executor: generate AST instead of SQL for foreign key cascade

executor/BUILD.bazel

@@ -150,6 +150,7 @@ go_library(
         "//telemetry",
         "//tidb-binlog/node",
         "//types",
+        "//types/parser_driver",
         "//util",
         "//util/admin",
         "//util/bitmap",

executor/adapter.go

@@ -611,6 +611,17 @@ func (a *ExecStmt) handleForeignKeyTrigger(ctx context.Context, e Executor, dept
 	return nil
 }
 
+// handleForeignKeyCascade uses to execute foreign key cascade behaviour, the progress is:
+//  1. Build delete/update executor for foreign key on delete/update behaviour.
+//     a. Construct delete/update AST. We used to try generated SQL string first and then parse the SQL to get AST,
+//     but we need convert Datum to string, there may be some risks here, since assert_eq(datum_a, parse(datum_a.toString())) may be broken.
+//     so we chose to construct AST directly.
+//     b. Build plan by the delete/update AST.
+//     c. Build executor by the delete/update plan.
+//  2. Execute the delete/update executor.
+//  3. Close the executor.
+//  4. `StmtCommit` to commit the kv change to transaction mem-buffer.
+//  5. If the foreign key cascade behaviour has more fk value need to be cascaded, go to step 1.
 func (a *ExecStmt) handleForeignKeyCascade(ctx context.Context, fkc *FKCascadeExec, depth int) error {
 	if len(fkc.fkValues) == 0 && len(fkc.fkUpdatedValuesMap) == 0 {
 		return nil

executor/fktest/BUILD.bazel

@@ -13,10 +13,14 @@ go_test(
         "//executor",
         "//kv",
         "//meta/autoid",
+        "//parser/ast",
+        "//parser/format",
         "//parser/model",
+        "//parser/mysql",
         "//planner/core",
         "//testkit",
         "//types",
+        "//util/sqlexec",
         "@com_github_stretchr_testify//require",
         "@com_github_tikv_client_go_v2//tikv",
         "@org_uber_go_goleak//:goleak",

executor/fktest/foreign_key_test.go

@@ -16,6 +16,7 @@ package fk_test
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"strconv"
 	"strings"
@@ -25,10 +26,14 @@ import (
 
 	"github.com/pingcap/tidb/executor"
 	"github.com/pingcap/tidb/kv"
+	"github.com/pingcap/tidb/parser/ast"
+	"github.com/pingcap/tidb/parser/format"
 	"github.com/pingcap/tidb/parser/model"
+	"github.com/pingcap/tidb/parser/mysql"
 	plannercore "github.com/pingcap/tidb/planner/core"
 	"github.com/pingcap/tidb/testkit"
 	"github.com/pingcap/tidb/types"
+	"github.com/pingcap/tidb/util/sqlexec"
 	"github.com/stretchr/testify/require"
 )
 
@@ -1256,44 +1261,57 @@ func TestForeignKeyOnDeleteCascade2(t *testing.T) {
 	tk.MustQuery("select count(*) from t2").Check(testkit.Rows("0"))
 }
 
-func TestForeignKeyGenerateCascadeSQL(t *testing.T) {
-	fk := &model.FKInfo{
-		Cols: []model.CIStr{model.NewCIStr("c0"), model.NewCIStr("c1")},
-	}
+func TestForeignKeyGenerateCascadeAST(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test;")
 	fkValues := [][]types.Datum{
 		{types.NewDatum(1), types.NewDatum("a")},
 		{types.NewDatum(2), types.NewDatum("b")},
 	}
-	sql, err := executor.GenCascadeDeleteSQL(model.NewCIStr("test"), model.NewCIStr("t"), model.NewCIStr(""), fk, fkValues)
-	require.NoError(t, err)
-	require.Equal(t, "DELETE FROM `test`.`t` WHERE (`c0`, `c1`) IN ((1,'a'), (2,'b'))", sql)
-
-	sql, err = executor.GenCascadeDeleteSQL(model.NewCIStr("test"), model.NewCIStr("t"), model.NewCIStr("idx"), fk, fkValues)
-	require.NoError(t, err)
-	require.Equal(t, "DELETE FROM `test`.`t` USE INDEX(`idx`) WHERE (`c0`, `c1`) IN ((1,'a'), (2,'b'))", sql)
-
-	sql, err = executor.GenCascadeSetNullSQL(model.NewCIStr("test"), model.NewCIStr("t"), model.NewCIStr(""), fk, fkValues)
-	require.NoError(t, err)
-	require.Equal(t, "UPDATE `test`.`t` SET `c0` = NULL, `c1` = NULL WHERE (`c0`, `c1`) IN ((1,'a'), (2,'b'))", sql)
-
-	sql, err = executor.GenCascadeSetNullSQL(model.NewCIStr("test"), model.NewCIStr("t"), model.NewCIStr("idx"), fk, fkValues)
-	require.NoError(t, err)
-	require.Equal(t, "UPDATE `test`.`t` USE INDEX(`idx`) SET `c0` = NULL, `c1` = NULL WHERE (`c0`, `c1`) IN ((1,'a'), (2,'b'))", sql)
-
+	cols := []*model.ColumnInfo{
+		{ID: 1, Name: model.NewCIStr("a"), FieldType: *types.NewFieldType(mysql.TypeLonglong)},
+		{ID: 2, Name: model.NewCIStr("name"), FieldType: *types.NewFieldType(mysql.TypeVarchar)},
+	}
+	restoreFn := func(stmt ast.StmtNode) string {
+		var sb strings.Builder
+		fctx := format.NewRestoreCtx(format.DefaultRestoreFlags, &sb)
+		err := stmt.Restore(fctx)
+		require.NoError(t, err)
+		return sb.String()
+	}
+	checkStmtFn := func(stmt ast.StmtNode, sql string) {
+		exec, ok := tk.Session().(sqlexec.RestrictedSQLExecutor)
+		require.True(t, ok)
+		expectedStmt, err := exec.ParseWithParams(context.Background(), sql)
+		require.NoError(t, err)
+		require.Equal(t, restoreFn(expectedStmt), restoreFn(stmt))
+	}
+	var stmt ast.StmtNode
+	stmt = executor.GenCascadeDeleteAST(model.NewCIStr("test"), model.NewCIStr("t2"), model.NewCIStr(""), cols, fkValues)
+	checkStmtFn(stmt, "delete from test.t2 where (a,name) in ((1,'a'), (2,'b'))")
+	stmt = executor.GenCascadeDeleteAST(model.NewCIStr("test"), model.NewCIStr("t2"), model.NewCIStr("idx"), cols, fkValues)
+	checkStmtFn(stmt, "delete from test.t2 use index(idx) where (a,name) in ((1,'a'), (2,'b'))")
+	stmt = executor.GenCascadeSetNullAST(model.NewCIStr("test"), model.NewCIStr("t2"), model.NewCIStr(""), cols, fkValues)
+	checkStmtFn(stmt, "update test.t2 set a = null, name = null where (a,name) in ((1,'a'), (2,'b'))")
+	stmt = executor.GenCascadeSetNullAST(model.NewCIStr("test"), model.NewCIStr("t2"), model.NewCIStr("idx"), cols, fkValues)
+	checkStmtFn(stmt, "update test.t2 use index(idx) set a = null, name = null where (a,name) in ((1,'a'), (2,'b'))")
 	newValue1 := []types.Datum{types.NewDatum(10), types.NewDatum("aa")}
 	couple := &executor.UpdatedValuesCouple{
 		NewValues:     newValue1,
 		OldValuesList: fkValues,
 	}
-	sql, err = executor.GenCascadeUpdateSQL(model.NewCIStr("test"), model.NewCIStr("t"), model.NewCIStr(""), fk, couple)
-	require.NoError(t, err)
-	require.Equal(t, "UPDATE `test`.`t` SET `c0` = 10, `c1` = 'aa' WHERE (`c0`, `c1`) IN ((1,'a'), (2,'b'))", sql)
-
-	newValue2 := []types.Datum{types.NewDatum(nil), types.NewDatum(nil)}
-	couple.NewValues = newValue2
-	sql, err = executor.GenCascadeUpdateSQL(model.NewCIStr("test"), model.NewCIStr("t"), model.NewCIStr("idx"), fk, couple)
-	require.NoError(t, err)
-	require.Equal(t, "UPDATE `test`.`t` USE INDEX(`idx`) SET `c0` = NULL, `c1` = NULL WHERE (`c0`, `c1`) IN ((1,'a'), (2,'b'))", sql)
+	stmt = executor.GenCascadeUpdateAST(model.NewCIStr("test"), model.NewCIStr("t2"), model.NewCIStr(""), cols, couple)
+	checkStmtFn(stmt, "update test.t2 set a = 10, name = 'aa' where (a,name) in ((1,'a'), (2,'b'))")
+	stmt = executor.GenCascadeUpdateAST(model.NewCIStr("test"), model.NewCIStr("t2"), model.NewCIStr("idx"), cols, couple)
+	checkStmtFn(stmt, "update test.t2 use index(idx) set a = 10, name = 'aa' where (a,name) in ((1,'a'), (2,'b'))")
+	// Test for 1 fk column.
+	fkValues = [][]types.Datum{{types.NewDatum(1)}, {types.NewDatum(2)}}
+	cols = []*model.ColumnInfo{{ID: 1, Name: model.NewCIStr("a"), FieldType: *types.NewFieldType(mysql.TypeLonglong)}}
+	stmt = executor.GenCascadeDeleteAST(model.NewCIStr("test"), model.NewCIStr("t2"), model.NewCIStr(""), cols, fkValues)
+	checkStmtFn(stmt, "delete from test.t2 where a in (1,2)")
+	stmt = executor.GenCascadeDeleteAST(model.NewCIStr("test"), model.NewCIStr("t2"), model.NewCIStr("idx"), cols, fkValues)
+	checkStmtFn(stmt, "delete from test.t2 use index(idx) where a in (1,2)")
 }
 
 func TestForeignKeyOnDeleteSetNull(t *testing.T) {