__in odd behaviour when given an empty list

[Colin Howe]

Hi,

I just noticed that if you do:

SomeDoc.objects(field__in=[])

It passes that through as a query parameter and returns no results as expected. However, if you are running in an environment where table scans are forbidden then this raises an exception saying it has caused a table scan. This behaviour is probably a bug in MongoDB itself. However, I was thinking that this case should be handled slightly differently in MongoEngine - by returning no results and not doing a query at all. What do you guys think? (We're hitting this because we pass through lists as arguments and sometimes we validly have empty lists)

Cheers,

Colin

[Dan Crosta]

I think this is a bug in MongoDB. I've created https://jira.mongodb.org/browse/SERVER-4317 to track it. Please vote for it if this is an important issue for you.

- Dan

[Colin Howe]

Awesome - thank you! :)

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