| From: | Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com> |
|---|---|
| To: | andres(at)anarazel(dot)de |
| Cc: | robertmhaas(at)gmail(dot)com, hlinnaka(at)iki(dot)fi, ideriha(dot)takeshi(at)jp(dot)fujitsu(dot)com, tomas(dot)vondra(at)2ndquadrant(dot)com, tgl(at)sss(dot)pgh(dot)pa(dot)us, tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com, alvherre(at)2ndquadrant(dot)com, bruce(at)momjian(dot)us, pgsql-hackers(at)lists(dot)postgresql(dot)org, michael(dot)paquier(at)gmail(dot)com, david(at)pgmasters(dot)net, craig(at)2ndquadrant(dot)com |
| Subject: | Re: Protect syscache from bloating with negative cache entries |
| Date: | 2020-11-20 07:08:40 |
| Message-ID: | 20201120.160840.339412173339307577.horikyota.ntt@gmail.com |
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| Lists: | pgsql-hackers |
At Thu, 19 Nov 2020 15:23:05 +0900 (JST), Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com> wrote in
> At Wed, 18 Nov 2020 21:42:02 -0800, Andres Freund <andres(at)anarazel(dot)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
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