Re: [PROPOSAL] Shared Ispell dictionaries

On 2018-03-19 14:52:34 +0100, Tomas Vondra wrote:
> On 03/19/2018 02:34 AM, Andres Freund wrote:
> > Hi,
> >
> > On 2018-03-19 01:52:41 +0100, Tomas Vondra wrote:
> >> I do agree with that. We have a working well-understood dsm-based
> >> solution, addressing the goals initially explained in this thread.
> >
> > Well, it's also awkward and manual to use. I do think that's
> > something we've to pay attention to.
> >
>
> Awkward in what sense?

You've to manually configure a setting that can only be set at server
start. You can't set it as big as necessary because it might use up
memory better used for other things. It needs the full space for
dictionaries even if the majority of it never will be needed. All of
those aren't needed in an mmap world.

> So, I'm not at all convinced the mmap approach is actually better than
> the dsm one. And I believe that if we come up with a good way to
> automate some of the tasks, I don't see why would that be possible in
> the mmap and not dsm.

To me it seems we'll end up needing a heck of a lot more code that the
OS already implements if we do it ourselves.

Greetings,

Andres Freund