*: add detailed intro to the TiDB X architecture

[dbsid]

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[ti-chi-bot]

Hi @dbsid. Thanks for your PR.

I'm waiting for a pingcap member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[gemini-code-assist]

Summary of Changes

Hello @dbsid, 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 introduces detailed documentation for the new TiDB X architecture, outlining its fundamental shift towards a cloud-native, 'Share-Everything' design. It addresses limitations of the classic TiDB architecture by implementing innovations such as object storage as the single source of truth, a 'Compute and Compute' separation for workload isolation, and an LSM Forest storage engine, all aimed at enhancing scalability, stability, cost-effectiveness, and performance predictability.

Highlights

• New TiDB X Architecture Documentation: This pull request introduces comprehensive documentation for the new TiDB X architecture, detailing its fundamental shift from a 'Share-Nothing' to a 'Share-Everything' Service-Oriented Architecture (SOA) designed for the AI era and massive cloud scalability.
• Object Storage Integration: TiDB X leverages object storage (e.g., Amazon S3) as the single source of truth for all data, enabling faster scaling, improved backup mechanisms, and instant node provisioning by decoupling data from local disks.
• Compute-Compute Separation: The architecture introduces a novel 'Separation of Compute and Compute' design, isolating online transactional workloads (lightweight compute) from heavy maintenance tasks (heavy compute) to ensure predictable performance and optimized Total Cost of Ownership (TCO).
• LSM Forest Storage Engine: TiDB X redesigns the storage engine from a single LSM-tree to an LSM Forest, assigning each Region its own independent LSM Tree. This eliminates compaction overhead and global mutex contention during cluster operations, improving stability and performance.

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[gemini-code-assist]

Code Review

This pull request introduces a new documentation page for the TiDB X architecture. The content provides a good high-level overview of the new architecture, its motivations, and key innovations. My review focuses on improving clarity, correcting some typos and grammatical errors, and ensuring consistency in terminology, as per the repository's style guide. I've provided several suggestions to enhance readability and technical accuracy.

[siddontang]

Review Comments

Terminology Suggestion: Share-Everything → Shared-Storage

The term Share-Everything is imprecise and creates an awkward comparison (as @likidu noted - comparing a distributed database to an SOA is not apples-to-apples).

Recommendation: Consider using Shared-Storage instead:

• Maintains linguistic symmetry with Share-Nothing
• Accurately describes what is actually shared (the storage layer, not everything)
• Industry-aligned terminology (similar to disaggregated storage used by Snowflake and modern data platforms)

Alternative framing for the intro:

TiDB X transitions from a Share-Nothing architecture with local storage to a disaggregated architecture with shared object storage as the persistent layer.

---

Structural Issues

1. Title mismatch (lines 2 vs 7): Frontmatter says title: TiDB X Architecture but the first heading is # TiDB X Introduction. These should align.

2. Heading levels: Since the frontmatter provides the page title, content headings should start at ## not #.

3. Missing newline at EOF (line 109): Add a trailing newline.

---

Content Issues

• Line 18: Incomplete sentence fragment - The Share-nothing architecture of TiDB Classic, effectively overcoming... needs restructuring
• Line 38: Typo - architecute should be architecture
• Line 43: Missing space - TiProxy(or load balancers) should be TiProxy (or load balancers)

---

PR Description

Please fill in the required What is changed, added or deleted? section before moving out of draft.

---

Overall the content is well-structured and provides good technical depth. The diagrams help illustrate the architectural differences clearly.

[lilin90]

/ok-to-test

[Frank945946]

There are some comparisons with classic TiDB in this section, such as “6TB+ data per TiKV node or 200k+ SST files,” which are duplicated in the section “The Architectural Ceiling: Challenges Hard to Overcome.” It would be better to remove the redundant descriptions.

[Frank945946]

There are many key advantages. It is recommended to end with a summary section that includes a comparison between TiDB Classic and TiDB X in key areas, making it easier for users to remember.

[ti-chi-bot]

@dbsid: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-verify	b978364	link	true	/test pull-verify

Full PR test history. Your PR dashboard.

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[lilin90]

I'll continue my review soon.

[lilin90]

Suggested change

	summary: Learn how TiDB X's shared-storage architecture delivers cloud-native scalability and cost optimization
	summary: Learn how the shared-storage, cloud-native TiDB X architecture delivers elastic scalability, predictable performance, and optimized total cost of ownership.

[lilin90]

Reason:

• Since this doc is about intro to TiDB X, the first intro should tell what it is clearly to help users quickly get it if they don't want to read details.
• The phrase "single source of truth" is marketing-oriented, not recommended in official docs.
• Clarify what is being separated (compute workloads), not just repeating the slogan.
• Use lowercase “total cost of ownership (TCO)” on first occurrence (common style-guide practice).

Definition reference:

• https://www.pingcap.com/press-release/pingcap-launches-tidb-x-new-ai-capabilities/
• https://www.pingcap.com/blog/introducing-tidb-x-a-new-foundation-distributed-sql-ai-era/

Suggested change

	TiDB X represents a fundamental architectural evolution from classic TiDB's Shared-Nothing design to a cloud-native Shared-Storage architecture. By leveraging object storage as the single source of truth, TiDB X introduces "Separation of Compute and Compute" design that isolates online transactional workloads from heavy background tasks. This architecture enables elastic scalability, predictable performance, and optimized Total Cost of Ownership (TCO) for AI-era workloads.
	TiDB X is a new distributed SQL architecture that makes cloud-native object storage the backbone of TiDB. This architecture enables elastic scalability, predictable performance, and optimized total cost of ownership (TCO) for AI-era workloads.
	TiDB X represents a fundamental evolution from classic TiDB's shared-nothing architecture to a cloud-native shared-storage architecture. By leveraging object storage as the shared persistent storage layer, TiDB X introduces a separation of compute workloads that isolates online transactional processing from resource-intensive background tasks.