fix: carry ON DELETE SET NULL/SET DEFAULT column list on foreign keys (#589)

[tianzhou]

Summary

ON DELETE SET NULL (cols) / ON DELETE SET DEFAULT (cols) (PG15+, pg_constraint.confdelsetcols) was never read by the inspector, so the column list was dropped from generated DDL and ignored by constraint comparison. A composite FK meant to clear one column cleared all of them, and plan reported no drift in either direction.

• ir/queries/queries.sql: both constraint queries now return delete_set_columns as a JSON array of column names via a LATERAL aggregate over to_jsonb(c) -> 'confdelsetcols', which stays safe on PG14 where the attribute does not exist. sqlc code regenerated.
• ir/ir.go / ir/inspector.go: new Constraint.DeleteSetColumns.
• internal/diff/constraint.go, internal/diff/table.go, internal/plan/rewrite.go: emit the column list after ON DELETE SET NULL/SET DEFAULT; constraintsEqual now compares it, so a database lacking the list gets the constraint recreated.

Fixes #589

Test plan

Folded into testdata/diff/create_table/add_fk: a composite FK with SET NULL (col), one with SET DEFAULT (col), and an existing FK without the list that gains it (drop + re-add). Fails before the fix, passes after.

PGSCHEMA_TEST_FILTER="create_table/add_fk" go test ./internal/diff -run TestDiffFromFiles
PGSCHEMA_TEST_FILTER="create_table/add_fk" go test ./cmd -run TestPlanAndApply

Also ran locally: all create_table/ diff cases, ./internal/plan, ./ir, and create_table/add_uk on PG14 to confirm the query works without confdelsetcols.

🤖 Generated with Claude Code

[Copilot]

🟡 Changes recommended

Delete-action column lists need order-independent comparison to avoid unnecessary constraint recreation.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Preserves PostgreSQL foreign-key column lists for ON DELETE SET NULL/SET DEFAULT during inspection, comparison, and DDL generation.

Changes:

• Safely reads and stores confdelsetcols.
• Compares and renders delete-action column lists.
• Adds regression fixtures for creation and drift detection.

A moderate issue remains: delete-action columns are compared in order, causing unnecessary constraint recreation when semantically equivalent lists are reordered.

File summaries

File	Description
testdata/diff/create_table/add_fk/plan.txt	Updates text plan fixture.
testdata/diff/create_table/add_fk/plan.sql	Updates SQL plan fixture.
testdata/diff/create_table/add_fk/plan.json	Updates JSON plan fixture.
testdata/diff/create_table/add_fk/old.sql	Adds source FK scenarios.
testdata/diff/create_table/add_fk/new.sql	Adds desired column-list definitions.
testdata/diff/create_table/add_fk/diff.sql	Records expected migration DDL.
ir/queries/queries.sql.go	Regenerates sqlc bindings.
ir/queries/queries.sql	Extracts delete-set column names.
ir/ir.go	Adds DeleteSetColumns to constraints.
ir/inspector.go	Decodes inspected column lists.
internal/plan/rewrite.go	Preserves lists during online FK rewrites.
internal/diff/table.go	Uses shared delete-clause rendering.
internal/diff/constraint.go	Compares and renders lists; comparison must ignore column order.

Review details

Files not reviewed (1)

• ir/queries/queries.sql.go: Generated file

• Files reviewed: 12/13 changed files
• Comments generated: 1
• Review effort level: Balanced

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[greptile-apps]

Greptile Summary

This PR preserves PostgreSQL 15+ foreign-key delete-action column lists throughout catalog inspection, IR comparison, canonical DDL generation, and online constraint rewrites.

• Reads pg_constraint.confdelsetcols through PostgreSQL-version-compatible catalog queries.
• Adds the inspected column list to the constraint IR and drift comparison.
• Quotes and renders the list for both ordinary and rewritten foreign-key creation.
• Extends the foreign-key fixtures to cover SET NULL, SET DEFAULT, and constraint recreation when the list changes.

Confidence Score: 5/5

The PR appears safe to merge; the new foreign-key metadata remains aligned across inspection, comparison, SQL rendering, rewrites, and regression fixtures.

No actionable correctness, security, compatibility, or repository-rule violation remains after reviewing the changed catalog contract and all downstream consumers.

Important Files Changed

Filename	Overview
ir/queries/queries.sql	Adds compatibility-safe extraction of delete-action column names to both constraint queries while preserving catalog order.
ir/queries/queries.sql.go	Regenerates the typed query rows and scan order consistently with the updated SQL.
ir/inspector.go	Decodes the query's JSON column-name array into the constraint IR and returns contextual errors for malformed data.
ir/ir.go	Adds the PostgreSQL 15+ delete-action column list to the shared constraint representation.
internal/diff/constraint.go	Compares the new field and centralizes quoted rendering of foreign-key ON DELETE clauses.
internal/diff/table.go	Reuses the shared ON DELETE renderer for foreign keys emitted during table diff generation.
internal/plan/rewrite.go	Preserves and quotes delete-action column lists when foreign-key additions are rewritten through NOT VALID and validation steps.
testdata/diff/create_table/add_fk/new.sql	Adds desired-state coverage for SET NULL, SET DEFAULT, and changing an existing foreign key's delete column list.
testdata/diff/create_table/add_fk/old.sql	Defines the corresponding source states used to verify additions and recreation.
testdata/diff/create_table/add_fk/diff.sql	Captures expected canonical DDL including quoted-capable delete-action column-list rendering.
testdata/diff/create_table/add_fk/plan.json	Updates structured plan expectations for staged creation and validation of the new foreign keys.
testdata/diff/create_table/add_fk/plan.sql	Updates executable plan SQL expectations with the preserved column lists.
testdata/diff/create_table/add_fk/plan.txt	Updates human-readable plan output and transaction-group numbering for the added cases.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart LR
    PG[(pg_constraint.confdelsetcols)] --> Q[Catalog queries]
    Q --> I[Inspector]
    I --> IR[Constraint.DeleteSetColumns]
    IR --> C[Constraint comparison]
    IR --> D[Canonical FK DDL]
    IR --> R[Online FK rewrite]
    C -->|Drift detected| D
    D --> P[Migration plan]
    R --> P

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[Copilot]

🟢 Approval recommended

The reviewed changes have regression coverage and no unresolved issues.

Review details

Files not reviewed (1)

• ir/queries/queries.sql.go: Generated file

• Files reviewed: 12/13 changed files
• Comments generated: 0 new
• Review effort level: Balanced