commit problems

[Richard Harley]

We have had a problem with postgresql 8.3 on a Windows server 2008. I
wonder whether there has been any other experiences like this. We have
connected to Potsgres from Zope via a Psycopg adapter and noticed that
sometimes when data is inserted via a form in Zope, the data is
available in Zope but doesn't get committed to the database. This has
come to a head over the weekend where at least one month's worth of data
has disappeared and this includes changes to the actual database
structure - luckily only on a testing machine, but concerning nevertheless.
The data seemed to disappear after we upgraded to the most recent
version of Zpsycopg2 database adapter, previously we were using version
1 (I know it's old, we are only testing after all) and have never had
these sorts of problem before. It's almost as if all the data and
changes to the db were held in memory, and Postgres continued to work
fine from there, but when the db adapter was changed and Zope restarted
everything was cleared from memory.
Has anyone had similar experinces or can anyone cast any light on where
the problem may lie. To us it seems the db adapter is the most likely
candidate but we can't understand how this could happen, explanations
also welcome.
Regards
Garry

[Federico Di Gregorio]

Post by Richard Harley
We have had a problem with postgresql 8.3 on a Windows server 2008. I
wonder whether there has been any other experiences like this. We have
connected to Potsgres from Zope via a Psycopg adapter and noticed that
sometimes when data is inserted via a form in Zope, the data is
available in Zope but doesn't get committed to the database. This has
come to a head over the weekend where at least one month's worth of data
has disappeared and this includes changes to the actual database
structure - luckily only on a testing machine, but concerning nevertheless.
The data seemed to disappear after we upgraded to the most recent
version of Zpsycopg2 database adapter, previously we were using version
1 (I know it's old, we are only testing after all) and have never had
these sorts of problem before. It's almost as if all the data and
changes to the db were held in memory, and Postgres continued to work
fine from there, but when the db adapter was changed and Zope restarted
everything was cleared from memory.
Has anyone had similar experinces or can anyone cast any light on where
the problem may lie. To us it seems the db adapter is the most likely
candidate but we can't understand how this could happen, explanations
also welcome.

What you describe, PostgreSQL keeping 1 month worth of changes to the
database schema "in memory" and then loosing everything can happen only
if you have a single transaction 1 month long and sincerely I don't see
how this is possible. Also, from what I know Zope doesn't cache the
results of an ALTER, INSERT or any other non-SELECT query so, again, I
can't see how what you describe can happen. If you insert some data and
in a successive request the data is there then an explicit delete (or
DROP/CREATE TABLE) is required to remove it.

This seems like a bug in your application to me.

federico