| From: | "Mark Woodward" <pgsql(at)mohawksoft(dot)com> |
|---|---|
| To: | "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com> |
| Cc: | "Heikki Linnakangas" <hlinnaka(at)iki(dot)fi>, "Jan Wieck" <janwieck(at)yahoo(dot)com>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Csaba Nagy" <nagy(at)ecircle-ag(dot)com>, "Hannu Krosing" <hannu(at)skype(dot)net>, "Christopher Browne" <cbbrowne(at)acm(dot)org>, "postgres hackers" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: vacuum, performance, and MVCC |
| Date: | 2006-06-24 18:24:31 |
| Message-ID: | 18804.24.91.171.78.1151173471.squirrel@mail.mohawksoft.com |
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| Thread: | |
| Lists: | pgsql-hackers |
> On 6/24/06, Mark Woodward <pgsql(at)mohawksoft(dot)com> wrote:
>> > On 6/24/06, Mark Woodward <pgsql(at)mohawksoft(dot)com> wrote:
>> >> In the scenario, as previously outlined:
>> >>
>> >> ver001->verN->...->ver003->ver2->|
>> >> ^-----------------------------/
>> >
>> > So you want to always keep an old version around?
>>
>> Prior to vacuum, it will be there anyway, and after vacuum, the new
>> version will become ver001.
>
> So you do intend to move verN into ver001's slot? What about the
> other conditions you had mentioned where you have to follow
> PostgreSQL's current behavior? How are you going to have a pointer
> chain in that case?
Who said anything about moving anything. When vacuum comes along, it
cleans out previous versions of rows. Very little will change.
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