tikv: clarify the description of config 'in-memory-engine.capacity' (#21828)

[ti-chi-bot]

This is an automated cherry-pick of #21828

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• This PR is translated from: tikv: clarify the description of config 'in-memory-engine.capacity' docs-cn#20923
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[gemini-code-assist]

Summary of Changes

Hello @ti-chi-bot, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the documentation for TiKV's in-memory-engine.capacity configuration. The changes aim to provide a clearer understanding of how this parameter controls memory usage for the MVCC in-memory engine, including its default behavior and how it impacts Region caching and eviction. This improvement helps users configure TiKV more effectively and avoid potential memory-related issues.

Highlights

• Configuration Clarity: The description for the in-memory-engine.capacity configuration in TiKV has been significantly clarified to better explain its purpose and behavior.
• Default Value Update: The default value for in-memory-engine.capacity is now precisely defined as min(10% of the total system memory, 5 GiB), resolving previous ambiguities.
• Memory Management Details: The updated documentation provides more insight into how the in-memory engine utilizes this capacity for caching Regions and its eviction strategy based on Region MVCC redundancy.

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[gemini-code-assist]

Code Review

This pull request clarifies the description for the in-memory-engine.capacity configuration. The new description is more precise, especially regarding the default value. I've suggested a minor wording change to improve clarity and ensure terminology consistency with other related documentation.

[qiancai]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: qiancai

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