diff --git a/executor/builder.go b/executor/builder.go
index e04a51245b824..2b5de81ee15e7 100644
--- a/executor/builder.go
+++ b/executor/builder.go
@@ -550,7 +550,12 @@ func (b *executorBuilder) buildShow(v *plannercore.Show) Executor {
 		is:           b.is,
 	}
 	if e.Tp == ast.ShowGrants && e.User == nil {
-		e.User = e.ctx.GetSessionVars().User
+		// The input is a "show grants" statement, fulfill the user and roles field.
+		// Note: "show grants" result are different from "show grants for current_user",
+		// The former determine privileges with roles, while the later doesn't.
+		vars := e.ctx.GetSessionVars()
+		e.User = vars.User
+		e.Roles = vars.ActiveRoles
 	}
 	if e.Tp == ast.ShowMasterStatus {
 		// show master status need start ts.
diff --git a/executor/show_test.go b/executor/show_test.go
index 0e3ce9a481991..64218826245e8 100644
--- a/executor/show_test.go
+++ b/executor/show_test.go
@@ -157,6 +157,21 @@ func (s *testSuite2) TestIssue3641(c *C) {
 	c.Assert(err.Error(), Equals, plannercore.ErrNoDB.Error())
 }
 
+func (s *testSuite2) TestIssue10549(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("CREATE DATABASE newdb;")
+	tk.MustExec("CREATE ROLE 'app_developer';")
+	tk.MustExec("GRANT ALL ON newdb.* TO 'app_developer';")
+	tk.MustExec("CREATE USER 'dev';")
+	tk.MustExec("GRANT 'app_developer' TO 'dev';")
+	tk.MustExec("SET DEFAULT ROLE app_developer TO 'dev';")
+
+	c.Assert(tk.Se.Auth(&auth.UserIdentity{Username: "dev", Hostname: "localhost", AuthUsername: "dev", AuthHostname: "localhost"}, nil, nil), IsTrue)
+	tk.MustQuery("SHOW DATABASES;").Check(testkit.Rows("INFORMATION_SCHEMA", "newdb"))
+	tk.MustQuery("SHOW GRANTS;").Check(testkit.Rows("GRANT USAGE ON *.* TO 'dev'@'%'", "GRANT ALL PRIVILEGES ON newdb.* TO 'dev'@'%'", "GRANT 'app_developer'@'%' TO 'dev'@'%'"))
+	tk.MustQuery("SHOW GRANTS FOR CURRENT_USER").Check(testkit.Rows("GRANT USAGE ON *.* TO 'dev'@'%'", "GRANT 'app_developer'@'%' TO 'dev'@'%'"))
+}
+
 // TestShow2 is moved from session_test
 func (s *testSuite2) TestShow2(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
diff --git a/executor/simple.go b/executor/simple.go
index 4ee51342d3838..87d76ba8bdf0b 100644
--- a/executor/simple.go
+++ b/executor/simple.go
@@ -221,17 +221,20 @@ func (e *SimpleExec) setDefaultRoleAll(s *ast.SetDefaultRoleStmt) error {
 	return nil
 }
 
-func (e *SimpleExec) executeSetDefaultRole(s *ast.SetDefaultRoleStmt) error {
+func (e *SimpleExec) executeSetDefaultRole(s *ast.SetDefaultRoleStmt) (err error) {
 	switch s.SetRoleOpt {
 	case ast.SetRoleAll:
-		return e.setDefaultRoleAll(s)
+		err = e.setDefaultRoleAll(s)
 	case ast.SetRoleNone:
-		return e.setDefaultRoleNone(s)
+		err = e.setDefaultRoleNone(s)
 	case ast.SetRoleRegular:
-		return e.setDefaultRoleRegular(s)
+		err = e.setDefaultRoleRegular(s)
 	}
-	err := domain.GetDomain(e.ctx).PrivilegeHandle().Update(e.ctx.(sessionctx.Context))
-	return err
+	if err != nil {
+		return
+	}
+	domain.GetDomain(e.ctx).NotifyUpdatePrivilege(e.ctx)
+	return
 }
 
 func (e *SimpleExec) setRoleRegular(s *ast.SetRoleStmt) error {
diff --git a/privilege/privileges/privileges_test.go b/privilege/privileges/privileges_test.go
index 3a9e1b09b9cf3..b75dbeeac589c 100644
--- a/privilege/privileges/privileges_test.go
+++ b/privilege/privileges/privileges_test.go
@@ -494,7 +494,6 @@ func (s *testPrivilegeSuite) TestUseDB(c *C) {
 	mustExec(c, se, `CREATE USER 'dev'@'localhost'`)
 	mustExec(c, se, `GRANT 'app_developer' TO 'dev'@'localhost'`)
 	mustExec(c, se, `SET DEFAULT ROLE 'app_developer' TO 'dev'@'localhost'`)
-	mustExec(c, se, `FLUSH PRIVILEGES`)
 	c.Assert(se.Auth(&auth.UserIdentity{Username: "dev", Hostname: "localhost", AuthUsername: "dev", AuthHostname: "localhost"}, nil, nil), IsTrue)
 	_, err = se.Execute(context.Background(), "use app_db")
 	c.Assert(err, IsNil)