From a41a92978ddeaf8c789b42936861578b93403f3f Mon Sep 17 00:00:00 2001
From: Daniel Liu <139250065@qq.com>
Date: Tue, 17 Jun 2025 13:17:07 +0800
Subject: [PATCH] trie: small optimization of delete in fullNode case #22979
 (#1069)

---
 trie/trie.go | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/trie/trie.go b/trie/trie.go
index a1529ba4d2..45a2d6aecb 100644
--- a/trie/trie.go
+++ b/trie/trie.go
@@ -484,6 +484,14 @@ func (t *Trie) delete(n node, prefix, key []byte) (bool, node, error) {
 		n.flags = t.newFlag()
 		n.Children[key[0]] = nn
 
+		// Because n is a full node, it must've contained at least two children
+		// before the delete operation. If the new child value is non-nil, n still
+		// has at least two children after the deletion, and cannot be reduced to
+		// a short node.
+		if nn != nil {
+			return true, n, nil
+		}
+		// Reduction:
 		// Check how many non-nil entries are left after deleting and
 		// reduce the full Node to a short Node if only one entry is
 		// left. Since n must've contained at least two children