| From: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Sawada Masahiko <sawada(dot)mshk(at)gmail(dot)com>, Greg Stark <stark(at)mit(dot)edu>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> |
| Subject: | Re: Freeze avoidance of very large table. |
| Date: | 2015-04-23 07:42:59 |
| Message-ID: | 5538A283.6060107@iki.fi |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On 04/22/2015 09:24 PM, Robert Haas wrote:
>> I would feel safer if we added a completely new "epoch" counter to the page
>> >header, instead of reusing LSNs. But as we all know, changing the page
>> >format is a problem for in-place upgrade, and takes some space too.
> Yeah. We have a serious need to reduce the size of our on-disk
> format. On a TPC-C-like workload Jan Wieck recently tested, our data
> set was 34% larger than another database at the beginning of the test,
> and 80% larger by the end of the test. And we did twice the disk
> writes. See "The Elephants in the Room.pdf" at
> https://sites.google.com/site/robertmhaas/presentations
Meh. Adding an 8-byte header to every 8k block would add 0.1% to the
disk size. No doubt it would be nice to reduce our disk footprint, but
the page header is not the elephant in the room.
- Heikki
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Andres Freund | 2015-04-23 07:45:14 | Re: Code paths where LWLock should be released on failure |
| Previous Message | Sawada Masahiko | 2015-04-23 07:20:59 | Re: Freeze avoidance of very large table. |