Re: [gnome-db] gda_column_get_primary_key()

["Vivien Malerba" <vmalerba gmail com>]

2008/11/20 Murray Cumming <murrayc murrayc com>

On Thu, 2008-11-20 at 20:30 +0100, Vivien Malerba wrote:

>         I still don't understand. Is the "this field is a primary key"
>         information something that is stored in the server (PostgreSQL
>         in this
>         case) or not?
>
> The default is, as for V3, that Libgda creates its own dictionary file
> (in V3 it was an XML file, and in V4 it's an SQLite DB file). This can
> be changed and it's possible to store the meta data in the database
> being accessed. See
> http://library.gnome.org/devel/libgda/unstable/gda-dict.html#GdaMetaStoreSetup for some example.

Is it normally in the database server, other than in this extra libgda
meta data that you store in the database?

It's up to you (as a programmer) to decide how you organize where data is stored. For example the foolowing stiuations:
* the gda-sql console tool for example can't afford to modify the database schema which is accessed for its own needs (no generic tool can), so it uses a separate SQLite database file (located in ~/.libgda) to store the extracted meta data and some of its own data
* if the database being accessed is managed by you (eg. you define its schema), then you can decide that the meta data will also be stored in that database (so you end up with only one database which is easier to manage).
* if you're not interrested in meta data then you don't have to worry about the meta data DB at all.

This offers much more flexibility than there was in V3.

I guess you use a special table to store that metadata. Is that table
name and data format documented somewhere?

There are several tables and views (all starting with an undersore), see the description here:  http://library.gnome.org/devel/libgda/3.99/information_schema.html

Cheers,

Vivien