Fix acceptance test failures

Signed-off-by: 🌲 Harry 🌊 John 🏔 <[email protected]>

Author: harry671003

logicalplan/logical_nodes.go

@@ -73,6 +73,7 @@ type VectorSelector struct {
 	Filters         []*labels.Matcher
 	BatchSize       int64
 	SelectTimestamp bool
+	Invariant       bool
 	Projection      Projection
 	// When set, histogram iterators can return objects which only have their
 	// CounterResetHint, Count and Sum values populated. Histogram buckets and spans

logicalplan/plan.go

@@ -248,7 +248,13 @@ func replacePrometheusNodes(plan parser.Expr) Node {
 		// parents of matrixselector nodes are always expected to be functions, not step invariant
 		// operators.
 		if m, ok := t.Expr.(*parser.MatrixSelector); ok {
-			return replacePrometheusNodes(m)
+			n := replacePrometheusNodes(m)
+			if ms, ok := n.(*MatrixSelector); ok {
+				// For cases such as predict_linear(metric[5m] @start() , 0.3), we mark the
+				// vector selector to be invariant. The scanner will only scan points once in such cases.
+				ms.VectorSelector.Invariant = true
+			}
+			return n
 		}
 		return &StepInvariantExpr{Expr: replacePrometheusNodes(t.Expr)}
 	case *parser.MatrixSelector:

storage/prometheus/scanners.go

@@ -126,6 +126,11 @@ func (p Scanners) NewMatrixSelector(
 		selector = newHistogramStatsSelector(selector)
 	}
 
+	var ts *int64
+	if logicalNode.VectorSelector.Invariant {
+		ts = logicalNode.VectorSelector.Timestamp
+	}
+
 	operators := make([]model.VectorOperator, 0, opts.DecodingConcurrency)
 	for i := 0; i < opts.DecodingConcurrency; i++ {
 		operator, err := NewMatrixSelector(
@@ -134,7 +139,7 @@ func (p Scanners) NewMatrixSelector(
 			call.Func.Name,
 			arg,
 			arg2,
-			logicalNode.VectorSelector.Timestamp,
+			ts,
 			opts,
 			logicalNode.Range,
 			vs.Offset,