diff --git a/infoschema/info_store.go b/infoschema/info_store.go
new file mode 100644
index 0000000000000..9ffd78e64fa2c
--- /dev/null
+++ b/infoschema/info_store.go
@@ -0,0 +1,160 @@
+// Copyright 2022 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 infoschema
+
+import (
+	"github.com/pingcap/tidb/parser/model"
+	"github.com/pingcap/tidb/table"
+	"github.com/pingcap/tidb/table/tables"
+)
+
+// InfoStore is a simple structure that stores DBInfo and TableInfo. It's modifiable and not thread-safe.
+type InfoStore struct {
+	lowerCaseTableNames int // same as variable lower_case_table_names
+
+	dbs    map[string]*model.DBInfo
+	tables map[string]map[string]*model.TableInfo
+}
+
+// NewInfoStore creates a InfoStore.
+func NewInfoStore(lowerCaseTableNames int) *InfoStore {
+	return &InfoStore{
+		lowerCaseTableNames: lowerCaseTableNames,
+		dbs:                 map[string]*model.DBInfo{},
+		tables:              map[string]map[string]*model.TableInfo{},
+	}
+}
+
+func (i *InfoStore) ciStr2Key(name model.CIStr) string {
+	if i.lowerCaseTableNames == 0 {
+		return name.O
+	}
+	return name.L
+}
+
+// SchemaByName returns the DBInfo of given name. nil if not found.
+func (i *InfoStore) SchemaByName(name model.CIStr) *model.DBInfo {
+	key := i.ciStr2Key(name)
+	return i.dbs[key]
+}
+
+// PutSchema puts a DBInfo, it will overwrite the old one.
+func (i *InfoStore) PutSchema(dbInfo *model.DBInfo) {
+	key := i.ciStr2Key(dbInfo.Name)
+	i.dbs[key] = dbInfo
+	if i.tables[key] == nil {
+		i.tables[key] = map[string]*model.TableInfo{}
+	}
+}
+
+// DeleteSchema deletes the schema from InfoSchema. Returns true when the schema exists, false otherwise.
+func (i *InfoStore) DeleteSchema(name model.CIStr) bool {
+	key := i.ciStr2Key(name)
+	_, ok := i.dbs[key]
+	if !ok {
+		return false
+	}
+	delete(i.dbs, key)
+	delete(i.tables, key)
+	return true
+}
+
+// TableByName returns the TableInfo. It will also return the error like an infoschema.
+func (i *InfoStore) TableByName(schema, table model.CIStr) (*model.TableInfo, error) {
+	schemaKey := i.ciStr2Key(schema)
+	tables, ok := i.tables[schemaKey]
+	if !ok {
+		return nil, ErrDatabaseNotExists.GenWithStackByArgs(schema)
+	}
+
+	tableKey := i.ciStr2Key(table)
+	tbl, ok := tables[tableKey]
+	if !ok {
+		return nil, ErrTableNotExists.GenWithStackByArgs(schema, table)
+	}
+	return tbl, nil
+}
+
+// PutTable puts a TableInfo, it will overwrite the old one. If the schema doesn't exist, it will return ErrDatabaseNotExists.
+func (i *InfoStore) PutTable(schemaName model.CIStr, tblInfo *model.TableInfo) error {
+	schemaKey := i.ciStr2Key(schemaName)
+	tables, ok := i.tables[schemaKey]
+	if !ok {
+		return ErrDatabaseNotExists.GenWithStackByArgs(schemaName)
+	}
+	tableKey := i.ciStr2Key(tblInfo.Name)
+	tables[tableKey] = tblInfo
+	return nil
+}
+
+// DeleteTable deletes the TableInfo, it will return ErrDatabaseNotExists or ErrTableNotExists when schema or table does
+// not exist.
+func (i *InfoStore) DeleteTable(schema, table model.CIStr) error {
+	schemaKey := i.ciStr2Key(schema)
+	tables, ok := i.tables[schemaKey]
+	if !ok {
+		return ErrDatabaseNotExists.GenWithStackByArgs(schema)
+	}
+
+	tableKey := i.ciStr2Key(table)
+	_, ok = tables[tableKey]
+	if !ok {
+		return ErrTableNotExists.GenWithStackByArgs(schema, table)
+	}
+	delete(tables, tableKey)
+	return nil
+}
+
+// InfoStoreAdaptor convert InfoStore to InfoSchema, it only implements a part of InfoSchema interface to be
+// used by DDL interface.
+// nolint:unused
+type InfoStoreAdaptor struct {
+	InfoSchema
+	inner *InfoStore
+}
+
+// SchemaByName implements the InfoSchema interface.
+// nolint:unused
+func (i InfoStoreAdaptor) SchemaByName(schema model.CIStr) (*model.DBInfo, bool) {
+	dbInfo := i.inner.SchemaByName(schema)
+	return dbInfo, dbInfo != nil
+}
+
+// TableExists implements the InfoSchema interface.
+// nolint:unused
+func (i InfoStoreAdaptor) TableExists(schema, table model.CIStr) bool {
+	tableInfo, _ := i.inner.TableByName(schema, table)
+	return tableInfo != nil
+}
+
+// TableIsView implements the InfoSchema interface.
+// nolint:unused
+func (i InfoStoreAdaptor) TableIsView(schema, table model.CIStr) bool {
+	tableInfo, _ := i.inner.TableByName(schema, table)
+	if tableInfo == nil {
+		return false
+	}
+	return tableInfo.IsView()
+}
+
+// TableByName implements the InfoSchema interface.
+// nolint:unused
+func (i InfoStoreAdaptor) TableByName(schema, table model.CIStr) (t table.Table, err error) {
+	tableInfo, err := i.inner.TableByName(schema, table)
+	if err != nil {
+		return nil, err
+	}
+	return tables.MockTableFromMeta(tableInfo), nil
+}
diff --git a/infoschema/info_store_test.go b/infoschema/info_store_test.go
new file mode 100644
index 0000000000000..07ee9d87d9de5
--- /dev/null
+++ b/infoschema/info_store_test.go
@@ -0,0 +1,115 @@
+// Copyright 2022 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 infoschema
+
+import (
+	"testing"
+
+	"github.com/pingcap/tidb/parser/model"
+	"github.com/stretchr/testify/require"
+)
+
+func TestInfoStoreLowerCaseTableNames(t *testing.T) {
+	dbName := model.NewCIStr("DBName")
+	lowerDBName := model.NewCIStr("dbname")
+	tableName := model.NewCIStr("TableName")
+	lowerTableName := model.NewCIStr("tablename")
+	dbInfo := &model.DBInfo{Name: dbName}
+	tableInfo := &model.TableInfo{Name: tableName}
+
+	// case-sensitive
+
+	is := NewInfoStore(0)
+	is.PutSchema(dbInfo)
+	got := is.SchemaByName(dbName)
+	require.NotNil(t, got)
+	got = is.SchemaByName(lowerDBName)
+	require.Nil(t, got)
+
+	err := is.PutTable(lowerDBName, tableInfo)
+	require.True(t, ErrDatabaseNotExists.Equal(err))
+	err = is.PutTable(dbName, tableInfo)
+	require.NoError(t, err)
+	got2, err := is.TableByName(dbName, tableName)
+	require.NoError(t, err)
+	require.NotNil(t, got2)
+	got2, err = is.TableByName(lowerTableName, tableName)
+	require.True(t, ErrDatabaseNotExists.Equal(err))
+	require.Nil(t, got2)
+	got2, err = is.TableByName(dbName, lowerTableName)
+	require.True(t, ErrTableNotExists.Equal(err))
+	require.Nil(t, got2)
+
+	// compare-insensitive
+
+	is = NewInfoStore(2)
+	is.PutSchema(dbInfo)
+	got = is.SchemaByName(dbName)
+	require.NotNil(t, got)
+	got = is.SchemaByName(lowerDBName)
+	require.NotNil(t, got)
+	require.Equal(t, dbName, got.Name)
+
+	err = is.PutTable(lowerDBName, tableInfo)
+	require.NoError(t, err)
+	got2, err = is.TableByName(dbName, tableName)
+	require.NoError(t, err)
+	require.NotNil(t, got2)
+	got2, err = is.TableByName(dbName, lowerTableName)
+	require.NoError(t, err)
+	require.NotNil(t, got2)
+	require.Equal(t, tableName, got2.Name)
+}
+
+func TestInfoStoreDeleteTables(t *testing.T) {
+	is := NewInfoStore(0)
+	dbName1 := model.NewCIStr("DBName1")
+	dbName2 := model.NewCIStr("DBName2")
+	tableName1 := model.NewCIStr("TableName1")
+	tableName2 := model.NewCIStr("TableName2")
+	dbInfo1 := &model.DBInfo{Name: dbName1}
+	dbInfo2 := &model.DBInfo{Name: dbName2}
+	tableInfo1 := &model.TableInfo{Name: tableName1}
+	tableInfo2 := &model.TableInfo{Name: tableName2}
+
+	is.PutSchema(dbInfo1)
+	err := is.PutTable(dbName1, tableInfo1)
+	require.NoError(t, err)
+	err = is.PutTable(dbName1, tableInfo2)
+	require.NoError(t, err)
+
+	// db2 not created
+	ok := is.DeleteSchema(dbName2)
+	require.False(t, ok)
+	err = is.PutTable(dbName2, tableInfo1)
+	require.True(t, ErrDatabaseNotExists.Equal(err))
+	err = is.DeleteTable(dbName2, tableName1)
+	require.True(t, ErrDatabaseNotExists.Equal(err))
+
+	is.PutSchema(dbInfo2)
+	err = is.PutTable(dbName2, tableInfo1)
+	require.NoError(t, err)
+
+	err = is.DeleteTable(dbName2, tableName2)
+	require.True(t, ErrTableNotExists.Equal(err))
+	err = is.DeleteTable(dbName2, tableName1)
+	require.NoError(t, err)
+
+	// delete db will remove its tables
+	ok = is.DeleteSchema(dbName1)
+	require.True(t, ok)
+	_, err = is.TableByName(dbName1, tableName1)
+	require.True(t, ErrDatabaseNotExists.Equal(err))
+}