Martijn Faassen writes:
For some reason, at random times, Postgresql seems to magically lose some records that were already there and should've been committed. This seems to happen within a few hours of the time the records were first created. All trace of the records disappears from the database; we can see the holes in the autoincrement primary key fields (and we never do any delete ourselves that could cause this). Several months ago, someone reported (zope-dev mailing list) a hole in the database adapters transaction handling. Jim confirmed the bug.
When my memory is right, the hole means that database transactions may be hanging, Zope forgets to either commit or abort them. I does not look like your problem, but maybe the two problems are related... Dieter