[Zope] Re: Data loss after packing in 2.6.1?

[Dieter Maurer]

Maik Jablonski wrote at 2003-5-12 14:33 +0200:
 > Marius Gedminas wrote:
 > > I'm not sure if this is a known bug, or if I've stumbled on something
 > > new.  I've packed a 300 Mb Data.fs recently (leaving 7 days of history).
 > > Thie resulting data.fs was still biggish, so I packed it again (leaving
 > > 0 days of history).  Then interesting effects started to happen: a
 > > Folder just disappeared, then appeared back for a short time, and then
 > > disappeared again after a couple of seconds.  (Of course, this might
 > > have been caused by caching effects or a bug in Mozilla.)
 > 
 > That's what happened to me for 2 times... Objects simply disappeared 
 > after packing (they are appeared for a short time too in one case, 
 > before they definitivly disappeared).

The reappearing might be ZEO (or more precisely ZEO client cache)
related.

Packing is not expected to loose or modify any data. Therefore,
no cache invalidation messages are issued. When "pack" looses
data, it may still be in the ZEO client cache and served thereof.
After a restart of the ZEO client, the object will be dropped
from the cache as the client verifies the validity of its cache
entries with the server.


One of my colleagues reported (now twice) dangling ZODB references.
As he heavily packs, this might be pack related.
I did not yet investigate his problem, but maybe, I should...


Dieter