Reduce db connections, improve merge mt/lt

crates/items_2/src/eventsdim0.rs

@@ -859,9 +859,9 @@ impl<STY: ScalarOps> Events for EventsDim0<STY> {
         Box::new(Self::empty())
     }
 
-    fn drain_into_evs(&mut self, dst: &mut Box<dyn Events>, range: (usize, usize)) -> Result<(), MergeError> {
+    fn drain_into_evs(&mut self, dst: &mut dyn Events, range: (usize, usize)) -> Result<(), MergeError> {
         // TODO as_any and as_any_mut are declared on unrelated traits. Simplify.
-        if let Some(dst) = dst.as_mut().as_any_mut().downcast_mut::<Self>() {
+        if let Some(dst) = dst.as_any_mut().downcast_mut::<Self>() {
             // TODO make it harder to forget new members when the struct may get modified in the future
             let r = range.0..range.1;
             dst.tss.extend(self.tss.drain(r.clone()));
@@ -869,7 +869,12 @@ impl<STY: ScalarOps> Events for EventsDim0<STY> {
             dst.values.extend(self.values.drain(r.clone()));
             Ok(())
         } else {
-            error!("downcast to EventsDim0 FAILED");
+            error!(
+                "downcast to EventsDim0 FAILED\n\n{}\n\n{}\n\n",
+                self.type_name(),
+                dst.type_name()
+            );
+            panic!();
             Err(MergeError::NotCompatible)
         }
     }
@@ -989,6 +994,12 @@ impl<STY: ScalarOps> Events for EventsDim0<STY> {
         ciborium::into_writer(&ret, &mut buf).unwrap();
         buf
     }
+
+    fn clear(&mut self) {
+        self.tss.clear();
+        self.pulses.clear();
+        self.values.clear();
+    }
 }
 
 #[derive(Debug)]