Collection Of using SPSiteDataQuery in whole site

To set up a query across a whole site collection you can use the SPSiteDataQuery object.

The following method fetches all .doc files from all doclibs of the site collection and prints out a list of urls to those items.

public void TestSiteDataQuery()
{
  using (SPSite site = new SPSite("http://localhost"))
  {
    using (SPWeb web = site.OpenWeb("/"))
    {
      SPSiteDataQuery query = new SPSiteDataQuery();

      // Search in doclibs only
      query.Lists = "<Lists BaseType='1' />";

      // Only .doc files
      query.Query =
      @"<Where>
          <Eq>
            <FieldRef Name='DocIcon' />
            <Value Type='Computed'>doc</Value>
          </Eq>
        </Where>";

      // Select only needed columns: file reference
      query.ViewFields = "<FieldRef Name='FileRef' />";

      // Search in all webs of the site collection
      query.Webs = "<Webs Scope='SiteCollection' />";

      // Perform the query
      DataTable table = web.GetSiteData(query);

      // Generate an absolute url for each document
      foreach (DataRow row in table.Rows)
      {
        string relativeUrl =
          row["FileRef"].ToString().Substring(
            row["FileRef"].ToString().IndexOf("#") + 1);
        string fullUrl = site.MakeFullUrl(relativeUrl);

        // Write urls to console
        Console.WriteLine(fullUrl);
      }
    }
  }
}

If you have better solution, just tell me !