br: add function to get dbs created or modified by users (#36008)

close pingcap/tidb#36006

br/pkg/restore/db.go

@@ -12,10 +12,12 @@ import (
 	"github.com/pingcap/tidb/br/pkg/glue"
 	"github.com/pingcap/tidb/br/pkg/metautil"
 	"github.com/pingcap/tidb/br/pkg/utils"
+	"github.com/pingcap/tidb/domain"
 	"github.com/pingcap/tidb/kv"
 	"github.com/pingcap/tidb/parser/model"
 	"github.com/pingcap/tidb/parser/mysql"
 	"github.com/pingcap/tidb/sessionctx/variable"
+	tidbutil "github.com/pingcap/tidb/util"
 	"go.uber.org/zap"
 	"golang.org/x/exp/slices"
 )
@@ -450,6 +452,24 @@ func DDLJobBlockListRule(ddlJob *model.Job) bool {
 	return checkIsInActions(ddlJob.Type, incrementalRestoreActionBlockList)
 }
 
+// GetExistedUserDBs get dbs created or modified by users
+func GetExistedUserDBs(dom *domain.Domain) []*model.DBInfo {
+	databases := dom.InfoSchema().AllSchemas()
+	existedDatabases := make([]*model.DBInfo, 0, 16)
+	for _, db := range databases {
+		dbName := db.Name.L
+		if tidbutil.IsMemOrSysDB(dbName) {
+			continue
+		} else if dbName == "test" && len(db.Tables) == 0 {
+			continue
+		} else {
+			existedDatabases = append(existedDatabases, db)
+		}
+	}
+
+	return existedDatabases
+}
+
 func getDatabases(tables []*metautil.Table) (dbs []*model.DBInfo) {
 	dbIDs := make(map[int64]bool)
 	for _, table := range tables {

br/pkg/restore/db_test.go

@@ -18,6 +18,7 @@ import (
 	"github.com/pingcap/tidb/br/pkg/mock"
 	"github.com/pingcap/tidb/br/pkg/restore"
 	"github.com/pingcap/tidb/br/pkg/storage"
+	"github.com/pingcap/tidb/infoschema"
 	"github.com/pingcap/tidb/meta/autoid"
 	"github.com/pingcap/tidb/parser/model"
 	"github.com/pingcap/tidb/parser/mysql"
@@ -368,3 +369,52 @@ func TestFilterDDLJobByRules(t *testing.T) {
 		assert.Equal(t, expectedDDLTypes[i], ddlJob.Type)
 	}
 }
+
+func TestGetExistedUserDBs(t *testing.T) {
+	m, err := mock.NewCluster()
+	require.Nil(t, err)
+	defer m.Stop()
+	dom := m.Domain
+
+	dbs := restore.GetExistedUserDBs(dom)
+	require.Equal(t, 0, len(dbs))
+
+	builder, err := infoschema.NewBuilder(m.Store(), nil).InitWithDBInfos(
+		[]*model.DBInfo{
+			{Name: model.NewCIStr("mysql")},
+			{Name: model.NewCIStr("test")},
+		},
+		nil, 1)
+	require.Nil(t, err)
+	dom.MockInfoCacheAndLoadInfoSchema(builder.Build())
+	dbs = restore.GetExistedUserDBs(dom)
+	require.Equal(t, 0, len(dbs))
+
+	builder, err = infoschema.NewBuilder(m.Store(), nil).InitWithDBInfos(
+		[]*model.DBInfo{
+			{Name: model.NewCIStr("mysql")},
+			{Name: model.NewCIStr("test")},
+			{Name: model.NewCIStr("d1")},
+		},
+		nil, 1)
+	require.Nil(t, err)
+	dom.MockInfoCacheAndLoadInfoSchema(builder.Build())
+	dbs = restore.GetExistedUserDBs(dom)
+	require.Equal(t, 1, len(dbs))
+
+	builder, err = infoschema.NewBuilder(m.Store(), nil).InitWithDBInfos(
+		[]*model.DBInfo{
+			{Name: model.NewCIStr("mysql")},
+			{Name: model.NewCIStr("d1")},
+			{
+				Name:   model.NewCIStr("test"),
+				Tables: []*model.TableInfo{{Name: model.NewCIStr("t1"), State: model.StatePublic}},
+				State:  model.StatePublic,
+			},
+		},
+		nil, 1)
+	require.Nil(t, err)
+	dom.MockInfoCacheAndLoadInfoSchema(builder.Build())
+	dbs = restore.GetExistedUserDBs(dom)
+	require.Equal(t, 2, len(dbs))
+}