golang-migrate / migrate / 34422391442

55%

master: 55%

Pull #1426

github

postgres: exclude extension-owned and internally-dependent types from Drop()

A follow-up review of this branch found two real regressions in the
type-selection query added in the previous commit:

- Any type an extension installs into the current schema (citext, hstore,
  postgis, ...) was selected and DROP TYPE fails on it -- only dropping the
  extension can remove it. Drop() would return that error and abort with
  the tables already gone.

- A range type's auto-generated multirange type has an internal dependency
  on its range type. If the multirange sorts before the range type in the
  (unordered) query result, its DROP fails immediately for the same reason,
  again aborting with tables already dropped. Reordering wouldn't fully fix
  this either -- it would just make the failure order-dependent.

Exclude anything with an extension ('e') or internal ('i') pg_depend entry.
Verified against a real Postgres 16 instance: citext extension + enum +
range type (which also exercises its implicit multirange) + a table, in
combination. Before this commit, Drop() failed outright. After, it succeeds
and drops everything droppable, leaving only the extension-owned type,
which is correct since removing it means dropping the extension.

Adds testDropWithExtensionAndRangeTypes alongside the existing
testDropWithCustomTypes.

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