aggregation framework - Mongodb aggregate works slowly with 200Gb collection -


i have sharded mongo collection 10m elements (200gb).

document structure:

{   _id   updatedate   cleandate   events1: [{...}, {...}, ...]   events2: [{...}, {...}, ...]   events3: [{...}, {...}, ...] }

there no indexes except _id.

1st java application creates, reads , updates documents collection.

2nd java application has scheduled task finds documents updatedate > cleandate , removes old objects eventx arrays. when task cleans object, updates cleandate.

i use mycollection.aggregate({ $project : { delta : { $cmp : ['$updatedate', '$cleandate'] } } }, { $match : { delta : { $gt : 0 } } } , { $limit : 10000}) query next portion cleaning.

the query execution takes lot of time (sometimes 10 min , more) when first elements cleaned in collection.

how can speed 2nd app?

the point whole collection projects , $match after that. if know last updatedate or cleandate (maybe store last scheduled task run time somewhere) can limit initial aggregation set field prior projecting.


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