diff --git a/internal/unionstore/memdb.go b/internal/unionstore/memdb.go
index cd0703e06..621e41bfe 100644
--- a/internal/unionstore/memdb.go
+++ b/internal/unionstore/memdb.go
@@ -833,3 +833,13 @@ func (n *memdbNode) getKeyFlags() kv.KeyFlags {
 func (n *memdbNode) setKeyFlags(f kv.KeyFlags) {
 	n.flags = (^nodeFlagsMask & n.flags) | uint16(f)
 }
+
+// RemoveFromBuffer removes a record from the mem buffer. It should be only used for test.
+func (db *MemDB) RemoveFromBuffer(key []byte) {
+	x := db.traverse(key, false)
+	if x.isNull() {
+		return
+	}
+	db.size -= len(db.vlog.getValue(x.vptr))
+	db.deleteNode(x)
+}
diff --git a/internal/unionstore/memdb_norace_test.go b/internal/unionstore/memdb_norace_test.go
index 6610cac46..ed0405638 100644
--- a/internal/unionstore/memdb_norace_test.go
+++ b/internal/unionstore/memdb_norace_test.go
@@ -72,7 +72,7 @@ func TestRandom(t *testing.T) {
 	for _, k := range keys {
 		op := rand.Float64()
 		if op < 0.35 {
-			p1.DeleteKey(k)
+			p1.RemoveFromBuffer(k)
 			p2.Delete(k)
 		} else {
 			newValue := make([]byte, rand.Intn(19)+1)
diff --git a/internal/unionstore/memdb_test.go b/internal/unionstore/memdb_test.go
index d5d682407..18bed9fc0 100644
--- a/internal/unionstore/memdb_test.go
+++ b/internal/unionstore/memdb_test.go
@@ -53,16 +53,6 @@ func init() {
 	testMode = true
 }
 
-// DeleteKey is used in test to verify the `deleteNode` used in `vlog.revertToCheckpoint`.
-func (db *MemDB) DeleteKey(key []byte) {
-	x := db.traverse(key, false)
-	if x.isNull() {
-		return
-	}
-	db.size -= len(db.vlog.getValue(x.vptr))
-	db.deleteNode(x)
-}
-
 func TestGetSet(t *testing.T) {
 	require := require.New(t)