[agammann]

Summary

Fixes #702.

• Explain that ClickHouse applies http_max_field_value_size (128 KiB by default) to each URL parameter value, including the URL-encoded query statement.
• Retain http_max_uri_size (1 MiB by default) as the separate whole-URI limit, and note that a query-level setting cannot raise the parsing limit.
• Correct the HTTP guide and both public XML comments; add the required changelog fragment.

Verification

• Against ClickHouse Server 26.11.1.704, an encoded query value of 131,072 bytes returned HTTP 200; 131,073 bytes returned Field value too long (HTTP 500). Sending the same SQL in the POST body succeeded.
• .NET 10 build completed with no errors. The changelog checker, XML fragment parse, and git diff --check passed.

Checklist

• A human-readable description of the changes was provided to include in CHANGELOG

No runtime behavior is changed.

---

Note

Low Risk
Documentation and XML comment updates only; no runtime or API behavior changes.

Overview
Documentation fix (#702) for InsertQueryPlacement.Url: the docs now state that the URL-encoded query string is capped by ClickHouse’s per-parameter limit http_max_field_value_size (128 KiB default), not only by http_max_uri_size (1 MiB whole URI) and the .NET ~65,519-character URI limit the driver already documents.

The same clarification is applied in InsertOptions, InsertQueryPlacement, docs/http.mdx, and a changelog fragment. No driver behavior changes—only accurate limits for operators choosing URL placement for binary inserts.

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[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	⚠️ Failed 2026-10-25T23:26:40.901387Z We couldn’t complete this review. Comment @codex review to try again.	f301c94	PR opened

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🟢 Approval recommended

The documentation-only changes consistently reflect the supplied server evidence and leave no unresolved findings.

No open issues 🎉

What changed in this PR

Clarifies the HTTP client’s documented URL limits for InsertQueryPlacement.Url, addressing #702 without changing runtime behavior or public signatures.

Changes:

• Documents the default 128 KiB limit on each URL-encoded parameter value.
• Distinguishes the separate 1 MiB whole-URI limit and explains that query-level settings cannot raise the parsing limit.
• Updates both public XML comments and adds a documentation changelog fragment.

File	Description
docs/​http.mdx	Clarifies URL query limits in the HTTP insert guide.
ClickHouse.Driver/​InsertQueryPlacement.cs	Updates the Url enum value’s XML documentation.
ClickHouse.Driver/​InsertOptions.cs	Aligns QueryPlacement XML documentation with the guide.
changelog.d/​702-url-query-limit.docs.md	Records the documentation correction for #702.

_{Review effort: Balanced}