Re: To what extent should tests rely on VACUUM ANALYZE?

When running multiple 027_stream_regress.pl test instances in parallel
(and with aggressive autovacuum) on a rather slow machine, I encountered
test failures due to the subselect test instability just as the following
failures on buildfarm:
1) https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=grassquit&dt=2024-03-27%2010%3A16%3A12

--- /home/bf/bf-build/grassquit/HEAD/pgsql/src/test/regress/expected/subselect.out 2024-03-19 22:20:34.435867114 +0000
+++ /home/bf/bf-build/grassquit/HEAD/pgsql.build/testrun/recovery/027_stream_regress/data/results/subselect.out
2024-03-27 10:28:38.185776605 +0000
@@ -2067,16 +2067,16 @@
                     QUERY PLAN
  -------------------------------------------------
   Hash Join
-   Hash Cond: (c.odd = b.odd)
+   Hash Cond: (c.hundred = a.hundred)
     ->  Hash Join
-         Hash Cond: (a.hundred = c.hundred)
-         ->  Seq Scan on tenk1 a
+         Hash Cond: (b.odd = c.odd)
+         ->  Seq Scan on tenk2 b
           ->  Hash
                 ->  HashAggregate
                       Group Key: c.odd, c.hundred
                       ->  Seq Scan on tenk2 c
     ->  Hash
-         ->  Seq Scan on tenk2 b
+         ->  Seq Scan on tenk1 a
  (11 rows)