Met some memory limit of MongoDB

[gtoffoli]

Recently I got many times the error message "Sort operation used more than the maximum 33554432 bytes of RAM. Add an index, or specify a smaller limit.", while using the Query Builder, more precisely when trying to create interactively a clause OR-ing many object ids. Said message is emitted by LL when constructing an option list with items representing automatic continuations of the user input. See also: https://stackoverflow.com/questions/54396869/mongo-exec-error-operationfailed-sort-operation-used-more-than-the-maximum-3

I don't know if someone can change the LL configuration appropriately. However, the suggestion "or specify a smaller limit" confuses me a bit.

[michzimny]

We could adjust the configuration but we would need to investiage it deeper to be sure what should be changed.

We could also create indexes that are recommended by the LL documentation that we do not have in our instances.

See also #10. Perhaps, we should first upgrade the LL app to 3.x and also upgrade the underlying Mongo db (LL v.3.x requires a newer version of Mongo than we currently have) in order not to fight this issue more than once.

@gtoffoli, any suggestions are welcomed.

[gtoffoli]

Thank you Michal: I think it's quite likely that creating the indexes recommended by the documentation would solve the problem.

By the way, I met a similar problem in querying LL through the HTTP API; but in that case the cause is the limited length of the query-string encoding the MongoDB query in a GET request. The problem can only be circumvented by redesigning the algorithm.

[michzimny]

@gtoffoli, so I just created the indexes suggested by the docs, for both Up2U instances. Could you please check if it solves the issue?

[michzimny]

@gtoffoli, have you experienced similar problems after my changes?

[gtoffoli]

Yes, I've experienced similar problems, but much less frequently. Thank you. I think that you can close this issue for now.