system-variables: add tidb_paging_size_bytes (internal use) (#23565)

[ti-chi-bot]

This is an automated cherry-pick of #23565

What is changed, added or deleted? (Required)

This PR is translated from: pingcap/docs-cn#21752

Which TiDB version(s) do your changes apply to? (Required)

• master (the latest development version)

What is the related PR or file link(s)?

• Other reference link(s):
  • pingcap/tidb PR: *: add tidb_paging_size_bytes and forward it to coprocessor RPC tidb#68091
  • pingcap/tidb PR（恢复默认值为 0）: sessionctx: restore tidb_paging_size_bytes default to 0 tidb#70052
  • kvproto PR: proto: add paging_size_bytes to coprocessor.Request kvproto#1448

Summary by CodeRabbit

• Documentation
  • Documented the tidb_paging_size_bytes system variable for limiting coprocessor response pages by byte size.
  • Added details on supported scopes, default value, valid range, SET_VAR support, and availability.
  • Noted requirements for byte-based pagination, including resource control with a fixed RU quota and advance RU estimation.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between a3645ed and 2b3943c.

📒 Files selected for processing (1)

• system-variables.md

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📝 Walkthrough

Walkthrough

Adds reference documentation for the tidb_paging_size_bytes system variable, including its scope, availability, byte-based pagination behavior, prerequisites, default value, range, and SET_VAR support.

Changes

Paging variable documentation

Layer / File(s)	Summary
System variable reference system-variables.md	Documents tidb_paging_size_bytes, including scope, availability, byte-based pagination, interaction with tidb_max_paging_size, resource-control prerequisites, default value, range, and SET_VAR support.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Merge Risk: ⚪ Minimal · up to 2b394

This change adds reference documentation for the internal paging-size system variable. No current documentation defect affecting configuration behavior or users remains identified.

Suggested reviewers: qiancai

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description includes version and reference sections, but it does not explain the change in the required section and lists master instead of the release-8.5 target stated in the PR objectives.	Add a concise change summary under “What is changed, added or deleted?” and select v8.5 to match the target branch. Retain master only if the change also applies there.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the addition of the internal-use tidb_paging_size_bytes system variable and matches the documented change.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0 files. (1 skipped: 1 unsupported.)

• Fix all pre-merge checks with AI

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 3

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📥 Commits

Reviewing files that changed from the base of the PR and between ae3312e and a3645ed.

📒 Files selected for processing (1)

• system-variables.md

Included review availability: Your plan provides up to 4 included reviews per hour; 3 remain after this review.

[coderabbitai]

🗄️ Data Integrity & Integration | 🟡 Minor | ⚡ Quick win

🔎 Supported by static analysis

🏁 Script executed:

printf '%s\n' '--- applicable conventions ---'
find /tmp/coderabbit-repo-knowledge/pingcap-docs-9c73f70c -path '*/\*.md' -print | sort
printf '%s\n' '--- target entry ---'
sed -n '5398,5424p' system-variables.md
printf '%s\n' '--- resource-control references ---'
rg -n -C 4 'Essential|non-burst|nonburstable|Resource Control|tidb_paging_size_bytes' \
  --glob '*.md' \
  /tmp/coderabbit-repo-knowledge/pingcap-docs-9c73f70c system-variables.md

Repository: pingcap/docs

Length of output: 5045

---

🏁 Script executed:

printf '%s\n' '--- applicable conventions ---'
find /tmp/coderabbit-repo-knowledge/pingcap-docs-9c73f70c -type f -name '*.md' -print | sort
printf '%s\n' '--- target entry ---'
sed -n '5398,5424p' system-variables.md
printf '%s\n' '--- resource-control references ---'
rg -n -C 4 'Essential|non-burst|nonburstable|Resource Control|tidb_paging_size_bytes' \
  --glob '*.md' \
  /tmp/coderabbit-repo-knowledge/pingcap-docs-9c73f70c system-variables.md

Repository: pingcap/docs

Length of output: 5310

---

🏁 Script executed:

printf '%s\n' '--- repository convention ---'
cat /tmp/coderabbit-repo-knowledge/pingcap-docs-9c73f70c/conventions/repo-wide.md
printf '%s\n' '--- resource-control document ---'
resource_doc=$(find . -name 'tidb-resource-control-ru-groups.md' -print -quit)
if [ -n "$resource_doc" ]; then
  rg -n -C 5 'Starter|Essential|Premium|fixed RU|non-burst|burstable|Resource Control' "$resource_doc"
else
  printf '%s\n' 'resource-control document not present in checkout'
fi

Repository: pingcap/docs

Length of output: 7668

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Clarify TiDB Cloud Essential availability.

Resource Control is unavailable on TiDB Cloud Essential, but this variable requires Resource Control to take effect. Remove Essential from the scope, or document the internal exception that provides the required Resource Group.

[ti-chi-bot]

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