You cannot quite do this. Each http request is wrapped in a transaction.
Even if the db object stays cached, the connection inside may be closed
when the first request ends, unless the transaction logic is overwritten.
On Saturday, 26 May 2012 11:45:31 UTC-5, David McKeone wrote:
>
> *Massimo and Nico:*
> Thanks for looking into those things, can't wait!
>
> *RAM Cache and DAL?*
> I've been looking into conditional models and attempting to combine them
> with the module based system just to see how far I can take it and I've run
> into a question:
>
> Is there any reason I shouldn't use cache.ram for a DAL instance? I can't
> use the automatic migration tools since our data-structure wouldn't allow
> for that kind of thing (running a single column update against some of the
> bigger tables can take 30 minutes+ and we want that in a controlled
> environment, probably outside of web2py). So, with migration out of the
> picture could I do this in the models to avoid recurring re-definition of
> tables?
>
> def load_models():
> db = DAL('postgres://localhost:5432/Demo')
> db.define_table('table', Field('field')
> db.define_table('table2', Field('field')
> #etc...
> return db
>
> db = cache.ram('datamodels', lambda: load_models(), time_expire=None)
>
> My real goal is to just get the datamodel remembered between requests
> (since it'd be redundant to load it every time). I suppose it's really
> just a process specific singleton, but it does make some difference. Here
> are some non-scientific benchmarks I performed on my data model:
>
> All tables defined in request: ~420ms
> All tables defined in request w/ cache hit: ~90ms
>
> All tables defined in request (compiled app): ~350ms
> All tables defined in request w/ cache hit (compiled app): ~25ms
>
> Obviously the first request off of a cold start would be fairly slow, but
> all subsequent requests would benefit greatly. By using caching with the
> DAL class am I potentially hurting myself in some way?
>
>
> On Saturday, May 26, 2012 11:13:17 AM UTC+1, Nico de Groot wrote:
>>
>> Hi David,
>> Got Jenkins running on mac and windows with unittests, will send you
>> details later.
>> Nico de Groot
>
>
