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Type:
New Feature
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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: Aggregation Framework
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Labels:None
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Query Optimization
I would like to be able to use the $out pipeline embedded into the aggregation in multiple locations to snapshot the current output.
Example
[stock] is made up like:
{ _id:1, type:'widgets', material:'metal', name:'item1', count:5 }
{ _id:2, type:'widgets', material:'metal', name:'item2', count:3 }
{ _id:3, type:'widgets', material:'wood', name:'item3', count:2 }
{ _id:4, type:'widgets', material:'wood', name:'item4', count:5 }
{ _id:5, type:'widgets', material:'plastic',name:'item5', count:6 }
{ _id:6, type:'casing', material:'metal', name:'item6', count:0 }
{ _id:7, type:'casing', material:'wood', name:'item7', count:1 }
{ _id:8, type:'casing', material:'plastic', name:'item8', count:9 }
{ _id:9, type:'casing', material:'plastic', name:'item9', count:2 }
db.stock.aggregate([
{ $group:{ _id: { k1:'$type', k2:'$material' }, totalcount:{$sum:'$count'} } },
{ $out:'group_type_material' },
{ $group:{ _id: '$_id.k1', totalcount:{$sum:'$totalcount'} } },
{ $out:'group_type' },
{ $group:{ _id: null, totalcount:{$sum:'$totalcount'} } },
{ $out:'group_all' },
])
which would result in collections of
[group_type_material]:
{ _id: { k1:'widgets', k2:'metal'}, totalcount:8 }
{ _id: { k1:'widgets', k2:'wood'}, totalcount:7 }
{ _id: { k1:'widgets', k2:'plastic'}, totalcount:6 }
{ _id: { k1:'casing', k2:'metal'}, totalcount:0 }
{ _id: { k1:'casing', k2:'wood'}, totalcount:1 }
{ _id: { k1:'casing', k2:'plastic'}, totalcount:11 }
[group_type]:
{ _id: 'widgets', totalcount:21 }
{ _id: 'casing', totalcount:12 }
[group_all]:
{ _id: null, totalcount:33 }
This would make this aggregation truly powerful in my opinion.
- is duplicated by
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- Closed
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- Closed
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- is related to
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- Closed
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