[This message has also been posted.] See followup comment below... On Sat, 15 May 2010 07:44:04 -0700 (PDT), Michael Bayer <mike...@zzzcomputing.com> wrote: > > > On May 15, 2:52 am, Faheem Mitha <fah...@email.unc.edu> wrote: >> Hi, >> >> I was trying to figure out a way to close all connections to a db. >> >> Apparently >> >> db = create_engine(dbstring) >> conn = db.connect() >> [...] >> conn.close() >> >> doesn't actually close the connection initiated by conn. I have to call >> >> db.dispose() >> >> which seems to do so, though I cannot find any clear documentation that >> says so. It would be nice if this was mentioned in the section that >> describes connections. > > its mentioned in pool.dispose() and engine.dispose() is likely missing > a docstring (also the 0.5 docs are not nearly as up to date as those > of 0.6). the method is not guaranteed to close all open connections, > only those which are not currently checked out.
Belated update - I just looked at this message again, and realised I don't have a clear idea of what 'checked out' means in this context. The term is used in http://www.sqlalchemy.org/docs/05/reference/sqlalchemy/pooling.html several times for example, but I don't see an actual definition there. Regards, Faheem. >> In any case, I'm writing to ask what recommended usage for connecting to a >> db is. Let's say I am writing a script which has various functions >> connecting to the same db. Should I pass around a db string corresponding >> to the engine, or should I pass around an engine itself, or should I pass >> around a connection object? I suppose the third might cause problems, >> since presumably only one user can use a connection at a time. > > passing a connection between various methods and functions implies a > single thread of execution so there's no concurrency concern there, if > that's what you mean by "one user". The issue comes down to how you'd > like your application to deal with transactions, whether you'd like a > group of operations to proceed on the same Connection (can be made to > be on all one transaction more easily) or not. A lot of related > discussion is at http://www.sqlalchemy.org/docs/dbengine.html, > including the discussion about transactions, threadlocal strategies, > etc. But none of that makes a choice for you. > > >> If so, with option 1, when passing dbstring to a function, should I close >> the connection and dispose of the created engine, > > option 1 is not an option here and is vastly inefficient. your > application should have one engine per database backend. > -- 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.
