pkg/query: Handle queries when no columns are found

This happens when the timestamp for the query is too old or simply doesn't exist. Parca should return NotFound and not Unknown gRPC codes.

Author: metalmatze

pkg/parcacol/arrow.go

@@ -24,6 +24,15 @@ import (
 	"github.com/parca-dev/parca/pkg/profile"
 )
 
+type ErrMissingColumn struct {
+	column  string
+	columns int
+}
+
+func (e ErrMissingColumn) Error() string {
+	return fmt.Sprintf("expected column %s, got %d columns", e.column, e.columns)
+}
+
 func ArrowRecordToStacktraceSamples(
 	ctx context.Context,
 	m pb.MetastoreServiceClient,
@@ -34,13 +43,13 @@ func ArrowRecordToStacktraceSamples(
 	schema := ar.Schema()
 	indices := schema.FieldIndices("stacktrace")
 	if len(indices) != 1 {
-		return nil, fmt.Errorf("expected exactly one stacktrace column, got %d", len(indices))
+		return nil, ErrMissingColumn{column: "stacktrace", columns: len(indices)}
 	}
 	stacktraceColumn := ar.Column(indices[0]).(*array.Binary)
 
 	indices = schema.FieldIndices("sum(value)")
 	if len(indices) != 1 {
-		return nil, fmt.Errorf("expected exactly one value column, got %d", len(indices))
+		return nil, ErrMissingColumn{column: "value", columns: len(indices)}
 	}
 	valueColumn := ar.Column(indices[0]).(*array.Int64)
 

pkg/query/columnquery.go

@@ -563,6 +563,11 @@ func (q *ColumnQueryAPI) selectSingle(ctx context.Context, s *pb.SingleProfile)
 	t := s.Time.AsTime()
 	p, err := q.findSingle(ctx, s.Query, t)
 	if err != nil {
+		// if the column cannot be found the timestamp is too far in the past and we don't have data
+		var colErr parcacol.ErrMissingColumn
+		if errors.As(err, &colErr) {
+			return nil, status.Error(codes.NotFound, "could not find profile at requested time and selectors")
+		}
 		return nil, err
 	}