app/vminsert/influx: try converting string values to numeric values, since Influx agents may send numeric values as strings

Fixes https://github.com/VictoriaMetrics/VictoriaMetrics/issues/34

app/vminsert/influx/parser.go

@@ -293,8 +293,10 @@ func parseFieldValue(s string, hasQuotedFields bool) (float64, error) {
 		if len(s) < 2 || s[len(s)-1] != '"' {
 			return 0, fmt.Errorf("missing closing quote for quoted field value %s", s)
 		}
-		// Quoted string is translated to empty value.
+		// Try converting quoted string to number, since sometimes Influx agents
-		return 0, nil
+		// send numbers as strings.
+		s = s[1 : len(s)-1]
+		return fastfloat.ParseBestEffort(s), nil
 	}
 	ch := s[len(s)-1]
 	if ch == 'i' {

app/vminsert/influx/parser_test.go

@@ -241,17 +241,27 @@ func TestRowsUnmarshalSuccess(t *testing.T) {
 	})
 
 	// Line with multiple tags, multiple fields and timestamp
-	f(`system,host=ip-172-16-10-144 uptime_format="3 days, 21:01" 1557761040000000000`, &Rows{
+	f(`system,host=ip-172-16-10-144 uptime_format="3 days, 21:01",quoted_float="-1.23",quoted_int="123" 1557761040000000000`, &Rows{
 		Rows: []Row{{
 			Measurement: "system",
 			Tags: []Tag{{
 				Key:   "host",
 				Value: "ip-172-16-10-144",
 			}},
-			Fields: []Field{{
+			Fields: []Field{
-				Key:   "uptime_format",
+				{
-				Value: 0,
+					Key:   "uptime_format",
-			}},
+					Value: 0,
+				},
+				{
+					Key:   "quoted_float",
+					Value: -1.23,
+				},
+				{
+					Key:   "quoted_int",
+					Value: 123,
+				},
+			},
 			Timestamp: 1557761040000000000,
 		}},
 	})