SharePoint List Item Operations

Do not use SPList.Items.
SPList.Items selects all items from all subfolders, including all fields in the list. Use the following alternatives for each use case.

• Adding an item
  Instead of calling SPList.Items.Add, use SPList.AddItem.
  
• Retrieving all items in a list
  Instead of using SPList.Items, use SPList.GetItems(SPQuery query) . Apply filters, if appropriate, and specify only the fields you need to make the query more efficient. If the list contains more than 2,000 items, paginate the list in increments of no more than 2,000 items. The following code example shows how to paginate a large list.

Good Coding Practice Retrieving items with SPList.GetItems

SPQuery query = new SPQuery();
SPListItemCollection spListItems ; 
string lastItemIdOnPage = null; // Page position.
int itemCount = 2000
 
while (itemCount == 2000)
{
    // Include only the fields you will use.
    query.ViewFields = "<FieldRef Name=\"ID\"/><FieldRef Name=\"ContentTypeId\"/>";   
    query.RowLimit = 2000; // Only select the top 2000.
    // Include items in a subfolder (if necessary).
    query.ViewAttributes = "Scope=\"Recursive\"";
    StringBuilder sb = new StringBuilder();
    // To make the query order by ID and stop scanning the table, specify the OrderBy override attribute.
    sb.Append("<OrderBy Override=\"TRUE\"><FieldRef Name=\"ID\"/></OrderBy>");
    //.. Append more text as necessary ..
    query.Query = sb.ToString();
    // Get 2,000 more items.
 
    SPListItemCollectionPosition pos = new SPListItemCollectionPosition(lastItemIdOnPage);
    query.ListItemCollectionPosition = pos; //Page info.
    spListItems = spList.GetItems(query);
    lastItemIdOnPage = spListItems.ListItemCollectionPosition.PagingInfo;
    // Code to enumerate the spListItems.
    // If itemCount <2000, finish the enumeration.
    itemCount = spListItems.Count;

}

**********************************************

SPWeb oWebsite = SPContext.Current.Web;
SPList oList = oWebsite.Lists["Announcements"];

SPQuery oQuery = new SPQuery();
oQuery.RowLimit = 10;
int intIndex = 1;

do
{
    Response.Write("<BR>Page: " + intIndex + "<BR>");
    SPListItemCollection collListItems = oList.GetItems(oQuery);

    foreach (SPListItem oListItem in collListItems)
    {
        Response.Write(SPEncode.HtmlEncode(oListItem["Title"].ToString()) +"<BR>");
    }

    oQuery.ListItemCollectionPosition = collListItems.ListItemCollectionPosition;
    intIndex++;
} while (oQuery.ListItemCollectionPosition != null);

***********************************************

        


          
Poor Performing Methods and Properties
            
          
Better Performing Alternatives
            
        

          
SPList.Items.Count
              
            
          
SPList.ItemCount
              
            
        

          
SPList.Items.XmlDataSchema
              
            
          
Create an SPQuery object to retrieve only the items you want.
        

          
SPList.Items.NumberOfFields
              
            
          
Create an SPQuery object (specifying the ViewFields) to retrieve only the items you want.
        

          
SPList.Items[System.Guid] 
              
            
          
SPList.GetItemByUniqueId(System.Guid) 
              
            
        

          
SPList.Items[System.Int32] 
              
            
          
SPList.GetItemById(System.Int32) 
              
            
        

          
SPList.Items.GetItemById(System.Int32) 
              
            
          
SPList.GetItemById(System.Int32) 
              
            
        

          
SPList.Items.ReorderItems(System.Boolean[],System.Int32[],System.Int32) 
              
            
          
Perform a paged query by using SPQuery and reorder the items within each page.
        

          
SPList.Items.ListItemCollectionPosition
              
            
          
ContentIterator.ProcessListItems(SPList, ContentIterator.ItemProcessor, ContentIterator.ItemProcessorErrorCallout)
               (Microsoft SharePoint Server 2010 only)
        

          
SPList.Items.ListItemCollectionPosition
              
            
          
ContentIterator.ProcessListItems(SPList, ContentIterator.ItemProcessor, ContentIterator.ItemProcessorErrorCallout)
               (SharePoint Server 2010 only)