Index: branches/5.2.x/core/kernel/db/dbitem.php
===================================================================
--- branches/5.2.x/core/kernel/db/dbitem.php
+++ branches/5.2.x/core/kernel/db/dbitem.php
@@ -736,7 +736,25 @@
 
 		$sql = '';
 
-		$set_fields = isset($update_fields) ? $update_fields : array_keys($this->FieldValues);
+		if ( isset($update_fields) ) {
+			$set_fields = $update_fields;
+			$forgotten_fields = array_diff(array_keys($this->GetChangedFields()), $set_fields);
+
+			if ( $forgotten_fields ) {
+				trigger_error(
+					sprintf(
+						'These fields weren\'t updated for #%s record in "%s" unit: %s',
+						$this->GetID(),
+						$this->getPrefixSpecial(),
+						implode(', ', $forgotten_fields)
+					),
+					E_USER_WARNING
+				);
+			}
+		}
+		else {
+			$set_fields = array_keys($this->FieldValues);
+		}
 
 		foreach ($set_fields as $field_name) {
 			if ( $this->skipField($field_name) ) {