*: remove support for hidden sysvars

executor/set_test.go

@@ -679,7 +679,6 @@ func TestSetVar(t *testing.T) {
 	tk.MustQuery("select @@global.tidb_enable_new_cost_interface").Check(testkit.Rows("0")) // default value is 0
 	tk.MustExec("set global tidb_enable_new_cost_interface=1")
 	tk.MustQuery("select @@global.tidb_enable_new_cost_interface").Check(testkit.Rows("1"))
-	tk.MustQuery("show global variables like 'tidb_enable_new_cost_interface'").Check(testkit.Rows()) // hidden
 	tk.MustExec("set global tidb_enable_new_cost_interface=0")
 	tk.MustQuery("select @@global.tidb_enable_new_cost_interface").Check(testkit.Rows("0"))
 

executor/show.go

@@ -835,7 +835,7 @@ func (e *ShowExec) fetchShowVariables() (err error) {
 				} else if fieldPatternsLike != nil && !fieldPatternsLike.DoMatch(v.Name) {
 					continue
 				}
-				if v.Hidden || e.sysVarHiddenForSem(v.Name) {
+				if e.sysVarHiddenForSem(v.Name) {
 					continue
 				}
 				value, err = variable.GetGlobalSystemVar(sessionVars, v.Name)
@@ -860,7 +860,7 @@ func (e *ShowExec) fetchShowVariables() (err error) {
 		} else if fieldPatternsLike != nil && !fieldPatternsLike.DoMatch(v.Name) {
 			continue
 		}
-		if v.Hidden || e.sysVarHiddenForSem(v.Name) {
+		if e.sysVarHiddenForSem(v.Name) {
 			continue
 		}
 		value, err = variable.GetSessionOrGlobalSystemVar(sessionVars, v.Name)

executor/showtest/show_test.go

@@ -1586,10 +1586,6 @@ func TestShowVar(t *testing.T) {
 	sessionVars := make([]string, 0, len(variable.GetSysVars()))
 	globalVars := make([]string, 0, len(variable.GetSysVars()))
 	for _, v := range variable.GetSysVars() {
-		if v.Hidden {
-			continue
-		}
-
 		if v.Scope == variable.ScopeSession {
 			sessionVars = append(sessionVars, v.Name)
 		} else {
@@ -1614,10 +1610,6 @@ func TestShowVar(t *testing.T) {
 	res = tk.MustQuery(showSQL)
 	require.Len(t, res.Rows(), len(globalVars))
 
-	// Test Hidden tx_read_ts
-	res = tk.MustQuery("show variables like '%tx_read_ts'")
-	require.Len(t, res.Rows(), 0)
-
 	// Test versions' related variables
 	res = tk.MustQuery("show variables like 'version%'")
 	for _, row := range res.Rows() {

sessionctx/variable/variable.go

@@ -122,7 +122,8 @@ type SysVar struct {
 	SetGlobal func(*SessionVars, string) error
 	// IsHintUpdatable indicate whether it's updatable via SET_VAR() hint (optional)
 	IsHintUpdatable bool
-	// Hidden means that it still responds to SET but doesn't show up in SHOW VARIABLES
+	// Deprecated: Hidden previously meant that the variable still responds to SET but doesn't show up in SHOW VARIABLES
+	// However, this feature is no longer used. All variables are visble.
 	Hidden bool
 	// Aliases is a list of sysvars that should also be updated when this sysvar is updated.
 	// Updating aliases calls the SET function of the aliases, but does not update their aliases (preventing SET recursion)

statistics/handle/handle_test.go

@@ -2554,18 +2554,6 @@ func TestHideIndexUsageSyncLease(t *testing.T) {
 	}
 }
 
-func TestHideExtendedStatsSwitch(t *testing.T) {
-	store, clean := testkit.CreateMockStore(t)
-	defer clean()
-	// NOTICE: remove this test when this extended-stats reaches GA state.
-	tk := testkit.NewTestKit(t, store)
-	rs := tk.MustQuery("show variables").Rows()
-	for _, r := range rs {
-		require.NotEqual(t, "tidb_enable_extended_stats", strings.ToLower(r[0].(string)))
-	}
-	tk.MustQuery("show variables like 'tidb_enable_extended_stats'").Check(testkit.Rows())
-}
-
 func TestRepetitiveAddDropExtendedStats(t *testing.T) {
 	store, clean := testkit.CreateMockStore(t)
 	defer clean()