The result of scan context is wrong when query at the first time

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

$ tiup playground nightly

$ tiup bench tpch prepare --host 127.0.0.1 --port 4000

$ mysql --comments --host 127.0.0.1 --port 4000 -u root

mysql> alter database test set tiflash replica 1;
Query OK, 0 rows affected (0.66 sec)
In total 8 tables: 8 succeed, 0 failed, 0 skipped

mysql> use test
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> select * from information_schema.tiflash_replica;
+--------------+------------+----------+---------------+-----------------+-----------+----------+
| TABLE_SCHEMA | TABLE_NAME | TABLE_ID | REPLICA_COUNT | LOCATION_LABELS | AVAILABLE | PROGRESS |
+--------------+------------+----------+---------------+-----------------+-----------+----------+
| test         | region     |       98 |             1 |                 |         1 |        1 |
| test         | nation     |       96 |             1 |                 |         1 |        1 |
| test         | part       |      100 |             1 |                 |         1 |        1 |
| test         | supplier   |      102 |             1 |                 |         1 |        1 |
| test         | partsupp   |      104 |             1 |                 |         1 |        1 |
| test         | lineitem   |      110 |             1 |                 |         1 |        1 |
| test         | customer   |      106 |             1 |                 |         1 |        1 |
| test         | orders     |      108 |             1 |                 |         1 |        1 |
+--------------+------------+----------+---------------+-----------------+-----------+----------+
8 rows in set (0.00 sec)

mysql> explain analyze select count(*) from orders where O_CUSTKEY in (0, 150000);
+------------------------------+------------+---------+--------------+---------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+--------------------------------------------+-----------+------+
| id                           | estRows    | actRows | task         | access object | execution info                                                                                                                                                                                                                                                                                                                  | operator info                              | memory    | disk |
+------------------------------+------------+---------+--------------+---------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+--------------------------------------------+-----------+------+
| StreamAgg_12                 | 1.00       | 1       | root         |               | time:62.5ms, loops:2, RU:0.000000                                                                                                                                                                                                                                                                                               | funcs:count(1)->Column#10                  | 388 Bytes | N/A  |
| └─TableReader_41             | 25.35      | 0       | root         |               | time:62.5ms, loops:1, cop_task: {num: 1, max: 0s, proc_keys: 0, copr_cache_hit_ratio: 0.00}                                                                                                                                                                                                                                     | MppVersion: 2, data:ExchangeSender_40      | 301 Bytes | N/A  |
|   └─ExchangeSender_40        | 25.35      | 0       | mpp[tiflash] |               | tiflash_task:{time:61.5ms, loops:0, threads:3}                                                                                                                                                                                                                                                                                  | ExchangeType: PassThrough                  | N/A       | N/A  |
|     └─Selection_39           | 25.35      | 0       | mpp[tiflash] |               | tiflash_task:{time:61.5ms, loops:0, threads:3}                                                                                                                                                                                                                                                                                  | in(test.orders.o_custkey, 0, 150000)       | N/A       | N/A  |
|       └─TableFullScan_38     | 1262431.00 | 583494  | mpp[tiflash] | table:orders  | tiflash_task:{time:61.5ms, loops:10, threads:3}, tiflash_scan:{dtfile:{total_scanned_packs:144, total_skipped_packs:381, total_scanned_rows:1179648, total_skipped_rows:3105483, total_rs_index_load_time: 0ms, total_read_time: 18ms}, total_create_snapshot_time: 0ms, total_local_region_num: 1, total_remote_region_num: 1} | pushed down filter:empty, keep order:false | N/A       | N/A  |
+------------------------------+------------+---------+--------------+---------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+--------------------------------------------+-----------+------+
5 rows in set (0.07 sec)

mysql> explain analyze select count(*) from orders where O_CUSTKEY in (0, 150000);
+------------------------------+------------+---------+--------------+---------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+--------------------------------------------+-----------+------+
| id                           | estRows    | actRows | task         | access object | execution info                                                                                                                                                                                                                                                                                                          | operator info                              | memory    | disk |
+------------------------------+------------+---------+--------------+---------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+--------------------------------------------+-----------+------+
| StreamAgg_12                 | 1.00       | 1       | root         |               | time:90.1ms, loops:2, RU:0.000000                                                                                                                                                                                                                                                                                       | funcs:count(1)->Column#10                  | 388 Bytes | N/A  |
| └─TableReader_41             | 25.35      | 0       | root         |               | time:90ms, loops:1, cop_task: {num: 1, max: 0s, proc_keys: 0, copr_cache_hit_ratio: 0.00}                                                                                                                                                                                                                               | MppVersion: 2, data:ExchangeSender_40      | 298 Bytes | N/A  |
|   └─ExchangeSender_40        | 25.35      | 0       | mpp[tiflash] |               | tiflash_task:{time:87.2ms, loops:0, threads:1}                                                                                                                                                                                                                                                                          | ExchangeType: PassThrough                  | N/A       | N/A  |
|     └─Selection_39           | 25.35      | 0       | mpp[tiflash] |               | tiflash_task:{time:87.2ms, loops:0, threads:1}                                                                                                                                                                                                                                                                          | in(test.orders.o_custkey, 0, 150000)       | N/A       | N/A  |
|       └─TableFullScan_38     | 1262431.00 | 1500000 | mpp[tiflash] | table:orders  | tiflash_task:{time:78.2ms, loops:50, threads:1}, tiflash_scan:{dtfile:{total_scanned_packs:350, total_skipped_packs:0, total_scanned_rows:2856754, total_skipped_rows:0, total_rs_index_load_time: 0ms, total_read_time: 39ms}, total_create_snapshot_time: 0ms, total_local_region_num: 3, total_remote_region_num: 0} | pushed down filter:empty, keep order:false | N/A       | N/A  |
+------------------------------+------------+---------+--------------+---------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+--------------------------------------------+-----------+------+
5 rows in set (0.09 sec)

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

total_skipped_packs:0 and the scan context keep the same all the time:

tiflash_task:{time:78.2ms, loops:50, threads:1}, tiflash_scan:{dtfile:{total_scanned_packs:350, total_skipped_packs:0, total_scanned_rows:2856754, total_skipped_rows:0, total_rs_index_load_time: 0ms, total_read_time: 39ms}, total_create_snapshot_time: 0ms, total_local_region_num: 3, total_remote_region_num: 0}

3. What did you see instead (Required)

tiflash_task:{time:61.5ms, loops:10, threads:3}, tiflash_scan:{dtfile:{total_scanned_packs:144, total_skipped_packs:381, total_scanned_rows:1179648, total_skipped_rows:3105483, total_rs_index_load_time: 0ms, total_read_time: 18ms}, total_create_snapshot_time: 0ms, total_local_region_num: 1, total_remote_region_num: 1}

4. What is your TiFlash version? (Required)

master

Reproduce the issue with tiup playground, the TPC-H preparation steps, and two identical EXPLAIN ANALYZE queries against TiFlash. Compare the tiflash_task and tiflash_scan context between the first and second executions; done means repeated queries retain the expected scan context and pack statistics.