restore: fix failed to restore due to no such policy (#42795)

close #42796

br/pkg/gluetidb/glue.go

@@ -163,6 +163,11 @@ func (gs *tidbSession) ExecuteInternal(ctx context.Context, sql string, args ...
 	if err != nil {
 		return errors.Trace(err)
 	}
+	defer func() {
+		// We need to manually clean the TxnCtx here.
+		// Or we may get stale information schema in the consequent calls.
+		gs.se.GetSessionVars().TxnCtx.InfoSchema = nil
+	}()
 	// Some of SQLs (like ADMIN RECOVER INDEX) may lazily take effect
 	// when we polling the result set.
 	// At least call `next` once for triggering theirs side effect.

br/pkg/gluetidb/glue_test.go

@@ -0,0 +1,87 @@
+// Copyright 2023 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package gluetidb
+
+import (
+	"context"
+	"testing"
+
+	"github.com/pingcap/tidb/br/pkg/glue"
+	"github.com/pingcap/tidb/parser/model"
+	"github.com/pingcap/tidb/testkit"
+	"github.com/pingcap/tidb/types"
+	"github.com/stretchr/testify/require"
+)
+
+func TestTheSessionIsoation(t *testing.T) {
+	req := require.New(t)
+	store, _, clean := testkit.CreateMockStoreAndDomain(t)
+	defer clean()
+	ctx := context.Background()
+
+	g := Glue{}
+	session, err := g.CreateSession(store)
+	req.NoError(err)
+
+	req.NoError(session.ExecuteInternal(ctx, "use test;"))
+	infos := []*model.TableInfo{}
+	infos = append(infos, &model.TableInfo{
+		Name: model.NewCIStr("tables_1"),
+		Columns: []*model.ColumnInfo{
+			{Name: model.NewCIStr("foo"), FieldType: *types.NewFieldType(types.KindBinaryLiteral), State: model.StatePublic},
+		},
+	})
+	infos = append(infos, &model.TableInfo{
+		Name: model.NewCIStr("tables_2"),
+		PlacementPolicyRef: &model.PolicyRefInfo{
+			Name: model.NewCIStr("threereplication"),
+		},
+		Columns: []*model.ColumnInfo{
+			{Name: model.NewCIStr("foo"), FieldType: *types.NewFieldType(types.KindBinaryLiteral), State: model.StatePublic},
+		},
+	})
+	infos = append(infos, &model.TableInfo{
+		Name: model.NewCIStr("tables_3"),
+		PlacementPolicyRef: &model.PolicyRefInfo{
+			Name: model.NewCIStr("fivereplication"),
+		},
+		Columns: []*model.ColumnInfo{
+			{Name: model.NewCIStr("foo"), FieldType: *types.NewFieldType(types.KindBinaryLiteral), State: model.StatePublic},
+		},
+	})
+	polices := []*model.PolicyInfo{
+		{
+			PlacementSettings: &model.PlacementSettings{
+				Followers: 4,
+			},
+			Name: model.NewCIStr("fivereplication"),
+		},
+		{
+			PlacementSettings: &model.PlacementSettings{
+				Followers: 2,
+			},
+			Name: model.NewCIStr("threereplication"),
+		},
+	}
+	for _, pinfo := range polices {
+		before := session.(*tidbSession).se.GetInfoSchema().SchemaMetaVersion()
+		req.NoError(session.CreatePlacementPolicy(ctx, pinfo))
+		after := session.(*tidbSession).se.GetInfoSchema().SchemaMetaVersion()
+		req.Greater(after, before)
+	}
+	req.NoError(session.(glue.BatchCreateTableSession).CreateTables(ctx, map[string][]*model.TableInfo{
+		"test": infos,
+	}))
+}