diff --git a/crates/dbsp/src/operator/dynamic/input_upsert.rs b/crates/dbsp/src/operator/dynamic/input_upsert.rs
index 38e0c68e925..a923f4b532e 100644
--- a/crates/dbsp/src/operator/dynamic/input_upsert.rs
+++ b/crates/dbsp/src/operator/dynamic/input_upsert.rs
@@ -307,7 +307,6 @@ where
                 .add_binary_operator(
                     <InputUpsert<Spine<B>, U, B>>::new(
                         factories.batch_factories.clone(),
-                        factories.opt_key_factory,
                         factories.opt_val_factory,
                         patch_func,
                     ),
@@ -480,7 +479,6 @@ where
     U: DataTrait + ?Sized,
 {
     batch_factories: B::Factories,
-    opt_key_factory: &'static dyn Factory<DynOpt<B::Key>>,
     opt_val_factory: &'static dyn Factory<DynOpt<B::Val>>,
     patch_func: PatchFunc<T::Val, U>,
 
@@ -501,13 +499,11 @@ where
 {
     pub fn new(
         batch_factories: B::Factories,
-        opt_key_factory: &'static dyn Factory<DynOpt<B::Key>>,
         opt_val_factory: &'static dyn Factory<DynOpt<B::Val>>,
         patch_func: PatchFunc<T::Val, U>,
     ) -> Self {
         Self {
             batch_factories,
-            opt_key_factory,
             opt_val_factory,
             patch_func,
             input_batch_stats: BatchSizeStats::new(),
@@ -579,7 +575,7 @@ where
             B::Builder::with_capacity(&self.batch_factories, n_updates * 2, n_updates * 2);
 
         // Current key for which we are processing updates.
-        let mut cur_key: Box<DynOpt<T::Key>> = self.opt_key_factory.default_box();
+        let mut cur_key = None;
 
         // Current value associated with the key after applying all processed updates
         // to it.
@@ -603,9 +599,9 @@ where
 
             // We finished processing updates for the previous key. Push them to the
             // builder and generate a retraction for the new key.
-            if cur_key.get() != Some(key) {
+            if cur_key != Some(key) {
                 // Push updates for the previous key to the builder.
-                if let Some(cur_key) = cur_key.get_mut() {
+                if let Some(cur_key) = cur_key {
                     if let Some(val) = cur_val.get_mut() {
                         key_updates.push_with(&mut |item| {
                             let (v, w) = item.split_mut();
@@ -625,7 +621,7 @@ where
                     key_updates.clear();
                 }
 
-                cur_key.from_ref(key);
+                cur_key = Some(key);
                 cur_val.set_none();
 
                 // Generate retraction if `key` is present in the trace.
@@ -670,7 +666,7 @@ where
         }
 
         // Push updates for the last key.
-        if let Some(cur_key) = cur_key.get_mut() {
+        if let Some(cur_key) = cur_key {
             if let Some(val) = cur_val.get_mut() {
                 key_updates.push_with(&mut |item| {
                     let (v, w) = item.split_mut();
@@ -839,7 +835,7 @@ where
         );
 
         // Current key for which we are processing updates.
-        let mut cur_key: Box<DynOpt<T::Key>> = self.factories.opt_key_factory.default_box();
+        let mut cur_key = None;
 
         // Current value associated with the key after applying all processed updates
         // to it.
@@ -867,9 +863,9 @@ where
 
             // We finished processing updates for the previous key. Push them to the
             // builder and generate a retraction for the new key.
-            if cur_key.get() != Some(key) {
+            if cur_key != Some(key) {
                 // Push updates for the previous key to the builder.
-                if let Some(cur_key) = cur_key.get_mut() {
+                if let Some(cur_key) = cur_key {
                     if let Some(val) = cur_val.get_mut() {
                         key_updates.push_with(&mut |item| {
                             let (v, w) = item.split_mut();
@@ -890,7 +886,7 @@ where
                 }
 
                 skip_key = false;
-                cur_key.from_ref(key);
+                cur_key = Some(key);
                 cur_val.set_none();
 
                 // Generate retraction if `key` is present in the trace.
@@ -970,7 +966,7 @@ where
         }
 
         // Push updates for the last key.
-        if let Some(cur_key) = cur_key.get_mut() {
+        if let Some(cur_key) = cur_key {
             if let Some(val) = cur_val.get_mut() {
                 key_updates.push_with(&mut |item| {
                     let (v, w) = item.split_mut();
diff --git a/crates/dbsp/src/trace/cursor/cursor_list.rs b/crates/dbsp/src/trace/cursor/cursor_list.rs
index d4082d82c04..2c43519a8ed 100644
--- a/crates/dbsp/src/trace/cursor/cursor_list.rs
+++ b/crates/dbsp/src/trace/cursor/cursor_list.rs
@@ -692,6 +692,10 @@ where
     fn seek_key_exact(&mut self, key: &K, hash: Option<u64>) -> bool {
         self.set_key_direction(None);
 
+        if self.cursors.is_empty() {
+            return false;
+        }
+
         let hash = hash.unwrap_or_else(|| key.default_hash());
         self.current_key.clear();
 
diff --git a/crates/dbsp/src/trace/ord/vec/indexed_wset_batch.rs b/crates/dbsp/src/trace/ord/vec/indexed_wset_batch.rs
index 6a05f101bee..a5f08b9228f 100644
--- a/crates/dbsp/src/trace/ord/vec/indexed_wset_batch.rs
+++ b/crates/dbsp/src/trace/ord/vec/indexed_wset_batch.rs
@@ -245,9 +245,20 @@ where
     O: OrdOffset,
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("VecIndexedWSet")
-            .field("layer", &self.layer)
-            .finish()
+        writeln!(f, "VecIndexedWSet:")?;
+        let mut cursor = self.cursor();
+        while let Some(key) = cursor.get_key() {
+            writeln!(f, "    key {key:?}:")?;
+            while let Some(val) = cursor.get_val() {
+                writeln!(f, "        value {val:?}:")?;
+                cursor.map_times(&mut |time, diff| {
+                    let _ = writeln!(f, "            ({time:?}, {diff:?})");
+                });
+                cursor.step_val();
+            }
+            cursor.step_key();
+        }
+        Ok(())
     }
 }