On Oct 10, 2014, at 6:15 PM, Jonathan Vanasco <[email protected]> wrote:

> After reloading postgres's config, my web app had an error from a terminated 
> PostgreSQL connection.  After hitting reload a few times, the situation 
> corrected itself ( there were multiple uwsgi workers with stale connections ).
> 
> I started looking at the docs for dealing with disconnects ( 
> http://docs.sqlalchemy.org/en/latest/core/pooling.html#dealing-with-disconnects
>  ), specifically the 'Pessimistic' strategy, and that made me think -- would 
> it be possible (and preferable) to handle a pessimistic option with the 
> initial "BEGIN" transaction command ?  

it is very possible, I was doing this in openstack for a bit until folks 
revealed they were using non-transactional executions.   You do the "select 1" 
inside the after_begin() event.

as far as preferable, depends on what you're doing.  if you're always using a 
transaction (like with a Session), then sure, it's probably more appropriate, 
but then again if you do it on checkout, it works out to more or less the same 
thing.



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