Re: BufFileWrite across MAX_PHYSICAL_FILESIZE boundary

Alvaro Herrera wrote:
> Bruce Momjian wrote:
> >
> > This has been saved for the 8.4 release:
> >
> > http://momjian.postgresql.org/cgi-bin/pgpatches_hold
>
> Huh, no, this is a bug and should be fixed right away.

OK, moved to the 8.3 patch queue.

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>
> > ---------------------------------------------------------------------------
> >
> > Tom Lane wrote:
> > > "Kurt Harriman" <kharriman(at)greenplum(dot)com> writes:
> > > > Just noticed buffile.c:292 doesn't look quite right where
> > > > BufFileDumpBuffer calls FileWrite:
> > > > bytestowrite = FileWrite(thisfile, file->buffer, bytestowrite);
> > > > It looks as though it would write the same data each time the
> > > > loop is iterated. Would this be better?
> > > > bytestowrite = FileWrite(thisfile, file->buffer + wpos, bytestowrite);
> > >
> > > Yeah, I think you're right. We've probably not seen this because in
> > > most usages the buffer is always block-aligned, but it looks possible
> > > for tuplestore.c to get out of alignment if its concurrent write/read
> > > feature is exercised just so. Do you want to try demonstrating the bug
> > > with a smaller-than-normal setting of MAX_PHYSICAL_FILESIZE?
>
>
> --
> Alvaro Herrera http://www.CommandPrompt.com/
> The PostgreSQL Company - Command Prompt, Inc.

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Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
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