Query failed by: ERROR 1105 (HY000): DB::Exception: Duplicate names in enum: 'a' = 27 and 'a' = 1

[xzhangxian1008]

reproduce step:

create table t(a int, b enum('a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z') not null);
alter table t set tiflash replica 1;
insert into t values (1, "a");
select * from t as t1 right join t as t2 on t1.a != t2.a;

error message:

ERROR 1105 (HY000): DB::Exception: Duplicate names in enum: 'a' = 27 and 'a' = 1

version:
20210617 tiup playground nightly

mysql> select * from information_schema.cluster_info;
+---------+-----------------+-----------------+----------------------------+------------------------------------------+---------------------------+---------------+-----------+
| TYPE    | INSTANCE        | STATUS_ADDRESS  | VERSION                    | GIT_HASH                                 | START_TIME                | UPTIME        | SERVER_ID |
+---------+-----------------+-----------------+----------------------------+------------------------------------------+---------------------------+---------------+-----------+
| tidb    | 127.0.0.1:4000  | 127.0.0.1:10080 | 5.2.0-alpha                | ed52601e6eb560138db8cdccdfa1b5e2d33a11f0 | 2021-06-17T16:51:29+08:00 | 13m18.356991s |         0 |
| pd      | 127.0.0.1:2379  | 127.0.0.1:2379  | 5.1.0-alpha                | 2cc069fb77d96231533c2dc78ac687b19560af9d | 2021-06-17T16:51:22+08:00 | 13m25.357003s |         0 |
| tikv    | 127.0.0.1:20160 | 127.0.0.1:20180 | 5.1.0-alpha                | 36ff487de23b574180e289d90f889e7a461ba2bd | 2021-06-17T16:51:25+08:00 | 13m22.357006s |         0 |
| tiflash | 127.0.0.1:3930  | 127.0.0.1:20292 | v5.2.0-alpha-37-g74c69fb1d | 74c69fb1d35da3582cb9279ecb4d8597e4a78d00 | 2021-06-17T16:51:31+08:00 | 13m16.357009s |         0 |
+---------+-----------------+-----------------+----------------------------+------------------------------------------+---------------------------+---------------+-----------+

[xzhangxian1008]

TiDB add enum types repeatedly in the following codes:

file: tidb/planner/core/plan_to_pb.go

func (e *PhysicalExchangeReceiver) ToPB(ctx sessionctx.Context, storeType kv.StoreType) (*tipb.Executor, error) {

...

for _, column := range e.Schema().Columns {
	pbType := expression.ToPBFieldType(column.RetType)
	if column.RetType.Tp == mysql.TypeEnum {
		pbType.Elems = append(pbType.Elems, column.RetType.Elems...)
	}
	fieldTypes = append(fieldTypes, pbType)

...

}
pbTypes.Elems has been initialized in the clause pbType := expression.ToPBFieldType(column.RetType) and there is no need to append Elems again in pbType.Elems = append(pbType.Elems, column.RetType.Elems...).

I suggest to delete the pbType.Elems = append(pbType.Elems, column.RetType.Elems...)

[ti-srebot]

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