fix: order function recreation after dependent view recreation (#480)

[tianzhou]

Summary

Fixes a dependency-ordering bug where apply fails with cannot drop view ... because other objects depend on it (SQLSTATE 2BP01).

When a function's RETURNS/parameter type references a view, the function depends on that view's composite rowtype. If both the view must be recreated (DROP + CREATE, e.g. a column added mid-list) and the function's signature changes (so it's a drop+add rather than an in-place CREATE OR REPLACE), pgschema emitted the operations in this order:

DROP FUNCTION fn_create_user(text);          -- drop phase
CREATE OR REPLACE FUNCTION fn_create_user(...) RETURNS vw_users ...;  -- create phase ❌ re-pins old view
ALTER TABLE tb_users ADD COLUMN role ...;    -- modify phase
DROP VIEW vw_users RESTRICT;                  -- modify phase ❌ FAILS: function depends on it
CREATE OR REPLACE VIEW vw_users ...;

The function's DROP already runs in the drop phase, but its CREATE ran in the create phase — before the view's DROP — re-pinning the old view and blocking the RESTRICT drop.

Fix

The existing function-deferral logic only considered newly added views (buildViewLookup(d.addedViews)). This adds the same handling for views being recreated (modifiedViews with RequiresRecreate): added functions whose type references such a view are pulled out of the create phase into functionsAwaitingRecreatedViews and emitted in the modify phase, after generateModifyViewsSQL recreates the view.

Resulting order (now applies cleanly):

DROP FUNCTION fn_create_user(text);
ALTER TABLE tb_users ADD COLUMN role ...;
DROP VIEW vw_users RESTRICT;                  -- ✅ no dependents
CREATE OR REPLACE VIEW vw_users ...;
CREATE OR REPLACE FUNCTION fn_create_user(...) RETURNS vw_users ...;  -- ✅ after view

Test plan

Added testdata/diff/dependency/issue_480_view_function_recreate/ (the issue's exact reproduction: table <- view <- function, adding a role column).

• internal/diff TestDiffFromFiles — asserts the corrected DDL ordering.
• cmd TestPlanAndApply — applies the migration end-to-end against embedded PostgreSQL, proving the new order is valid (previously failed with 2BP01).

PGSCHEMA_TEST_FILTER="dependency/issue_480_view_function_recreate" go test ./internal/diff -run TestDiffFromFiles
PGSCHEMA_TEST_FILTER="dependency/issue_480_view_function_recreate" go test ./cmd -run TestPlanAndApply

Both green; full suite runs in CI.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Fixes an apply dependency-ordering failure when a function’s return/parameter type references a view that must be recreated (DROP+CREATE), by deferring creation of such functions until after the view recreation step in the modify phase.

Changes:

• Track views being recreated (RequiresRecreate) and defer added functions whose signature references those view composite types.
• Emit these deferred functions after generateModifyViewsSQL recreates the views (issue #480).
• Add a regression test case under testdata/diff/dependency/issue_480_view_function_recreate/ asserting correct DDL order across plan outputs.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
internal/diff/diff.go	Defers function creation until after recreated views are dropped/recreated; adds recreated-view lookup helper.
testdata/diff/dependency/issue_480_view_function_recreate/plan.txt	Golden plan text showing corrected DDL ordering.
testdata/diff/dependency/issue_480_view_function_recreate/plan.sql	Golden plan SQL showing corrected DDL ordering.
testdata/diff/dependency/issue_480_view_function_recreate/plan.json	Golden plan JSON capturing the corrected step ordering.
testdata/diff/dependency/issue_480_view_function_recreate/old.sql	Repro old-state schema (table → view → function).
testdata/diff/dependency/issue_480_view_function_recreate/new.sql	Repro new-state schema that forces view recreation and function signature change.
testdata/diff/dependency/issue_480_view_function_recreate/diff.sql	Golden diff SQL reflecting the intended execution order.

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[greptile-apps]

Greptile Summary

This PR fixes a dependency-ordering bug (#480) where apply would fail with cannot drop view ... because other objects depend on it (2BP01) when a function's return/parameter type references a view that both requires recreation (DROP + CREATE) and whose signature also changes (making it a drop+add rather than an in-place CREATE OR REPLACE).

• Extends the existing function-deferral logic in generateCreateSQL to also check functions against a newly computed recreatedViewLookup (modified views with RequiresRecreate), pulling matching functions out of both the with-view-deps and without-view-deps buckets into a new functionsAwaitingRecreatedViews slice on the diff struct.
• Emits those deferred functions in generateModifySQL immediately after generateModifyViewsSQL recreates the view, guaranteeing the function is created only once the view's new composite rowtype exists and the old view has no dependents during its RESTRICT drop.
• Adds a complete test case covering the exact scenario from the issue report, including both a TestDiffFromFiles DDL-order assertion and a TestPlanAndApply end-to-end integration test.

Confidence Score: 5/5

Safe to merge. The change is a targeted fix to function-deferral ordering that follows the existing pattern exactly, and the test case directly reproduces the previously-failing scenario end-to-end.

The new buildRecreatedViewLookup + functionsAwaitingRecreatedViews path is a faithful mirror of the existing buildViewLookup + functionsAwaitingDeferredViews path. A function referencing both a newly-added view and a recreated view is removed from functionsWithViewDeps before the deferred-view logic runs, so it can only land in one bucket. Guards and nil-map handling are consistent with the rest of the file. Both the DDL-ordering unit test and the end-to-end integration test exercise the fix.

No files require special attention.

Important Files Changed

Filename	Overview
internal/diff/diff.go	Core fix: adds functionsAwaitingRecreatedViews field and buildRecreatedViewLookup helper; defers matching functions from the create phase to the modify phase. Logic mirrors the existing functionsAwaitingDeferredViews pattern.
testdata/diff/dependency/issue_480_view_function_recreate/diff.sql	Expected migration DDL showing correct ordering: DROP FUNCTION then ALTER TABLE then DROP VIEW then CREATE VIEW then CREATE FUNCTION.
testdata/diff/dependency/issue_480_view_function_recreate/old.sql	Starting state: table without role column, view selecting 3 columns, function with single-parameter signature returning the view rowtype.
testdata/diff/dependency/issue_480_view_function_recreate/new.sql	Desired state: table with role column added mid-list, view selecting 4 columns, function with 2-parameter signature forcing drop+add.
testdata/diff/dependency/issue_480_view_function_recreate/plan.json	Plan JSON snapshot: 5 steps in correct dependency order, function create step last.

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