fix: route engine to handle column truncation for execute after lookup

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

go/vt/vtgate/engine/route.go

@@ -130,11 +130,12 @@ func (route *Route) GetTableName() string {
 
 // TryExecute performs a non-streaming exec.
 func (route *Route) TryExecute(ctx context.Context, vcursor VCursor, bindVars map[string]*querypb.BindVariable, wantfields bool) (*sqltypes.Result, error) {
-	qr, err := route.executeInternal(ctx, vcursor, bindVars, wantfields)
+	rss, bvs, err := route.findRoute(ctx, vcursor, bindVars)
 	if err != nil {
 		return nil, err
 	}
-	return qr.Truncate(route.TruncateColumnCount), nil
+
+	return route.executeShards(ctx, vcursor, bindVars, wantfields, rss, bvs)
 }
 
 type cxtKey int
@@ -143,20 +144,6 @@ const (
 	IgnoreReserveTxn cxtKey = iota
 )
 
-func (route *Route) executeInternal(
-	ctx context.Context,
-	vcursor VCursor,
-	bindVars map[string]*querypb.BindVariable,
-	wantfields bool,
-) (*sqltypes.Result, error) {
-	rss, bvs, err := route.findRoute(ctx, vcursor, bindVars)
-	if err != nil {
-		return nil, err
-	}
-
-	return route.executeShards(ctx, vcursor, bindVars, wantfields, rss, bvs)
-}
-
 func (route *Route) executeShards(
 	ctx context.Context,
 	vcursor VCursor,
@@ -212,11 +199,15 @@ func (route *Route) executeShards(
 		}
 	}
 
-	if len(route.OrderBy) == 0 {
-		return result, nil
+	if len(route.OrderBy) != 0 {
+		var err error
+		result, err = route.sort(result)
+		if err != nil {
+			return nil, err
+		}
 	}
 
-	return route.sort(result)
+	return result.Truncate(route.TruncateColumnCount), nil
 }
 
 func filterOutNilErrors(errs []error) []error {
@@ -373,10 +364,8 @@ func (route *Route) sort(in *sqltypes.Result) (*sqltypes.Result, error) {
 	// the contents of any row.
 	out := in.ShallowCopy()
 
-	if err := route.OrderBy.SortResult(out); err != nil {
-		return nil, err
-	}
-	return out.Truncate(route.TruncateColumnCount), nil
+	err := route.OrderBy.SortResult(out)
+	return out, err
 }
 
 func (route *Route) description() PrimitiveDescription {