I even restarted the MySQL server, no effect and same problem. On Sunday, February 16, 2014 8:37:01 PM UTC-5, Mike Lessings wrote: > > You are right, MySQL itself is doing something odd. However I feel like > SQLAlchemy must have done some funny locking that is causing the database > to act strangely, and I'd like to find out how and how to avoid that. > > Here's the output from the query with echo=True: > > SELECT object.id AS object_id, object.name AS object_name > FROM object FOR UPDATE > > Any ideas what could be happening? > > On Sunday, February 16, 2014 8:19:54 PM UTC-5, Michael Bayer wrote: >> >> >> On Feb 16, 2014, at 7:50 PM, Mike Lessings <twotimes...@gmail.com> wrote: >> >> I'm trying to lock rows when I select because I intend to update them >> shortly thereafter. I don't want another session in another process to >> simultaneously be reading/updating. In code: >> >> # ... all necessary setup and Session creation >> session = Session() >> >> with session.no_autoflush: >> >> session.begin_nested() >> objects_protected_from_concurrent_access = >> session.query(Object).with_for_update().all() >> # ... edit some of the objects here >> objects_protected_from_concurrent_access[0].field_one += 1 >> session.commit() >> >> But for some reason on the `with_for_update()`, the connection hangs >> until a timeout error (1205 Operational Error) occurs. There's no other >> processes talking to the database. Checking MySQL's >> >> SHOW PROCESSLIST; >> >> Reveals nothing unexpected (no processes except Sequel Pro before, then1 >> process from the box I'm running SQLAlchemy on, and 1 making the SHOW >> PROCESSLIST query from Sequel Pro afterwards). >> >> How can I best do what I'm trying to do? And is what I'm seeing a bug or >> a feature? >> >> >> its nothing on SQLAlchemy’s side; turn on echo=True on your engine and >> watch the SQL going by. You’ll see the “SELECT.. FOR UPDATE” happening, >> and that’s all SQLA is doing, sending a string to the connection. Try to >> break out the SQL strings into a test script against your DBAPI directly. >> >> >> >> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "sqlalchemy" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to sqlalchemy+...@googlegroups.com. >> To post to this group, send email to sqlal...@googlegroups.com. >> Visit this group at http://groups.google.com/group/sqlalchemy. >> For more options, visit https://groups.google.com/groups/opt_out. >> >> >>
-- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/groups/opt_out.
