Foreign key cascade planning for DELETE and UPDATE queries (#13823)

Signed-off-by: Harshit Gangal <[email protected]>
Signed-off-by: Manan Gupta <[email protected]>
Co-authored-by: Manan Gupta <[email protected]>

go/mysql/sqlerror/sql_error.go

@@ -212,6 +212,7 @@ var stateToMysqlCode = map[vterrors.State]mysqlCode{
 	vterrors.ServerNotAvailable:           {num: ERServerIsntAvailable, state: SSNetError},
 	vterrors.CantDoThisInTransaction:      {num: ERCantDoThisDuringAnTransaction, state: SSCantDoThisDuringAnTransaction},
 	vterrors.RequiresPrimaryKey:           {num: ERRequiresPrimaryKey, state: SSClientError},
+	vterrors.RowIsReferenced2:             {num: ERRowIsReferenced2, state: SSConstraintViolation},
 	vterrors.NoSuchSession:                {num: ERUnknownComError, state: SSNetError},
 	vterrors.OperandColumns:               {num: EROperandColumns, state: SSWrongNumberOfColumns},
 	vterrors.WrongValueCountOnRow:         {num: ERWrongValueCountOnRow, state: SSWrongValueCountOnRow},

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

@@ -76,11 +76,26 @@ func TestDeleteWithFK(t *testing.T) {
 
 	// table's child foreign key has cross shard fk, so query will fail at vtgate.
 	_, err = utils.ExecAllowError(t, conn, `delete from t1 where id = 42`)
-	assert.ErrorContains(t, err, "VT12002: unsupported: foreign keys management at vitess (errno 1235) (sqlstate 42000)")
+	assert.ErrorContains(t, err, "VT12002: unsupported: cross-shard foreign keys (errno 1235) (sqlstate 42000)")
 
-	// child foreign key is cascade, so query will fail at vtgate.
-	_, err = utils.ExecAllowError(t, conn, `delete from multicol_tbl1 where cola = 100`)
-	assert.ErrorContains(t, err, "VT12002: unsupported: foreign keys management at vitess (errno 1235) (sqlstate 42000)")
+	// child foreign key is cascade, so this should work as expected.
+	qr = utils.Exec(t, conn, `delete from multicol_tbl1 where cola = 100`)
+	assert.EqualValues(t, 1, qr.RowsAffected)
+	// we also verify that the rows in the child table were deleted.
+	qr = utils.Exec(t, conn, `select * from multicol_tbl2 where cola = 100`)
+	assert.Zero(t, qr.Rows)
+
+	// Unsharded keyspace tests
+	utils.Exec(t, conn, `use uks`)
+	// insert some data.
+	utils.Exec(t, conn, `insert into u_t1(id, col1) values (100, 123), (10, 12), (1, 13), (1000, 1234)`)
+	utils.Exec(t, conn, `insert into u_t2(id, col2) values (342, 123), (19, 1234)`)
+
+	// Delete from u_t1 which has a foreign key constraint to t2 with SET NULL type.
+	qr = utils.Exec(t, conn, `delete from u_t1 where id = 100`)
+	assert.EqualValues(t, 1, qr.RowsAffected)
+	// Verify the result in u_t2 as well
+	utils.AssertMatches(t, conn, `select * from u_t2`, `[[INT64(342) NULL] [INT64(19) INT64(1234)]]`)
 }
 
 // TestUpdations tests that update work as expected when foreign key management is enabled in Vitess.
@@ -91,7 +106,7 @@ func TestUpdateWithFK(t *testing.T) {
 	// insert some data.
 	utils.Exec(t, conn, `insert into t1(id, col) values (100, 123),(10, 12),(1, 13),(1000, 1234)`)
 	utils.Exec(t, conn, `insert into t2(id, col, mycol) values (100, 125, 'foo'), (1, 132, 'bar')`)
-	utils.Exec(t, conn, `insert into t4(id, col, t2_mycol) values (1, 321, 'bar')`)
+	utils.Exec(t, conn, `insert into t4(id, col, t2_col, t2_mycol) values (1, 321, 132, 'bar')`)
 	utils.Exec(t, conn, `insert into t5(pk, sk, col1) values (1, 1, 1),(2, 1, 1),(3, 1, 10),(4, 1, 20),(5, 1, 30),(6, 1, 40)`)
 	utils.Exec(t, conn, `insert into t6(pk, sk, col1) values (10, 1, 1), (20, 1, 20)`)
 
@@ -106,15 +121,38 @@ func TestUpdateWithFK(t *testing.T) {
 	qr := utils.Exec(t, conn, `update t4 set col = 20 where id = 1`)
 	assert.EqualValues(t, 1, qr.RowsAffected)
 
-	// child table have cascade which is cross shard. Query will fail at vtgate.
-	_, err = utils.ExecAllowError(t, conn, `update t2 set col = 125 where id = 100`)
-	assert.ErrorContains(t, err, "VT12002: unsupported: foreign keys management at vitess (errno 1235) (sqlstate 42000)")
-
 	// updating column which does not have foreign key constraint, so query will succeed.
 	_ = utils.Exec(t, conn, `update t2 set mycol = 'baz' where id = 100`)
 	assert.EqualValues(t, 1, qr.RowsAffected)
 
 	// child table have restrict in shard scoped and value exists in parent table.
 	_ = utils.Exec(t, conn, `update t6 set col1 = 40 where pk = 20`)
 	assert.EqualValues(t, 1, qr.RowsAffected)
+
+	// Unsharded keyspace tests
+	utils.Exec(t, conn, `use uks`)
+	// insert some data.
+	utils.Exec(t, conn, `insert into u_t1(id, col1) values (100, 123), (10, 12), (1, 13), (1000, 1234)`)
+	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`)
+	})
+
+	// 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`)
+	assert.EqualValues(t, 1, qr.RowsAffected)
+	// 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(13)]]`)
+
+	// Update u_t1 which has a foreign key constraint to u_t2 with SET NULL type, and to u_t3 with CASCADE type.
+	// This update however doesn't change the table.
+	qr = utils.Exec(t, conn, `update u_t1 set col1 = 1234 where id = 1000`)
+	assert.EqualValues(t, 0, qr.RowsAffected)
+	// 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(13)]]`)
 }

go/test/endtoend/vtgate/foreignkey/main_test.go

@@ -35,13 +35,19 @@ var (
 	clusterInstance *cluster.LocalProcessCluster
 	vtParams        mysql.ConnParams
 	shardedKs       = "ks"
+	unshardedKs     = "uks"
 	Cell            = "test"
-
 	//go:embed sharded_schema.sql
 	shardedSchemaSQL string
 
+	//go:embed unsharded_schema.sql
+	unshardedSchemaSQL string
+
 	//go:embed sharded_vschema.json
 	shardedVSchema string
+
+	//go:embed unsharded_vschema.json
+	unshardedVSchema string
 )
 
 func TestMain(m *testing.M) {
@@ -70,6 +76,21 @@ func TestMain(m *testing.M) {
 			return 1
 		}
 
+		uKs := &cluster.Keyspace{
+			Name:      unshardedKs,
+			SchemaSQL: unshardedSchemaSQL,
+			VSchema:   unshardedVSchema,
+		}
+		err = clusterInstance.StartUnshardedKeyspace(*uKs, 0, false)
+		if err != nil {
+			return 1
+		}
+
+		err = clusterInstance.VtctlclientProcess.ExecuteCommand("RebuildVSchemaGraph")
+		if err != nil {
+			return 1
+		}
+
 		// Start vtgate
 		err = clusterInstance.StartVtgate()
 		if err != nil {
@@ -99,6 +120,10 @@ func start(t *testing.T) (*mysql.Conn, func()) {
 		for _, table := range tables {
 			_ = utils.Exec(t, conn, "delete from "+table)
 		}
+		_ = utils.Exec(t, conn, "use `uks`")
+		for _, table := range []string{"u_t1", "u_t2"} {
+			_ = utils.Exec(t, conn, "delete from "+table)
+		}
 		_ = utils.Exec(t, conn, "use `ks`")
 	}
 

go/test/endtoend/vtgate/foreignkey/unsharded_schema.sql

@@ -0,0 +1,23 @@
+create table u_t1
+(
+    id bigint,
+    col1 bigint,
+    index(col1),
+    primary key (id)
+) Engine = InnoDB;
+
+create table u_t2
+(
+    id bigint,
+    col2 bigint,
+    primary key (id),
+    foreign key (col2) references u_t1 (col1) on delete set null on update set null
+) Engine = InnoDB;
+
+create table u_t3
+(
+    id bigint,
+    col3 bigint,
+    primary key (id),
+    foreign key (col3) references u_t1 (col1) on delete cascade on update cascade
+) Engine = InnoDB;

go/test/endtoend/vtgate/foreignkey/unsharded_vschema.json

@@ -0,0 +1,8 @@
+{
+  "sharded": false,
+  "foreignKeyMode": "FK_MANAGED",
+  "tables": {
+    "u_a": {},
+    "u_b": {}
+  }
+}

go/vt/vterrors/code.go

@@ -76,6 +76,7 @@ var (
 	VT09013 = errorWithoutState("VT09013", vtrpcpb.Code_FAILED_PRECONDITION, "semi-sync plugins are not loaded", "Durability policy wants Vitess to use semi-sync, but the MySQL instances don't have the semi-sync plugin loaded.")
 	VT09014 = errorWithoutState("VT09014", vtrpcpb.Code_FAILED_PRECONDITION, "vindex cannot be modified", "The vindex cannot be used as table in DML statement")
 	VT09015 = errorWithoutState("VT09015", vtrpcpb.Code_FAILED_PRECONDITION, "schema tracking required", "This query cannot be planned without more information on the SQL schema. Please turn on schema tracking or add authoritative columns information to your VSchema.")
+	VT09016 = errorWithState("VT09016", vtrpcpb.Code_FAILED_PRECONDITION, RowIsReferenced2, "Cannot delete or update a parent row: a foreign key constraint fails", "SET DEFAULT is not supported by InnoDB")
 
 	VT10001 = errorWithoutState("VT10001", vtrpcpb.Code_ABORTED, "foreign key constraints are not allowed", "Foreign key constraints are not allowed, see https://vitess.io/blog/2021-06-15-online-ddl-why-no-fk/.")
 
@@ -143,6 +144,7 @@ var (
 		VT09013,
 		VT09014,
 		VT09015,
+		VT09016,
 		VT10001,
 		VT12001,
 		VT12002,

go/vt/vterrors/state.go

@@ -55,6 +55,7 @@ const (
 	CantDoThisInTransaction
 	RequiresPrimaryKey
 	OperandColumns
+	RowIsReferenced2
 	UnknownStmtHandler
 
 	// not found

go/vt/vtgate/engine/fk_cascade.go

@@ -39,7 +39,7 @@ type FkCascade struct {
 	// Selection is the Primitive that is used to find the rows that are going to be modified in the child tables.
 	Selection Primitive
 	// Children is a list of child foreign key Primitives that are executed using rows from the Selection Primitive.
-	Children []FkChild
+	Children []*FkChild
 	// Parent is the Primitive that is executed after the children are modified.
 	Parent Primitive
 
@@ -168,17 +168,30 @@ func (fkc *FkCascade) TryStreamExecute(ctx context.Context, vcursor VCursor, bin
 
 // Inputs implements the Primitive interface.
 func (fkc *FkCascade) Inputs() []Primitive {
-	inputs := []Primitive{fkc.Selection}
-	for _, child := range fkc.Children {
-		inputs = append(inputs, child.Exec)
-	}
-	inputs = append(inputs, fkc.Parent)
-	return inputs
+	return nil
 }
 
 func (fkc *FkCascade) description() PrimitiveDescription {
+	var childrenDesc []PrimitiveDescription
+	for _, child := range fkc.Children {
+		childrenDesc = append(childrenDesc, PrimitiveDescription{
+			OperatorType: "FkCascadeChild",
+			Inputs: []PrimitiveDescription{
+				PrimitiveToPlanDescription(child.Exec),
+			},
+			Other: map[string]any{
+				"BvName": child.BVName,
+				"Cols":   child.Cols,
+			},
+		})
+	}
 	return PrimitiveDescription{
 		OperatorType: fkc.RouteType(),
+		Other: map[string]any{
+			"Selection": PrimitiveToPlanDescription(fkc.Selection),
+			"Parent":    PrimitiveToPlanDescription(fkc.Parent),
+			"Children":  childrenDesc,
+		},
 	}
 }
 

go/vt/vtgate/engine/fk_cascade_test.go

@@ -58,7 +58,7 @@ func TestDeleteCascade(t *testing.T) {
 	}
 	fkc := &FkCascade{
 		Selection: inputP,
-		Children:  []FkChild{{BVName: "__vals", Cols: []int{0, 1}, Exec: childP}},
+		Children:  []*FkChild{{BVName: "__vals", Cols: []int{0, 1}, Exec: childP}},
 		Parent:    parentP,
 	}
 
@@ -119,7 +119,7 @@ func TestUpdateCascade(t *testing.T) {
 	}
 	fkc := &FkCascade{
 		Selection: inputP,
-		Children:  []FkChild{{BVName: "__vals", Cols: []int{0, 1}, Exec: childP}},
+		Children:  []*FkChild{{BVName: "__vals", Cols: []int{0, 1}, Exec: childP}},
 		Parent:    parentP,
 	}
 

go/vt/vtgate/planbuilder/delete.go

@@ -46,46 +46,39 @@ func gen4DeleteStmtPlanner(
 		}
 	}
 
-	ksName := ""
-	if ks, _ := vschema.DefaultKeyspace(); ks != nil {
-		ksName = ks.Name
-	}
-	semTable, err := semantics.Analyze(deleteStmt, ksName, vschema)
+	ctx, err := plancontext.CreatePlanningContext(deleteStmt, reservedVars, vschema, version)
 	if err != nil {
 		return nil, err
 	}
 
-	// record any warning as planner warning.
-	vschema.PlannerWarning(semTable.Warning)
 	err = rewriteRoutedTables(deleteStmt, vschema)
 	if err != nil {
 		return nil, err
 	}
 
-	if ks, tables := semTable.SingleUnshardedKeyspace(); ks != nil {
+	if ks, tables := ctx.SemTable.SingleUnshardedKeyspace(); ks != nil {
 		if fkManagementNotRequired(vschema, tables) {
 			plan := deleteUnshardedShortcut(deleteStmt, ks, tables)
 			plan = pushCommentDirectivesOnPlan(plan, deleteStmt)
 			return newPlanResult(plan.Primitive(), operators.QualifiedTables(ks, tables)...), nil
 		}
 	}
 
-	if err := checkIfDeleteSupported(deleteStmt, semTable); err != nil {
+	if err := checkIfDeleteSupported(deleteStmt, ctx.SemTable); err != nil {
 		return nil, err
 	}
 
-	err = queryRewrite(semTable, reservedVars, deleteStmt)
+	err = queryRewrite(ctx.SemTable, reservedVars, deleteStmt)
 	if err != nil {
 		return nil, err
 	}
 
-	ctx := plancontext.NewPlanningContext(reservedVars, semTable, vschema, version)
 	op, err := operators.PlanQuery(ctx, deleteStmt)
 	if err != nil {
 		return nil, err
 	}
 
-	plan, err := transformToLogicalPlan(ctx, op, true)
+	plan, err := transformToLogicalPlan(ctx, op)
 	if err != nil {
 		return nil, err
 	}