| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Peter Geoghegan <pg(at)bowt(dot)ie> |
| Cc: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Dmitry Dolgov <9erthalion6(at)gmail(dot)com>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Claudio Freire <klaussfreire(at)gmail(dot)com>, Anastasia Lubennikova <a(dot)lubennikova(at)postgrespro(dot)ru>, "Andrey V(dot) Lepikhov" <a(dot)lepikhov(at)postgrespro(dot)ru> |
| Subject: | Re: Making all nbtree entries unique by having heap TIDs participate in comparisons |
| Date: | 2019-03-12 18:40:24 |
| Message-ID: | CA+TgmoaNO9puEj09+LVnLFhY-pKn=j=QJUnhukBZjGC8EiSnww@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Mar 12, 2019 at 2:34 PM Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
> On Tue, Mar 12, 2019 at 11:32 AM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> > If I wanted to try to say this in fewer words, would it be fair to say
> > that reducing the size of an index by 40% without changing anything
> > else can increase contention on the remaining pages?
>
> Yes.
Hey, I understood something today!
I think it's pretty clear that we have to view that as acceptable. I
mean, we could reduce contention even further by finding a way to make
indexes 40% larger, but I think it's clear that nobody wants that.
Now, maybe in the future we'll want to work on other techniques for
reducing contention, but I don't think we should make that the problem
of this patch, especially because the regressions are small and go
away after a few hours of heavy use. We should optimize for the case
where the user intends to keep the database around for years, not
hours.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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