Poor lookup aggregation performance

by

from https://docs.mongodb.com/manual/reference/operator/aggregation/lookup/

foreignField Specifies the field from the documents in the from
collection. $lookup performs an equality match on the foreignField to
the localField from the input documents. If a document in the from
collection does not contain the foreignField, the $lookup treats the
value as null for matching purposes.

This will be performed the same as any other query.

If you don’t have an index on the field _AccountId, it will do a full tablescan query for each one of the 10,000 posts. The bulk of the time will be spent in that tablescan.

db.users.ensureIndex("_AccountId", 1)

speeds up the process so it’s doing 10,000 index hits instead of 10,000 table scans.

More Related Contents:

  1. Group result by 15 minutes time interval in MongoDb
  2. Moongoose aggregate $match does not match id’s
  3. Find in Double Nested Array MongoDB
  4. Check if every element in array matches condition
  5. How to aggregate sum in MongoDB to get a total count?
  6. Get a count of total documents with MongoDB when using limit
  7. Include all existing fields and add new fields to document
  8. Matching ObjectId to String for $graphLookup
  9. mongodb count num of distinct values per field/key
  10. What’s the $unwind operator in MongoDB?
  11. Mongodb Explain for Aggregation framework
  12. MongoDB aggregation comparison: group(), $group and MapReduce
  13. Mongodb aggregation lookup with conditions
  14. How to get back the Original document back after aggregation
  15. MongoDB group by array inner-elements
  16. Exception: can’t convert from BSON type EOO to Date
  17. Multiple Counts with single query in mongodb
  18. How to aggregate by year-month-day on a different timezone
  19. Mongodb Aggregation Framework: Does $group use index?
  20. How to return array of string with mongodb aggregation
  21. How to return just the nested documents of an array from all documents
  22. $skip and $limit in aggregation framework
  23. Get n-th element of an array in MongoDB
  24. How do I rename fields when performing search/projection in MongoDB?
  25. $unwind an object in aggregation framework
  26. Mongodb Aggregation Framework | Group over multiple values?
  27. mongodb aggregation framework match by nested documents
  28. count array occurrences across all documents with mongo
  29. Mongodb concat int and string
  30. Return actual type of a field in MongoDB

Leave a Comment