distsql: refine code for setting LimitSize of kvRequest

[XuHuaiyu]

What problem does this PR solve?

Issue Number: close #41591

Problem Summary:

What is changed and how it works?

#41120 fix the problem partly.
This PR refines the code of check logic.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
  Before:

+----------------------------------+----------+---------+-----------+--------------------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------+----------+------+
| TopN_9                           | 0.07     | 100     | root      |                                                  | time:3.28s, loops:2                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | test.present.deadline_time, offset:0, count:100 | 7.73 KB  | N/A  |
| └─IndexLookUp_17                 | 0.07     | 6700    | root      | partition:p0                                     | time:3.28s, loops:9, index_task: {total_time: 2.9s, fetch_handle: 2.9s, build: 24.2µs, wait: 63.6µs}, table_task: {total_time: 1.35s, num: 7, concurrency: 5}, next: {wait_index: 1.97s, wait_table_lookup_build: 4.46ms, wait_table_lookup_resp: 1.3s}                                                                                                                                                                                                                                                                                                         |                                                 | 404.0 KB | N/A  |
|   ├─Limit_16(Build)              | 0.07     | 6700    | cop[tikv] |                                                  | time:2.89s, loops:13, cop_task: {num: 67, max: 128.9ms, min: 39.6ms, avg: 43.3ms, p95: 44.1ms, max_proc_keys: 224, p95_proc_keys: 224, rpc_num: 67, rpc_time: 2.9s, copr_cache_hit_ratio: 0.00, build_task_duration: 58.7µs, max_distsql_concurrency: 1}, tikv_task:{proc max:1ms, min:0s, avg: 134.3µs, p80:0s, p95:1ms, iters:201, tasks:67}, scan_detail: {total_process_keys: 15000, total_process_keys_size: 1260000, total_keys: 15067, get_snapshot_time: 1.8ms, rocksdb: {key_skipped_count: 15000, block: {cache_hit_count: 151}}}                     | offset:0, count:100                             | N/A      | N/A  |
|   │ └─Selection_15               | 0.07     | 15000   | cop[tikv] |                                                  | tikv_task:{proc max:1ms, min:0s, avg: 134.3µs, p80:0s, p95:1ms, iters:201, tasks:67}                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | eq(test.present.delete_time, 0)                 | N/A      | N/A  |
|   │   └─IndexRangeScan_13        | 25093.65 | 15000   | cop[tikv] | table:present, index:idx(user_id, deadline_time) | tikv_task:{proc max:1ms, min:0s, avg: 134.3µs, p80:0s, p95:1ms, iters:201, tasks:67}                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | range:[1,1], keep order:false                   | N/A      | N/A  |
|   └─TableRowIDScan_14(Probe)     | 0.07     | 6700    | cop[tikv] | table:present                                    | time:1.35s, loops:18, cop_task: {num: 7, max: 543ms, min: 41.4ms, avg: 192.5ms, p95: 543ms, max_proc_keys: 3200, p95_proc_keys: 3200, tot_proc: 128ms, rpc_num: 7, rpc_time: 1.35s, copr_cache_hit_ratio: 0.43, build_task_duration: 306.9µs, max_distsql_concurrency: 1}, tikv_task:{proc max:79ms, min:4ms, avg: 22.6ms, p80:27ms, p95:79ms, iters:33, tasks:7}, scan_detail: {total_process_keys: 5700, total_process_keys_size: 353400, total_keys: 11400, get_snapshot_time: 357µs, rocksdb: {key_skipped_count: 5700, block: {cache_hit_count: 22800}}}   | keep order:false                                | N/A      | N/A  |
+----------------------------------+----------+---------+-----------+--------------------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------+----------+------+
6 rows in set (3.33 sec)

After:

+----------------------------------+----------+---------+-----------+--------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------+---------+------+
| id                               | estRows  | actRows | task      | access object                                    | execution info                                                                                                                                                                                                                                                                                                                                                                                                                | operator info                                   | memory  | disk |
+----------------------------------+----------+---------+-----------+--------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------+---------+------+
| TopN_9                           | 0.07     | 100     | root      |                                                  | time:85.7ms, loops:2                                                                                                                                                                                                                                                                                                                                                                                                          | test.present.deadline_time, offset:0, count:100 | 5.82 KB | N/A  |
| └─IndexLookUp_17                 | 0.07     | 100     | root      | partition:p0                                     | time:85.6ms, loops:2, index_task: {total_time: 42.2ms, fetch_handle: 42.1ms, build: 1.65µs, wait: 5.94µs}, table_task: {total_time: 43.2ms, num: 1, concurrency: 5}, next: {wait_index: 42.4ms, wait_table_lookup_build: 161.1µs, wait_table_lookup_resp: 43ms}                                                                                                                                                               |                                                 | 8.63 KB | N/A  |
|   ├─Limit_16(Build)              | 0.07     | 100     | cop[tikv] |                                                  | time:42ms, loops:2, cop_task: {num: 1, max: 41.9ms, proc_keys: 224, rpc_num: 1, rpc_time: 41.8ms, copr_cache_hit_ratio: 0.00, build_task_duration: 90.9µs, max_distsql_concurrency: 1}, tikv_task:{time:0s, loops:3}, scan_detail: {total_process_keys: 224, total_process_keys_size: 18816, total_keys: 225, get_snapshot_time: 41.2µs, rocksdb: {key_skipped_count: 224, block: {cache_hit_count: 2}}}                      | offset:0, count:100                             | N/A     | N/A  |
|   │ └─Selection_15               | 0.07     | 224     | cop[tikv] |                                                  | tikv_task:{time:0s, loops:3}                                                                                                                                                                                                                                                                                                                                                                                                  | eq(test.present.delete_time, 0)                 | N/A     | N/A  |
|   │   └─IndexRangeScan_13        | 25093.65 | 224     | cop[tikv] | table:present, index:idx(user_id, deadline_time) | tikv_task:{time:0s, loops:3}                                                                                                                                                                                                                                                                                                                                                                                                  | range:[1,1], keep order:false                   | N/A     | N/A  |
|   └─TableRowIDScan_14(Probe)     | 0.07     | 100     | cop[tikv] | table:present                                    | time:42.9ms, loops:2, cop_task: {num: 1, max: 42.8ms, proc_keys: 100, tot_proc: 2ms, rpc_num: 1, rpc_time: 42.7ms, copr_cache_hit_ratio: 0.00, build_task_duration: 22.9µs, max_distsql_concurrency: 1}, tikv_task:{time:2ms, loops:3}, scan_detail: {total_process_keys: 100, total_process_keys_size: 6200, total_keys: 200, get_snapshot_time: 75.4µs, rocksdb: {key_skipped_count: 100, block: {cache_hit_count: 400}}}   | keep order:false                                | N/A     | N/A  |
+----------------------------------+----------+---------+-----------+--------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------+---------+------+
6 rows in set (0.13 sec)

• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• tiancaiamao
• wshwsh12

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

The full list of commands accepted by this bot can be found here.

Reviewer can indicate their review by submitting an approval review.
Reviewer can cancel approval by submitting a request changes review.

[solotzg]

lgtm

[XuHuaiyu]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 0c3338a

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #41607.