PYTHON-5169 - Deprecate Hedged Reads option #2213
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pymongo/read_preferences.py
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| @@ -103,6 +104,11 @@ def _validate_hedge(hedge: Optional[_Hedge]) -> Optional[_Hedge]: | |||
| if not isinstance(hedge, dict): | |||
| raise TypeError(f"hedge must be a dictionary, not {hedge!r}") | |||
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| warnings.warn( | |||
| "Hedged reads are deprecated starting in server version 8.0.", | |||
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Mentioning the server side deprecation is good but we should first mention the driver side deprecation. Something like:
the read preference "hedge" option is deprecated in PyMongo 4.12+ because hedged reads are deprecated in MongoDB version 8.0+. Support for "hedge" will be removed in PyMongo 5.0.
pyproject.toml
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| @@ -119,6 +119,7 @@ filterwarnings = [ | |||
| "module:please use dns.resolver.Resolver.resolve:DeprecationWarning", | |||
| # https://github.com/dateutil/dateutil/issues/1314 | |||
| "module:datetime.datetime.utc:DeprecationWarning", | |||
| "module:Hedged reads are deprecated:DeprecationWarning", | |||
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Rather than using this approach we should manually catch/silence hedge errors only in tests that are intended to use it. We should also add a new test that we do raise the warning when hedge is used.
| :class:`~pymongo.read_preferences.PrimaryPreferred`, | ||
| :class:`~pymongo.read_preferences.Secondary`, | ||
| :class:`~pymongo.read_preferences.SecondaryPreferred`, | ||
| :class:`~pymongo.read_preferences.Nearest`. Support for ``hedge`` will be removed in PyMongo 5.0. |
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Can hedge also appear in the URI/MongoClient kwarg?
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It's not listed in our docs page, so I don't believe so. You can create a read preference instance and pass that as a kwarg, but that will still pass through the read preference constructor.
pymongo/read_preferences.py
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| "The read preference 'hedge' option is deprecated in PyMongo 4.12+ because hedged reads are deprecated in MongoDB version 8.0+. Support for 'hedge' will be removed in PyMongo 5.0.", | ||
| DeprecationWarning, | ||
| stacklevel=2, | ||
| ) |
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Let's update all the hedge param docs to say:
:param hedge: **DEPRECATED** - The :attr:`~hedge` for this read preference.
| @@ -203,6 +214,12 @@ def hedge(self) -> Optional[_Hedge]: | |||
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| .. versionadded:: 3.11 | |||
| """ | |||
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Let's update this docstring with **DEPRECATED** and include the explanation as well.
pymongo/read_preferences.py
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| @@ -143,6 +149,11 @@ def document(self) -> dict[str, Any]: | |||
| if self.__max_staleness != -1: | |||
| doc["maxStalenessSeconds"] = self.__max_staleness | |||
| if self.__hedge not in (None, {}): | |||
| warnings.warn( | |||
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The document helper should not raise a warning. We already raised a warning in the constructor. We do need to keep the warning in hedge() since we will remove that api in 5.0.
pymongo/read_preferences.py
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| warnings.warn( | ||
| "The read preference 'hedge' option is deprecated in PyMongo 4.12+ because hedged reads are deprecated in MongoDB version 8.0+. Support for 'hedge' will be removed in PyMongo 5.0.", | ||
| DeprecationWarning, | ||
| stacklevel=2, |
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One last question. I'm wondering about the stacklevel here. Can you provide an example of the warning in the ReadPreference constructor?
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stacklevel=2:
/Users/nstapp/Github/mongo-python-driver/pymongo/read_preferences.py:131: DeprecationWarning: The read preference 'hedge' option is deprecated in PyMongo 4.12+ because hedged reads are deprecated in MongoDB version 8.0+. Support for 'hedge' will be removed in PyMongo 5.0.
self.__hedge = _validate_hedge(hedge)
stacklevel=4:
/Users/nstapp/Github/mongo-python-driver/test/asynchronous/test_read_preferences.py:583: DeprecationWarning: The read preference 'hedge' option is deprecated in PyMongo 4.12+ because hedged reads are deprecated in MongoDB version 8.0+. Support for 'hedge' will be removed in PyMongo 5.0.
cls(hedge={"enabled": True})
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I think we want stacklevel=4 to provide a useful traceback.
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