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PYTHON-5169 - Deprecate Hedged Reads option (#2213)

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Co-authored-by: Shane Harvey <shnhrv@gmail.com>
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Noah Stapp 2025-03-25 17:00:19 -04:00 committed by GitHub
parent eea8a37257
commit 2c1a1608f2
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4 changed files with 96 additions and 51 deletions
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5
doc/changelog.rst
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@ -14,6 +14,11 @@ PyMongo 4.12 brings a number of changes including:
- Added index hinting support to the
:meth:`~pymongo.asynchronous.collection.AsyncCollection.distinct` and
:meth:`~pymongo.collection.Collection.distinct` commands.
- Deprecated the ``hedge`` parameter for
: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.
Issues Resolved
...............

24
pymongo/read_preferences.py
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@ -19,6 +19,7 @@
from __future__ import annotations
import warnings
from collections import abc
from typing import TYPE_CHECKING, Any, Mapping, Optional, Sequence
@ -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}")
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=4,
)
return hedge
@ -183,7 +189,9 @@ class _ServerMode:
@property
def hedge(self) -> Optional[_Hedge]:
"""The read preference ``hedge`` parameter.
"""**DEPRECATED** - 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.
The read preference ``hedge`` parameter.
A dictionary that configures how the server will perform hedged reads.
It consists of the following keys:
@ -203,6 +211,12 @@ class _ServerMode:
.. versionadded:: 3.11
"""
if self.__hedge is not None:
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,
)
return self.__hedge
@property
@ -312,7 +326,7 @@ class PrimaryPreferred(_ServerMode):
replication before it will no longer be selected for operations.
Default -1, meaning no maximum. If it is set, it must be at least
90 seconds.
:param hedge: The :attr:`~hedge` to use if the primary is not available.
:param hedge: **DEPRECATED** - The :attr:`~hedge` for this read preference.
.. versionchanged:: 3.11
Added ``hedge`` parameter.
@ -354,7 +368,7 @@ class Secondary(_ServerMode):
replication before it will no longer be selected for operations.
Default -1, meaning no maximum. If it is set, it must be at least
90 seconds.
:param hedge: The :attr:`~hedge` for this read preference.
:param hedge: **DEPRECATED** - The :attr:`~hedge` for this read preference.
.. versionchanged:: 3.11
Added ``hedge`` parameter.
@ -397,7 +411,7 @@ class SecondaryPreferred(_ServerMode):
replication before it will no longer be selected for operations.
Default -1, meaning no maximum. If it is set, it must be at least
90 seconds.
:param hedge: The :attr:`~hedge` for this read preference.
:param hedge: **DEPRECATED** - The :attr:`~hedge` for this read preference.
.. versionchanged:: 3.11
Added ``hedge`` parameter.
@ -441,7 +455,7 @@ class Nearest(_ServerMode):
replication before it will no longer be selected for operations.
Default -1, meaning no maximum. If it is set, it must be at least
90 seconds.
:param hedge: The :attr:`~hedge` for this read preference.
:param hedge: **DEPRECATED** - The :attr:`~hedge` for this read preference.
.. versionchanged:: 3.11
Added ``hedge`` parameter.

59
test/asynchronous/test_read_preferences.py
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@ -35,6 +35,7 @@ from test.asynchronous import (
)
from test.utils_shared import (
OvertCommandListener,
_ignore_deprecations,
async_wait_until,
one,
)
@ -542,33 +543,44 @@ class TestMongosAndReadPreference(AsyncIntegrationTest):
for mode, cls in cases.items():
with self.assertRaises(TypeError):
cls(hedge=[]) # type: ignore
with _ignore_deprecations():
pref = cls(hedge={})
self.assertEqual(pref.document, {"mode": mode})
out = _maybe_add_read_preference({}, pref)
if cls == SecondaryPreferred:
# SecondaryPreferred without hedge doesn't add $readPreference.
self.assertEqual(out, {})
else:
self.assertEqual(out, SON([("$query", {}), ("$readPreference", pref.document)]))
pref = cls(hedge={})
self.assertEqual(pref.document, {"mode": mode})
out = _maybe_add_read_preference({}, pref)
if cls == SecondaryPreferred:
# SecondaryPreferred without hedge doesn't add $readPreference.
self.assertEqual(out, {})
else:
hedge: dict[str, Any] = {"enabled": True}
pref = cls(hedge=hedge)
self.assertEqual(pref.document, {"mode": mode, "hedge": hedge})
out = _maybe_add_read_preference({}, pref)
self.assertEqual(out, SON([("$query", {}), ("$readPreference", pref.document)]))
hedge: dict[str, Any] = {"enabled": True}
pref = cls(hedge=hedge)
self.assertEqual(pref.document, {"mode": mode, "hedge": hedge})
out = _maybe_add_read_preference({}, pref)
self.assertEqual(out, SON([("$query", {}), ("$readPreference", pref.document)]))
hedge = {"enabled": False}
pref = cls(hedge=hedge)
self.assertEqual(pref.document, {"mode": mode, "hedge": hedge})
out = _maybe_add_read_preference({}, pref)
self.assertEqual(out, SON([("$query", {}), ("$readPreference", pref.document)]))
hedge = {"enabled": False}
pref = cls(hedge=hedge)
self.assertEqual(pref.document, {"mode": mode, "hedge": hedge})
out = _maybe_add_read_preference({}, pref)
self.assertEqual(out, SON([("$query", {}), ("$readPreference", pref.document)]))
hedge = {"enabled": False, "extra": "option"}
pref = cls(hedge=hedge)
self.assertEqual(pref.document, {"mode": mode, "hedge": hedge})
out = _maybe_add_read_preference({}, pref)
self.assertEqual(out, SON([("$query", {}), ("$readPreference", pref.document)]))
hedge = {"enabled": False, "extra": "option"}
pref = cls(hedge=hedge)
self.assertEqual(pref.document, {"mode": mode, "hedge": hedge})
out = _maybe_add_read_preference({}, pref)
self.assertEqual(out, SON([("$query", {}), ("$readPreference", pref.document)]))
def test_read_preference_hedge_deprecated(self):
cases = {
"primaryPreferred": PrimaryPreferred,
"secondary": Secondary,
"secondaryPreferred": SecondaryPreferred,
"nearest": Nearest,
}
for _, cls in cases.items():
with self.assertRaises(DeprecationWarning):
cls(hedge={"enabled": True})
async def test_send_hedge(self):
cases = {
@ -582,7 +594,8 @@ class TestMongosAndReadPreference(AsyncIntegrationTest):
client = await self.async_rs_client(event_listeners=[listener])
await client.admin.command("ping")
for _mode, cls in cases.items():
pref = cls(hedge={"enabled": True})
with _ignore_deprecations():
pref = cls(hedge={"enabled": True})
coll = client.test.get_collection("test", read_preference=pref)
listener.reset()
await coll.find_one()

59
test/test_read_preferences.py
View File

@ -35,6 +35,7 @@ from test import (
)
from test.utils_shared import (
OvertCommandListener,
_ignore_deprecations,
one,
wait_until,
)
@ -522,33 +523,44 @@ class TestMongosAndReadPreference(IntegrationTest):
for mode, cls in cases.items():
with self.assertRaises(TypeError):
cls(hedge=[]) # type: ignore
with _ignore_deprecations():
pref = cls(hedge={})
self.assertEqual(pref.document, {"mode": mode})
out = _maybe_add_read_preference({}, pref)
if cls == SecondaryPreferred:
# SecondaryPreferred without hedge doesn't add $readPreference.
self.assertEqual(out, {})
else:
self.assertEqual(out, SON([("$query", {}), ("$readPreference", pref.document)]))
pref = cls(hedge={})
self.assertEqual(pref.document, {"mode": mode})
out = _maybe_add_read_preference({}, pref)
if cls == SecondaryPreferred:
# SecondaryPreferred without hedge doesn't add $readPreference.
self.assertEqual(out, {})
else:
hedge: dict[str, Any] = {"enabled": True}
pref = cls(hedge=hedge)
self.assertEqual(pref.document, {"mode": mode, "hedge": hedge})
out = _maybe_add_read_preference({}, pref)
self.assertEqual(out, SON([("$query", {}), ("$readPreference", pref.document)]))
hedge: dict[str, Any] = {"enabled": True}
pref = cls(hedge=hedge)
self.assertEqual(pref.document, {"mode": mode, "hedge": hedge})
out = _maybe_add_read_preference({}, pref)
self.assertEqual(out, SON([("$query", {}), ("$readPreference", pref.document)]))
hedge = {"enabled": False}
pref = cls(hedge=hedge)
self.assertEqual(pref.document, {"mode": mode, "hedge": hedge})
out = _maybe_add_read_preference({}, pref)
self.assertEqual(out, SON([("$query", {}), ("$readPreference", pref.document)]))
hedge = {"enabled": False}
pref = cls(hedge=hedge)
self.assertEqual(pref.document, {"mode": mode, "hedge": hedge})
out = _maybe_add_read_preference({}, pref)
self.assertEqual(out, SON([("$query", {}), ("$readPreference", pref.document)]))
hedge = {"enabled": False, "extra": "option"}
pref = cls(hedge=hedge)
self.assertEqual(pref.document, {"mode": mode, "hedge": hedge})
out = _maybe_add_read_preference({}, pref)
self.assertEqual(out, SON([("$query", {}), ("$readPreference", pref.document)]))
hedge = {"enabled": False, "extra": "option"}
pref = cls(hedge=hedge)
self.assertEqual(pref.document, {"mode": mode, "hedge": hedge})
out = _maybe_add_read_preference({}, pref)
self.assertEqual(out, SON([("$query", {}), ("$readPreference", pref.document)]))
def test_read_preference_hedge_deprecated(self):
cases = {
"primaryPreferred": PrimaryPreferred,
"secondary": Secondary,
"secondaryPreferred": SecondaryPreferred,
"nearest": Nearest,
}
for _, cls in cases.items():
with self.assertRaises(DeprecationWarning):
cls(hedge={"enabled": True})
def test_send_hedge(self):
cases = {
@ -562,7 +574,8 @@ class TestMongosAndReadPreference(IntegrationTest):
client = self.rs_client(event_listeners=[listener])
client.admin.command("ping")
for _mode, cls in cases.items():
pref = cls(hedge={"enabled": True})
with _ignore_deprecations():
pref = cls(hedge={"enabled": True})
coll = client.test.get_collection("test", read_preference=pref)
listener.reset()
coll.find_one()