Again, this investigative test is loosely based on SQLAlchemy's
sharding test: sqlalchemy/test/orm/sharding/test_shard.py
def test_update(self):
print "\n"
session = create_session()
query = session.query(WeatherLocation)
# query_chooser returns: ['asia']
print "get tokyo:"
tokyo =
query.filter_by(city='Tokyo').filter_by(continent='Asia').first()
# no new SQL
print "access tokyo:"
assert tokyo.city == "Tokyo"
# no new SQL
print "change tokyo:"
tokyo.city = "Tokyo_city_name_changed"
# uses shard_chooser by instance
print "save tokyo:"
session.add(tokyo)
session.commit()
# query_chooser returns: ['north_america', 'asia', 'europe',
'south_america']
print "access tokyo 2:"
assert tokyo.city == "Tokyo_city_name_changed"
My question #2: If we already have an instance of tokyo from the 'save
tokyo' code snippet, why is a new query_cls being instantiated to
refresh the tokyo object in 'access tokyo 2' (thus having to traverse
all 4 shards) rather than using shard_chooser and the got instance to
compute the shard based on its continent value? Is there some way I
can optimize this case, perhaps by setting the shard_id somewhere, so
that 4 queries aren't executed in this case?
Thanks,
--diana
On Mon, Jan 11, 2010 at 3:38 PM, Diana Clarke
<diana.joan.cla...@gmail.com> wrote:
> Question #2 similar, but w/ session.add(). I'll send a new email for
> Question #2.
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