MongoDB to Use Sharding with $lookup Aggregation Operator

by

As the docs you quote indicate, you can’t use $lookup on a sharded collection. So the best practice workaround is to perform the lookup yourself in a separate query.

  1. Perform your aggregate query.
  2. Pull the “localField” values from your query results into an array, possibly using Array#map.
  3. Perform a find query against the “from” collection, using a query like {foreignField: {$in: localFieldArray}}
  4. Merge your results into whatever format you need.

Don’t let the $lookup limitation stop you from sharding collections that require it for scalability, just perform the lookup function yourself.

More Related Contents:

  1. Update MongoDB field using value of another field
  2. Does MongoDB’s $in clause guarantee order
  3. $lookup on ObjectId’s in an array
  4. MongoDB SELECT COUNT GROUP BY
  5. Mongodb sort inner array
  6. Return only matched sub-document elements within a nested array
  7. Converting string to date in mongodb
  8. MongoDB nested lookup with 3 levels
  9. MongoDB : Aggregation framework : Get last dated document per grouping ID
  10. Average Aggregation Queries in Meteor
  11. MongoDB Full and Partial Text Search
  12. Mongodb Join on _id field from String to ObjectId
  13. Rounding to 2 decimal places using MongoDB aggregation framework
  14. Find duplicate records in MongoDB
  15. $unwind empty array
  16. How to get back the Original document back after aggregation
  17. Find all duplicate documents in a MongoDB collection by a key field
  18. MongoDB lookup when foreign field is an array of objects
  19. MongoDB: Calculate dwell time between every status value change
  20. Search on multiple collections in MongoDB
  21. Using stored JavaScript functions in the Aggregation pipeline, MapReduce or runCommand
  22. MongoDB – The argument to $size must be an Array, but was of type: EOO / missing
  23. How to flatten a subdocument into root level in MongoDB?
  24. Remove Duplicates from MongoDB
  25. $skip and $limit in aggregation framework
  26. Mongodb Aggregation Framework | Group over multiple values?
  27. Sum in nested document MongoDB
  28. count array occurrences across all documents with mongo
  29. Mongodb concat int and string
  30. MongoDB aggregate within daily grouping [duplicate]

Leave a Comment