On Mon, May 11, 2020 at 07:41:55PM -0500, Justin Pryzby wrote: > On Mon, May 11, 2020 at 10:52:41AM +0530, Amit Kapila wrote: > > One more observation: > > > > Allow inserts to trigger autovacuum activity (Laurenz Albe, Darafei > > Praliaskouski) > > This new behavior allows pages to be set as all-visible, which then > > allows index-only scans, ... > > > The above sentence sounds to mean that this feature allows index-only > > scans in more number of cases after this feature. Is that what you > > intend to say? If so, is that correct? Because I think this will > > allow index-only scans to skip "Heap Fetches" in more cases. > > I think what you mean is that the autovacuum feature, in addition to > encouraging the *planner* to choose an indexonly scan, will *also* allow (at > execution time) fewer heap fetches for a plan which would have > already/previously used IOS. Right ? So maybe it should say "allows OR > IMPROVES index-only scans" or "allows plans which use IOS to run more > efficiently".
Yes, I see your point now. New text is: This new behavior reduces the work necessary when the table needs to be frozen and allows pages to be set as all-visible. All-visible pages allow index-only scans to access fewer heap rows. -- Bruce Momjian <br...@momjian.us> https://momjian.us EnterpriseDB https://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Ancient Roman grave inscription +