[ZODB-Dev] Pluggable transactions logic

[JohnD.Heintz]

Steve,

I agree that putting this into the ZODB might be overkill, but I would be=
=20
interested in it because my use of the ZODB involves objects being refere=
nces=20
from many places very often.  (I think that Zope's use of an object datab=
ase=20
"hierachtically" is really the special case, most OODBMes I believe maint=
ain=20
more graph-like data structures.)

Here is my logic:
My persistent object is used in by many "soft" containers.
I want to know when (or maybe force) no more containers refer to my objec=
t.
I could implement this with Subject-Observer style ref counting.
The ZODB already *has* this information.
Wouldn't it be great to just get "where used" from the DB?

All of this is pretty far removed from me right now.  I can imagine this =
all=20
becoming more important to me if I need to support archival/destroy from =
my=20
application.  This is a topic that I've brought up on the list before and=
 I=20
don't think ZODB (nor too many other OODBs) have a viable story on yet.

Anyway, I'm not at a point where I'm campaining for API changes or anythi=
ng=20
yet, but I don't think we should rule out exposing the DB garbage collect=
ion=20
functionality from the ZODB API.

John

On Wednesday 22 August 2001 15:09, Steve Alexander wrote:
> I think supporting indexing any object at the ZODB level by putting thi=
s
> into the persistence/transaction machinery is overkill.
>
=2E..
>
> 1: objects that derive from Item and are stored in ObjectManagers
>
> 2: objects that are mounted in a Rack (which, for the ZODB, is basicall=
y
> a BTree)
>
=2E..
>
> In both cases, the object itself knows when it has been deleted, and
> thus can be responsible for unindexing itself.
>
=2E..
>
> This wouldn't work well with databases where an object can be contained
> in more than one place (that is, hard links).
>
>
> My apologies to ZODB folk for talking so Zope-centrically :-)
>
> --
> Steve Alexander
> Software Engineer
> Cat-Box limited
>
>
>
> _______________________________________________
> For more information about ZODB, see the ZODB Wiki:
> http://www.zope.org/Wikis/ZODB/
>
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--=20
=2E . . . . . . . . . . . . . . . . . . . . . . .

John D. Heintz | Senior Engineer

1016 La Posada Dr. | Suite 240 | Austin TX 78752
T 512.633.1198 | jheintz@isogen.com

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