Custom Model - iface->get_iter & iface->get_value questions

[Rodrigo Miguel <rodrmigu gmail com>]

All,

I've a working code that uses list store to navigate through postgres result
set and DBFrecords by add/delete the top/bottom rows of a list store, but
the code is quite complex and hard to maintain, due to lots of workarounds
to handle how many visible rows, resizing, scroll bars, etc.

Anyway, I think the same can be achieved by using custom models and I found
really good examples in gconf-editor, gnucash and the Gtk Treeview tutorial
from Tim-Philip, so I decide write a generic custom model like Win32
Listview that passes to callback function the cell coords (row and col
number). However I notice the iface->get_iter/get_value goes through all the
records (especifeid by the number of rows) so that would work fine for
postgres result set, since I get it from row and cols coords (PQgetvalue),
but It might not work for a DBF files where I would have thousands/millions
of rows.

My question is. Is this the normal behavior? Is there any way to prevent it,
I mean, just go through or ask for those items that need to be visible only?

Any information about it will be helpful.

Thanks in advance
Rodrigo