Re: Migrating to Oracle on Windows

On 21 mai, 15:28, Mladen Gogala <mgogala.SPAM_ME...._at_verizon.net> wrote:
> On Sun, 20 May 2007 12:10:51 -0700, hasta_l3 wrote:
> > Hmm.. Not sure what you mean here, Mladen. Memory-mapped files can be
> > used to share memory between processes.
>
> Moreover, memory mapped files are not shared in real time.
> For the change to be visible by other processes, it has first
> to be flushed to the disk. This type of sharing is completely
> inadequate.

I think that is incorrect, Mladen

" With one important exception, file views derived from a single file mapping object
are coherent or identical at a specific time. If multiple processes have handles of
the same file mapping object, they see a coherent view of the data when they
map a view of the file." (http://msdn2.microsoft.com/en-us/library/ aa366537.aspx)

Recall that mapped files are backed up in virtual memory. You need to flush if
you want to update the underlying file. But people using mapped files for shared
memory usually dont even have such a file (you can map directly the paging file)

This said, I would really *love* to be shown wrong...

> What is needed are standard IPC primitives, not supported by windows.

Which primitive do you feel is missing ?

> That is why Oracle has multi-threaded architecture on Windows,
> as opposed to the independent processes everywhere else.

Well, I suspect that oracle chose the standard multi-threaded architecture for efficiency reasons alone.

For example, some reports on the improvements of bulk collect lead me to suspect that the PL/SQL -> SQL switch is faster under windows than under unix.

• Raoul