$lookup as reference

[Redsandro]

$lookups are safe. No need to clone.

As @kofrasa said:

forgot to remove the clone. must fix

[codecov-io]

Codecov Report

Merging #63 into development will not change coverage.
The diff coverage is 100%.

@@             Coverage Diff              @@
##           development      #63   +/-   ##
============================================
  Coverage        97.53%   97.53%           
============================================
  Files               52       52           
  Lines             1178     1178           
============================================
  Hits              1149     1149           
  Misses              29       29

Impacted Files	Coverage Δ
lib/operators/pipeline/lookup.js	100% <100%> (ø)	⬆️

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[kofrasa]

I have some changes ready to go that do more optimizations. Basically, iterating the indexes can also be removed by putting the objects put in the hash buckets directly.

[Redsandro]

Ok. I can remove this?

This was an attempt to help speeding an npm release without the clone along for me to play with. 😎
I didn't know you were already working on more optimizations.

[Redsandro]

Thanks!

One question: hash[k] should be an object?

[kofrasa]

The mongo docs do not specify what happens when the join field is not matched. Returning a collection seems reasonable.

[Redsandro]

You are correct. My mistake. I have tunnel vision. I often match one and $unwind.

The good news, if I am correct, is that I can use a custom operator to create $lookupOne based on $lookup, that always adds a single document to a field, so I don't have to $unwind.

[kofrasa]

👍
I think you will discover that custom operators will afford you all the flexibility you need.