planner: allow insert default into generated columns

ddl/db_integration_test.go

@@ -1931,3 +1931,65 @@ func (s *testIntegrationSuite4) TestDropAutoIncrementIndex(c *C) {
 	dropIndexSQL = "alter table t1 drop index a"
 	assertErrorCode(c, tk, dropIndexSQL, mysql.ErrWrongAutoKey)
 }
+
+func (s *testIntegrationSuite3) TestInsertIntoGeneratedColumnWithDefaultExpr(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("create database if not exists test")
+	tk.MustExec("use test")
+
+	// insert into virtual / stored columns
+	tk.MustExec("drop table if exists t1")
+	tk.MustExec("create table t1 (a int, b int as (-a) virtual, c int as (-a) stored)")
+	tk.MustExec("insert into t1 values (1, default, default)")
+	tk.MustQuery("select * from t1").Check(testkit.Rows("1 -1 -1"))
+	tk.MustExec("delete from t1")
+
+	// insert multiple rows
+	tk.MustExec("insert into t1(a,b) values (1, default), (2, default)")
+	tk.MustQuery("select * from t1").Check(testkit.Rows("1 -1 -1", "2 -2 -2"))
+	tk.MustExec("delete from t1")
+
+	// insert into generated columns only
+	tk.MustExec("insert into t1(b) values (default)")
+	tk.MustQuery("select * from t1").Check(testkit.Rows("<nil> <nil> <nil>"))
+	tk.MustExec("delete from t1")
+	tk.MustExec("insert into t1(c) values (default)")
+	tk.MustQuery("select * from t1").Check(testkit.Rows("<nil> <nil> <nil>"))
+	tk.MustExec("delete from t1")
+
+	// generated columns with index
+	tk.MustExec("drop table if exists t2")
+	tk.MustExec("create table t2 like t1")
+	tk.MustExec("alter table t2 add index idx1(a)")
+	tk.MustExec("alter table t2 add index idx2(b)")
+	tk.MustExec("insert into t2 values (1, default, default)")
+	tk.MustQuery("select * from t2").Check(testkit.Rows("1 -1 -1"))
+	tk.MustExec("delete from t2")
+	tk.MustExec("alter table t2 drop index idx1")
+	tk.MustExec("alter table t2 drop index idx2")
+	tk.MustExec("insert into t2 values (1, default, default)")
+	tk.MustQuery("select * from t2").Check(testkit.Rows("1 -1 -1"))
+
+	// generated columns in different position
+	tk.MustExec("drop table if exists t3")
+	tk.MustExec("create table t3 (gc1 int as (r+1), gc2 int as (r+1) stored, gc3 int as (gc2+1), gc4 int as (gc1+1) stored, r int)")
+	tk.MustExec("insert into t3 values (default, default, default, default, 1)")
+	tk.MustQuery("select * from t3").Check(testkit.Rows("2 2 3 3 1"))
+
+	// generated columns in replace statement
+	tk.MustExec("create table t4 (a int key, b int, c int as (a+1), d int as (b+1) stored)")
+	tk.MustExec("insert into t4 values (1, 10, default, default)")
+	tk.MustQuery("select * from t4").Check(testkit.Rows("1 10 2 11"))
+	tk.MustExec("replace into t4 values (1, 20, default, default)")
+	tk.MustQuery("select * from t4").Check(testkit.Rows("1 20 2 21"))
+
+	// generated columns with default function is not allowed
+	tk.MustExec("create table t5 (a int default 10, b int as (a+1))")
+	assertErrorCode(c, tk, "insert into t5 values (20, default(a))", mysql.ErrBadGeneratedColumn)
+
+	tk.MustExec("drop table t1")
+	tk.MustExec("drop table t2")
+	tk.MustExec("drop table t3")
+	tk.MustExec("drop table t4")
+	tk.MustExec("drop table t5")
+}

executor/insert_common.go

@@ -116,9 +116,6 @@ func (e *InsertValues) initInsertColumns() error {
 		for _, v := range e.Columns {
 			columns = append(columns, v.Name.O)
 		}
-		for _, v := range e.GenColumns {
-			columns = append(columns, v.Name.O)
-		}
 		cols, err = table.FindCols(tableCols, columns, e.Table.Meta().PKIsHandle)
 		if err != nil {
 			return errors.Errorf("INSERT INTO %s: %s", e.Table.Meta().Name.O, err)
@@ -128,6 +125,9 @@ func (e *InsertValues) initInsertColumns() error {
 		cols = tableCols
 	}
 	for _, col := range cols {
+		if !col.IsGenerated() {
+			e.insertColumns = append(e.insertColumns, col)
+		}
 		if col.Name.L == model.ExtraHandleName.L {
 			if !e.ctx.GetSessionVars().AllowWriteRowID {
 				return errors.Errorf("insert, update and replace statements for _tidb_rowid are not supported.")
@@ -142,7 +142,6 @@ func (e *InsertValues) initInsertColumns() error {
 	if err != nil {
 		return err
 	}
-	e.insertColumns = cols
 	return nil
 }
 

planner/core/planbuilder.go

@@ -1755,12 +1755,6 @@ func (b *PlanBuilder) buildValuesListOfInsert(ctx context.Context, insert *ast.I
 		if len(insert.Lists[0]) != len(affectedValuesCols) {
 			return ErrWrongValueCountOnRow.GenWithStackByArgs(1)
 		}
-		// No generated column is allowed.
-		for _, col := range affectedValuesCols {
-			if col.IsGenerated() {
-				return ErrBadGeneratedColumn.GenWithStackByArgs(col.Name.O, insertPlan.Table.Meta().Name.O)
-			}
-		}
 	}
 
 	insertPlan.AllAssignmentsAreConstant = true
@@ -1778,8 +1772,17 @@ func (b *PlanBuilder) buildValuesListOfInsert(ctx context.Context, insert *ast.I
 		for j, valueItem := range valuesItem {
 			var expr expression.Expression
 			var err error
+			var generatedColumnWithDefaultExpr bool
+			col := affectedValuesCols[j]
 			switch x := valueItem.(type) {
 			case *ast.DefaultExpr:
+				if col.IsGenerated() {
+					if x.Name != nil {
+						return ErrBadGeneratedColumn.GenWithStackByArgs(col.Name.O, insertPlan.Table.Meta().Name.O)
+					}
+					generatedColumnWithDefaultExpr = true
+					break
+				}
 				if x.Name != nil {
 					expr, err = b.findDefaultValue(totalTableCols, x.Name)
 				} else {
@@ -1800,6 +1803,15 @@ func (b *PlanBuilder) buildValuesListOfInsert(ctx context.Context, insert *ast.I
 				_, isConstant := expr.(*expression.Constant)
 				insertPlan.AllAssignmentsAreConstant = isConstant
 			}
+			// insert value into a generated column is not allowed
+			if col.IsGenerated() {
+				// but there is only one exception:
+				// it is allowed to insert the `default` value into a generated column
+				if generatedColumnWithDefaultExpr {
+					continue
+				}
+				return ErrBadGeneratedColumn.GenWithStackByArgs(col.Name.O, insertPlan.Table.Meta().Name.O)
+			}
 			exprList = append(exprList, expr)
 		}
 		insertPlan.Lists = append(insertPlan.Lists, exprList)