/// <summary>
		/// Deletes all data associated to a document.
		/// </summary>
		/// <param name="document">The document.</param>
		/// <param name="state">A state object passed from the index (can be <c>null</c> or a <see cref="T:DbTransaction" />).</param>
		private void DeleteDataForDocument(IDocument document, object state) {
			// 1. Delete all data related to a document
			// 2. Delete all words that have no more mappings

			ICommandBuilder builder = GetCommandBuilder();
			QueryBuilder queryBuilder = new QueryBuilder(builder);

			string query = queryBuilder.DeleteFrom("IndexDocument");
			query = queryBuilder.Where(query, "Name", WhereOperator.Equals, "DocName");
			List<Parameter> parameters = new List<Parameter>(1);
			parameters.Add(new Parameter(ParameterType.String, "DocName", document.Name));

			string subQuery = queryBuilder.SelectFrom("IndexWordMapping", new string[] { "Word" });
			subQuery = queryBuilder.GroupBy(subQuery, new string[] { "Word" });
			string query2 = queryBuilder.DeleteFrom("IndexWord");
			query2 = queryBuilder.WhereNotInSubquery(query2, "IndexWord", "Id", subQuery);

			query = queryBuilder.AppendForBatch(query, query2);
            query = queryBuilder.BuildBatchCommand(query);
			DbCommand command = null;
			if(state != null) command = builder.GetCommand((DbTransaction)state, query, parameters);
			else command = builder.GetCommand(connString, query, parameters);

			// Close only if state is null
			ExecuteNonQuery(command, state == null);
		}