Re: Block-level CRC checks

Alvaro Herrera wrote:
> Tom Lane wrote:
> 
> > Basically, you can't make any critical changes to a shared buffer
> > if you haven't got exclusive lock on it.  But that's exactly what
> > this patch is assuming it can do.
> 
> It seems to me that the only possible way to close this hole is to
> acquire an exclusive lock before calling FlushBuffers, not shared.
> This lock would be held until the flag has been examined and reset; the
> actual WAL record and write would continue with a shared lock, as now.

We don't seem to have an API for reducing LWLock strength though ...

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
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