Re: BufFileWrite across MAX_PHYSICAL_FILESIZE boundary

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.

> ---------------------------------------------------------------------------
> 
> Tom Lane wrote:
> > "Kurt Harriman" <kharriman@greenplum.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.