The row count of selection in Limit->Selection->TableFullScan(mpp) is incorrect

[time-and-fate]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

use test;
create table t(a int, b int);
alter table t set tiflash replica 1;
explain select * from t where a + 1 > 20 limit 100;

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

+--------------------------------+---------+--------------+---------------+--------------------------------+
| id                             | estRows | task         | access object | operator info                  |
+--------------------------------+---------+--------------+---------------+--------------------------------+
| Limit_10                       | 100.00  | root         |               | offset:0, count:100            |
| └─TableReader_21               | 100.00  | root         |               | data:ExchangeSender_20         |
|   └─ExchangeSender_20          | 100.00  | mpp[tiflash] |               | ExchangeType: PassThrough      |
|     └─Limit_19                 | 100.00  | mpp[tiflash] |               | offset:0, count:100            |
|       └─Selection_18           | 100.00  | mpp[tiflash] |               | gt(plus(test.t.a, 1), 20)      |
|         └─TableFullScan_17     | 125.00  | mpp[tiflash] | table:t       | keep order:false, stats:pseudo |
+--------------------------------+---------+--------------+---------------+--------------------------------+

3. What did you see instead (Required)

+--------------------------------+---------+--------------+---------------+--------------------------------+
| id                             | estRows | task         | access object | operator info                  |
+--------------------------------+---------+--------------+---------------+--------------------------------+
| Limit_10                       | 100.00  | root         |               | offset:0, count:100            |
| └─TableReader_21               | 100.00  | root         |               | data:ExchangeSender_20         |
|   └─ExchangeSender_20          | 100.00  | mpp[tiflash] |               | ExchangeType: PassThrough      |
|     └─Limit_19                 | 100.00  | mpp[tiflash] |               | offset:0, count:100            |
|       └─Selection_18           | 8000.00 | mpp[tiflash] |               | gt(plus(test.t.a, 1), 20)      |
|         └─TableFullScan_17     | 125.00  | mpp[tiflash] | table:t       | keep order:false, stats:pseudo |
+--------------------------------+---------+--------------+---------------+--------------------------------+

4. What is your TiDB version? (Required)

master