocument();
			PrepareFragmentFromFields(partial, source, fields);
			return partial;
		}

		private void PrepareFragmentFromFields(BsonDocument target, BsonDocument source, string[] fields)
		{
			foreach (string field in fields)
			{
				string[] elementNames = field.Split('.');
				if (source.Contains(elementNames[0]))
				{
					BsonElement currentElement = source.GetElement(elementNames[0]);

					if (elementNames.Length > 1)
					{
						//make sure the target has the current element
						BsonElement partialElement = null;
						if (!target.Contains(currentElement.Name))
						{
							if (currentElement.Value.IsBsonDocument)
								partialElement = new BsonElement(currentElement.Name, new BsonDocument());
							else if (currentElement.Value.IsBsonArray)
								partialElement = new BsonElement(currentElement.Name, new BsonArray());
							else
								continue; //nothing to do, not supported

							target.SetElement(partialElement);
						}
						else
							partialElement = target.GetElement(currentElement.Name);

						if (partialElement.Value.IsBsonDocument)
							PrepareFragmentFromFields(partialElement.Value.AsBsonDocument, currentElement.Value.AsBsonDocument, new string[] {string.Join(".", elementNames, 1, elementNames.Length - 1)});
						else if (partialElement.Value.IsBsonArray)
						{
							//for each element in the source array we need to see if we have a corresponding
							//element in this array
							BsonArray partialArray = partialElement.Value.AsBsonArray;
							BsonArray currentArray = currentElement.Value.AsBsonArray;

							for (int i = 0; i < currentArray.Count; i++)
							{
								BsonValue currentValue = currentArray[i];
								BsonValue partialValue = null;
								if (partialArray.Count > i)
									partialValue = partialArray[i];

								if (partialValue == null)
								{
									if (currentValue.IsBsonDocument)
									{
										partialValue = new BsonDocument();
										partialArray.Add(partialValue);
									}
								}

								if (partialValue != null)
									PrepareFragmentFromFields(partialValue.AsBsonDocument, currentValue.AsBsonDocument, new string[] { string.Join(".", elementNames, 1, elementNames.Length - 1) });	
							}
						}
					}
					else
					{
						if(!target.Contains(currentElement.Name))
							target.SetElement(currentElement);
					}
				}
			}
		}

		public virtual int Count(Query query)
		{
			return Count(query, null);
		}

		public virtual int Count(Query query, SqlTransaction transaction)
		{
			CollectionInstance instance = GetConfiguration();
			CollectionServerInstance[] servers = instance.Servers;

			Query q = query.Compile();
			

			StringBuilder sql = new StringBuilder(500);
			sql.Append(@"SELECT COUNT([BD].BsonDocumentID) as TotalCount
					FROM dbo." + _configuration.Prefix);
			sql.Append(instance.CollectionName);
			sql.Append(@"_I [BI]
						INNER JOIN dbo." + _configuration.Prefix);
			sql.Append(instance.CollectionName);
			sql.Append(@" [BD] ON ([BD].BsonDocumentID = [BI].BsonDocumentID)
					");
			sql.Append(q.SqlWhereClause);

			string finalSql = sql.ToString();

			if (servers.Length == 1)
				return ExecuteCountAgainstSingleConnection(servers[0].ConnectionId, query, transaction, instance, finalSql);
			else
			{
				int bucketThrowAway = 0;
				string connectionId = instance.GetConnectionIdForValues(query.StringValues, out bucketThrowAway);

				if (transaction != null && connectionId == null)
					throw new InvalidOperationException("can't execute a shard query using a transaction - distributed transactions not supported");

				if (connectionId != null)
					return ExecuteCountAgainstSingleConnection(connectionId, query, transaction, instance, finalSql);
				else
				{
					int combinedCount = 0;
					object syncCount = new object();

					//go through all of our servers and execute them
					Parallel.ForEach(servers, server =>
					{
						int singleCount = ExecuteCountAgainstSingleConnection(server.ConnectionId, query, transaction, instance, finalSql);
						if (singleCount > 0)
						{
							lock (syncCount)
							{
								combinedCount += singleCount;
							}
						}
					});

					return combinedCount;
				}
			}
		}

		public virtual BsonSqlCursor FindAs(Type documentType, Query query)
		{
			return BsonSqlCursor.Create(documentType, this, query);
		}

		public virtual BsonSqlCursor<TDocument> FindAs<TDocument>(Query query) where TDocument: class
		{
			return new BsonSqlCursor<TDocument>(this, query);
		}

		
		public virtual TDocument FindOneAs<TDocument>(Query query) where TDocument : class
		{
			return new BsonSqlCursor<TDocument>(this, query).SetLimit(1).FirstOrDefault<TDocument>();
		}

		public virtual TDocument FindOneAs<TDocument>(Query query, SqlTransaction transaction) where TDocument : class
		{
			return new BsonSqlCursor<TDocument>(this, query).SetLimit(1).SetTransaction(transaction).FirstOrDefault<TDocument>();
		}

		public virtual TDocument FindOneAs<TDocument>(Query query, bool replicaOk) where TDocument : class
		{
			return new BsonSqlCursor<TDocument>(this, query).SetLimit(1).SetReplicaOk(replicaOk).FirstOrDefault<TDocument>();
		}

		public virtual TDocument FindOneAs<TDocument>(Query query, params string[] fields) where TDocument : class
		{
			return new BsonSqlCursor<TDocument>(this, query).SetLimit(1).SetFields(fields).FirstOrDefault<TDocument>();
		}

		public virtual TDocument FindOneAs<TDocument>(Query query, QueryFlags flags) where TDocument : class
		{
			return new BsonSqlCursor<TDocument>(this, query).SetLimit(1).SetFlags(flags).FirstOrDefault<TDocument>();
		}

		public virtual TDocument FindOneAs<TDocument>(Query query, SqlTransaction transaction, QueryFlags flags, params string[] fields) where TDocument : class
		{
			return new BsonSqlCursor<TDocument>(this, query).SetLimit(1).SetTransaction(transaction).SetFlags(flags).SetFields(fields).FirstOrDefault<TDocument>();
		}

		public virtual TDocument FindOneByIdAs<TDocument>(Guid id) where TDocument : class
		{
			return FindOneByIdAs<TDocument>(id, null, QueryFlags.None, null);
		}

		public virtual TDocument FindOneByIdAs<TDocument>(Guid id, SqlTransaction transaction) where TDocument : class
		{
			return FindOneByIdAs<TDocument>(id, transaction, QueryFlags.None, null);
		}

		public virtual TDocument FindOneByIdAs<TDocument>(Guid id, bool replicaOk) where TDocument : class
		{
			return FindOneByIdAs<TDocument>(id, null, (replicaOk) ? QueryFlags.ReplicaOk : QueryFlags.None, null);
		}

		public virtual TDocument FindOneByIdAs<TDocument>(Guid id, params string[] fields) where TDocument : class
		{
			return FindOneByIdAs<TDocument>(id, null, QueryFlags.None, fields);
		}

		public virtual TDocument FindOneByIdAs<TDocument>(Guid id, QueryFlags flags) where TDocument : class
		{
			return FindOneByIdAs<TDocument>(id, null, flags, null);
		}

		public virtual TDocument FindOneByIdAs<TDocument>(Guid id, SqlTransaction transaction, QueryFlags flags, params string[] fields) where TDocument : class
		{
			return new BsonSqlCursor<TDocument>(this, _findOneById.Bind(new BsonDocument() { {"BsonDocumentID", id.ToString()} })).SetLimit(1).SetTransaction(transaction).SetFlags(flags).SetFields(fields).FirstOrDefault<TDocument>();
		}

		public virtual TDocument FindAndModify<TDocument>(Query q, object update) where TDocument : class
		{
			return FindAndModify<TDocument>(q, update, null, false, null);
		}

		public virtual TDocument FindAndModify<TDocument>(Query q, object update, SqlTransaction transaction) where TDocument : class
		{
			return FindAndModify<TDocument>(q, update, null, false, transaction);
		}

		public virtual TDocument FindAndModify<TDocument>(Query q, object update, IEnumerable<string> fields) where TDocument : class
		{
			return FindAndModify<TDocument>(q, update, fields, false, null);
		}

		public virtual TDocument FindAndModify<TDocument>(Query q, object update, IEnumerable<string> fields, SqlTransaction transaction) where TDocument : class
		{
			return FindAndModify<TDocument>(q, update, fields, false, transaction);
		}

		public virtual TDocument FindAndModify<TDocument>(Query q, object update, bool returnOld) where TDocument : class
		{
			return FindAndModify<TDocument>(q, update, null, returnOld, null);
		}

		public virtual TDocument FindAndModify<TDocument>(Query q, object update, bool returnOld, SqlTransaction transaction) where TDocument : class
		{
			return FindAndModify<TDocument>(q, update, null, returnOld, transaction);
		}

		/// <summary>
		/// updates 1 document with the update fragment
		/// </summary>
		/// <typeparam name="TDocument"></typeparam>
		/// <param name="q">the query to use to find the document</param>
		/// <param name="update">the fragment to use for the update</param>
		/// <param name="fields">optional set of fields to return - instead of entire object</param>
		/// <param name="returnOld">true if you want the before version, otherwise you get the after</param>
		/// <returns></returns>
		public virtual TDocument FindAndModify<TDocument>(Query q, object update, IEnumerable<string> fields, bool returnOld, SqlTransaction transaction) where TDocument : class
		{
			//need to first find the single document by creating our own cursor
			BsonSqlCursor documentFinder = this.FindAs<BsonDocument>(q).SetTransaction(transaction).SetLimit(1);
			
			BsonDocument document = null;
			foreach (BsonDocument found in documentFinder)
			{
				document = found;
			}

			if (document == null)
				return default(TDocument);

			BsonDocument original = null;
			if (returnOld)
				original = document.DeepClone().AsBsonDocument; //so we have the original

			//now we merge with the fragment
			BsonDocument fragment = BsonSqlSerializer.SerializeToDocument(update);
			document.Merge(fragment, true);

			//now we save the updated document
			//TODO: worry about any consistency here???
			this.Upsert(document, transaction);

			//now we return the right thing
			BsonDocument toReturn = (returnOld) ? original : document;

			if (fields != null && fields.Count() > 0)
			{
				return BsonSqlSerializer.Deserialize<TDocument>(PrepareFragmentFromFields(toReturn, fields.ToArray()));
			}

			//the version can cause problems with documents not expecting it
			//so should it be removed if not deserializing into a bson document
			if (typeof(TDocument) == typeof(BsonDocument))
				return toReturn as TDocument;
			else if (toReturn.Contains("_v"))
				toReturn.Remove("_v");
				
			return BsonSqlSerializer.Deserialize<TDocument>(toReturn);
		}

		public virtual void Remove(Query query)
		{
			Remove(query, 0);
		}

		public virtual void Remove(Query query, int limit)
		{
			Remove(query, limit, null);
		}

		public virtual void Remove(Query query, int limit, SqlTransaction transaction)
		{
			CollectionInstance instance = GetConfiguration();
			CollectionServerInstance[] servers = instance.Servers;
			Query q = query.Compile();

			StringBuilder sql = new StringBuilder();
			sql.Append("DELETE ");
			if (limit > 0)
			{
				sql.Append("TOP ");
				sql.Append(limit.ToString());
			}

            sql.Append(" dbo." + _configuration.Prefix);
			sql.Append(instance.CollectionName);
			sql.Append(@" 
					FROM dbo." + _configuration.Prefix);
			sql.Append(instance.CollectionName);
			sql.Append(@"_I [BI]
						INNER JOIN dbo." + _configuration.Prefix);
			sql.Append(instance.CollectionName);
			sql.Append(@" [BD] ON ([BD].BsonDocumentID = [BI].BsonDocumentID)
					");
			sql.AppendLine(q.SqlWhereClause);
			sql.AppendLine(q.SqlOrderByClause);

			sql.AppendLine();

			sql.Append("DELETE ");
			if (limit > 0)
			{
				sql.Append("TOP ");
				sql.Append(limit.ToString());
			}

            sql.Append(" dbo." + _configuration.Prefix);
			sql.Append(instance.CollectionName);
			sql.Append(@"_I 
					FROM dbo." + _configuration.Prefix);
			sql.Append(instance.CollectionName);
			sql.Append(@"_I [BI]
						");
			sql.AppendLine(q.SqlWhereClause);
			sql.AppendLine(q.SqlOrderByClause);

			string finalSql = sql.ToString();

			if (servers.Length == 1)
				ExecuteRemoveAgainstSingleConnection(servers[0].ConnectionId, query, limit, transaction, instance, finalSql);
			else
			{
				int bucketThrowAway = 0;
				string connectionId = instance.GetConnectionIdForValues(query.StringValues, out bucketThrowAway);

				if (transaction != null && connectionId == null)
					throw new InvalidOperationException("can't execute a shard query using a transaction - distributed transactions not supported");

				if (connectionId != null)
					ExecuteRemoveAgainstSingleConnection(connectionId, query, limit, transaction, instance, finalSql);
				else
				{
					//go through all of our servers and execute them
					Parallel.ForEach(servers, server =>
					{
						ExecuteRemoveAgainstSingleConnection(server.ConnectionId, query, limit, transaction, instance, finalSql);
					});
				}
			}
		}

		public virtual void RemoveById(Guid documentId)
		{
			RemoveById(documentId, null);
		}

		public virtual void RemoveById(Guid documentId, SqlTransaction transaction)
		{
			Query q = QueryBuilder.Where(WhereClauseBuilder.CreateStatic("BsonDocumentID", Comparison.Equals, documentId.ToString()));
			Remove(q, 0, transaction);
		}


		private void ExecuteRemoveAgainstSingleConnection(string connectionId, Query query, int limit, SqlTransaction transaction, CollectionInstance instance, string sql)
		{
            SqlCommand command = query.PrepareCommandForExecution(GetIndexCache(instance).UniqueList);
			command.CommandText = sql;
			ExecuteCommandNonQuery(command, connectionId, transaction, true, null, null);
		}

		private class IndexSqlCache
		{
			public string InsertOnlySql { get; set; }
			public string Sql { get; set; }
			public Dictionary<string, IndexKey> ParameterMap { get; set; }
			public SqlCommand Command { get; set; }
			public bool DoNothing { get; set; }
            public Dictionary<string, IndexKey> UniqueList { get; set; }

			public IndexSqlCache()
			{
				ParameterMap = new Dictionary<string, IndexKey>();
				DoNothing = true;
			}
		}

		

		

	}

	
}