without looking too deeply, you can modify that get_history() call to not emit any SQL, assuming you’re on 0.9 (maybe on 0.8 also but the API has been fixed up).
Take a look at passing the “passive” flag to get_history(), or alternatively using inspect().attrs.data.history: http://docs.sqlalchemy.org/en/rel_0_9/changelog/migration_09.html#attributes-get-history-will-query-from-the-db-by-default-if-value-not-present I’m not sure if you’re on 0.8 or 0.9 but I would think 0.9 if that’s emitting SQL? again, haven’t looked closely. if this fixes your issue we might want to update the recipe also, not sure. On Jan 24, 2014, at 11:22 AM, Simon King <si...@simonking.org.uk> wrote: > Hi again, > > While testing the complicated relationship from the other thread, I > noticed that I was generating a lot of queries that I couldn't > immediately explain. After a bit of digging, it turned out that it was > due to my use of code based on the "versioned objects" example at > http://docs.sqlalchemy.org/en/rel_0_9/_modules/examples/versioned_history/history_meta.html. > > In the test script below we have 3 classes. Users belong to Companies, > and Companies reference a single Terms row. In the example, only the > Company class is versioned. > > The test script inserts a single user, company and terms row, then in > new transaction loads the company and adds a new user. If you look at > the SQL output, you should see that it loads the company.terms > relationship, which doesn't seem like it should be necessary. > > I think it's due to the following code from history_meta.py: > > if not obj_changed: > # not changed, but we have relationships. OK > # check those too > for prop in obj_mapper.iterate_properties: > if isinstance(prop, RelationshipProperty) and \ > attributes.get_history(obj, prop.key).has_changes(): > for p in prop.local_columns: > if p.foreign_keys: > obj_changed = True > break > if obj_changed is True: > break > > I can't figure out the circumstances when this should be necessary - > can someone explain it to me? > > Thanks a lot, > > Simon > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sqlalchemy+unsubscr...@googlegroups.com. > To post to this group, send email to sqlalchemy@googlegroups.com. > Visit this group at http://groups.google.com/group/sqlalchemy. > For more options, visit https://groups.google.com/groups/opt_out.
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