On Mon, Apr 15, 2019 at 01:22:30PM -0400, Tom Lane wrote: > In connection with the issue discussed at [1], I tried to run > the core regression tests with extremely aggressive autovacuuming > (I set autovacuum_naptime = 1s, autovacuum_vacuum_threshold = 5, > autovacuum_vacuum_cost_delay = 0). I found that the timestamp > test tends to fail with diffs caused by unstable row order in > timestamp_tbl. This is evidently because it does a couple of > DELETEs before inserting the table's final contents; if autovac > comes along at the right time then some of those slots can get > recycled in between insertions. I'm thinking of committing the > attached patch to prevent this, since in principle such failures > could occur even without hacking the autovac settings. Thoughts?
Aren't extra ORDER BY clauses the usual response to tuple ordering? I really think that we should be more aggressive with that. For table AM, it can prove to be very useful to run the main regression test suite with default_table_access_method enforced, and most likely AMs will not ensure the same tuple ordering as heap. -- Michael
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