Re: Protect syscache from bloating with negative cache entries

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.

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center