diff --git a/.gitignore b/.gitignore
index 831b7c8a..d8b0e0a4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,6 +6,9 @@ datasets.toml
 scratch/
 *.ipynb_checkpoints
 .ruff_cache
+notebooks/
+*.parquet
+.DS_Store
 
 # DuckDB
 *.duckdb
diff --git a/src/matchbox/server/postgresql/utils/insert.py b/src/matchbox/server/postgresql/utils/insert.py
index c58abd84..c68ede77 100644
--- a/src/matchbox/server/postgresql/utils/insert.py
+++ b/src/matchbox/server/postgresql/utils/insert.py
@@ -207,67 +207,59 @@ def _cluster_results_to_hierarchical(
         clusters: Connected components at each threshold
 
     Returns:
-        List of (parent, child, threshold) tuples representing the hierarchy
+        list of (parent, child, threshold) tuples representing the hierarchy
     """
-    # Create initial hierarchy from base components
     prob_df = probabilities.dataframe
     cluster_df = clusters.dataframe
 
+    # Sort thresholds in descending order
     thresholds = sorted(cluster_df["threshold"].unique(), reverse=True)
 
-    # Add all clusters corresponding to a simple two-item probability edge
-    hierarchy = []
-    for _, row in prob_df.iterrows():
-        parent, left_id, right_id, prob = row[
-            ["hash", "left_id", "right_id", "probability"]
-        ]
-        hierarchy.extend(
-            [(parent, left_id, float(prob)), (parent, right_id, float(prob))]
-        )
-
-    # Create adjacency structure for quick lookups
-    adj_dict: dict[bytes, set[tuple[bytes, float]]] = defaultdict(set)
-    for parent, child, prob in hierarchy:
-        adj_dict[child].add((parent, prob))
+    hierarchy: list[tuple[bytes, bytes, float]] = []
+    ultimate_parents: dict[bytes, set[bytes]] = defaultdict(set)
 
-    # Process each threshold level, getting clusters at each threshold
+    # Process each threshold level
     for threshold in thresholds:
         threshold_float = float(threshold)
 
-        current_clusters = cluster_df[cluster_df["threshold"] == threshold]
+        # Add new pairwise relationships at this threshold
+        current_probs = prob_df[prob_df["probability"] == threshold_float]
+
+        for _, row in current_probs.iterrows():
+            parent = row["hash"]
+            left_id = row["left_id"]
+            right_id = row["right_id"]
+
+            hierarchy.extend(
+                [
+                    (parent, left_id, threshold_float),
+                    (parent, right_id, threshold_float),
+                ]
+            )
+
+            ultimate_parents[left_id].add(parent)
+            ultimate_parents[right_id].add(parent)
+
+        # Process clusters at this threshold
+        current_clusters = cluster_df[cluster_df["threshold"] == threshold_float]
 
-        # Group by parent to process each component
+        # Group by parent to process components together
         for parent, group in current_clusters.groupby("parent"):
-            members = set(group["child"])
-            if len(members) <= 2:
-                continue
-
-            seen = set(members)
-            current = set(members)
-            ultimate_parents = set()
-
-            # Keep traversing until we've explored all paths
-            while current:
-                next_level = set()
-                # If any current nodes have no parents above threshold,
-                # they are ultimate parents for this threshold
-                for node in current:
-                    parents = {
-                        p for p, prob in adj_dict[node] if prob >= threshold_float
-                    }
-                    next_parents = parents - seen
-                    if not parents:  # No parents = ultimate parent
-                        ultimate_parents.add(node)
-
-                    next_level.update(next_parents)
-                    seen.update(parents)
-
-                current = next_level
-
-            for up in ultimate_parents:
+            children = set(group["child"])
+            if len(children) <= 2:
+                continue  # Skip pairs already handled by pairwise probabilities
+
+            current_ultimate_parents: set[bytes] = set()
+            for child in children:
+                current_ultimate_parents.update(ultimate_parents[child])
+
+            for up in current_ultimate_parents:
                 hierarchy.append((parent, up, threshold_float))
-                adj_dict[up].add((parent, threshold_float))
 
+            for child in children:
+                ultimate_parents[child] = {parent}
+
+    # Sort hierarchy by threshold (descending), then parent, then child
     return sorted(hierarchy, key=lambda x: (x[2], x[0], x[1]), reverse=True)