Re: [PATCH] remove condition always true (/src/backend/access/heap/vacuumlazy.c)
| От | Ranier Vilela |
|---|---|
| Тема | Re: [PATCH] remove condition always true (/src/backend/access/heap/vacuumlazy.c) |
| Дата | |
| Msg-id | CAEudQAp-276PzV_cLjfLhWWoe_JrXCvtYm_0CdetntQ97WS7sA@mail.gmail.com обсуждение исходный текст |
| Ответ на | [PATCH] remove condition always true (/src/backend/access/heap/vacuumlazy.c) (Ranier Vilela <ranier.vf@gmail.com>) |
| Ответы |
Re: [PATCH] remove condition always true (/src/backend/access/heap/vacuumlazy.c)
|
| Список | pgsql-hackers |
Em seg., 30 de mar. de 2020 às 18:14, Andres Freund <andres@anarazel.de> escreveu:
Hi,
On 2020-03-30 14:10:29 -0700, Andres Freund wrote:
> On 2020-03-30 17:08:01 -0300, Ranier Vilela wrote:
> > Em seg., 30 de mar. de 2020 às 16:05, Andres Freund <andres@anarazel.de>
> > escreveu:
> >
> > > Hi,
> > >
> > > On 2020-03-30 15:07:40 -0300, Ranier Vilela wrote:
> > > > I'm not sure that the patch is 100% correct.
> > >
> > > This is *NOT* correct.
> > >
> > Anyway, the original source, still wrong.
> > What is the use of testing PageIsNew (page) twice in a row, if nothing has
> > changed.
>
> Yea, that can be reduced. It's pretty harmless though.
>
> We used to require a cleanup lock (which requires dropping the lock,
> acquiring a cleanup lock - which allows for others to make the page be
> not empty) before acting on the empty page in vacuum. That's why
> PageIsNew() had to be checked again.
Well, this is what the patch does, promove reduced and continue to check PageIsNew after unlock.
Ranier Vilela
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