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Type:
Task
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Resolution: Fixed
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Priority:
Major - P3
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Affects Version/s: None
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Component/s: None
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None
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Fully Compatible
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QE 2022-04-04, QE 2022-02-21, QE 2022-03-07, QE 2022-03-21
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162
This final stage is likely to be the same for all types of joins (NLJ, INLJ and HJ).
Be careful re paths in "as" field. The expected semantics are:
db.left.drop(); db.right.drop();
db.left.insertMany([
{ "a":1, "obj" : {b: 2 } },
{ "a":1, "obj" : {b: 2 } },
])
db.right.insertMany([
{ "z": 1},
])
> db.left.aggregate([{$lookup: {from: "right", localField: "a", foreignField: "z", as: "obj", pipeline: [{$project:{_id:0}}]}},{$project:{_id:0}}])
{ "a" : 1, "obj" : [ { "z" : 1 } ] }
{ "a" : 1, "obj" : [ { "z" : 1 } ] }
> db.left.aggregate([{$lookup: {from: "right", localField: "a", foreignField: "z", as: "obj.b", pipeline: [{$project:{_id:0}}]}},{$project:{_id:0}}])
{ "a" : 1, "obj" : { "b" : [ { "z" : 1 } ] } }
{ "a" : 1, "obj" : { "b" : [ { "z" : 1 } ] } }
> db.left.aggregate([{$lookup: {from: "right", localField: "a", foreignField: "z", as: "obj.obj", pipeline: [{$project:{_id:0}}]}},{$project:{_id:0}}])
{ "a" : 1, "obj" : { "b" : 2, "obj" : [ { "z" : 1 } ] } }
{ "a" : 1, "obj" : { "b" : 2, "obj" : [ { "z" : 1 } ] } }
And for paths with numeric components, these are treated as field names rather than indices into arrays.