Prometheus API set query version

internal/api/promql.go

@@ -37,6 +37,7 @@ func HandleInstantQuery(r *httpRequestHandler) {
 	q := promql.Query{
 		Expr: r.FormValue("query"),
 		Options: promql.Options{
+			Version:   r.version(),
 			Mode:      data_model.InstantQuery,
 			Compat:    true,
 			TimeNow:   time.Now().Unix(),
@@ -72,6 +73,7 @@ func HandleRangeQuery(r *httpRequestHandler) {
 	q := promql.Query{
 		Expr: r.FormValue("query"),
 		Options: promql.Options{
+			Version:   r.version(),
 			Compat:    true,
 			Namespace: r.Header.Get("X-StatsHouse-Namespace"),
 		},
@@ -138,6 +140,7 @@ func HandlePromSeriesQuery(r *httpRequestHandler) {
 					End:   end,
 					Expr:  expr,
 					Options: promql.Options{
+						Version:       r.version(),
 						Version3Start: r.Version3Start.Load(),
 						Limit:         1000,
 						Mode:          data_model.TagsQuery,
@@ -212,6 +215,7 @@ func HandlePromLabelValuesQuery(r *httpRequestHandler) {
 							End:   end,
 							Expr:  expr,
 							Options: promql.Options{
+								Version:       r.version(),
 								Version3Start: r.Version3Start.Load(),
 								Limit:         1000,
 								Mode:          data_model.TagsQuery,

internal/promql/engine.go

@@ -158,13 +158,12 @@ func (ng Engine) Exec(ctx context.Context, h Handler, qry Query) (parser.Value,
 }
 
 func (ev *evaluator) Run() (parser.Value, func(), error) {
-	// parse query
-	if ev.t.Empty() {
-		return &TimeSeries{Time: []int64{}}, func() {}, nil
-	}
 	if e, ok := ev.ast.(*parser.StringLiteral); ok {
 		return String{T: ev.t.Start, V: e.Val}, func() {}, nil
 	}
+	if ev.t.Empty() {
+		return &TimeSeries{Time: []int64{}}, func() {}, nil
+	}
 	// evaluate query
 	ev.Tracef(ev.ast.String())
 	if ev.opt.Debug {
@@ -281,10 +280,12 @@ func (ng Engine) NewEvaluator(ctx context.Context, h Handler, qry Query) (evalua
 		Location:      ng.location,
 		UTCOffset:     ng.utcOffset,
 	})
-
-	if err != nil || ev.t.Empty() {
+	if err != nil {
 		return evaluator{}, Error{what: err}
 	}
+	if ev.t.Empty() {
+		return ev, nil
+	}
 	// evaluate reduction rules
 	ev.ars = make(map[parser.Expr]parser.Expr)
 	stepMin := ev.t.LODs[len(ev.t.LODs)-1].Step
@@ -1344,7 +1345,11 @@ func (ev *evaluator) getTagValue(metric *format.MetricMetaValue, tagX int, tagV
 		if err != nil {
 			return data_model.TagValue{}, err
 		}
-		return data_model.NewTagValueM(v), nil
+		if v != 0 {
+			return data_model.NewTagValueM(v), nil
+		} else {
+			return data_model.NewTagValue("", 0), nil
+		}
 	}
 	if tagX < 0 || len(metric.Tags) <= tagX {
 		return data_model.TagValue{}, ErrNotFound