diff --git a/configs/milvus.yaml b/configs/milvus.yaml
index 45398b2238..313781d2b9 100644
--- a/configs/milvus.yaml
+++ b/configs/milvus.yaml
@@ -287,6 +287,7 @@ dataCoord:
     # (smallProportion * segment max # of rows).
     compactableProportion: 0.5 # A compaction will happen on small segments if the segment after compaction will have
     # over (compactableProportion * segment max # of rows) rows.
+    # MUST BE GREATER THAN OR EQUAL TO <smallProportion>!!!
     expansionRate: 1.25 # During compaction, the size of segment # of rows is able to exceed segment max # of rows by (expansionRate-1) * 100%.
 
   compaction:
diff --git a/internal/datacoord/compaction_trigger.go b/internal/datacoord/compaction_trigger.go
index eb83791925..4ead43be5a 100644
--- a/internal/datacoord/compaction_trigger.go
+++ b/internal/datacoord/compaction_trigger.go
@@ -613,7 +613,8 @@ func (t *compactionTrigger) generatePlans(segments []*SegmentInfo, force bool, i
 		}
 		// only merge if candidate number is large than MinSegmentToMerge or if target row is large enough
 		if len(bucket) >= Params.DataCoordCfg.MinSegmentToMerge.GetAsInt() ||
-			targetRow > int64(float64(segment.GetMaxRowNum())*Params.DataCoordCfg.SegmentCompactableProportion.GetAsFloat()) {
+			len(bucket) > 1 &&
+				targetRow > int64(float64(segment.GetMaxRowNum())*Params.DataCoordCfg.SegmentCompactableProportion.GetAsFloat()) {
 			plan := segmentsToPlan(bucket, compactTime)
 			log.Info("generate a plan for small candidates",
 				zap.Int64s("plan segment IDs", lo.Map(bucket, getSegmentIDs)),