In this case, there are no updates/deleted - only inserts. For now, I have set per-table autovacuum rules in order to minimize the frequency of vacuums but to ensure the statistics are updated frequently with analyze:
> On 11/16/11 4:24 PM, Jason Buberel wrote: >> Just wondering if there is ever a reason to vacuum a very large table >> (> 1B rows) containing rows that never has rows deleted.
> no updates either?
To clarify: in Postgres, an "update" means an insert and a delete. So unless you mean that this table is insert-only, you certainly still need vacuum.
> you still want to do a vacuum analyze every so often to update the > statistics used by the planner.
If it's purely an insert-only table, such as a logging table, then in principle you only need periodic ANALYZEs and not any VACUUMs.
VACUUM could still be worthwhile though, because (a) it will set commit hint bits on all pages and (b) it will set visibility-map bits on all pages. An ANALYZE would only do those things for the random sample of pages that it visits. While neither of those things are critical, they do offload work from future queries that would otherwise have to do that work in-line. So if you've got a maintenance window where the database isn't answering queries anyway, it could be worthwhile to run a VACUUM just to get those bits set.
