Use OrderedDicts in ORM only when needed
|Reported by:||Anssi Kääriäinen||Owned by:||nobody|
|Component:||Database layer (models, ORM)||Version:||master|
|Has patch:||yes||Needs documentation:||no|
|Needs tests:||no||Patch needs improvement:||no|
Initializing OrderedDicts seem to be really slow, at least on Python 2.7. By instantiating OrderedDicts in Query only when needed one can save considerable time. For example model_save_existing benchmark is 1.3x faster, qs_filter_chaining 1.35x faster. Nearly all of the query_ benchmarks have at least 10% speedup.
Patch at https://github.com/akaariai/django/tree/ordered_dict_on_need. Together with splitted_clone branch this gives over 1.5x speedup to model_save_existing.
There might be some cleaner way to implement the "initiate only on need" for Query._aggregates and Query._extra. Ideas welcome.
Ill accept this directly as this seems like a good idea to do. This trades code-cleanness for performance, but in this particular case I think it is worth it.