| From: | Hannu Krosing <hannu(at)skype(dot)net> |
|---|---|
| To: | Mark Woodward <pgsql(at)mohawksoft(dot)com> |
| Cc: | Jan Wieck <JanWieck(at)Yahoo(dot)com>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Csaba Nagy <nagy(at)ecircle-ag(dot)com>, Christopher Browne <cbbrowne(at)acm(dot)org>, postgres hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: vacuum, performance, and MVCC |
| Date: | 2006-06-25 19:51:28 |
| Message-ID: | 1151265089.4096.20.camel@localhost.localdomain |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Ühel kenal päeval, P, 2006-06-25 kell 06:52, kirjutas Mark Woodward:
> I'm not sure why vacuum can't run similarly to the way it does now.
What do you mean ?
Currently vacuum runs a three-step process
1) runs a full scan over heap and collects all dead tuple ctids from
heap
2) run full scans over all indexes of the relation and removes any
pointers pointing to dead tuples.
3) runs another full scan over heap and removes the tuples in the list
collected at step 1.
There is no modifications done to live tuples (ok, they *may* get frozen
if they are above certain age, but this is not relevant to current
discussion).
--
----------------
Hannu Krosing
Database Architect
Skype Technologies OÜ
Akadeemia tee 21 F, Tallinn, 12618, Estonia
Skype me: callto:hkrosing
Get Skype for free: http://www.skype.com
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Bruce Momjian | 2006-06-25 21:18:10 | Re: vacuum, performance, and MVCC |
| Previous Message | Hannu Krosing | 2006-06-25 19:42:01 | Re: vacuum, performance, and MVCC |