ddl: disallow dropping index on auto_increment column (#11360) (#11399)

ddl/db_integration_test.go

@@ -426,6 +426,8 @@ func (s *testIntegrationSuite5) TestMySQLErrorCode(c *C) {
  assertErrorCode(c, tk, sql, tmysql.ErrPrimaryCantHaveNull)
  sql = "create table t2 (id int null, age int, primary key(id));"
  assertErrorCode(c, tk, sql, tmysql.ErrPrimaryCantHaveNull)
+ sql = "create table t2 (id int auto_increment);"
+ assertErrorCode(c, tk, sql, tmysql.ErrWrongAutoKey)
 
  sql = "create table t2 (id int primary key , age int);"
  tk.MustExec(sql)
@@ -1830,3 +1832,19 @@ func (s *testIntegrationSuite11) TestChangingDBCharset(c *C) {
  tk.MustExec("ALTER SCHEMA CHARACTER SET = 'utf8mb4' COLLATE = 'utf8mb4_general_ci'")
  verifyDBCharsetAndCollate("alterdb2", "utf8mb4", "utf8mb4_general_ci")
 }
+
+func (s *testIntegrationSuite4) TestDropAutoIncrementIndex(c *C) {
+ tk := testkit.NewTestKit(c, s.store)
+ tk.MustExec("create database if not exists test")
+ tk.MustExec("use test")
+
+ tk.MustExec("drop table if exists t1")
+ tk.MustExec("create table t1 (a int auto_increment, unique key (a))")
+ dropIndexSQL := "alter table t1 drop index a"
+ assertErrorCode(c, tk, dropIndexSQL, mysql.ErrWrongAutoKey)
+
+ tk.MustExec("drop table if exists t1")
+ tk.MustExec("create table t1 (a int(11) not null auto_increment, b int(11), c bigint, unique key (a, b, c))")
+ dropIndexSQL = "alter table t1 drop index a"
+ assertErrorCode(c, tk, dropIndexSQL, mysql.ErrWrongAutoKey)
+}

ddl/ddl_api.go

@@ -3159,10 +3159,18 @@ func (d *ddl) DropIndex(ctx sessionctx.Context, ti ast.Ident, indexName model.CI
  return errors.Trace(infoschema.ErrTableNotExists.GenWithStackByArgs(ti.Schema, ti.Name))
  }
 
- if indexInfo := t.Meta().FindIndexByName(indexName.L); indexInfo == nil {
+ indexInfo := t.Meta().FindIndexByName(indexName.L)
+ if indexInfo == nil {
  return ErrCantDropFieldOrKey.GenWithStack("index %s doesn't exist", indexName)
  }
 
+ cols := t.Cols()
+ for _, idxCol := range indexInfo.Columns {
+ if mysql.HasAutoIncrementFlag(cols[idxCol.Offset].Flag) {
+ return autoid.ErrWrongAutoKey
+ }
+ }
+
  job := &model.Job{
  SchemaID: schema.ID,
  TableID: t.Meta().ID,

meta/autoid/errors.go

@@ -21,12 +21,14 @@ import (
 // Error instances.
 var (
  ErrAutoincReadFailed = terror.ClassAutoid.New(mysql.ErrAutoincReadFailed, mysql.MySQLErrName[mysql.ErrAutoincReadFailed])
+ ErrWrongAutoKey = terror.ClassAutoid.New(mysql.ErrWrongAutoKey, mysql.MySQLErrName[mysql.ErrWrongAutoKey])
 )
 
 func init() {
  // Map error codes to mysql error codes.
  tableMySQLErrCodes := map[terror.ErrCode]uint16{
  mysql.ErrAutoincReadFailed: mysql.ErrAutoincReadFailed,
+ mysql.ErrWrongAutoKey: mysql.ErrWrongAutoKey,
  }
  terror.ErrClassToMySQLCodes[terror.ClassAutoid] = tableMySQLErrCodes
 }

planner/core/preprocess.go

@@ -26,6 +26,7 @@ import (
  "github.com/pingcap/tidb/ddl"
  "github.com/pingcap/tidb/expression"
  "github.com/pingcap/tidb/infoschema"
+ "github.com/pingcap/tidb/meta/autoid"
  "github.com/pingcap/tidb/sessionctx"
  "github.com/pingcap/tidb/types"
  "github.com/pingcap/tidb/types/parser_driver"
@@ -295,7 +296,7 @@ func (p *preprocessor) checkAutoIncrement(stmt *ast.CreateTableStmt) {
  }
  }
  if (autoIncrementMustBeKey && !isKey) || count > 1 {
- p.err = errors.New("Incorrect table definition; there can be only one auto column and it must be defined as a key")
+ p.err = autoid.ErrWrongAutoKey.GenWithStackByArgs()
  }
 
  switch autoIncrementCol.Tp.Tp {

planner/core/preprocess_test.go

@@ -53,11 +53,11 @@ func (s *testValidatorSuite) TestValidator(c *C) {
  {"create table t(id int auto_increment default null, primary key (id))", true, nil},
  {"create table t(id int default null auto_increment, primary key (id))", true, nil},
  {"create table t(id int not null auto_increment)", true,
- errors.New("Incorrect table definition; there can be only one auto column and it must be defined as a key")},
+ errors.New("[autoid:1075]Incorrect table definition; there can be only one auto column and it must be defined as a key")},
  {"create table t(id int not null auto_increment, c int auto_increment, key (id, c))", true,
- errors.New("Incorrect table definition; there can be only one auto column and it must be defined as a key")},
+ errors.New("[autoid:1075]Incorrect table definition; there can be only one auto column and it must be defined as a key")},
  {"create table t(id int not null auto_increment, c int, key (c, id))", true,
- errors.New("Incorrect table definition; there can be only one auto column and it must be defined as a key")},
+ errors.New("[autoid:1075]Incorrect table definition; there can be only one auto column and it must be defined as a key")},
  {"create table t(id decimal auto_increment, key (id))", true,
  errors.New("Incorrect column specifier for column 'id'")},
  {"create table t(id float auto_increment, key (id))", true, nil},