针对 SQL Server 2008 使用 NHibernate 2.1.2.4000。目标表没有触发器或无关索引。很简单：
create table LogEntries (
Id INT IDENTITY NOT NULL,
HostName NVARCHAR(32) not null,
UserName NVARCHAR(64) not null,
LogName NVARCHAR(512) not null,
Timestamp DATETIME not null,
Level INT not null,
Thread NVARCHAR(64) not null,
Message NVARCHAR(MAX) not null,
primary key (Id)
)
我的实体映射是：
<class name="LogEntry" table="LogEntries">
<id name="Id" unsaved-value="0">
<generator class="native"/>
</id>
<property name="HostName" length="32" not-null="true"/>
<property name="UserName" length="64" not-null="true"/>
<property name="LogName" length="512" not-null="true"/>
<property name="Timestamp" type="utcdatetime" not-null="true"/>
<property name="Level" not-null="true"/>
<property name="Thread" length="64" not-null="true"/>
<property name="Message">
<column name="Message" sql-type="NVARCHAR(MAX)" not-null="true"/>
</property>
</class>
现在，考虑以下测试用例：
[Fact]
public void bulk_insert_test()
{
var batchSize = 100;
var numberItems = 10000;
var configuration = new NHibernate.Cfg.Configuration().Configure();
configuration.SetProperty("connection.connection_string", @"my_conn_string");
configuration.SetProperty("adonet.batch_size", batchSize.ToString());
var sessionFactory = configuration.BuildSessionFactory();
var ts = this.WriteWithNH(sessionFactory, numberItems);
////var ts = this.WriteWithBC(sessionFactory, numberItems, batchSize);
Console.WriteLine("Saving {0} items with batch size {1}: {2}", numberItems, batchSize, ts);
}
public TimeSpan WriteWithNH(ISessionFactory sessionFactory, int numberItems)
{
using (var session = sessionFactory.OpenStatelessSession())
using (var transaction = session.BeginTransaction())
{
session.Insert(new LogEntry()
{
HostName = "host",
UserName = "user",
LogName = "log",
Level = 0,
Thread = "thread",
Timestamp = DateTime.UtcNow,
Message = "Warm up"
});
transaction.Commit();
}
var sw = Stopwatch.StartNew();
using (var session = sessionFactory.OpenStatelessSession())
using (var transaction = session.BeginTransaction())
{
for (var i = 0; i < numberItems; ++i)
{
session.Insert(new LogEntry()
{
HostName = "host",
UserName = "user",
LogName = "log",
Level = 0,
Thread = "thread",
Timestamp = DateTime.UtcNow,
Message = "Message " + i
});
}
transaction.Commit();
}
return sw.Elapsed;
}
public TimeSpan WriteWithBC(ISessionFactory sessionFactory, int numberItems, int batchSize)
{
using (var session = sessionFactory.OpenStatelessSession())
using (var bulkCopy = new SqlBulkCopy((SqlConnection)session.Connection))
{
bulkCopy.BatchSize = batchSize;
bulkCopy.DestinationTableName = "LogEntries";
var table = new DataTable("LogEntries");
table.Columns.Add("Id", typeof(int));
table.Columns.Add("HostName", typeof(string));
table.Columns.Add("UserName", typeof(string));
table.Columns.Add("LogName", typeof(string));
table.Columns.Add("Timestamp", typeof(DateTime));
table.Columns.Add("Level", typeof(int));
table.Columns.Add("Thread", typeof(string));
table.Columns.Add("Message", typeof(string));
var row = table.NewRow();
row["HostName"] = "host";
row["UserName"] = "user";
row["LogName"] = "log";
row["Timestamp"] = DateTime.UtcNow;
row["Level"] = 0L;
row["Thread"] = "thread";
row["Message"] = "Warm up";
table.Rows.Add(row);
bulkCopy.WriteToServer(table);
}
var sw = Stopwatch.StartNew();
using (var session = sessionFactory.OpenStatelessSession())
using (var bulkCopy = new SqlBulkCopy((SqlConnection)session.Connection))
{
bulkCopy.BatchSize = batchSize;
bulkCopy.DestinationTableName = "LogEntries";
var table = new DataTable("LogEntries");
table.Columns.Add("Id", typeof(int));
table.Columns.Add("HostName", typeof(string));
table.Columns.Add("UserName", typeof(string));
table.Columns.Add("LogName", typeof(string));
table.Columns.Add("Timestamp", typeof(DateTime));
table.Columns.Add("Level", typeof(int));
table.Columns.Add("Thread", typeof(string));
table.Columns.Add("Message", typeof(string));
for (var i = 0; i < numberItems; ++i)
{
var row = table.NewRow();
row["HostName"] = "host";
row["UserName"] = "user";
row["LogName"] = "log";
row["Timestamp"] = DateTime.UtcNow;
row["Level"] = 0;
row["Thread"] = "thread";
row["Message"] = "Message " + i;
table.Rows.Add(row);
}
bulkCopy.WriteToServer(table);
}
return sw.Elapsed;
}
以下是使用 NHibernate 执行插入时的一些示例输出：
Saving 10000 items with batch size 500: 00:00:12.3064936
Saving 10000 items with batch size 100: 00:00:12.3600981
Saving 10000 items with batch size 1: 00:00:12.8102670
作为一个比较点，您会看到我还实现了一个基于 BCP 的解决方案。这是一些示例输出：
Saving 10000 items with batch size 500: 00:00:00.3142613
Saving 10000 items with batch size 100: 00:00:00.6757417
Saving 10000 items with batch size 1: 00:00:26.2509605
显然，BCP 解决方案比 NH 解决方案快几英里。同样明显的是，批处理会影响 BCP 解决方案的速度，但不会影响 NH 解决方案的速度。当使用 NHibernate 进行插入时，NHProf 显示如下：
替代文字 http://img9.imageshack.us/img9/8407/screenshotac.png
只有INSERTs，没有SELECTs。有趣的是，NHProf 从来没有给我这个警告。
我已经尝试adonet.batch_size根据上面的测试用例在我的配置文件和代码中指定。
现在，我不希望 NH 解决方案能够达到 BCP 解决方案的速度，但我至少想知道为什么批处理不起作用。如果启用批处理功能足够好，那么我可能会在 BCP 上使用 NH 解决方案，以保持代码库更简单。
谁能解释为什么 NH 拒绝遵守 ADO.NET 批处理，以及我能做些什么来解决它？我读过的所有分散的 NH “文档”都指出，您需要做的就是指定adonet.batch_size并（最好）使用无状态会话，但我正在做这两件事。
谢谢