Support anchored and smoothed modifiers

engine/engine.go

@@ -74,6 +74,11 @@ type Opts struct {
 	// This will default to false.
 	EnableXFunctions bool
 
+	// EnableExtendedRangeSelectors enables the anchored and smoothed modifiers
+	// for range vector selectors.
+	// See https://github.com/prometheus/proposals/blob/main/proposals/0052-extended-range-selectors-semantics.md
+	EnableExtendedRangeSelectors bool
+
 	// EnableAnalysis enables query analysis.
 	EnableAnalysis bool
 
@@ -183,7 +188,8 @@ func NewWithScanners(opts Opts, scanners engstorage.Scanners) *Engine {
 		scanners:           scanners,
 		activeQueryTracker: queryTracker,
 
-		disableDuplicateLabelChecks: opts.DisableDuplicateLabelChecks,
+		disableDuplicateLabelChecks:  opts.DisableDuplicateLabelChecks,
+		enableExtendedRangeSelectors: opts.EnableExtendedRangeSelectors,
 
 		logger:             opts.Logger,
 		lookbackDelta:      opts.LookbackDelta,
@@ -213,7 +219,8 @@ type Engine struct {
 	scanners           engstorage.Scanners
 	activeQueryTracker promql.QueryTracker
 
-	disableDuplicateLabelChecks bool
+	disableDuplicateLabelChecks  bool
+	enableExtendedRangeSelectors bool
 
 	logger             *slog.Logger
 	lookbackDelta      time.Duration
@@ -236,6 +243,14 @@ func (e *Engine) MakeInstantQuery(ctx context.Context, q storage.Queryable, opts
 	}
 	defer e.activeQueryTracker.Delete(idx)
 
+	// NOTE: parser.EnableExtendedRangeSelectors is a process-global variable
+	// in the upstream Prometheus parser. Once set to true, it remains enabled
+	// for all subsequent parses in the process, matching how Prometheus handles
+	// it (set once at startup via --enable-feature). Two engine instances in
+	// the same process cannot independently control this flag.
+	if e.enableExtendedRangeSelectors {
+		parser.EnableExtendedRangeSelectors = true
+	}
 	expr, err := parser.NewParser(qs, parser.WithFunctions(e.functions)).ParseExpr()
 	if err != nil {
 		return nil, err
@@ -334,6 +349,14 @@ func (e *Engine) MakeRangeQuery(ctx context.Context, q storage.Queryable, opts *
 	}
 	defer e.activeQueryTracker.Delete(idx)
 
+	// NOTE: parser.EnableExtendedRangeSelectors is a process-global variable
+	// in the upstream Prometheus parser. Once set to true, it remains enabled
+	// for all subsequent parses in the process, matching how Prometheus handles
+	// it (set once at startup via --enable-feature). Two engine instances in
+	// the same process cannot independently control this flag.
+	if e.enableExtendedRangeSelectors {
+		parser.EnableExtendedRangeSelectors = true
+	}
 	expr, err := parser.NewParser(qs, parser.WithFunctions(e.functions)).ParseExpr()
 	if err != nil {
 		return nil, err

engine/engine_test.go

@@ -75,7 +75,9 @@ func (s *skipTest) Run(name string, t func(*testing.T)) bool {
 func TestPromqlAcceptance(t *testing.T) {
 	// promql acceptance tests disable experimental functions again
 	// since we use them in our tests too we need to enable them afterwards again
-	t.Cleanup(func() { parser.EnableExperimentalFunctions = true })
+	t.Cleanup(func() {
+		parser.EnableExperimentalFunctions = true
+	})
 
 	engine := engine.New(engine.Opts{
 		EngineOpts: promql.EngineOpts{
@@ -85,13 +87,14 @@ func TestPromqlAcceptance(t *testing.T) {
 			MaxSamples:               5e10,
 			Timeout:                  1 * time.Hour,
 			NoStepSubqueryIntervalFn: func(rangeMillis int64) int64 { return 30 * time.Second.Milliseconds() },
-		}})
+		},
+		EnableExtendedRangeSelectors: true,
+	})
 
 	st := &skipTest{
 		skipTests: []string{
 			"testdata/name_label_dropping.test", // feature unsupported
 			"testdata/type_and_unit.test",       // feature unsupported
-			"testdata/extended_vectors.test",    // experimental anchored/smoothed modifiers unsupported
 			"testdata/info.test",                // info() function unsupported
 			"testdata/literals.test",            // string literal expressions as query results unsupported
 			"testdata/range_queries.test",       // matrix selector as instant query result unsupported