pingcap / pingcap/tidb

Wrong returned exception from tiflash when table has virtual column that's generated by no other columns

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#57,947 3 comments 0 reactions 0 assignees View on GitHub
may-affects-5.4 may-affects-6.1 may-affects-6.5 may-affects-7.1 may-affects-7.5 may-affects-8.1 may-affects-8.5 severity/major sig/execution type/bug
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Description

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)

```sql
DROP TABLE IF EXISTS t0;

CREATE TABLE t0 (
c0 NUMERIC ZEROFILL AS (1) VIRTUAL
);

ALTER TABLE t0 SET TIFLASH REPLICA 1;

SELECT /*+ read_from_storage(tikv[t0]) */
t0.c0
FROM t0
WHERE c0 != NULL
ORDER BY (1 = ((t0.c0 <= 1))) DESC;

SELECT /*+ read_from_storage(tiflash[t0]) */
t0.c0
FROM t0
WHERE c0 != NULL
ORDER BY (1 = ((t0.c0 <= 1))) DESC;
```

### 2. What did you expect to see? (Required)

The same behavior between two queries

### 3. What did you see instead (Required)

```sql
mysql> SELECT /*+ read_from_storage(tikv[t0]) */
-> t0.c0
-> FROM t0
-> WHERE c0 != NULL
-> ORDER BY (1 = ((t0.c0 <= 1))) DESC;
Empty set (0.04 sec)

mysql> SELECT /*+ read_from_storage(tiflash[t0]) */ t0.c0 FROM t0 WHERE c0 != NULL ORDER BY (1 = ((t0.c0 <= 1))) DESC;
ERROR 1105 (HY000): other error for mpp stream: Code: 0, e.displayText() = DB::TiFlashException: The tidb table scan schema size 1 is different from the tiflash storage schema size 0, table id is 3509, e.what() = DB::TiFlashException,
```

### 4. What is your TiDB version? (Required)

TiDB v8.4.0

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