Make PostgreSQL foreign key drops idempotent#27
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Emit DROP CONSTRAINT IF EXISTS for delete_reference statements so a prior cascading table drop cannot make the generated migration fail.
Bump the package version and document the idempotent PostgreSQL foreign-key drop fix.
joe-thom
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Jul 17, 2026
joe-thom
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seems fine, we'll need to republish the package and bump in web
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TLDR
Makes generated PostgreSQL foreign-key removals idempotent so database publishing does not fail when a cascading table drop already removed the constraint.
Why
Drizzle can generate
DROP TABLE ... CASCADEfollowed by an explicit foreign-key removal. PostgreSQL removes the foreign key during the cascade, so the subsequentDROP CONSTRAINTfails even though the database has reached the intended state.What changed
PostgreSQL
delete_referencestatements now render asDROP CONSTRAINT IF EXISTS. This fixes the behavior in the SQL generator rather than rewriting rendered SQL in pid2.Added schema-diff regression coverage for removing a foreign key.
Validations performed
If this breaks
Generated PostgreSQL migrations may behave differently when removing foreign-key constraints.
Rollout and rollback
Rolls out in the next
@drizzle-team/drizzle-kitrelease. Safe to revert; reverting restores strict failure when a generated foreign-key removal targets an already-absent constraint.~ written by Zerg 👾 (lurking-cyclone-5507)