It's possible I'm doing something wrong, but it appears that indexes are not used when performing $in queries. Here's an example Mongo query:
>>> import pymongo
>>> db = pymongo.MongoClient('mongodb://10.101.0.44:27016/')['discord']
>>> db.users.find({ '_id': { '$in': [ 3187217, 4248493 ] } })On the backend trace, this is emitted:
<Event Severity="10" Time="1562606405.236166" Type="SlowQuery" ID="0000000000000000"
Database="discord" Collection="users" Query="{ _id: { $in: [ 3187217, 4248493 ] } }"
Plan="{ type: "filter",
source_plan: { type: "table scan" },
filter: "ANY(ExtPath(_id) matching OR(EQUALS('3187217'), EQUALS('4248493')))" }"
Machine="0.0.0.0:27016" LogGroup="default" />I verified, just to be sure, that the index exists:
>>> import pprint
>>> pprint.pprint(db.users.index_information())
{u'_id_': {u'key': [(u'_id', 1)],
u'metadata version': 1,
u'ns': u'discord.users',
u'status': u'ready',
u'unique': True}}My expectation in this case would be that the document layer would do two indexed lookups and return the results, and it shouldn't need to do a table scan to accomplish this? I read through the differences and caveats but don't see this documented anywhere.
It's possible I'm doing something wrong, but it appears that indexes are not used when performing
$inqueries. Here's an example Mongo query:On the backend trace, this is emitted:
I verified, just to be sure, that the index exists:
My expectation in this case would be that the document layer would do two indexed lookups and return the results, and it shouldn't need to do a table scan to accomplish this? I read through the differences and caveats but don't see this documented anywhere.