The --empty pre-clean picked its candidates by owner, on the stated
assumption that extension members are superuser-owned and would never be
selected. That holds only when a superuser installed the extension. A role
that installs one itself owns its functions, so they were listed for a
one-by-one DROP that postgres refuses:
cannot drop function vector_in(cstring,oid,integer)
because extension vector requires it
Under ON_ERROR_STOP that ends the whole restore, which is how a discourse
generation - it declares the vector extension - became unreplayable.
Membership now comes from pg_depend rather than from ownership. Each branch
carries its oid and classid so one NOT EXISTS covers all seven instead of
seven separate predicates, and the schema branch gets the same guard because
an extension can own a schema too. Skipping the members is enough: the dump's
CREATE EXTENSION IF NOT EXISTS finds the surviving extension either way.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
The dump replay ran statement-by-statement with autocommit. When restore --empty runs against a LIVE database, the pre-clean drops a table, the replay recreates it and autocommits, and a concurrent writer (discourse's mini_scheduler upserting scheduler_stats(id=1)) inserts the same primary key into the empty table before the dump's COPY loads it. The COPY then aborts with a duplicate-key violation under ON_ERROR_STOP and the whole restore fails. Running the replay with --single-transaction keeps the recreated table invisible to other sessions until commit, so the writer can never insert the racing row.
The --empty pre-clean stays multi-statement (\gexec, one DROP per statement): running every DROP in one transaction exhausts max_locks_per_transaction on large schemas (e.g. gitlab).
Extract the pre-clean SQL from the inline string into restore/db/empty_preclean.sql (loaded via dirname(__file__)) and declare it as package-data so it ships in the wheel. Add a unit test guarding the single-transaction/multi-statement split and an e2e that reproduces the live-writer race.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
kevinveenbirkenbachandClaude Opus 5