| From: | Markus Wanner <markus(at)bluegap(dot)ch> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: changing MyDatabaseId |
| Date: | 2010-11-17 15:58:01 |
| Message-ID: | 4CE3FB89.5080808@bluegap.ch |
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| Lists: | pgsql-hackers |
On 11/17/2010 04:25 PM, Tom Lane wrote:
> I'm afraid that any such change would trade a visible, safe failure
> mechanism (no avworker) for invisible, impossible-to-debug data
> corruption scenarios (due to failure to reset some bit of cached state).
> It certainly won't give me any warm fuzzy feeling that I can trust
> autovacuum.
Well, Alvaro doesn't quite seem have a warm fuzzy feeling with the
status quo, either. And I can certainly understand his concerns.
But yes, the os-level process separation and cache state reset guarantee
that an exit() / fork() pair provides is hard to match up against in
user space.
So, Alvaro's argument for robustness only stands under the assumption
that we can achieve a perfect cache state reset mechanism. Now, how
feasible is that? Are there any kind of tools that could help us check?
Regards
Markus Wanner
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