sortByCount and $group and $count - delivers not the same order

Hi Everyone,

the test UsingAggregationBuilders.aggregateSeveralStages() fails because the order of the results are not equal. The ordering of attribute count is of course correct but the order of _id (here cast-name) is different.


<[Document{{_id=Leonor Silveira, count=8}}, Document{{_id=Joaquim de Almeida, count=6}},
 Document{{_id=Isabel Ruth, count=6}}, Document{{_id=Maria de Medeiros, count=5}},
 Document{{_id=Catherine Deneuve, count=5}}, Document{{_id=John Malkovich, count=5}},
 Document{{_id=Ricardo Trèpa, count=5}}, Document{{_id=Joèo Cèsar Monteiro, count=5}},...

but was:

<[Document{{_id=Leonor Silveira, count=8}}, Document{{_id=Isabel Ruth, count=6}},
 Document{{_id=Joaquim de Almeida, count=6}}, Document{{_id=Joèo Cèsar Monteiro,
 count=5}}, Document{{_id=Maria de Medeiros, count=5}}, Document{{_id=Ricardo Trèpa,
 count=5}}, Document{{_id=Catherine Deneuve, count=5}}, Document{{_id=John Malkovich,

it looks like the second attribute is ordered differently (natural vs random?)
the size of the collection is the same.

any hints?


its the same issue as discussed in UsingAggregationBuilders.aggregateSeveralStages assertion fails

the solution/workaround is: change the type of “sortByCountResults” and “groupByResults” from ArrayList to HashSet and it will work.

this topic can be closed. thanks

Closed as requested by @Sebastian_Hort as this was solved in the linked topic :slight_smile:

Best regards

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