对相同对象的数据检索分组
上次修改时间： 2011年5月27日
适用范围： SharePoint Foundation 2010
为了改进性能，总是会尝试将针对同一对象的数据检索请求组合在一起。
在下面的示例中，Method1 和 Method2 都将检索网站的标题和说明以及"通知"列表的说明，只不过 Method1 的性能高于 Method2 的性能。
using System;
using Microsoft.SharePoint.Client;
namespace Microsoft.SDK.SharePointServices.Samples
{
class RetrieveData
{
// The following example increases performance by grouping the Title and Description
// property calls together in the same Load method call.
static void Method1()
{
ClientContext clientContext = new ClientContext("http://MyServer/sites/MySiteCollection");
Web oWebsite = clientContext.Web;
List oList = oWebsite.Lists.GetByTitle("Announcements");
clientContext.Load(oWebsite,
website => website.Title,
website => website.Description);
clientContext.Load(oList,
list => list.Description);
clientContext.ExecuteQuery();
}
// The following example decreases performance because the Title and Description
// property calls are not grouped together in the same Load method call.
static void Method2()
{
ClientContext clientContext = new ClientContext("http://MyServer/sites/MySiteCollection");
Web oWebsite = clientContext.Web;
List oList = oWebsite.Lists.GetByTitle("Announcements");
clientContext.Load(oWebsite,
website => website.Title);
clientContext.Load(oList,
list => list.Description);
clientContext.Load(oWebsite,
website => website.Description);
clientContext.ExecuteQuery();
}
}
}
Imports System
Imports Microsoft.SharePoint.Client
Namespace Microsoft.SDK.SharePointServices.Samples
Class RetrieveData
// The following example increases performance by grouping the Title and Description
// property calls together in the same Load method call.
Shared Sub Method1()
Dim clientContext As New ClientContext("http://MyServer/sites/MySiteCollection")
Dim oWebsite As Web = clientContext.Web
Dim oList As List = oWebsite.Lists.GetByTitle("Announcements")
clientContext.Load(oWebsite, Function(website) website.Title, _
Function(website) website.Description)
clientContext.Load(oList, Function(list) list.Description)
clientContext.ExecuteQuery()
End Sub 'Method1
' The following example decreases performance because the Title and Description
' property calls are not grouped together in the same Load method call.
Shared Sub Method2()
Dim clientContext As New ClientContext("http://MyServer/sites/MySiteCollection")
Dim oWebsite As Web = clientContext.Web
Dim oList As List = oWebsite.Lists.GetByTitle("Announcements")
clientContext.Load(oWebsite, Function(website) website.Title)
clientContext.Load(oList, Function(list) list.Description)
clientContext.Load(oWebsite, Function(website) website.Description)
clientContext.ExecuteQuery()
End Sub
End Class
End Namespace
// The following example increases performance by grouping the Title and Description
// property calls together in the same Load method call.
function Method1 () {
var clientContext = new SP.ClientContext('/sites/TestWebs/TestWeb1');
this.oWebsite = clientContext.get_web();
this.oList = oWebsite.get_lists().getByTitle('Announcements');
clientContext.load(oWebsite, 'Title', 'Description');
clientContext.load(oList, 'Description');
clientContext.executeQueryAsync(Function.createDelegate(this, this.onQuerySucceeded), Function.createDelegate(this, this.onQueryFailed));
}
// The following example decreases performance because the Title and Description
// property calls are not grouped together in the same Load method call.
function Method2 () {
var clientContext = new SP.ClientContext('/sites/TestWebs/TestWeb1');
this.oWebsite = clientContext.get_web();
this.oList = oWebsite.get_lists().getByTitle('Announcements');
clientContext.load(oWebsite, 'Title');
clientContext.load(oList, 'Description');
clientContext.load(oWebsite, 'Description');
clientContext.executeQueryAsync(Function.createDelegate(this, this.onQuerySucceeded), Function.createDelegate(this, this.onQueryFailed));
}
在 Method1 中，用于检索网站的标题和说明的代码将组合在一起；而在 Method2 中，用于检索这些属性的代码将由其他操作分离。Method2 将触发对同一网站对象的两个单独查询，从而导致出现针对同一对象的两个结果集。由于客户端库旨在返回一致的数据，因此第二个结果集将包含网站的标题和说明，而第一个结果集也将包含网站的标题。
下面的 SQL 命令之间的差异说明了上述两种方法之间的不同之处。
Method1:
SELECT Title, Description FROM Webs WHERE ...
SELECT Description FROM Lists WHERE ...
Method2:
SELECT Title FROM Webs WHERE ...
SELECT Description FROM Lists WHERE ...
SELECT Title, Description FROM Webs WHERE ...