Re: [sqlalchemy] Re: sqlite transaction isolation, select for update, race condition

2011-04-29 Thread Torsten Landschoff
Hi Clay, On Wed, 2011-04-27 at 11:21 -0700, Clay Gerrard wrote: ... and all connections would automatically issue the correct begin statement and acquire a reserved lock at the beginning of the transaction. But as it is, they don't do anything until they get down to the update, and it's

[sqlalchemy] Re: sqlite transaction isolation, select for update, race condition

2011-04-27 Thread Clay Gerrard
On Apr 27, 9:19 am, Michael Bayer mike...@zzzcomputing.com wrote: SQLite doesn't have support for SELECT..FOR UPDATE, and with_lockmode() ultimately has no impact when using SQLite as nothing is rendered.   IDK why sqlite doesn't support a way to elevate the lock on a select in the middle of

Re: [sqlalchemy] Re: sqlite transaction isolation, select for update, race condition

2011-04-27 Thread Michael Bayer
On Apr 27, 2011, at 11:18 AM, Clay Gerrard wrote: On Apr 27, 9:19 am, Michael Bayer mike...@zzzcomputing.com wrote: SQLite doesn't have support for SELECT..FOR UPDATE, and with_lockmode() ultimately has no impact when using SQLite as nothing is rendered. IDK why sqlite doesn't

[sqlalchemy] Re: sqlite transaction isolation, select for update, race condition

2011-04-27 Thread Clay Gerrard
On Apr 27, 9:37 am, Daniel Holth dho...@gmail.com wrote: Is this pysqlite issue about SELECT not starting a transaction related?http://code.google.com/p/pysqlite/issues/detail?id=21 Hrmmm... well... that's interesting... it might be related, but maybe not? I'm not setting the isolation

[sqlalchemy] Re: sqlite transaction isolation, select for update, race condition

2011-04-27 Thread Clay Gerrard
On Apr 27, 10:41 am, Michael Bayer mike...@zzzcomputing.com wrote: then yes, for your case this is exactly the pysqlite bug Daniel mentions:   http://code.google.com/p/pysqlite/issues/detail?id=21.  Pysqlite doesn't open the transaction until DML is encountered specifically to reduce file