| From: | Florian Weimer <fweimer(at)bfk(dot)de> |
|---|---|
| To: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
| Cc: | Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Block-level CRC checks |
| Date: | 2008-10-01 16:04:06 |
| Message-ID: | 82d4ik8fpl.fsf@mid.bfk.de |
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| Lists: | pgsql-hackers |
* Heikki Linnakangas:
> Currently, hint bit updates are not WAL-logged, and thus no full page
> write is done when only hint bits are changed. Imagine what happens if
> hint bits are updated on a page, but there's no other changes, and we
> crash so that only one half of the new page version makes it to disk
> (= torn page). The CRC would not match, even though the page is
> actually valid.
The non-logged hint bit writes are somewhat dangerous anyway. Maybe
it's time to get rid of this peculiarity, despite the performance
impact?
--
Florian Weimer <fweimer(at)bfk(dot)de>
BFK edv-consulting GmbH http://www.bfk.de/
Kriegsstraße 100 tel: +49-721-96201-1
D-76133 Karlsruhe fax: +49-721-96201-99
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