Hoi,
We're starting to do some pretty complicated things with the SQLAlchemy
bakery (because we have some pretty complicated queries) and I have
something I'd like to verify.
We have queries that are constructed like so (each letter is a step):
A B C .. M N0
A B C .. M N1
A B C .. M N2
A B C .. M N3
So we have lots of steps and only at the end does something change. Not all
the time, but much more often than the steps A to M. The way the bakery is
set up only the last step is actually cached, meaning that steps A to M get
done each time the last step changes.
However, suppose we could, after step M, do a kind of checkpoint so that at
least that part is done only once. AFAICT it would work like the "spoil"
method, except leave spoil as False. So something like:
class BakedQuery(object):
def checkpoint(self):
_check_point = self._clone()
_check_point._cache_key += ('_query_only', )
self.steps = [_check_point._retrieve_baked_query]
return self
It's not a great name I agree, but the alternatives I can think of are
mark, save, stuff like that.
Anyway, AFAICT this should just work. The assumption is that the query
construction takes significant time, but I think we are sure of that. When
an N4 comes, after executing the checkpoint after M, the last step simply
extracts the cached intermediate step, applies N4 and we're done.
Am I missing something? Is this something that could be considered an
submittable improvement?
Thanks in advance,
Martijn
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http://www.sqlalchemy.org/
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