Change comment.

config/config.go

@@ -85,7 +85,7 @@ const (
 	DefExpensiveQueryTimeThreshold = 60
 	// DefMemoryUsageAlarmRatio is the threshold triggering an alarm which the memory usage of tidb-server instance exceeds.
 	DefMemoryUsageAlarmRatio = 0.8
-	// DefFastReorgLocalPath is the default sort dir for add index lightning solution
+	// DefFastReorgLocalPath is the default sort dir for add index with lightning.
 	DefFastReorgLocalPath = "/tmp/tidb"
 )
 
@@ -274,7 +274,7 @@ type Config struct {
 	CheckMb4ValueInUTF8        AtomicBool `toml:"check-mb4-value-in-utf8" json:"check-mb4-value-in-utf8"`
 	EnableCollectExecutionInfo bool       `toml:"enable-collect-execution-info" json:"enable-collect-execution-info"`
 	Plugin                     Plugin     `toml:"plugin" json:"plugin"`
-	// FastReorgLocalPath used to specific the lighting DDL local sort path.
+	// FastReorgLocalPath is used to specify the lighting DDL local sort path.
 	FastReorgLocalPath string `toml:"fast-reorg-local-path" json:"fast-reorg-local-path"`
 }
 

sessionctx/variable/sysvar_test.go

@@ -1136,7 +1136,7 @@ func TestSetTIDBDiskQuota(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, strconv.FormatInt(pb, 10), val)
 
-	// MaxValue is 1 PB, set to 2 Pb is not allowed
+	// MaxValue is 1 PB, set to 2 Pb is not allowed, it will set back to 1 PB max allowed value.
 	err = mock.SetGlobalSysVar(TiDBDDLDiskQuota, strconv.FormatInt(2*pb, 10))
 	require.NoError(t, err)
 	val, err = mock.GetGlobalSysVar(TiDBDDLDiskQuota)

sessionctx/variable/tidb_vars.go

@@ -1057,8 +1057,8 @@ var (
 	DDLForce2Queue                    = atomic.NewBool(false)
 	EnableNoopVariables               = atomic.NewBool(DefTiDBEnableNoopVariables)
 	// EnableFastReorg indicates whether to use lightning to enhance DDL reorg performance.
-	EnableFastReorg = atomic.NewBool(false)
-	// Temporary Variable for set dist quota for lightning add index, int type, GB as unit
+	EnableFastReorg = atomic.NewBool(DefTiDBEnableFastReorg)
+	// DDLDiskQuota is the temporary variable for set disk quota for lightning
 	DDLDiskQuota = atomic.NewInt64(DefTiDBDDLDiskQuota)
 )