dex recommends incorrect index

[rl-ilasic]

When I run dex during mongodump i get a recommendation to insert below index into my collections.

{
    "key" : {
        "query" : 1,
        "$snapshot" : 1
    },
    "collection" : "reportDetail"
},

Feedback from MongoDB support on the recommended index:

Dex is confused and wrong. That is not an index you should create. You may want to file an issue with them if you are active there.

[esedor]

Your assertion is absolutely correct. This is wrong and should not be created. At-issue is the nitty code in parsers.QueryLineHandler.standardize_query, https://github.com/mongolab/dex/blob/master/dex/parsers.py#L206.

The logic is faulty owing to the inconsistent logging of $query vs. query, $sort vs, sort, and the the inclusion of special indicators like $cmd, $snapshot. Because this involves various versions of logs, and differences per operation, it is taking longer to plan a fix than I would like; therefore any suggestions are appreciated.