我正在寻找插入实体框架的最快方法。

我之所以问这个问题,是因为您有一个活动的TransactionScope,并且插入量很大(4000+)。它可能会持续超过10分钟(事务的默认超时),这将导致事务不完整。


当前回答

下面是使用实体框架和使用SqlBulkCopy类之间的性能比较,具体示例为:如何将复杂对象批量插入SQL Server数据库

正如其他人已经强调的,ORM不应用于批量操作。它们提供了灵活性、关注点分离和其他好处,但批量操作(批量读取除外)不是其中之一。

其他回答

另一种选择是使用Nuget提供的SqlBulkTools。它非常容易使用,并且具有一些强大的功能。

例子:

var bulk = new BulkOperations();
var books = GetBooks();

using (TransactionScope trans = new TransactionScope())
{
    using (SqlConnection conn = new SqlConnection(ConfigurationManager
    .ConnectionStrings["SqlBulkToolsTest"].ConnectionString))
    {
        bulk.Setup<Book>()
            .ForCollection(books)
            .WithTable("Books") 
            .AddAllColumns()
            .BulkInsert()
            .Commit(conn);
    }

    trans.Complete();
}

有关更多示例和高级用法,请参阅文档。免责声明:我是这个图书馆的作者,任何观点都是我自己的观点。

记下几点,这是我的实施,我的改进以及其他回答和评论。

改进:

从我的实体获取SQL连接字符串仅在某些部分使用SQLBulk,其余部分仅使用实体框架使用与SQL数据库相同的日期表列名,无需映射每个列使用与SQL Datatable相同的Datatable名称public void InsertBulkDatatable(DataTable数据表){EntityConnectionStringBuilder entityBuilder=新的EntityConnectionStringBuilder(ConfigurationManager.ConnectionStrings[“MyDbContextConnectionName”].ConnectionString);string cs=entityBuilder.ProviderConnectionString;使用(varconnection=newSqlConnection(cs)){SqlTransaction事务=null;connection.Open();尝试{transaction=connection.BegginTransaction();使用(var sqlBulkCopy=新的sqlBulkCopy(连接,SqlBulkCopyOptions.TableLock,事务)){sqlBulkCopy.DestinationTableName=dataTable.TableName//使用SQL数据表在c中命名数据表#//映射列foreach(dataTable.Columns中的DataColumn列){sqlBulkCopy.ColumnMappings.Add(column.ColumnName,column.ColumnName);}sqlBulkCopy.WriteToServer(数据表);}transaction.Commit();}catch(异常){transaction.Rollback();}}}

〔2019更新〕EF Core 3.1

如上所述,在EF Core中禁用AutoDetectChangesEnabled非常有效:插入时间除以100(从几分钟到几秒,10k条记录具有交叉表关系)

更新的代码为:

context.ChangeTracker.AutoDetectChangesEnabled = false;
foreach (IRecord record in records) {
    //Add records to your database        
}
context.ChangeTracker.DetectChanges();
context.SaveChanges();
context.ChangeTracker.AutoDetectChangesEnabled = true; //do not forget to re-enable

我知道这是一个非常古老的问题,但这里的一个家伙说,他开发了一个扩展方法,可以在EF中使用批量插入,当我检查时,我发现这个库今天的价格是599美元(对于一个开发人员来说)。也许对于整个库来说这是有意义的,但是对于大容量插入来说这太多了。

这是我做的一个非常简单的扩展方法。我首先将其与数据库配对使用(不首先使用代码进行测试,但我认为这是一样的)。使用上下文名称更改YourEntitys:

public partial class YourEntities : DbContext
{
    public async Task BulkInsertAllAsync<T>(IEnumerable<T> entities)
    {
        using (var conn = new SqlConnection(Database.Connection.ConnectionString))
        {
            await conn.OpenAsync();

            Type t = typeof(T);

            var bulkCopy = new SqlBulkCopy(conn)
            {
                DestinationTableName = GetTableName(t)
            };

            var table = new DataTable();

            var properties = t.GetProperties().Where(p => p.PropertyType.IsValueType || p.PropertyType == typeof(string));

            foreach (var property in properties)
            {
                Type propertyType = property.PropertyType;
                if (propertyType.IsGenericType &&
                    propertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
                {
                    propertyType = Nullable.GetUnderlyingType(propertyType);
                }

                table.Columns.Add(new DataColumn(property.Name, propertyType));
            }

            foreach (var entity in entities)
            {
                table.Rows.Add(
                    properties.Select(property => property.GetValue(entity, null) ?? DBNull.Value).ToArray());
            }

            bulkCopy.BulkCopyTimeout = 0;
            await bulkCopy.WriteToServerAsync(table);
        }
    }

    public void BulkInsertAll<T>(IEnumerable<T> entities)
    {
        using (var conn = new SqlConnection(Database.Connection.ConnectionString))
        {
            conn.Open();

            Type t = typeof(T);

            var bulkCopy = new SqlBulkCopy(conn)
            {
                DestinationTableName = GetTableName(t)
            };

            var table = new DataTable();

            var properties = t.GetProperties().Where(p => p.PropertyType.IsValueType || p.PropertyType == typeof(string));

            foreach (var property in properties)
            {
                Type propertyType = property.PropertyType;
                if (propertyType.IsGenericType &&
                    propertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
                {
                    propertyType = Nullable.GetUnderlyingType(propertyType);
                }

                table.Columns.Add(new DataColumn(property.Name, propertyType));
            }

            foreach (var entity in entities)
            {
                table.Rows.Add(
                    properties.Select(property => property.GetValue(entity, null) ?? DBNull.Value).ToArray());
            }

            bulkCopy.BulkCopyTimeout = 0;
            bulkCopy.WriteToServer(table);
        }
    }

    public string GetTableName(Type type)
    {
        var metadata = ((IObjectContextAdapter)this).ObjectContext.MetadataWorkspace;
        var objectItemCollection = ((ObjectItemCollection)metadata.GetItemCollection(DataSpace.OSpace));

        var entityType = metadata
                .GetItems<EntityType>(DataSpace.OSpace)
                .Single(e => objectItemCollection.GetClrType(e) == type);

        var entitySet = metadata
            .GetItems<EntityContainer>(DataSpace.CSpace)
            .Single()
            .EntitySets
            .Single(s => s.ElementType.Name == entityType.Name);

        var mapping = metadata.GetItems<EntityContainerMapping>(DataSpace.CSSpace)
                .Single()
                .EntitySetMappings
                .Single(s => s.EntitySet == entitySet);

        var table = mapping
            .EntityTypeMappings.Single()
            .Fragments.Single()
            .StoreEntitySet;

        return (string)table.MetadataProperties["Table"].Value ?? table.Name;
    }
}

您可以对继承自IEnumerable的任何集合使用它,如下所示:

await context.BulkInsertAllAsync(items);

SqlBulkCopy速度极快

这是我的实现:

// at some point in my calling code, I will call:
var myDataTable = CreateMyDataTable();
myDataTable.Rows.Add(Guid.NewGuid,tableHeaderId,theName,theValue); // e.g. - need this call for each row to insert

var efConnectionString = ConfigurationManager.ConnectionStrings["MyWebConfigEfConnection"].ConnectionString;
var efConnectionStringBuilder = new EntityConnectionStringBuilder(efConnectionString);
var connectionString = efConnectionStringBuilder.ProviderConnectionString;
BulkInsert(connectionString, myDataTable);

private DataTable CreateMyDataTable()
{
    var myDataTable = new DataTable { TableName = "MyTable"};
// this table has an identity column - don't need to specify that
    myDataTable.Columns.Add("MyTableRecordGuid", typeof(Guid));
    myDataTable.Columns.Add("MyTableHeaderId", typeof(int));
    myDataTable.Columns.Add("ColumnName", typeof(string));
    myDataTable.Columns.Add("ColumnValue", typeof(string));
    return myDataTable;
}

private void BulkInsert(string connectionString, DataTable dataTable)
{
    using (var connection = new SqlConnection(connectionString))
    {
        connection.Open();
        SqlTransaction transaction = null;
        try
        {
            transaction = connection.BeginTransaction();

            using (var sqlBulkCopy = new SqlBulkCopy(connection, SqlBulkCopyOptions.TableLock, transaction))
            {
                sqlBulkCopy.DestinationTableName = dataTable.TableName;
                foreach (DataColumn column in dataTable.Columns) {
                    sqlBulkCopy.ColumnMappings.Add(column.ColumnName, column.ColumnName);
                }

                sqlBulkCopy.WriteToServer(dataTable);
            }
            transaction.Commit();
        }
        catch (Exception)
        {
            transaction?.Rollback();
            throw;
        }
    }
}