On 8/11/16 10:59 AM, Jeff Janes wrote:
On Thu, Aug 11, 2016 at 8:32 AM, Amit Kapila <amit.kapil...@gmail.com> wrote:
On Thu, Aug 11, 2016 at 2:09 AM, Jeff Janes <jeff.ja...@gmail.com> wrote:
I wanted to create a new relopt named something like
autovacuum_vacuum_pagevisible_factor which would cause autovacuum to
vacuum a table once less than a certain fraction of the relation's
pages are marked allvisible.
Why would it more convenient for a user to set such a parameter as
compare to existing parameters (autovacuum_vacuum_threshold +
autovacuum_vacuum_scale_factor)?
Insertions and HOT-updates clear vm bits but don't increment the
counters that those existing parameters are compared to.
Also, the relationship between number of updated/deleted rows and the
number of hint-bits cleared can be hard to predict due to possible
clustering of the updates into the same blocks. So it would be hard
to know what to set the values to.
I'm wondering if also creating the same options for all-frozen pages
would be worthwhile. I don't see an obvious use for that, but maybe
someone else does (and adding both at once would presumably be the least
amount of work...)
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