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Convert documents to dicts during insertion #256

merged 2 commits into from Dec 4, 2018


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msiemens commented Nov 17, 2018


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caichinger commented Nov 22, 2018

I have not yet taken a look at the changes but since converting to dict or performing isinstance checks incurs an overhead (and was discussed in #218 ), I thought I provide a few primitive timings using IPython's %timeit

In [1]: from import Mapping
   ...: class CustomDocument(Mapping):
   ...:     def __init__(self, data):
   ...: = data
   ...:     def __repr__(self):
   ...:         return f'{self.__class__.__name__}({})'
   ...:     def __getitem__(self, key):
   ...:         return[key]
   ...:     def __iter__(self):
   ...:         return iter(
   ...:     def __len__(self):
   ...:         return len(
   ...: minimal_dict = {'int': 1}
   ...: minimal_doc = CustomDocument(minimal_dict)
   ...: another_dict = {key: list(range(1_000)) for key in range(10)}
   ...: another_doc = CustomDocument(another_dict)

In [2]: %timeit "{'int': 1}"
7.78 ns ± 0.154 ns per loop (mean ± std. dev. of 7 runs, 100000000 loops each)

In [3]: %timeit isinstance(minimal_dict, dict)  # of course similar for another_dict
66.1 ns ± 1.16 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)

In [4]: %timeit dict(minimal_dict)
181 ns ± 4 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)

In [5]: %timeit dict(minimal_doc)
1.63 µs ± 7.32 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)

In [6]: %timeit dict(another_dict)
360 ns ± 3.37 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)

In [7]: %timeit dict(another_doc)
3.24 µs ± 23 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)

To me it seems that converting a dict into a dict is quite fast - and this is the most likely scenario.
Changing the API to avoid a check/conversion (suggested in #218) is not really a good idea in my opinion; converting the Mapping takes longer but I too think that and not providing a custom converter is a too easy mistake to make (as addressed in #245 ).

From my point of view the performance overhead seems okay given that the library's selling point is simplicity and ease of use, not performance. However, I acknowledge that I do not know how it is used by others.

If desired/required, I can perform additional benchmarks.


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msiemens commented Dec 4, 2018

Thanks @caichinger for the microbenchmarks! I agree with your conclusion. Using dict(document) simply looks like the most clean (i.e. pythonic) solution. We'll have to convert Mappings to dicts anyway so I think this is the way to go.

@msiemens msiemens merged commit 43a0ab7 into master Dec 4, 2018
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@msiemens msiemens deleted the feature-dictify-docs-on-insert branch Jan 15, 2019
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