Hi Michael, I only noticed the activity on this thread today.
On Sat, 2010-08-14 at 11:07 -0400, Michael Bayer wrote: > > reproduce the problem and it suggests the problem stems from some > > behaviour of transactions or of the engine.base.Connection class. I > > don't quite know what to make of it yet, but I think it shows that the > > effect of "passing it through" is being counteracted by something > > else. I ran this on Python 2.6.5 with SA 0.6.3 on Windows. > > Postgresql and MS-SQL support transactional DDL, and I use this feature all > the time with SQLAlchemy which does nothing special to support them. That is out of the question. This seems only related to SQLite. > In addition, isolation_level=None with pysqlite disables the DBAPIs entire > transactional system. SQLAlchemy relies upon this system to handle proper > transactional behavior. Per their documentation, some statements will fail > if executed in a transaction - SQLAlchemy does not want to be involved in > reorganizing how the DBAPI wants to approach things, emitting manual 'begin' > and 'commit' strings, etc. Reading the pysqlite source, all that this magic isolation_level setting does is to emit an begin statement in front of UPDATE, DELETE, INSERT and REPLACE commands. And implicitly commit whenever any other non-select statement is executed (which includes SAVEPOINT commands!). I don't think it makes a huge difference for SQLAlchemy to rely on this insertion of "begin" statements. References: Emitting begin (via _pysqlite_connection_begin): http://code.google.com/p/pysqlite/source/browse/src/cursor.c?r=2.6.0#598 That's the only invocation to _pysqlite_connection_begin. After reading a bit more, I can see your point. Setting isolation_level to None actually disables the commit and rollback methods on cursor objects. Whee! > So I consider this a pysqlite bug, and they should offer a mode by which > there is no implicit commit for CREATE TABLE. > > See http://docs.python.org/library/sqlite3.html#controlling-transactions Agreed. Greetings, Torsten -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
