On 18/08/13 18:47 -0400, Jay Pipes wrote:
On 08/18/2013 06:28 PM, Joe Gordon wrote:
On Aug 18, 2013 3:58 PM, "Jay Pipes" <jaypi...@gmail.com
<mailto:jaypi...@gmail.com>> wrote:
>
> On 08/18/2013 03:53 AM, Joshua Harlow wrote:
>>
>> I always just liked SQL as the database abstraction layer ;)
>>
>> On a more serious note I think novas new object model might be a way
to go but in all honesty there won't be a one size fits all solution. I
just don't think sqlalchemy is that solution personally (maybe if we
just use sqlalchemy core it will be better and eject just the orm layer).
>
>
> What is specifically wrong with SQLAlchemy's ORM layer? What would
you replace it with? Why would use SQLAlchemy's "core" be better?
>
> I've seen little evidence that SQLAlchemy's ORM layer is the cause
for database performance problems. Rather, I've found that the database
schemas in use -- and in some cases, the *way* that the SQLAlchemy ORM
is called (for example, doing correlated subqueries instead of straight
joins) -- are primary causes for database performance issues.
From what I have seen the issue is both the queries and the ORM layer.
See https://bugs.launchpad.net/nova/+bug/1212418 for details.
Good point.
For the record, I'm not a fan of lazy/eager loading of relations in
the models themselves, but instead always being explicit about the
exact data you wish to query for.
It's similar in nature to the SQL best practice of never doing SELECT
* FROM <set> and instead of always being explicity about the columns
you wish to retrieve...
+1
I've seen a couple of cases where this is not being taken under
consideration. I'd like to see some of the lazy loaded relations being
explicitly loaded.
I think a good rule for this is:
"If you know you'll need it, then load it. If you don't know it, then
you're *probably* doing something wrong."
Cheers,
FF
--
@flaper87
Flavio Percoco
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