executor: fix issue of txn_ts of stale-read query is 0 in slow log

[crazycs520]

What problem does this PR solve?

Issue Number: close #45545

Problem Summary: fix issue of txn_ts of stale-read query is 0 in slow log

What changed and how does it work?

Before This PR

The slow log of stale-read query is the following, Txn_start_ts is 0, which is unexpected.

...
# Txn_start_ts: 0
...
select * from t;

This PR

...
# Txn_start_ts: 448987604713472000
...
select * from t;

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No need to test

  • I checked and no code files have been changed.

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

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[crazycs520]

/check-issue-triage-complete

[MyonKeminta]

Can we consider distinguishing the start_ts allocated from PD and the stale read ts that's calculated in other way, to avoid possible misunderstanding (e.g. the ts might be the same with another transaction's start_ts, and one may think that the statement is part of that transaction)?

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: zyguan

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-04-11 04:27:08.274765665 +0000 UTC m=+1109289.802306211: ☑️ agreed by zyguan.

[codecov]

Codecov Report

Merging #52484 (f046130) into master (e540f0f) will increase coverage by 2.0877%.
Report is 4 commits behind head on master.
The diff coverage is 100.0000%.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #52484        +/-   ##
================================================
+ Coverage   72.2050%   74.2928%   +2.0877%     
================================================
  Files          1467       1467                
  Lines        427020     427484       +464     
================================================
+ Hits         308330     317590      +9260     
+ Misses        99515      90046      -9469     
- Partials      19175      19848       +673     

Flag	Coverage Δ
integration	48.7543% <100.0000%> (?)
unit	71.0044% <100.0000%> (-0.0909%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	53.9957% <ø> (ø)
parser	∅ <ø> (∅)
br	49.6474% <ø> (+8.5451%)	⬆️

[crazycs520]

#52494 has a better fix than this.