Tidb panic when colNames2ResultFields

[lilinghai]

The sql

select count(*) as x from table_20_binary_undef as t1 group by t1. `col_int_key_signed` having x not in (select `col_decimal(40, 20)_undef_unsigned` from table_1_latin1_undef as t2 where x = t2. `col_decimal(40, 20)_key_signed`);

The panic log

[2021/05/23 23:01:51.574 +08:00] [ERROR] [conn.go:736] ["connection running loop panic"] [conn=39] [lastSQL="select count(*) as x from table_20_binary_undef as t1 group by t1. `col_int_key_signed` having x not in (select `col_decimal(40, 20)_undef_unsigned` from table_1_latin1_undef as t2 where x = t2. `col_decimal(40, 20)_key_signed`)"] [err="runtime error: index out of range [1] with length 1"] [stack="goroutine 766889 [running]:\ngit.luolix.top/pingcap/tidb/server.(*clientConn).Run.func1(0x40193a0, 0xc003566090, 0xc001ebe900)\n\t/home/jenkins/agent/workspace/_release5.0-hotfix-tiflash-patch/go/src/github.com/pingcap/tidb/server/conn.go:734 +0xee\npanic(0x37ab8a0, 0xc001511800)\n\t/usr/local/go/src/runtime/panic.go:679 +0x1b2\ngit.luolix.top/pingcap/tidb/server.(*clientConn).writeResultset.func1(0xc0011ad100, 0x40193a0, 0xc003322420, 0xc001ebe900)\n\t/home/jenkins/agent/workspace/_release5.0-hotfix-tiflash-patch/go/src/github.com/pingcap/tidb/server/conn.go:1749 +0x4e2\npanic(0x37ab8a0, 0xc001511800)\n\t/usr/local/go/src/runtime/panic.go:679 +0x1b2\ngit.luolix.top/pingcap/tidb/executor.colNames2ResultFields(0xc0021c6fa0, 0xc002b08478, 0x1, 0x1, 0xc004eca6e8, 0x2, 0x2dc0726, 0x0, 0x0)\n\t/home/jenkins/agent/workspace/_release5.0-hotfix-tiflash-patch/go/src/github.com/pingcap/tidb/executor/adapter.go:97 +0x64f\ngit.luolix.top/pingcap/tidb/executor.(*recordSet).Fields(0xc002f9c3c0, 0xc002f9c3c0, 0x2, 0xc0011acee8)\n\t/home/jenkins/agent/workspace/_release5.0-hotfix-tiflash-patch/go/src/github.com/pingcap/tidb/executor/adapter.go:88 +0xe0\ngit.luolix.top/pingcap/tidb/server.(*tidbResultSet).Columns(0xc002f9c410, 0x40193a0, 0xc003322420, 0xc002f9c460)\n\t/home/jenkins/agent/workspace/_release5.0-hotfix-tiflash-patch/go/src/github.com/pingcap/tidb/server/driver_tidb.go:346 +0xa8\ngit.luolix.top/pingcap/tidb/server.(*clientConn).writeChunks(0xc001ebe900, 0x40193a0, 0xc003322420, 0x4039b20, 0xc002f9c410, 0xc00002d000, 0x1e03786, 0x368a200, 0x0)\n\t/home/jenkins/agent/workspace/_release5.0-hotfix-tiflash-patch/go/src/github.com/pingcap/tidb/server/conn.go:1822 +0x708\ngit.luolix.top/pingcap/tidb/server.(*clientConn).writeResultset(0xc001ebe900, 0x40193a0, 0xc003322420, 0x4039b20, 0xc002f9c410, 0x29b00, 0x0, 0x0, 0x0, 0x0)\n\t/home/jenkins/agent/workspace/_release5.0-hotfix-tiflash-patch/go/src/github.com/pingcap/tidb/server/conn.go:1762 +0x201\ngit.luolix.top/pingcap/tidb/server.(*clientConn).handleStmt(0xc001ebe900, 0x40193a0, 0xc003322420, 0x4040060, 0xc00089f500, 0x5fb0120, 0x0, 0x0, 0x1, 0x0, ...)\n\t/home/jenkins/agent/workspace/_release5.0-hotfix-tiflash-patch/go/src/github.com/pingcap/tidb/server/conn.go:1656 +0x242\ngit.luolix.top/pingcap/tidb/server.(*clientConn).handleQuery(0xc001ebe900, 0x40192e0, 0xc0030aa1c0, 0xc0028b21e1, 0xe4, 0x0, 0x0)\n\t/home/jenkins/agent/workspace/_release5.0-hotfix-tiflash-patch/go/src/github.com/pingcap/tidb/server/conn.go:1503 +0x44f\ngit.luolix.top/pingcap/tidb/server.(*clientConn).dispatch(0xc001ebe900, 0x40192e0, 0xc0030aa1c0, 0xc0028b21e0, 0xe5, 0xe4, 0x0, 0x0)\n\t/home/jenkins/agent/workspace/_release5.0-hotfix-tiflash-patch/go/src/github.com/pingcap/tidb/server/conn.go:1037 +0x6f2\ngit.luolix.top/pingcap/tidb/server.(*clientConn).Run(0xc001ebe900, 0x40193a0, 0xc003566090)\n\t/home/jenkins/agent/workspace/_release5.0-hotfix-tiflash-patch/go/src/github.com/pingcap/tidb/server/conn.go:795 +0x293\ngit.luolix.top/pingcap/tidb/server.(*Server).onConn(0xc000b1d5f0, 0xc001ebe900)\n\t/home/jenkins/agent/workspace/_release5.0-hotfix-tiflash-patch/go/src/github.com/pingcap/tidb/server/server.go:477 +0xb1b\ncreated by github.com/pingcap/tidb/server.(*Server).Run\n\t/home/jenkins/agent/workspace/_release5.0-hotfix-tiflash-patch/go/src/github.com/pingcap/tidb/server/server.go:380 +0x8a5\n"]

The plan

+----------------------------------------+---------+-------------------+---------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| id                                     | estRows | task              | access object | operator info                                                                                                                                                                              |
+----------------------------------------+---------+-------------------+---------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| TableReader_40                         | 12.80   | root              |               | data:ExchangeSender_39                                                                                                                                                                     |
| └─ExchangeSender_39                    | 12.80   | batchCop[tiflash] |               | ExchangeType: PassThrough                                                                                                                                                                  |
|   └─HashJoin_10                        | 12.80   | batchCop[tiflash] |               | anti semi join, equal:[eq(Column#143, rs.table_1_latin1_undef.col_decimal(40, 20)_key_signed)], other cond:eq(cast(Column#95), rs.table_1_latin1_undef.col_decimal(40, 20)_undef_unsigned) |
|     ├─ExchangeReceiver_38(Build)       | 1.00    | batchCop[tiflash] |               |                                                                                                                                                                                            |
|     │ └─ExchangeSender_37              | 1.00    | batchCop[tiflash] |               | ExchangeType: Broadcast                                                                                                                                                                    |
|     │   └─TableFullScan_36             | 1.00    | batchCop[tiflash] | table:t2      | keep order:false, stats:pseudo                                                                                                                                                             |
|     └─Projection_24(Probe)             | 16.00   | batchCop[tiflash] |               | Column#95, cast(Column#95, decimal(20,0) BINARY)->Column#143                                                                                                                               |
|       └─Projection_32                  | 16.00   | batchCop[tiflash] |               | Column#95                                                                                                                                                                                  |
|         └─HashAgg_33                   | 16.00   | batchCop[tiflash] |               | group by:rs.table_20_binary_undef.col_int_key_signed, funcs:sum(Column#148)->Column#95                                                                                                     |
|           └─ExchangeReceiver_35        | 16.00   | batchCop[tiflash] |               |                                                                                                                                                                                            |
|             └─ExchangeSender_34        | 16.00   | batchCop[tiflash] |               | ExchangeType: HashPartition, Hash Cols: rs.table_20_binary_undef.col_int_key_signed                                                                                                        |
|               └─HashAgg_26             | 16.00   | batchCop[tiflash] |               | group by:rs.table_20_binary_undef.col_int_key_signed, funcs:count(1)->Column#148                                                                                                           |
|                 └─TableFullScan_31     | 20.00   | batchCop[tiflash] | table:t1      | keep order:false, stats:pseudo                                                                                                                                                             |
+----------------------------------------+---------+-------------------+---------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

[hanfei1991]

This bug also exists in TiDB. Observing the explain result, aggregation is eliminated unexpectly.

[hanfei1991]

env: mysql -h172.16.6.27 -uroot -P4019 -D rt