statistics: merge global stats even if some partition stats are missing (#41176)

[ti-chi-bot]

This is an automated cherry-pick of #41176

What problem does this PR solve?

Issue Number: ref #38999

Problem Summary:

What is changed and how it works?

Introduce a system variable tidb_skip_missing_partition_stats, whose default value is on. If tidb_skip_missing_partition_stats turns on, merging global stats would skip partitions whose stats are missing rather than fail.

Check List

Tests

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

This cherry pick PR is for a release branch and has not yet been approved by triage owners.
Adding the do-not-merge/cherry-pick-not-approved label.

To merge this cherry pick:

1. It must be approved by the approvers firstly.
2. AFTER it has been approved by approvers, please wait for the cherry-pick merging approval from triage owners.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[ti-chi-bot]

PR needs rebase.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-02-09 08:50:19.552342344 +0000 UTC m=+519545.119112229: ☑️ agreed by hawkingrei.
• 2024-08-26 09:00:24.578483915 +0000 UTC m=+774419.712934036: ☑️ agreed by winoros.

[fixdb]

/retest

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hawkingrei, qw4990, winoros

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

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [hawkingrei,qw4990,winoros]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[qw4990]

/test unit-test

[tiprow]

@qw4990: No presubmit jobs available for pingcap/[email protected]

In response to this:

/test unit-test

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[codecov]

Codecov Report

Attention: Patch coverage is 68.42105% with 24 lines in your changes missing coverage. Please review.

Please upload report for BASE (release-6.5@a08c685). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-6.5     #49471   +/-   ##
================================================
  Coverage               ?   73.6624%           
================================================
  Files                  ?       1097           
  Lines                  ?     352569           
  Branches               ?          0           
================================================
  Hits                   ?     259711           
  Misses                 ?      76149           
  Partials               ?      16709