[GNC-dev] Next shot at "Slow user interface in 3.x gnucash (for large files)"

[Christian Stimming]

Am Sonntag, 17. Juni 2018, 20:09:24 schrieb John Ralls:
> > I.e. the function qof_book_use_split_action_for_num_field is very very
> > expensive. Currently it does a KVP lookup on each call. What keeps us from
> > turning this KVP value into a normal gboolean value in the struct
> > _QofBook?
> 
> Christian,
> 
> It’s all about file compatibility, remember? As it stands, if you make
> something a regular member variable then you have to change the schema to
> add the element/column, and write a scrub to update older data. We strongly
> prefer not to do that during a stable release cycle and generally require
> that the last version of the previous stable series be able to read both
> formats.

Yes. Although what I'm concerned with is only the lookup performance, not the 
serialization place of that option. The serialization may be kept unchanged 
completely.

> One alternative would be to redo the backends so that member variables can
> be designated as stored in KVP, effectively moving KVP out of engine. That
> would be a bit of work but it’s an alternative to changing the schemas.
> It’s a route we’ve discussed before but nobody’s been inclined yet to take
> it on.
> 
> The less involved approaches would be to cache the value or to make KVP
> retrieval more efficient. I suspect in this case that caching will be the
> easiest.

Yes. I've introduced some caching of this value here, but I still need a 
little bit of help: 
https://github.com/cstim/gnucash/commit/376cc19b7143983ce297f2272abf1a44e72fd851
This change gets the register UI back to the old speed again. No more 1 second 
delay after hitting enter. (I wonder why I seem to be the only one who got 
bugged by this, but whatever.)

However, I broke the original feature in that change. To reproduce: Open some 
register where there is some text in the "Num" field, say "1111". Switch on 
the "Double Line" view mode. Then open File -> Properties, and on the first 
tab, activate the option "Use Split Action Field for Number". Press Ok. Before 
my commit, in the opened register the "1111" now moved from the first line of 
the txn to the second line, and vice versa after changing that option again. 
Unfortunately my commit broke that feature. Maybe someone has a good idea why? 
Thanks for some pointers.

Regards,

Christian