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PYTHON-2970 Prioritize electionId over setVersion for stale primary check (#845)
(cherry picked from commit 225d131)
1 parent 57fea8b commit 52d7795

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-52
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‎doc/changelog.rst

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Changelog
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=========
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Changes in Version 3.13.0
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-------------------------
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Issues Resolved
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...............
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PyMongo 3.13 drops support for Python 3.4.
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Bug fixes
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.........
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- Fixed a bug where the client could be unable to discover the new primary
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after a simultaneous replica set election and reconfig (`PYTHON-2970`_).
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Deprecations
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............
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- Deprecated :meth:`~pymongo.collection.Collection.map_reduce` and
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:meth:`~pymongo.collection.Collection.inline_map_reduce`.
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Use :meth:`~pymongo.collection.Collection.aggregate` instead.
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See the `PyMongo 3.13.0 release notes in JIRA`_ for the list of resolved issues
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in this release.
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.. _PYTHON-2970: https://jira.mongodb.org/browse/PYTHON-2970
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.. _PyMongo 3.13.0 release notes in JIRA: https://jira.mongodb.org/secure/ReleaseNote.jspa?projectId=10004&version=31570
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Changes in Version 3.12.3
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-------------------------
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Issues Resolved
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...............
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Version 3.12.3 fixes a bug that prevented :meth:`bson.json_util.loads` from
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decoding a document with a non-string "$regex" field (`PYTHON-3028`_).
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See the `PyMongo 3.12.3 release notes in JIRA`_ for the list of resolved issues
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in this release.
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.. _PYTHON-3028: https://jira.mongodb.org/browse/PYTHON-3028
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.. _PyMongo 3.12.3 release notes in JIRA: https://jira.mongodb.org/secure/ReleaseNote.jspa?projectId=10004&version=32505
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Changes in Version 3.12.2
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-------------------------
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‎pymongo/collection.py

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@@ -3170,19 +3170,20 @@ def inline_map_reduce(self, map, reduce, full_response=False, session=None, **kw
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helper method, e.g.::
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>>> db.test.inline_map_reduce(map, reduce, limit=2)
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.. versionchanged:: 3.13
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Support for this function is deprecated in
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MongoDB 4.0, and is removed in PyMongo 4.0. Migrate to
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:meth:`aggregate`. For more guidance on this migration see:
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- https://docs.mongodb.com/manual/reference/map-reduce-to-aggregation-pipeline/
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- https://docs.mongodb.com/manual/reference/aggregation-commands-comparison/
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.. _mapReduce command: https://docs.mongodb.com/manual/reference/command/mapReduce/
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.. versionchanged:: 3.6
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Added ``session`` parameter.
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.. versionchanged:: 3.4
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Added the `collation` option.
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.. _mapReduce command: https://docs.mongodb.com/manual/reference/command/mapReduce/
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"""
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warnings.warn(
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'inline_map_reduce is deprecated, use aggregate instead',

‎pymongo/topology_description.py

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@@ -16,6 +16,7 @@
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from collections import namedtuple
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from bson.min_key import MinKey
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from pymongo import common
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from pymongo.errors import ConfigurationError
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from pymongo.read_preferences import ReadPreference
@@ -493,24 +494,16 @@ def _update_rs_from_primary(
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sds.pop(server_description.address)
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return (_check_has_primary(sds), replica_set_name, max_set_version, max_election_id)
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max_election_tuple = max_set_version, max_election_id
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if None not in server_description.election_tuple:
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if (
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None not in max_election_tuple
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and max_election_tuple > server_description.election_tuple
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):
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# Stale primary, set to type Unknown.
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sds[server_description.address] = server_description.to_unknown()
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return (_check_has_primary(sds), replica_set_name, max_set_version, max_election_id)
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max_election_id = server_description.election_id
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if server_description.set_version is not None and (
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max_set_version is None or server_description.set_version > max_set_version
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):
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max_set_version = server_description.set_version
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new_election_tuple = server_description.election_id, server_description.set_version
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max_election_tuple = max_election_id, max_set_version
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new_election_safe = tuple(MinKey() if i is None else i for i in new_election_tuple)
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max_election_safe = tuple(MinKey() if i is None else i for i in max_election_tuple)
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if new_election_safe >= max_election_safe:
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max_election_id, max_set_version = new_election_tuple
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else:
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# Stale primary, set to type Unknown.
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sds[server_description.address] = server_description.to_unknown()
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return _check_has_primary(sds), replica_set_name, max_set_version, max_election_id
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# We've heard from the primary. Is it the same primary as before?
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for server in sds.values():

‎test/discovery_and_monitoring/rs/electionId_precedence_setVersion.json

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{
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"description": "ElectionId is considered higher precedence than setVersion",
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"uri": "mongodb://a/?replicaSet=rs",
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"phases": [
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{
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"responses": [
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[
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"a:27017",
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{
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"ok": 1,
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"helloOk": true,
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"isWritablePrimary": true,
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"hosts": [
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"a:27017",
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"b:27017"
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],
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"setName": "rs",
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"setVersion": 1,
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"electionId": {
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"$oid": "000000000000000000000001"
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},
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"minWireVersion": 0,
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"maxWireVersion": 6
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}
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],
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[
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"b:27017",
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{
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"ok": 1,
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"helloOk": true,
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"isWritablePrimary": true,
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"hosts": [
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"a:27017",
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"b:27017"
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],
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"setName": "rs",
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"setVersion": 2,
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"electionId": {
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"$oid": "000000000000000000000001"
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},
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"minWireVersion": 0,
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"maxWireVersion": 6
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}
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],
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[
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"a:27017",
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{
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"ok": 1,
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"helloOk": true,
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"isWritablePrimary": true,
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"hosts": [
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"a:27017",
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"b:27017"
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],
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"setName": "rs",
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"setVersion": 1,
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"electionId": {
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"$oid": "000000000000000000000002"
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},
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"minWireVersion": 0,
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"maxWireVersion": 6
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}
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]
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],
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"outcome": {
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"servers": {
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"a:27017": {
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"type": "RSPrimary",
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"setName": "rs",
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"setVersion": 1,
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"electionId": {
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"$oid": "000000000000000000000002"
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}
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},
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"b:27017": {
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"type": "Unknown",
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"setName": null,
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"setVersion": null,
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"electionId": null
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}
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},
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"topologyType": "ReplicaSetWithPrimary",
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"logicalSessionTimeoutMinutes": null,
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"setName": "rs",
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"maxSetVersion": 1,
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"maxElectionId": {
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"$oid": "000000000000000000000002"
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}
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}
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}
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]
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}

‎test/discovery_and_monitoring/rs/null_election_id.json

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"outcome": {
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"servers": {
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"a:27017": {
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"type": "RSPrimary",
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"setName": "rs",
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"setVersion": 1,
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"electionId": null
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},
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"b:27017": {
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"type": "Unknown",
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"setName": null,
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"setVersion": null,
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"electionId": null
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},
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"b:27017": {
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"type": "RSPrimary",
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"setName": "rs",
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"setVersion": 1,
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"electionId": {
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"$oid": "000000000000000000000002"
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}
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},
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"c:27017": {
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"type": "Unknown",
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"setName": null,
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"outcome": {
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"servers": {
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"a:27017": {
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"type": "RSPrimary",
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"setName": "rs",
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"setVersion": 1,
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"electionId": null
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},
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"b:27017": {
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"type": "Unknown",
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"setName": null,
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"setVersion": null,
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"electionId": null
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},
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"b:27017": {
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"type": "RSPrimary",
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"setName": "rs",
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"setVersion": 1,
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"electionId": {
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"$oid": "000000000000000000000002"
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}
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},
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"c:27017": {
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"type": "Unknown",
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"setName": null,

‎test/discovery_and_monitoring/rs/secondary_ignore_ok_0.json

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{
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"description": "New primary",
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"description": "Secondary ignored when ok is zero",
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"uri": "mongodb://a,b/?replicaSet=rs",
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"phases": [
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{

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