diff --git a/src/worktable.rs b/src/worktable.rs
index d2781a6..896fae9 100644
--- a/src/worktable.rs
+++ b/src/worktable.rs
@@ -245,10 +245,17 @@ impl WorkTable {
         }
     }
     pub fn retain(&mut self, f: impl Fn(&RowViewMut) -> bool) {
-        self.iter_mut().filter(f).for_each(|row| {
+        // remove from reverse order is generally faster
+        self.iter_mut().rev().filter(|x| !f(x)).for_each(|row| {
             row.remove();
         });
     }
+    pub fn clear(&mut self) {
+        self.column_values.iter_mut().for_each(|x| x.clear());
+        if let Some(primary_map) = &mut self.primary_map {
+            primary_map.clear();
+        }
+    }
 }
 
 pub type SyncWorkTable = Arc<RwLock<WorkTable>>;