statistics: fix unnecessary index fmsketch loading

[xuyifangreeneyes]

What problem does this PR solve?

Issue Number: close #42052

Problem Summary:

What is changed and how it works?

When loading index stats from storage, we don't need to load index fmsketch unless loadAll is true. We only use index fmsketch when merging partition stats to global stats, where loadAll is true.

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]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• Yisaer
• chrysan

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[xuyifangreeneyes]

/merge

[ti-chi-bot]

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

Commit hash: 735e171

[xuyifangreeneyes]

/test check-dev2

[xuyifangreeneyes]

/test unit-test

[ti-chi-bot]

@xuyifangreeneyes: PR needs rebase.

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[ti-chi-bot]

In response to a cherrypick label: new pull request could not be created: failed to create pull request against pingcap/tidb#release-5.3 from head ti-chi-bot:cherry-pick-42074-to-release-5.3: the GitHub API request returns a 403 error: {"message":"You have exceeded a secondary rate limit and have been temporarily blocked from content creation. Please retry your request again later.","documentation_url":"https://docs.github.com/rest/overview/resources-in-the-rest-api#secondary-rate-limits"}

[ti-chi-bot]

In response to a cherrypick label: new pull request could not be created: failed to create pull request against pingcap/tidb#release-6.0 from head ti-chi-bot:cherry-pick-42074-to-release-6.0: the GitHub API request returns a 403 error: {"message":"You have exceeded a secondary rate limit and have been temporarily blocked from content creation. Please retry your request again later.","documentation_url":"https://docs.github.com/rest/overview/resources-in-the-rest-api#secondary-rate-limits"}

[ti-chi-bot]

In response to a cherrypick label: new pull request could not be created: failed to create pull request against pingcap/tidb#release-6.1 from head ti-chi-bot:cherry-pick-42074-to-release-6.1: the GitHub API request returns a 403 error: {"message":"You have exceeded a secondary rate limit and have been temporarily blocked from content creation. Please retry your request again later.","documentation_url":"https://docs.github.com/rest/overview/resources-in-the-rest-api#secondary-rate-limits"}

[ti-chi-bot]

In response to a cherrypick label: new pull request could not be created: failed to create pull request against pingcap/tidb#release-6.5 from head ti-chi-bot:cherry-pick-42074-to-release-6.5: the GitHub API request returns a 403 error: {"message":"You have exceeded a secondary rate limit and have been temporarily blocked from content creation. Please retry your request again later.","documentation_url":"https://docs.github.com/rest/overview/resources-in-the-rest-api#secondary-rate-limits"}

[xuyifangreeneyes]

/cherry-pick release-6.5

[ti-chi-bot]

@xuyifangreeneyes: new pull request created to branch release-6.5: #44259.

In response to this:

/cherry-pick release-6.5

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[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.1: #45083.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-5.4: #45084.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #45085.