InfluxDB: fix numeric aliases in queries (#41531) (#41587)

* influxdb: alerting: handle out-of-range numeric aliases

* influxdb: updated documentation

(cherry picked from commit eb47a58029)

Co-authored-by: Gábor Farkas <gabor.farkas@gmail.com>

pkg/tsdb/influxdb/response_parser.go

@@ -113,7 +113,7 @@ func formatFrameName(row Row, column string, query *Query) string {
 		}
 
 		pos, err := strconv.Atoi(aliasFormat)
-		if err == nil && len(nameSegment) >= pos {
+		if err == nil && len(nameSegment) > pos {
 			return []byte(nameSegment[pos])
 		}
 

pkg/tsdb/influxdb/response_parser_test.go

@@ -293,6 +293,16 @@ func TestInfluxdbResponseParser(t *testing.T) {
 				t.Errorf("Result mismatch (-want +got):\n%s", diff)
 			}
 
+			query = &Query{Alias: "alias $0 $1 $2 $3 $4"}
+			result = parser.Parse(prepare(response), query)
+			frame = result.Responses["A"]
+			name = "alias cpu upc $2 $3 $4"
+			testFrame.Name = name
+			testFrame.Fields[1].Config.DisplayNameFromDS = name
+			if diff := cmp.Diff(testFrame, frame.Frames[0], data.FrameTestCompareOptions()...); diff != "" {
+				t.Errorf("Result mismatch (-want +got):\n%s", diff)
+			}
+
 			query = &Query{Alias: "alias $1"}
 			result = parser.Parse(prepare(response), query)
 			frame = result.Responses["A"]