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Type: Investigation
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Resolution: Unresolved
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Priority: Major - P3
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None
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Affects Version/s: None
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Component/s: mongoimport
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None
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1,110
Currently mongoimport's merge mode will $set the entire document from a CSV. This means that it overwrites subdocuments that already exist. It might be useful to merge subdocuments. For example, this CSV:
_id,a.b,a.c 1,2,3
With this document in the database:
{ _id: 1, a: { d: 4 } }
currently results in:
{ _id: 1, a: { b: 2, c: 3 } }
while we might want:
{ _id: 1, a: { b: 2, c: 3, d: 4 } }
We can do the following to set subdocument fields:
{$set: {"a.b": 2}}
but we will need separate handling for arrays. Merging arrays would also cause an issue with ordering since the CSV specifies the exact position of elements in the array.