config: Add index limit configuration

config/config.go

@@ -52,6 +52,10 @@ const (
 	DefMaxIndexLength = 3072
 	// DefMaxOfMaxIndexLength is the maximum index length(in bytes) for TiDB v3.0.7 and previous version.
 	DefMaxOfMaxIndexLength = 3072 * 4
+	// DefIndexLimit is the limitation of index on a single table. This value is consistent with MySQL.
+	DefIndexLimit = 64
+	// DefMaxOfIndexLimit is the maximum limitation of index on a single table for TiDB.
+	DefMaxOfIndexLimit = 64 * 8
 	// DefMinQuotaStatistics is the minimum statistic memory quota(in bytes).
 	DefMinQuotaStatistics = 32 << 30
 	// DefPort is the default port of TiDB
@@ -125,6 +129,7 @@ type Config struct {
 	PessimisticTxn             PessimisticTxn    `toml:"pessimistic-txn" json:"pessimistic-txn"`
 	CheckMb4ValueInUTF8        bool              `toml:"check-mb4-value-in-utf8" json:"check-mb4-value-in-utf8"`
 	MaxIndexLength             int               `toml:"max-index-length" json:"max-index-length"`
+	IndexLimit                 int               `toml:"index-limit" json:"index-limit"`
 	GracefulWaitBeforeShutdown int               `toml:"graceful-wait-before-shutdown" json:"graceful-wait-before-shutdown"`
 	// AlterPrimaryKey is used to control alter primary key feature.
 	AlterPrimaryKey bool `toml:"alter-primary-key" json:"alter-primary-key"`
@@ -644,6 +649,7 @@ var defaultConf = Config{
 	EnableBatchDML:               false,
 	CheckMb4ValueInUTF8:          true,
 	MaxIndexLength:               3072,
+	IndexLimit:                   64,
 	AlterPrimaryKey:              false,
 	TreatOldVersionUTF8AsUTF8MB4: true,
 	EnableTableLock:              false,
@@ -937,6 +943,9 @@ func (c *Config) Valid() error {
 	if c.MaxIndexLength < DefMaxIndexLength || c.MaxIndexLength > DefMaxOfMaxIndexLength {
 		return fmt.Errorf("max-index-length should be [%d, %d]", DefMaxIndexLength, DefMaxOfMaxIndexLength)
 	}
+	if c.IndexLimit < DefIndexLimit || c.IndexLimit > DefMaxOfIndexLimit {
+		return fmt.Errorf("index-limit should be [%d, %d]", DefIndexLimit, DefMaxOfIndexLimit)
+	}
 	if c.Log.File.MaxSize > MaxLogFileSize {
 		return fmt.Errorf("invalid max log file size=%v which is larger than max=%v", c.Log.File.MaxSize, MaxLogFileSize)
 	}

config/config.toml.example

@@ -77,6 +77,9 @@ treat-old-version-utf8-as-utf8mb4 = true
 # max-index-length is used to deal with compatibility issues from v3.0.7 and previous version upgrades. It can only be in [3072, 3072*4].
 max-index-length = 3072
 
+# index-limit is used to deal with compatibility issues. It can only be in [64, 64*4].
+index-limit = 64
+
 # enable-table-lock is used to control table lock feature. Default is false, indicate the table lock feature is disabled.
 enable-table-lock = false
 

config/config_test.go

@@ -191,6 +191,7 @@ mem-quota-query = 10000
 mem-quota-statistics = 10000
 nested-loop-join-cache-capacity = 100
 max-index-length = 3080
+index-limit = 70
 skip-register-to-dashboard = true
 deprecate-integer-display-length = true
 txn-scope = "dc-1"
@@ -269,6 +270,7 @@ spilled-file-encryption-method = "plaintext"
 	c.Assert(conf.NestedLoopJoinCacheCapacity, Equals, int64(100))
 	c.Assert(conf.IsolationRead.Engines, DeepEquals, []string{"tiflash"})
 	c.Assert(conf.MaxIndexLength, Equals, 3080)
+	c.Assert(conf.IndexLimit, Equals, 70)
 	c.Assert(conf.SkipRegisterToDashboard, Equals, true)
 	c.Assert(len(conf.Labels), Equals, 2)
 	c.Assert(conf.Labels["foo"], Equals, "bar")
@@ -478,6 +480,18 @@ func (s *testConfigSuite) TestMaxIndexLength(c *C) {
 	checkValid(DefMaxOfMaxIndexLength+1, false)
 }
 
+func (s *testConfigSuite) TestIndexLimit(c *C) {
+	conf := NewConfig()
+	checkValid := func(indexLimit int, shouldBeValid bool) {
+		conf.IndexLimit = indexLimit
+		c.Assert(conf.Valid() == nil, Equals, shouldBeValid)
+	}
+	checkValid(DefIndexLimit, true)
+	checkValid(DefIndexLimit-1, false)
+	checkValid(DefMaxOfIndexLimit, true)
+	checkValid(DefMaxOfIndexLimit+1, false)
+}
+
 func (s *testConfigSuite) TestParsePath(c *C) {
 	etcdAddrs, disableGC, err := ParsePath("tikv://node1:2379,node2:2379")
 	c.Assert(err, IsNil)

ddl/ddl_api.go

@@ -1091,8 +1091,8 @@ func checkTooManyColumns(colDefs []*model.ColumnInfo) error {
 }
 
 func checkTooManyIndexes(idxDefs []*model.IndexInfo) error {
-	if uint32(len(idxDefs)) > atomic.LoadUint32(&TableIndexCountLimit) {
-		return errTooManyKeys.GenWithStackByArgs(TableIndexCountLimit)
+	if len(idxDefs) > config.GetGlobalConfig().IndexLimit {
+		return errTooManyKeys.GenWithStackByArgs(config.GetGlobalConfig().IndexLimit)
 	}
 	return nil
 }