Le lundi 19 mars 2012 21:49:11, Jim Fulton a écrit : > sync should be deprecated. :) > > transaction.begin() is better.
Off-topic: it is possible that calling transaction.begin() does not offer a most up-to-date view of the database. This is easy to notice when using another database concurrently (ex: MySQL) with (implicit) referential integrity constraints, and with several clients for the same ZODB (ex: ZEO): - Transaction 1 alters a persistent object and, say, inserts a line in a table. - Transaction 1 commits: ZEO sends invalidations to other clients, MySQL makes the new row visible to any new transaction. - Transaction 2 starts: for some reason, it doesn't pick up the invalidation (nothing in the code guarantee that it picks it up), so it sees the object before the modification. Still the row is visible in MySQL. My point is that ZODB should try harder - or provide a way for its backend to try harder - to see the most up-to-date database state possible. In the case of ZEO, this means doing a network round-trip from client to ZEO: when the round-trip is over, any packet sent by ZEO up to "pong"-ish will have been received and handled by client. I do understand that there is anyway a chance for such event occurring even when such round-trip occurs (because of multi-database transactions, or actually multi-transactional-connection transactions), but in practice applying what I described above and using sortKey() API is enough to solve the issue wherever inter-database dependencies are one-way. -- Vincent Pelletier _______________________________________________ For more information about ZODB, see http://zodb.org/ ZODB-Dev mailing list - ZODB-Dev@zope.org https://mail.zope.org/mailman/listinfo/zodb-dev
