On Mon, Feb 25, 2019 at 08:47:28AM +0100, Julien Rouhaud wrote: > Ah good point. We could also use something like > pg_relation_size('reloptions_test') / > current_setting('block_size')::bigint but >0 should be enough for this > test.
Also, shouldn't the relopt check happen in should_attempt_truncation()? It seems to me that if we use this routine somewhere else then it should be controlled by the option. At the same time, we also have REL_TRUNCATE_FRACTION and REL_TRUNCATE_MINIMUM which could be made equally user-tunnable. That's more difficult to control, still why don't we also consider this part? Another thing that seems worth thinking about is a system-level GUC, and an option in the VACUUM command to control if truncation should happen or not. We have a lot of infrastructure to control such options between vacuum and autovacuum, so it could be a waste to not consider potential synergies. -- Michael
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