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。
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
这里编写的所有解决方案都无济于事,因为当您执行SaveChanges()时,insert语句会一个接一个地发送到数据库,这就是Entity的工作方式。
例如,如果您的数据库往返行程是50毫秒,那么插入所需的时间是记录数x 50毫秒。
您必须使用BulkInsert,以下是链接:https://efbulkinsert.codeplex.com/
通过使用它,我的插入时间从5-6分钟减少到10-12秒。
其他回答
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;
}
}
}
是的,SqlBulkUpdate确实是这类任务最快的工具。我想在.NETCore中找到“最省力”的通用方法,所以我最终使用了MarcGravell的优秀库FastMember,并为实体框架DB上下文编写了一个小小的扩展方法。工作速度极快:
using System.Collections.Generic;
using System.Linq;
using FastMember;
using Microsoft.Data.SqlClient;
using Microsoft.EntityFrameworkCore;
namespace Services.Extensions
{
public static class DbContextExtensions
{
public static void BulkCopyToServer<T>(this DbContext db, IEnumerable<T> collection)
{
var messageEntityType = db.Model.FindEntityType(typeof(T));
var tableName = messageEntityType.GetSchema() + "." + messageEntityType.GetTableName();
var tableColumnMappings = messageEntityType.GetProperties()
.ToDictionary(p => p.PropertyInfo.Name, p => p.GetColumnName());
using (var connection = new SqlConnection(db.Database.GetDbConnection().ConnectionString))
using (var bulkCopy = new SqlBulkCopy(connection))
{
foreach (var (field, column) in tableColumnMappings)
{
bulkCopy.ColumnMappings.Add(field, column);
}
using (var reader = ObjectReader.Create(collection, tableColumnMappings.Keys.ToArray()))
{
bulkCopy.DestinationTableName = tableName;
connection.Open();
bulkCopy.WriteToServer(reader);
connection.Close();
}
}
}
}
}
您应该考虑为此使用System.Data.SqlClient.SqlBulkCopy。这是文档,当然还有很多在线教程。
抱歉,我知道您正在寻找一个简单的答案来让EF做您想做的事情,但批量操作并不是ORM真正的用途。
如果您添加的实体()依赖于上下文中的其他预加载实体(例如导航财产),则Dispose()上下文会产生问题
我使用类似的概念来保持我的上下文较小,以实现相同的性能
但我只是分离已经SaveChanges()的实体,而不是Dispose()上下文并重新创建
public void AddAndSave<TEntity>(List<TEntity> entities) where TEntity : class {
const int CommitCount = 1000; //set your own best performance number here
int currentCount = 0;
while (currentCount < entities.Count())
{
//make sure it don't commit more than the entities you have
int commitCount = CommitCount;
if ((entities.Count - currentCount) < commitCount)
commitCount = entities.Count - currentCount;
//e.g. Add entities [ i = 0 to 999, 1000 to 1999, ... , n to n+999... ] to conext
for (int i = currentCount; i < (currentCount + commitCount); i++)
_context.Entry(entities[i]).State = System.Data.EntityState.Added;
//same as calling _context.Set<TEntity>().Add(entities[i]);
//commit entities[n to n+999] to database
_context.SaveChanges();
//detach all entities in the context that committed to database
//so it won't overload the context
for (int i = currentCount; i < (currentCount + commitCount); i++)
_context.Entry(entities[i]).State = System.Data.EntityState.Detached;
currentCount += commitCount;
} }
如果需要,用try-catch和TrasactionScope()将其包装起来,为了保持代码干净,没有在这里显示它们
尝试使用存储过程来获取要插入的数据的XML。