cloud: add release notes 20250923

[hfxsd]

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[gemini-code-assist]

Summary of Changes

Hello @hfxsd, 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 significantly refines and expands the documentation across TiDB Cloud and TiDB Self-Managed offerings. The changes aim to provide users with more comprehensive, accurate, and structured information on new features, best practices, and operational guidance. The updates span from detailed API and SQL function explanations to practical deployment and performance tuning advice, ensuring the documentation remains current and highly usable for developers and administrators alike.

Highlights

• Documentation Restructuring and Expansion: The pull request introduces significant restructuring and expansion of the documentation, particularly for TiDB Cloud (Starter, Essential, and Dedicated tiers) and TiDB Self-Managed. This includes new Table of Contents files and reorganization of existing ones to improve navigation and clarity.
• New Feature Documentation: Documentation for several new features has been added or expanded, such as C# language support, advanced multi-column index optimization, and detailed batch processing capabilities (Pipelined DML, non-transactional DML). Specific sections for Data Service and Vector Search have also been introduced with BETA tags.
• Improved Monitoring and Performance Tuning Guides: The monitoring and performance tuning sections have been enhanced with new alert subscription options, details on TiDB Cloud Clinic, and new resource allocation optimization guides (Resource Manager, TiDB Node Group). The EXPLAIN ANALYZE output interpretation has also been refined.
• Updated Compatibility and Best Practices: Compatibility matrices for TiDB Data Migration (DM) and Backup & Restore (BR) have been updated to reflect the latest versions. New best practices documents cover handling millions of tables in SaaS multi-tenant scenarios, optimizing multi-column indexes, and updated guidance for auto-increment/auto-random ID management.
• System Configuration and Tooling Enhancements: Detailed instructions for system configuration checks, including disabling swap and configuring firewalls, have been added. Updates to various tool-specific documentation (Dumpling, TiDB Lightning, TiUP) and command-line flag descriptions provide more comprehensive guidance.
• Codebase and Dependency Updates: The .lycheeignore file has been updated to ignore numerous new external URLs, and the OWNERS file reflects changes in approver roles. Internal links within the documentation have been updated to point to the correct release-8.5 branch where applicable.

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[gemini-code-assist]

Code Review

This pull request adds release notes for September 23, 2025. The changes are well-written and clear. I've made a couple of minor suggestions to fix some typos and formatting for better readability. Overall, great work!

[qiancai]

Rest LGTM

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-09-23 03:30:20.317246612 +0000 UTC m=+327430.387740284: ☑️ agreed by qiancai.

[hfxsd]

/approve

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