How to make a CAML Query union?

Question

I have a webpart with several CAML Querys that look like this:

SPSiteDataQuery qry = new SPSiteDataQuery();
qry.Lists = "<Lists ServerTemplate='104' Hidden='TRUE' />"; 
qry.Webs = "<Webs Scope='Recursive' />";
qry.ViewFields = "<FieldRef Name='Title' Nullable='TRUE' /><FieldRef Name='Author' /><FieldRef Name='Editor' /><FieldRef Name='Modified'/><FieldRef Name='Created'/>";
qry.RowLimit = 10;
qry.Query = "<OrderBy><FieldRef Name='Modified' Ascending='FALSE' /></OrderBy>";

return web.GetSiteData(qry);

With distincts ServerTemplates id for each query. They all are returning the same ViewFields.

The problem is that the execution of that can last more than 10 seconds. I would like to reduce this. Any idea how to do this? Is there any way to have an union of all CAML queries?

Answer 1

It looks like it isn't possible to include multiple ServerTemplates within one SpSiteDataQuery. Instead, you could try querying using ContentType.

For example:

// document libraries
qry.Lists = "<Lists BaseType=\"1\" />";
// ...
// code to query for "Document" or "Folder" content types
qry.Query = "<Where><Or><Eq><FieldRef Name="ContentType" /><Value Type="Text">Document</Value></Eq><Eq><FieldRef Name="ContentType" /><Value Type="Text">Folder</Value></Eq></Or></Where>";

Reference: Query multiple lists having different ServerTemplate with SpSiteDataQuery()