From 614b13cd1373c0e9d1da4141ecb09330dd548b51 Mon Sep 17 00:00:00 2001
From: Zexi Li <zexi.li@icloud.com>
Date: Thu, 18 Sep 2025 07:49:04 +0800
Subject: [PATCH] fix(monitor): diffTagKeys are empty when only one series in
 results (#23310)

---
 pkg/monitor/tsdb/driver/victoriametrics/vm.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pkg/monitor/tsdb/driver/victoriametrics/vm.go b/pkg/monitor/tsdb/driver/victoriametrics/vm.go
index a42f097e55..d6279878d4 100644
--- a/pkg/monitor/tsdb/driver/victoriametrics/vm.go
+++ b/pkg/monitor/tsdb/driver/victoriametrics/vm.go
@@ -164,6 +164,10 @@ func translateResponse(resp *Response, query *tsdb.Query) (*tsdb.QueryResult, er
 				}
 			}
 		}
+	} else if len(results) == 1 {
+		for tagKey := range results[0].Metric {
+			diffTagKeys.Insert(tagKey)
+		}
 	}
 
 	if !isUnionResult {