diff --git a/src/meta/src/hummock/metrics_utils.rs b/src/meta/src/hummock/metrics_utils.rs
index 8bcc1f1d2c1c6..9917d559a0709 100644
--- a/src/meta/src/hummock/metrics_utils.rs
+++ b/src/meta/src/hummock/metrics_utils.rs
@@ -483,15 +483,15 @@ pub fn trigger_split_stat(
         .with_label_values(&[&group_label])
         .set(member_table_id_len as _);
 
-    let branched_sst_count = branched_ssts
+    let branched_sst_count: usize = branched_ssts
         .values()
-        .map(|branched_map| branched_map.iter())
-        .flat_map(|branched_map| {
+        .map(|branched_map| {
             branched_map
-                .filter(|(group_id, _sst_id)| **group_id == compaction_group_id)
-                .map(|(_, v)| v)
+                .keys()
+                .filter(|group_id| **group_id == compaction_group_id)
+                .count()
         })
-        .sum::<u64>();
+        .sum();
 
     metrics
         .branched_sst_count