diff --git a/core/dbsearch.class.php b/core/dbsearch.class.php
index e27c2d6b2..e4880aff7 100644
--- a/core/dbsearch.class.php
+++ b/core/dbsearch.class.php
@@ -567,6 +567,10 @@ abstract class DBSearch
 		return $oSQLQuery;
 	}
 
+	public abstract function GetSQLQueryStructure(
+		$aAttToLoad, $bGetCount, $aGroupByExpr = null, $aSelectedClasses = null
+	);
+
 	////////////////////////////////////////////////////////////////////////////
 	//
 	// Cache/Trace/Log queries
diff --git a/core/dbunionsearch.class.php b/core/dbunionsearch.class.php
index 07f2b8cee..a533eb693 100644
--- a/core/dbunionsearch.class.php
+++ b/core/dbunionsearch.class.php
@@ -474,7 +474,7 @@ class DBUnionSearch extends DBSearch
 		throw new Exception('MakeUpdateQuery is not implemented for the unions!');
 	}
 
-	protected function GetSQLQueryStructure($aAttToLoad, $bGetCount, $aGroupByExpr = null, $aSelectedClasses = null)
+	public function GetSQLQueryStructure($aAttToLoad, $bGetCount, $aGroupByExpr = null, $aSelectedClasses = null)
 	{
 		if (count($this->aSearches) == 1)
 		{