[Modeling-users] Some more questions

[Ernesto R. <er...@si...>]

Hi again,

Queries with large resultsets:
I remember I read about this but I don't see where. What is returned for =
a fetch with a result set of, say, 10000 rows? A list? Or an iterator? =
Is there a concept like database cursors, which iterate over objects =
(wherever they are stored), instead of database rows?

Multi-user environment:
I read the deployment instructions of the user doc. Under SQLite, when =
two separe editing context (either different applications or one =
application but different editing context) save changes to the same =
object, the latter one overwrites silently the earlier ones, which is =
not that nice. Does this behave the same way with Postgres? And with =
mySQL?

Grand Totals, Counters, etc.
Say I have a heavily accesed table and I want to have grand totals per =
month. What is the best way to accomplish this? (The problem is that if =
I do this within the domain class, it has to read and update the total =
with added/updated/deleted data, but during these operations other =
people may also hace to need to update the same field, causing =
collisions or overwriting. If there was a 'add' operation which would be =
translated to SQL (field=3Dfiel+increment), this problem would =
disappear, as it would be executed inside a transaction. Also, the grand =
total should perhaps be a volatile field and no cached, that is, =
whenever we access entity.getGrandTotal() it would be read from the =
database.) In databases with triggers, this is easily resolved inside =
the DB, but we still need volatile attributes.

Simple question:
can an editingContext access (fetch and update) classes of different =
models at the same time?
(I think this is true, but still haven't tried it. It can also treat =
heterogenous data sources, although there may be no relations between =
different models, right?)

Would it be possible to create a Wiki? Wouldn't it be the right place to =
put questions like these?

best regards,
Erny