[odb-users] Performance issues for large sets

[Quentin Deldycke]

Hi boris

--
Deldycke Quentin


On 19 September 2014 13:04, Boris Kolpackov <boris at codesynthesis.com> wrote:

> Hi Quentin,
>
> Quentin Deldycke <quentindeldycke at gmail.com> writes:
>
> > Yes, but sadly they doesn't suits all my needs and limit quite much our
> > usage of ODB.
>
> ODB is not magic. It cannot somehow deliver advanced, high-level
> functionality (like polymorphism) at zero cost. Views allow you
> to execute tailor-made queries that can (a) load only data members
> that you need and (b) load multiple related objects with a single
> query.
>
> You are right. From my own personnal point of view, i really like the  way
of
ODB is working. The only bad thing is the high quantity of user code i
have. And
to modify all this code is not something possible for me.

>
> > Our 'old' system used C-ISAM. It can perform a "while" of 1000 elements
> in
> > 0.003s - 0.007s.
> > The same request with odb iterate this 1000 elements in 1.3s - 2.6s.
> >
> > The use of odb views allows me to perform this iteration in 0.01s -
> 0.03s.
>
> Was the 'old', C-ISAM system using the same MySQL database that you
> are using with ODB?
>
> No actually it is a different system. Really old school one, but the data
we are treating
are exactly the same beetween both.

>
> > But this mode take only the data i want (i don't know exactly the user
> > will need in the root object!)
>
> Then load all of them. Or, if some of them are expensive to load (e.g.,
> huge BLOBs), then load them with a separate view if and when necessary.
>
>
> > The main advantage i see of views, is because they don't resolve
> dependency
> > at 'iteration' but at 'query'
> >
> > While the basic way of working select data of root object at 'query' then
> > resolve dependency at 'iteration'.
>
> If by dependencies you mean related objects, then you can also control
> their loading with lazy pointers (Section 6.4, "Lazy Pointers"). Another
> useful feature is object sections (Chapter 9, "Sections"). They allow
> you to lazy-load huge BLOBs, etc.
>
> Yes, it is what i mean. I think that lazy pointers are a good option for
me. I will just modify
the way of working so it lazy load when the '->' operator gets used. So my
users won't need to change their code.


> Boris
>