openstack/neutron
Code Issues Proposed changes

Add notes on loading strategies for ORM relationships

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There have been a number of regressions caused by our inability
to thoroughly review relatiohships' loading strategies. We should
at least make an attempt to remind ourselves, and since I am guilty
as charged, this patch is my attempt to redemption.

Change-Id: I879cfceaa51386e9d6c683e7e02487df92b7e290
This commit is contained in:
armando-migliaccio 2015-12-18 16:34:21 -08:00
parent 495f8c606e
commit fce62cf424
1 changed files with 4 additions and 0 deletions

4
doc/source/devref/effective_neutron.rst

@ -104,6 +104,10 @@ Document common pitfalls as well as good practices done during database developm
transaction blocks, and the innermost block raises an error without proper transaction blocks, and the innermost block raises an error without proper
rollback. Consider if `savepoints <http://docs.sqlalchemy.org/en/rel_1_0/orm/session_transaction.html#using-savepoint>`_ rollback. Consider if `savepoints <http://docs.sqlalchemy.org/en/rel_1_0/orm/session_transaction.html#using-savepoint>`_
can fit your use case. can fit your use case.
* When designing data models that are related to each other, be careful to how
you model the relationships' loading `strategy <http://docs.sqlalchemy.org/en/latest/orm/loading_relationships.html#using-loader-strategies-lazy-loading-eager-loading>`_. For instance a joined relationship can
be very efficient over others (some examples include `router gateways <https://review.openstack.org/#/c/88665/>`_
or `network availability zones <https://review.openstack.org/#/c/257086/>`_).
System development System development
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