Flatten arrays in group stage
Have group operators to flatten document arrays into a single one with or without repeated elements.
So ->
doc1 = {arr: [1,2,3,4], gr: "group"}, doc2 = {arr: [5, 6, 7, 8], gr: "group"}
{$group: {id: "$gr", arrays: {$***: "$arr"} } }
=>
{id: "gr", arrays: [1, 2, 3, 4, 5, 6, 7, 8]}
2
votes
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This request is also tracked here https://jira.mongodb.org/browse/SERVER-16284