Re: [gnome-db] meta store.

[Bas Driessen <bas driessen xobas com>]

On Fri, 2009-07-17 at 13:35 +0200, Murray Cumming wrote:
> On Fri, 2009-07-17 at 21:26 +1000, Bas Driessen wrote:
> > Hello,
> > 
> > Question regarding meta store. There is a function to update the meta
> > store as follows:
> > 
> > gda_connection_update_meta_store
> > 
> > When I run this, it waits about 10 seconds or so,
>
> It was slow for Glom too, so we found a way to optimize it:
> http://bugzilla.gnome.org/show_bug.cgi?id=575235#c9
>
> I still don't understand how the optimization works, but at least we
> have actual code to do it:
> http://git.gnome.org/cgit/libgdamm/tree/libgda/src/connection.ccg#n367
> and here you can see the "public" (PostgreSQL) and "main" schema_name
> strings that we used:
> http://git.gnome.org/cgit/glom/commit/?id=087d27f48f080a3609142514ed5bf54ff0472ff2
>
> >  so I assume it is building the meta store. However, when it is
> > finished, I don't see any output. I would expect files to show up in
> > etc/libgda-4.0, but nothing is added there. Is there meant to be any
> > output?
> > 
> > Also if this generates a structure in memory only, does that mean that
> > I have to call this function every time when I start my application? 
> > 
> > My understanding was, that the meta store was written to an XML file
> > and that the libgda would reference that. Only when a table layout has
> > changed, you would run the gda_connection_update_meta_store function
> > to update the XML files.
> > 
> > Anyone who can shed some light on this?
> > 

Thanks Murray. This answered partially my questions.

Where is the meta data stored? You say that it is stored in a sqlite database in memory. So nothing is written to disk (as in a file) correct? This means that as soon as I close the application all is gone and therefore I have to call the gda_connection_update_meta_store again when I start the application, correct?

Further question I have reading your links. There is some talk about caching the meta store to speed up things. I don't believe there is a section of how that exactly works in the libgda documentation. How would this work?

Thanks again,
Bas.