sysvar: Do not allow set tidb_auto_analyze_ratio to 0 (#52190)

close #51582

pkg/sessionctx/variable/sysvar.go

@@ -723,7 +723,27 @@ var defaultSysVars = []*SysVar{
 		EnableLocalTxn.Store(newVal)
 		return nil
 	}},
-	{Scope: ScopeGlobal, Name: TiDBAutoAnalyzeRatio, Value: strconv.FormatFloat(DefAutoAnalyzeRatio, 'f', -1, 64), Type: TypeFloat, MinValue: 0, MaxValue: math.MaxUint64},
+	{
+		Scope:    ScopeGlobal,
+		Name:     TiDBAutoAnalyzeRatio,
+		Value:    strconv.FormatFloat(DefAutoAnalyzeRatio, 'f', -1, 64),
+		Type:     TypeFloat,
+		MinValue: 0,
+		MaxValue: math.MaxUint64,
+		// The value of TiDBAutoAnalyzeRatio should be greater than 0.00001 or equal to 0.00001.
+		Validation: func(vars *SessionVars, normalizedValue string, originalValue string, scope ScopeFlag) (string, error) {
+			ratio, err := strconv.ParseFloat(normalizedValue, 64)
+			if err != nil {
+				return "", err
+			}
+			const minRatio = 0.00001
+			const tolerance = 1e-9
+			if ratio < minRatio && math.Abs(ratio-minRatio) > tolerance {
+				return "", errors.Errorf("the value of %s should be greater than or equal to %f", TiDBAutoAnalyzeRatio, minRatio)
+			}
+			return normalizedValue, nil
+		},
+	},
 	{Scope: ScopeGlobal, Name: TiDBAutoAnalyzeStartTime, Value: DefAutoAnalyzeStartTime, Type: TypeTime},
 	{Scope: ScopeGlobal, Name: TiDBAutoAnalyzeEndTime, Value: DefAutoAnalyzeEndTime, Type: TypeTime},
 	{Scope: ScopeGlobal, Name: TiDBMemQuotaBindingCache, Value: strconv.FormatInt(DefTiDBMemQuotaBindingCache, 10), Type: TypeUnsigned, MaxValue: math.MaxInt32, GetGlobal: func(_ context.Context, sv *SessionVars) (string, error) {

pkg/sessionctx/variable/sysvar_test.go

@@ -1353,6 +1353,61 @@ func TestTiDBEnableRowLevelChecksum(t *testing.T) {
 	require.Equal(t, Off, val)
 }
 
+func TestTiDBAutoAnalyzeRatio(t *testing.T) {
+	ctx := context.Background()
+	vars := NewSessionVars(nil)
+	mock := NewMockGlobalAccessor4Tests()
+	mock.SessionVars = vars
+	vars.GlobalVarsAccessor = mock
+
+	// default to 0.5
+	val, err := mock.GetGlobalSysVar(TiDBAutoAnalyzeRatio)
+	require.NoError(t, err)
+	require.Equal(t, "0.5", val)
+
+	// set to 0.1
+	err = mock.SetGlobalSysVar(ctx, TiDBAutoAnalyzeRatio, "0.1")
+	require.NoError(t, err)
+	val, err = mock.GetGlobalSysVar(TiDBAutoAnalyzeRatio)
+	require.NoError(t, err)
+	require.Equal(t, "0.1", val)
+
+	// set to 1.1
+	err = mock.SetGlobalSysVar(ctx, TiDBAutoAnalyzeRatio, "1.1")
+	require.NoError(t, err)
+	val, err = mock.GetGlobalSysVar(TiDBAutoAnalyzeRatio)
+	require.NoError(t, err)
+	require.Equal(t, "1.1", val)
+
+	// set to 0
+	err = mock.SetGlobalSysVar(ctx, TiDBAutoAnalyzeRatio, "0")
+	require.Error(t, err)
+	val, err = mock.GetGlobalSysVar(TiDBAutoAnalyzeRatio)
+	require.NoError(t, err)
+	require.Equal(t, "1.1", val)
+
+	// set to 0.0000000001
+	err = mock.SetGlobalSysVar(ctx, TiDBAutoAnalyzeRatio, "0.0000000001")
+	require.Error(t, err)
+	val, err = mock.GetGlobalSysVar(TiDBAutoAnalyzeRatio)
+	require.NoError(t, err)
+	require.Equal(t, "1.1", val)
+
+	// set to 0.00001
+	err = mock.SetGlobalSysVar(ctx, TiDBAutoAnalyzeRatio, "0.00001")
+	require.NoError(t, err)
+	val, err = mock.GetGlobalSysVar(TiDBAutoAnalyzeRatio)
+	require.NoError(t, err)
+	require.Equal(t, "0.00001", val)
+
+	// set to 0.000009999
+	err = mock.SetGlobalSysVar(ctx, TiDBAutoAnalyzeRatio, "0.000009999")
+	require.Error(t, err)
+	val, err = mock.GetGlobalSysVar(TiDBAutoAnalyzeRatio)
+	require.NoError(t, err)
+	require.Equal(t, "0.00001", val)
+}
+
 func TestTiDBTiFlashReplicaRead(t *testing.T) {
 	vars := NewSessionVars(nil)
 	mock := NewMockGlobalAccessor4Tests()

pkg/statistics/handle/autoanalyze/autoanalyze_test.go

@@ -103,8 +103,7 @@ func TestDisableAutoAnalyze(t *testing.T) {
 	is := dom.InfoSchema()
 	require.NoError(t, h.Update(is))
 
-	// Set auto analyze ratio to 0.
-	tk.MustExec("set @@global.tidb_auto_analyze_ratio = 0")
+	tk.MustExec("set @@global.tidb_enable_auto_analyze = 0")
 	exec.AutoAnalyzeMinCnt = 0
 	defer func() {
 		exec.AutoAnalyzeMinCnt = 1000

pkg/statistics/handle/autoanalyze/refresher/refresher_test.go

@@ -54,8 +54,10 @@ func TestSkipAnalyzeTableWhenAutoAnalyzeRatioIsZero(t *testing.T) {
 	)
 	tk.MustExec("insert into t1 values (1, 1), (2, 2), (3, 3)")
 	tk.MustExec("insert into t2 values (1, 1), (2, 2), (3, 3)")
-	// Set the auto analyze ratio to 0.
-	tk.MustExec("set global tidb_auto_analyze_ratio = 0")
+	// HACK: Set the auto analyze ratio to 0.
+	// We don't allow users to set the ratio to 0 anymore, but we still need to test this case.
+	// Because we need to compilable with the old configuration.
+	tk.MustExec("update mysql.global_variables set variable_value = '0' where variable_name = 'tidb_auto_analyze_ratio'")
 	handle := dom.StatsHandle()
 	require.NoError(t, handle.DumpStatsDeltaToKV(true))
 	require.NoError(t, handle.Update(dom.InfoSchema()))

pkg/statistics/handle/updatetest/update_test.go

@@ -368,7 +368,7 @@ func TestAutoUpdate(t *testing.T) {
 		testKit.MustExec("set global tidb_auto_analyze_ratio = 0.2")
 		defer func() {
 			exec.AutoAnalyzeMinCnt = 1000
-			testKit.MustExec("set global tidb_auto_analyze_ratio = 0.0")
+			testKit.MustExec("set global tidb_auto_analyze_ratio = 0.5")
 		}()
 
 		do := dom
@@ -473,7 +473,7 @@ func TestAutoUpdatePartition(t *testing.T) {
 		testKit.MustExec("set global tidb_auto_analyze_ratio = 0.6")
 		defer func() {
 			exec.AutoAnalyzeMinCnt = 1000
-			testKit.MustExec("set global tidb_auto_analyze_ratio = 0.0")
+			testKit.MustExec("set global tidb_auto_analyze_ratio = 0.5")
 		}()
 
 		do := dom
@@ -806,7 +806,7 @@ func TestAutoUpdatePartitionInDynamicOnlyMode(t *testing.T) {
 		testKit.MustExec("set global tidb_auto_analyze_ratio = 0.1")
 		defer func() {
 			exec.AutoAnalyzeMinCnt = 1000
-			testKit.MustExec("set global tidb_auto_analyze_ratio = 0.0")
+			testKit.MustExec("set global tidb_auto_analyze_ratio = 0.5")
 		}()
 
 		require.NoError(t, h.Update(is))