Re: single task postgresql - Mailing list pgsql-hackers

On Wed, 27 Feb 2002, mlw wrote:

> Oleg Bartunov wrote:
> >
> > On Wed, 27 Feb 2002, mlw wrote:
> >
> > > Greg Copeland wrote:
> > > >
> > > > Windows does not really have shared memory support.  This has been a
> > > > beef with the Win32 API for a long time now.  Because it has been a long
> > > > time complaint, it was finally added in Win2000 and later.  Likewise,
> > > > I'd like to point out that thinks like sims, shared memory, pipes, etc,
> > > > and other entities commonly used for concurrent programming strategies
> > > > are slower in XP.  So, because shared memory really isn't well
> > > > supported, they elected to have what is, in essense, memory mapped
> > > > files.  Multiple processes then map the same file and read/write to it
> > > > as needed, more or less as you would shared memory.  Unless you plan on
> > > > only targetting on Win 2000 and XP, it sounds like a waste of time.
> > >
> > > This is not really true. Under DOS windows, i.e. 95,98, etc. Shared memory can
> > > be done in 16 bit land with a touch of assembly and a DLL. Allocate, with
> > > globalalloc, a shared memory segment. The base selector is a valid 32 bit
> > > selector, and the memory is mapped in the above 2G space shared and mapped to
> > > all 32bit processes.
> > >
> > > Under NT through 2K, yes using a memory mapped files is the way to do it, but
> > > you do not actually need to create a file, you can use (HANDLE)0xFFFFFFFF,
> > > which is the NT equivilent of the system memory file. The handle returned is a
> > > system global object which can be shared across processes.
> > >
> >
> > Mark,
> >
> > do you consider to work on this issue ?
>
> Yea, let me think about it. What is your time frame? When I offered to work on

yesterday :-) I think, at first we need to be sure this way could provide
performance win and compatibility.

> it, I thought it could be a leasurely thing. I have to get a machine running
> some form of Windows on which to develop and test.
>
> I want to say yes, and if no one else does it, I will, but I'm not sure what
> your timeframe is. If it is the mystical 7.3, then sure I can do it easily. If
> you need something quickly, I can help, but I don't think I could shoulder the
> whole thing.
>

looks like people will appreciate your work. Currently we're investigating
another possibility Tom suggested - standalone backend.  But things are
still dim, so we'll also track your development.


> I have a couple things I have promised people. Let me get those done. I will
> try to write an equivilent set of functions for shget, shmat, etc. as soon as I
> can. Anyone wanting to run with them can hack and test PostgreSQL on Windows.
>
> How does that sound?
>

Loosk great, we could run and test. I'm not sure if we have some funding
for this work but I think I could talk with project manager once I'd be
sure this way is promising.
Regards,    Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83