[Zope-DB] Which objects can be stored in Data.fs

[Tim Peters]

[rdl3 at compaqnet.fr]
> After a successful Database packing (thanks to Dieter!), I compared the
> old and new sizes of my databases. From 26 GB, it was 320 Mb after
> packing.
>
> I thought there was too much difference between both. I watched closely at
> the progression of my new database, and realised it had gained 100 MB in
> just a day !
>
> So I went to the "undo" part of the ZMI, and I saw that zope stored in the
> database every, EVERY transaction, that means even the simple fact of
> VIEWING a page.

A transaction adds info to the database if and only if a persistent
object was modified during the transaction -- and it's the _purpose_
of a database to keep track of changes to persistent objects, so
that's necessary.

Viewing a page alone should not be enough to modify the state of any
persistent object.  More must be going on than you currently know
about.  You can use fsdump.py to find out which objects are changing:

    http://zope.org/Wikis/ZODB/FileStorageBackup

> I began to understand why it increased so dramatically.
>
> So my questions are:
>
> 1) is it normal ?

If and only if you're running applications that do excessive
modification of persistent objects ;-)

> 2) is it possible to tell zope NOT to store some things in the database

No, and it doesn't make sense (as above, it's the database's purpose
to keep track of changes; if "too many" changes are happening, the
cure is to find the software responsible for making those changes, and
alter it to stop making so many changes).

> ...
> PS : I use zope 2.7.2