Re: Protect syscache from bloating with negative cache entries

At Thu, 19 Nov 2020 15:23:05 +0900 (JST), Kyotaro Horiguchi <horikyota.ntt@gmail.com> wrote in 
> At Wed, 18 Nov 2020 21:42:02 -0800, Andres Freund <andres@anarazel.de> wrote in 
> > Hi,
> > 
> > On 2020-11-19 14:25:36 +0900, Kyotaro Horiguchi wrote:
> > > # Creation, searching and expiration
> > > master     :  6393.23    (100.0)
> > > patched-off:  6527.94    (102.1)
> > > patched-on : 15880.01    (248.4)
> > 
> > What's the deal with this massive increase here?
> 
> CatCacheRemovedCTup(). If I replaced a call to the function in the
> cleanup functoin with dlist_delete(), the result changes as:
> 
> master      :  6372.04   (100.0) (2)
> patched-off :  6464.97   (101.5) (2)
> patched-on  :  5354.42   ( 84.0) (2)
> 
> We could boost the expiration if we reuse the "deleted" entry at the
> next entry creation.

That result should be bogus. It forgot to update cc_ntup..

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center