planner: keep partition processor for static pruning

[hawkingrei]

What problem does this PR solve?

Issue Number: close #57861

Problem Summary:

In static partition prune mode, partition_processor is required to rewrite a logical partitioned table scan into concrete partition scans. If the rule is disabled through mysql.opt_rule_blacklist, SELECT ... FOR UPDATE can be planned over the logical table scan and return an empty result even though the row exists in a partition.

What changed and how does it work?

This PR treats PartitionProcessor as a correctness rule when the statement uses static partition pruning. In that mode, the logical optimizer ignores the opt-rule blacklist entry for partition_processor, emits a warning, and still runs the static partition rewrite. Dynamic partition pruning keeps the existing blacklist behavior.

It also adds a regression test for a hash-partitioned table with a virtual generated column, SELECT ... FOR UPDATE, and both predicate_push_down and partition_processor listed in mysql.opt_rule_blacklist.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No need to test

  • I checked and no code files have been changed.

Test command:

go test --tags=intest ./pkg/executor -run TestSelectLockWithStaticPruneAndPartitionProcessorBlacklist -count=1

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Fix an issue that `SELECT ... FOR UPDATE` on partitioned tables could return empty results in static partition pruning mode when the partition processor rule is disabled.

Summary by CodeRabbit

• Tests

  • Added a test validating SELECT ... FOR UPDATE with static partition pruning when optimizer rules are blacklisted, ensuring queries on partitioned and non-partitioned tables return expected rows.

• Bug Fixes

  • Ensured the partition-processor rule is effectively enabled for correctness under static pruning and emits a deduplicated warning when a blacklist override occurs.

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: e136a1cf-fc86-4dc1-ba34-515e98470427

📥 Commits

Reviewing files that changed from the base of the PR and between 0cf7e30 and f4f96d1.

📒 Files selected for processing (2)

• pkg/executor/partition_table_test.go
• pkg/planner/core/optimizer.go

---

📝 Walkthrough

Walkthrough

Make logical-rule disablement plan-aware: optimizer now passes the current logical plan to rule-disable checks and forces PartitionProcessor active when static partition pruning requires it (emitting a one-time warning). Adds a test that exercises static prune with mysql.opt_rule_blacklist.

Changes

Plan-aware logical rule disabling

Layer / File(s)	Summary
Optimizer: plan-aware rule-disable checks pkg/planner/core/optimizer.go	isLogicalRuleDisabled now accepts the current logical plan; call sites in normalizeOptimize, logicalOptimize, and interaction re-opt scheduling pass the logical plan. Special-case *rule.PartitionProcessor: when static prune mode is active, it is not disabled and a one-time warning is appended.
Executor test for static prune + blacklist pkg/executor/partition_table_test.go	New test TestSelectLockWithStaticPruneAndPartitionProcessorBlacklist sets @@session.tidb_partition_prune_mode='static', manipulates mysql.opt_rule_blacklist (clear, reload, then insert predicate_push_down and partition_processor), runs SELECT ... FOR UPDATE before/after, and asserts the expected warning about partition_processor being ignored under static prune.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~40 minutes

Possibly related PRs

• pingcap/tidb#68425: Both PRs touch partition-processor/partition-pruning behavior; this PR makes rule disabling plan-aware and warns when partition_processor is ignored in static prune mode.

Suggested labels

size/S, approved, lgtm

Suggested reviewers

• AilinKid
• qw4990

Poem

I’m a rabbit through optimizer trees, I hop on rules with care,
When static pruning needs PartitionProcessor, I keep it there,
A blacklist tries to hide it, but I leave a tiny note,
A warning like a carrot tied to correctness on my coat,
Hoppity-hop — the plans stay sound, and queries still can float. 🐇

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	Title accurately summarizes the main change: keeping the partition processor rule enabled for static partition pruning despite blacklist entries.
Description check	✅ Passed	PR description covers problem statement, solution approach, test details, and release notes following the template structure, though some optional sections are incomplete.
Linked Issues check	✅ Passed	Changes directly address the root cause in issue #57861: treating partition_processor as a correctness rule in static pruning mode to prevent empty result sets.
Out of Scope Changes check	✅ Passed	Both changes focus on the partition processor and static pruning logic described in the linked issue; no unrelated or out-of-scope modifications detected.

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✨ Finishing Touches

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• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@pkg/planner/core/optimizer.go`:
- Around line 1021-1022: The code currently appends interactionRule to
againRuleList when isLogicalRuleDisabled(interactionRule, logic) is true, which
is inverted — change the condition so the rule is re-queued only when it is NOT
disabled; specifically, in the block that tests planChanged && ok &&
isLogicalRuleDisabled(interactionRule, logic), replace the disabled check with
its negation (or call an isLogicalRuleEnabled equivalent) so that
interactionRule is appended only when the rule is enabled.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

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Run ID: 857c7314-6e52-4d86-9735-67ba55ece808

📥 Commits

Reviewing files that changed from the base of the PR and between ae3b70a and 58d55de.

📒 Files selected for processing (2)

• pkg/executor/partition_table_test.go
• pkg/planner/core/optimizer.go

[codecov]

Codecov Report

❌ Patch coverage is 25.80645% with 23 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.4408%. Comparing base (ae3b70a) to head (f4f96d1).

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #68541        +/-   ##
================================================
- Coverage   76.3873%   75.4408%   -0.9466%     
================================================
  Files          2038       2020        -18     
  Lines        562779     565943      +3164     
================================================
- Hits         429892     426952      -2940     
- Misses       131969     138987      +7018     
+ Partials        918          4       -914     

Flag	Coverage Δ
integration	41.4499% <25.8064%> (+1.6710%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	60.4679% <ø> (ø)
parser	∅ <ø> (∅)
br	49.9201% <ø> (-13.0269%)	⬇️

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@pkg/planner/core/optimizer.go`:
- Around line 1041-1050: The override/warning in isLogicalRuleDisabled currently
only checks session dynamic-prune flag so it triggers for non-partitioned plans;
change isLogicalRuleDisabled (and the branch handling rule.PartitionProcessor)
to first scan the provided logical plan `logic` for any partitioned-scan nodes
(e.g., any node representing a partitioned table/partitioned table scan) and
only if such a node is present and UseDynamicPruneMode is false call
appendPartitionProcessorStaticPruneBlacklistWarning and return false; otherwise
treat the rule as disabled (return true). Ensure the detection traverses the
logical plan tree starting at `logic` (or use an existing helper that detects
partitioned scans) so the override and warning are plan-aware.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 9ec17418-8ace-4e0f-8dc7-a1817808b9df

📥 Commits

Reviewing files that changed from the base of the PR and between 58d55de and 0cf7e30.

📒 Files selected for processing (2)

• pkg/executor/partition_table_test.go
• pkg/planner/core/optimizer.go