On Aug 30, 2007, at 6:41 PM, Mike Orr wrote:
> > On 8/30/07, Moshe C. <[EMAIL PROTECTED]> wrote: >> >> I was hoping there was something more elegant than just trying and >> catching a possible exception. >> The motivation is just simpler and more readable code like >> if not connection.is_valid(): >> get another one > > The issue is that in a packet-based network, there's no way to tell if > the connection is alive without generating some traffic and seeing if > it succeeds. SQLAlchemy could, and perhaps should, encapsulate this > in a method but it doesn't. I've also argued that SQLAlchemy should > seamlessly retry a query if it finds a connection dead, but MikeB says > this is not safe in a transaction. > > The SQLAlchemy Way is to set the 'pool_recycle' engine option to a > value lower than the database's timeout. MySQL seems to be the main > culprit, and it has a default timeout of 8 hours or so, so setting > pool_recycle=3600 (one hour) is well within the limit. > we have a mechanism now such that a "connection pre-pinger" could be wired into the connection pool using a pool extension. Jason Kirtland has built the framework for it and I've asked that we have a standard "pre-ping" plugin available, or possibly just via a regular keyword argument. it will slow performance down a little bit. however in most cases keeping a low pool_recycle should take care of most common issues in this area... --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
