sessionctx: fix null max value to leading wrong warning (#57898) (#57933)

close #57889

Author: ti-chi-bot

pkg/executor/set_test.go

@@ -473,6 +473,12 @@ func TestSetVar(t *testing.T) {
 	tk.MustExec("set session tidb_dml_batch_size = -120")
 	tk.MustQuery(`show warnings`).Check(testkit.Rows("Warning 1292 Truncated incorrect tidb_dml_batch_size value: '-120'")) // without redaction
 
+	tk.MustExec("set global tidb_gogc_tuner_min_value=300")
+	tk.MustQuery("show warnings").Check(testkit.Rows())
+	tk.MustExec("set global tidb_gogc_tuner_max_value=600")
+	tk.MustQuery("show warnings").Check(testkit.Rows())
+	tk.MustExec("set global tidb_gogc_tuner_max_value=600000000000000000")
+	tk.MustQuery("show warnings").Check(testkit.Rows("Warning 1292 Truncated incorrect tidb_gogc_tuner_max_value value: '600000000000000000'"))
 	tk.MustExec("set @@session.tidb_dml_batch_size = 120")
 	tk.MustExec("set @@global.tidb_dml_batch_size = 200")                    // now permitted due to TiDB #19809
 	tk.MustQuery("select @@tidb_dml_batch_size;").Check(testkit.Rows("120")) // global only applies to new sessions

pkg/sessionctx/variable/sysvar.go

@@ -830,7 +830,7 @@ var defaultSysVars = []*SysVar{
 		return nil
 	}},
 	{Scope: ScopeGlobal, Name: TiDBGOGCTunerMaxValue, Value: strconv.Itoa(DefTiDBGOGCMaxValue),
-		Type: TypeInt, MinValue: 10, SetGlobal: func(_ context.Context, s *SessionVars, val string) error {
+		Type: TypeInt, MinValue: 10, MaxValue: math.MaxInt32, SetGlobal: func(_ context.Context, s *SessionVars, val string) error {
 			maxValue := TidbOptInt64(val, DefTiDBGOGCMaxValue)
 			gctuner.SetMaxGCPercent(uint32(maxValue))
 			gctuner.GlobalMemoryLimitTuner.UpdateMemoryLimit()
@@ -847,7 +847,7 @@ var defaultSysVars = []*SysVar{
 			return origin, nil
 		}},
 	{Scope: ScopeGlobal, Name: TiDBGOGCTunerMinValue, Value: strconv.Itoa(DefTiDBGOGCMinValue),
-		Type: TypeInt, MinValue: 10, SetGlobal: func(_ context.Context, s *SessionVars, val string) error {
+		Type: TypeInt, MinValue: 10, MaxValue: math.MaxInt32, SetGlobal: func(_ context.Context, s *SessionVars, val string) error {
 			minValue := TidbOptInt64(val, DefTiDBGOGCMinValue)
 			gctuner.SetMinGCPercent(uint32(minValue))
 			gctuner.GlobalMemoryLimitTuner.UpdateMemoryLimit()