The pg_advisory_xact_lock inside the WITH clause caused race conditions
in READ COMMITTED mode. When a transaction blocked on the lock and resumed
after acquiring it, it used a stale snapshot and computed the same reference
ID as the previous transaction, violating the unique constraint. Moving the
lock to a separate statement before the INSERT ensures the snapshot includes
all previously committed data.
Signed-off-by: Bryan Frimin <bryan@getprobo.com>
2e12c11c0c