infoschema: avoid strings.toUpper in the IsClusterTableByName (#59608)

close #59606

Author: hawkingrei

pkg/infoschema/cluster.go

@@ -25,6 +25,7 @@ import (
 	"github.com/pingcap/tidb/pkg/sessionctx"
 	"github.com/pingcap/tidb/pkg/types"
 	"github.com/pingcap/tidb/pkg/util"
+	"github.com/pingcap/tidb/pkg/util/intest"
 	"github.com/pingcap/tidb/pkg/util/sem"
 )
 
@@ -77,11 +78,15 @@ var memTableToAllTiDBClusterTables = map[string]string{
 	TableTiDBPlanCache:            ClusterTableTiDBPlanCache,
 }
 
+var memTableToAllTiDBClusterTablesWithLowerCase = make(map[string]string)
+
 // memTableToDDLOwnerClusterTables means add memory table to cluster table that will send cop request to DDL owner node.
 var memTableToDDLOwnerClusterTables = map[string]string{
 	TableTiFlashReplica: TableTiFlashReplica,
 }
 
+var memTableToDDLOwnerClusterTablesWithLowerCase = make(map[string]string)
+
 // ClusterTableCopDestination means the destination that cluster tables will send cop requests to.
 type ClusterTableCopDestination int
 
@@ -103,6 +108,7 @@ func GetClusterTableCopDestination(tableName string) ClusterTableCopDestination
 func init() {
 	var addrCol = columnInfo{name: util.ClusterTableInstanceColumnName, tp: mysql.TypeVarchar, size: 64}
 	for memTableName, clusterMemTableName := range memTableToAllTiDBClusterTables {
+		memTableToAllTiDBClusterTablesWithLowerCase[strings.ToLower(memTableName)] = strings.ToLower(clusterMemTableName)
 		memTableCols := tableNameToColumns[memTableName]
 		if len(memTableCols) == 0 {
 			continue
@@ -112,23 +118,34 @@ func init() {
 		cols = append(cols, memTableCols...)
 		tableNameToColumns[clusterMemTableName] = cols
 	}
+	for memTableName, clusterMemTableName := range memTableToDDLOwnerClusterTables {
+		memTableToDDLOwnerClusterTablesWithLowerCase[strings.ToLower(memTableName)] = strings.ToLower(clusterMemTableName)
+	}
 }
 
 // IsClusterTableByName used to check whether the table is a cluster memory table.
 // Export for PhysicalTableScan.ExplainID
 func IsClusterTableByName(dbName, tableName string) bool {
-	dbName = strings.ToUpper(dbName)
+	intest.AssertFunc(func() bool {
+		return dbName == strings.ToLower(dbName)
+	})
 	switch dbName {
-	case util.InformationSchemaName.O, util.PerformanceSchemaName.O:
-		tableName = strings.ToUpper(tableName)
-		for _, name := range memTableToAllTiDBClusterTables {
-			name = strings.ToUpper(name)
+	case util.InformationSchemaName.L, util.PerformanceSchemaName.L:
+		intest.AssertFunc(func() bool {
+			return tableName == strings.ToLower(tableName)
+		})
+		for _, name := range memTableToAllTiDBClusterTablesWithLowerCase {
+			intest.AssertFunc(func() bool {
+				return name == strings.ToLower(name)
+			})
 			if name == tableName {
 				return true
 			}
 		}
-		for _, name := range memTableToDDLOwnerClusterTables {
-			name = strings.ToUpper(name)
+		for _, name := range memTableToDDLOwnerClusterTablesWithLowerCase {
+			intest.AssertFunc(func() bool {
+				return name == strings.ToLower(name)
+			})
 			if name == tableName {
 				return true
 			}

pkg/infoschema/tables.go

@@ -2493,7 +2493,7 @@ func createInfoSchemaTable(_ autoid.Allocators, _ func() (pools.Resource, error)
 		columns[i] = table.ToColumn(col)
 	}
 	tp := table.VirtualTable
-	if IsClusterTableByName(util.InformationSchemaName.O, meta.Name.O) {
+	if IsClusterTableByName(util.InformationSchemaName.L, meta.Name.L) {
 		tp = table.ClusterTable
 	}
 	return &infoschemaTable{meta: meta, cols: columns, tp: tp}, nil

pkg/planner/core/explain.go

@@ -168,7 +168,7 @@ func (p *PhysicalTableScan) ExplainID() fmt.Stringer {
 
 // TP overrides the TP in order to match different range.
 func (p *PhysicalTableScan) TP() string {
-	if infoschema.IsClusterTableByName(p.DBName.O, p.Table.Name.O) {
+	if infoschema.IsClusterTableByName(p.DBName.L, p.Table.Name.L) {
 		return plancodec.TypeMemTableScan
 	} else if p.isChildOfIndexLookUp {
 		return plancodec.TypeTableRowIDScan
@@ -190,7 +190,7 @@ func (p *PhysicalTableScan) ExplainNormalizedInfo() string {
 
 // OperatorInfo implements dataAccesser interface.
 func (p *PhysicalTableScan) OperatorInfo(normalized bool) string {
-	if infoschema.IsClusterTableByName(p.DBName.O, p.Table.Name.O) {
+	if infoschema.IsClusterTableByName(p.DBName.L, p.Table.Name.L) {
 		return ""
 	}