Re: Patch to improve reliability of postgresql on linux nfs

On Tue, Sep 13, 2011 at 10:32:01AM -0400, Aidan Van Dyk wrote:
> On Tue, Sep 13, 2011 at 10:14 AM, Florian Pflug <fgp@phlo.org> wrote:
> 
> >> Personally, I'ld think that's ripe for bugs.   If the contract is that
> >> ret != amount is the "error" case, then don't return -1 for an error
> >> *sometimes*.
> >
> > Hm, but isn't that how write() works also? AFAIK (non-interruptible) write()
> > will return the number of bytes written, which may be less than the requested
> > number if there's not enough free space, or -1 in case of an error like
> > an invalid fd being passed.
> 
> Looking through the code, it appears as if all the write calls I've
> seen are checking ret != amount, so it's probably not as big a deal
> for PG as I fear...
> 
> But the subtle change in semantics (from system write ret != amount
> not necessarily a real error, hence no errno set) of pg_write ret !=
> amount only happening after a "real error" (errno should be set) is
> one that could yet lead to confusion.

I assume there is no TODO here.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
 + It's impossible for everything to be true. +