In this article we will be seeing about Searchable columns in SharePoint 2010.

You can exclude site columns from search and indexing. Go to Site Actions => Site Settings => Site Administration => Searchable Columns.

ShareColumn1.gif

ShareColumn2.gif

Using C# exclude columns:

 using (SPSite site = new SPSite("http://servername:1111/"))
{
using (SPWeb web = site.RootWeb)
{
SPField field = web.Fields["_test"];
field.NoCrawl = true;
field.Update();
}
}

Using powershell exclude columns:

$site=Get-SPSite "http://servername:1111/"
$web=$site.RootWeb
$field=$web.Fields["_test"]
$field.NoCrawl=$true
$field.Update()