Update Cascade Planning leading to Foreign key constraint verification

go/test/endtoend/vtgate/foreignkey/fk_test.go

@@ -136,10 +136,11 @@ func TestUpdateWithFK(t *testing.T) {
 	utils.Exec(t, conn, `insert into u_t2(id, col2) values (342, 123), (19, 1234)`)
 	utils.Exec(t, conn, `insert into u_t3(id, col3) values (32, 123), (1, 12)`)
 
-	t.Run("Cascade update with a new value", func(t *testing.T) {
-		t.Skip("This doesn't work right now. We are able to only cascade updates for which the data already exists in the parent table")
-		_ = utils.Exec(t, conn, `update u_t1 set col1 = 2 where id = 100`)
-	})
+	// Cascade update with a new value
+	_ = utils.Exec(t, conn, `update u_t1 set col1 = 2 where id = 100`)
+	// Verify the result in u_t2 and u_t3 as well.
+	utils.AssertMatches(t, conn, `select * from u_t2 order by id`, `[[INT64(19) INT64(1234)] [INT64(342) NULL]]`)
+	utils.AssertMatches(t, conn, `select * from u_t3 order by id`, `[[INT64(1) INT64(12)] [INT64(32) INT64(2)]]`)
 
 	// Update u_t1 which has a foreign key constraint to u_t2 with SET NULL type, and to u_t3 with CASCADE type.
 	qr = utils.Exec(t, conn, `update u_t1 set col1 = 13 where id = 100`)

go/vt/sqlparser/ast_funcs.go

@@ -2532,3 +2532,14 @@ func (v *visitor) visitAllSelects(in SelectStatement, f func(p *Select, idx int)
 	}
 	panic("switch should be exhaustive")
 }
+
+func IsNonLiteral(updExprs UpdateExprs) bool {
+	for _, updateExpr := range updExprs {
+		switch updateExpr.Expr.(type) {
+		case *Argument, *NullVal, BoolVal, *Literal:
+		default:
+			return true
+		}
+	}
+	return false
+}

go/vt/vterrors/code.go

@@ -82,7 +82,6 @@ var (
 
 	VT12001 = errorWithoutState("VT12001", vtrpcpb.Code_UNIMPLEMENTED, "unsupported: %s", "This statement is unsupported by Vitess. Please rewrite your query to use supported syntax.")
 	VT12002 = errorWithoutState("VT12002", vtrpcpb.Code_UNIMPLEMENTED, "unsupported: cross-shard foreign keys", "Vitess does not support cross shard foreign keys.")
-	VT12003 = errorWithoutState("VT12002", vtrpcpb.Code_UNIMPLEMENTED, "unsupported: foreign keys management at vitess", "Vitess does not support managing foreign keys tables.")
 
 	// VT13001 General Error
 	VT13001 = errorWithoutState("VT13001", vtrpcpb.Code_INTERNAL, "[BUG] %s", "This error should not happen and is a bug. Please file an issue on GitHub: https://github.com/vitessio/vitess/issues/new/choose.")
@@ -148,7 +147,6 @@ var (
 		VT10001,
 		VT12001,
 		VT12002,
-		VT12003,
 		VT13001,
 		VT13002,
 		VT14001,

go/vt/vtgate/engine/fk_verify.go

@@ -23,28 +23,30 @@ import (
 	"vitess.io/vitess/go/sqltypes"
 	querypb "vitess.io/vitess/go/vt/proto/query"
 	vtrpcpb "vitess.io/vitess/go/vt/proto/vtrpc"
-	"vitess.io/vitess/go/vt/sqlparser"
 	"vitess.io/vitess/go/vt/vterrors"
 )
 
-// FkParent is a primitive that represents a parent table foreign key constraint to verify against.
-type FkParent struct {
-	Values []sqlparser.Exprs
-	Cols   []CheckCol
-	BvName string
-
+// Verify contains the verification primitve and its type i.e. parent or child
+type Verify struct {
 	Exec Primitive
+	Typ  string
 }
 
 // FkVerify is a primitive that verifies that the foreign key constraints in parent tables are satisfied.
 // It does this by executing a select distinct query on the parent table with the values that are being inserted/updated.
 type FkVerify struct {
-	Verify []*FkParent
+	Verify []*Verify
 	Exec   Primitive
 
 	txNeeded
 }
 
+// constants for verification type.
+const (
+	ParentVerify = "VerifyParent"
+	ChildVerify  = "VerifyChild"
+)
+
 // RouteType implements the Primitive interface
 func (f *FkVerify) RouteType() string {
 	return "FKVerify"
@@ -67,78 +69,30 @@ func (f *FkVerify) GetFields(ctx context.Context, vcursor VCursor, bindVars map[
 
 // TryExecute implements the Primitive interface
 func (f *FkVerify) TryExecute(ctx context.Context, vcursor VCursor, bindVars map[string]*querypb.BindVariable, wantfields bool) (*sqltypes.Result, error) {
-	for _, fk := range f.Verify {
-		pt := newProbeTable(fk.Cols)
-		newBv := &querypb.BindVariable{
-			Type: querypb.Type_TUPLE,
-		}
-		for _, exprs := range fk.Values {
-			var row sqltypes.Row
-			var values []*querypb.Value
-			for _, expr := range exprs {
-				val, err := getValue(expr, bindVars)
-				if err != nil {
-					return nil, vterrors.Wrapf(err, "unable to get value for the expression %v", expr)
-				}
-				row = append(row, val)
-				values = append(values, sqltypes.ValueToProto(val))
-			}
-			if exists, err := pt.exists(row); err != nil {
-				return nil, err
-			} else if !exists {
-				newBv.Values = append(newBv.Values, &querypb.Value{Type: querypb.Type_TUPLE, Values: values})
-			}
-		}
-		distinctValues := len(newBv.Values)
-		qr, err := vcursor.ExecutePrimitive(ctx, fk.Exec, map[string]*querypb.BindVariable{fk.BvName: newBv}, wantfields)
+	for _, v := range f.Verify {
+		qr, err := vcursor.ExecutePrimitive(ctx, v.Exec, bindVars, wantfields)
 		if err != nil {
 			return nil, err
 		}
-		if distinctValues != len(qr.Rows) {
-			return nil, vterrors.NewErrorf(vtrpcpb.Code_FAILED_PRECONDITION, vterrors.NoReferencedRow2, "Cannot add or update a child row: a foreign key constraint fails")
+		if len(qr.Rows) > 0 {
+			return nil, getError(v.Typ)
 		}
 	}
 	return vcursor.ExecutePrimitive(ctx, f.Exec, bindVars, wantfields)
 }
 
 // TryStreamExecute implements the Primitive interface
 func (f *FkVerify) TryStreamExecute(ctx context.Context, vcursor VCursor, bindVars map[string]*querypb.BindVariable, wantfields bool, callback func(*sqltypes.Result) error) error {
-	for _, fk := range f.Verify {
-		pt := newProbeTable(fk.Cols)
-		newBv := &querypb.BindVariable{
-			Type: querypb.Type_TUPLE,
-		}
-		for _, exprs := range fk.Values {
-			var row sqltypes.Row
-			var values []*querypb.Value
-			for _, expr := range exprs {
-				val, err := getValue(expr, bindVars)
-				if err != nil {
-					return vterrors.Wrapf(err, "unable to get value for the expression %v", expr)
-				}
-				row = append(row, val)
-				values = append(values, sqltypes.ValueToProto(val))
+	for _, v := range f.Verify {
+		err := vcursor.StreamExecutePrimitive(ctx, v.Exec, bindVars, wantfields, func(qr *sqltypes.Result) error {
+			if len(qr.Rows) > 0 {
+				return getError(v.Typ)
 			}
-			if exists, err := pt.exists(row); err != nil {
-				return err
-			} else if !exists {
-				newBv.Values = append(newBv.Values, &querypb.Value{Type: querypb.Type_TUPLE, Values: values})
-			}
-		}
-		distinctValues := len(newBv.Values)
-
-		seenRows := 0
-		err := vcursor.StreamExecutePrimitive(ctx, fk.Exec, map[string]*querypb.BindVariable{fk.BvName: newBv}, wantfields, func(qr *sqltypes.Result) error {
-			seenRows += len(qr.Rows)
 			return nil
 		})
 		if err != nil {
 			return err
 		}
-
-		if distinctValues != seenRows {
-			return vterrors.NewErrorf(vtrpcpb.Code_FAILED_PRECONDITION, vterrors.NoReferencedRow2, "Cannot add or update a child row: a foreign key constraint fails")
-		}
 	}
 	return vcursor.StreamExecutePrimitive(ctx, f.Exec, bindVars, wantfields, callback)
 }
@@ -147,17 +101,15 @@ func (f *FkVerify) TryStreamExecute(ctx context.Context, vcursor VCursor, bindVa
 func (f *FkVerify) Inputs() ([]Primitive, []map[string]any) {
 	var inputs []Primitive
 	var inputsMap []map[string]any
-	for idx, parent := range f.Verify {
+	for idx, v := range f.Verify {
 		inputsMap = append(inputsMap, map[string]any{
-			inputName: fmt.Sprintf("VerifyParent-%d", idx+1),
-			"BvName":  parent.BvName,
-			"Cols":    parent.Cols,
+			inputName: fmt.Sprintf("%s-%d", v.Typ, idx+1),
 		})
-		inputs = append(inputs, parent.Exec)
+		inputs = append(inputs, v.Exec)
 	}
 	inputs = append(inputs, f.Exec)
 	inputsMap = append(inputsMap, map[string]any{
-		inputName: "Child",
+		inputName: "PostVerify",
 	})
 	return inputs, inputsMap
 
@@ -169,24 +121,9 @@ func (f *FkVerify) description() PrimitiveDescription {
 
 var _ Primitive = (*FkVerify)(nil)
 
-func getValue(expr sqlparser.Expr, bindVars map[string]*querypb.BindVariable) (sqltypes.Value, error) {
-	switch e := expr.(type) {
-	case *sqlparser.Literal:
-		return sqlparser.LiteralToValue(e)
-	case sqlparser.BoolVal:
-		b := int32(0)
-		if e {
-			b = 1
-		}
-		return sqltypes.NewInt32(b), nil
-	case *sqlparser.NullVal:
-		return sqltypes.NULL, nil
-	case *sqlparser.Argument:
-		bv, exists := bindVars[e.Name]
-		if !exists {
-			return sqltypes.Value{}, vterrors.Errorf(vtrpcpb.Code_INTERNAL, "[BUG] bind variable %s missing", e.Name)
-		}
-		return sqltypes.BindVariableToValue(bv)
+func getError(typ string) error {
+	if typ == ParentVerify {
+		return vterrors.NewErrorf(vtrpcpb.Code_FAILED_PRECONDITION, vterrors.NoReferencedRow2, "Cannot add or update a child row: a foreign key constraint fails")
 	}
-	return sqltypes.Value{}, vterrors.Errorf(vtrpcpb.Code_INTERNAL, "[BUG] unexpected expression type: %T", expr)
+	return vterrors.NewErrorf(vtrpcpb.Code_FAILED_PRECONDITION, vterrors.RowIsReferenced2, "Cannot delete or update a parent row: a foreign key constraint fails")
 }