Wrong precision:18446744073709551615

[lilinghai]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

create table t( a int primary key);
alter table t set tiflash replica 2;
select count(*) from t where case when a then isnull(a) else 12.991 end;
/*
+--------------------------------+----------+-------------------+---------------+---------------------------------+
| id                             | estRows  | task              | access object | operator info                   |
+--------------------------------+----------+-------------------+---------------+---------------------------------+
| HashAgg_21                     | 1.00     | root              |               | funcs:count(Column#4)->Column#2 |
| └─TableReader_23               | 1.00     | root              |               | data:ExchangeSender_22          |
|   └─ExchangeSender_22          | 1.00     | batchCop[tiflash] |               | ExchangeType: PassThrough       |
|     └─HashAgg_9                | 1.00     | batchCop[tiflash] |               | funcs:count(1)->Column#4        |
|       └─Selection_20           | 8000.00  | batchCop[tiflash] |               | case(c2.t.a, 0, 12.991)         |
|         └─TableFullScan_19     | 10000.00 | batchCop[tiflash] | table:t       | keep order:false, stats:pseudo  |
+--------------------------------+----------+-------------------+---------------+---------------------------------+
*/

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

successfully

3. What did you see instead (Required)

ERROR 1105 (HY000): other error for mpp stream: DB::Exception: Wrong precision:18446744073709551615

4. What is your TiFlash version? (Required)

master

[yibin87]

Reproduced on latest version on local dev.

[yibin87]

It seems type transformation error from TiDB type to TiFlash IDataType, and mistakenly take NewDecimal's prec as -1.