How to efficiently perform “distinct” with multiple keys?

by

If you are willing to wait for the upcoming 2.2 release of MongoDB, you can run this query efficiently using the aggregation framework:

collection = db.tb;
result = collection.aggregate( 
            [
                {"$group": { "_id": { market: "$market", code: "$code" } } }
            ]
        );
printjson(result);

On a million-record collection on my test machine, this ran in 4 seconds, while the map/reduce version took over a minute.

More Related Contents:

  1. MongoDB first time user setup [closed]
  2. How to execute mongo commands through shell scripts?
  3. pushing object into array schema in Mongoose
  4. Performing regex queries with PyMongo
  5. Check if every element in array matches condition
  6. What is the default database path for MongoDB?
  7. Updating nested arrays in mongoDB via mongo shell [duplicate]
  8. How can I get a random record from MongoDB?
  9. How do I convert a property in MongoDB from text to date type?
  10. Merging two collections in MongoDB
  11. MongoDB can’t find data directory after upgrading to Mac OS 10.15 (Catalina)
  12. Matching ObjectId to String for $graphLookup
  13. How to work around the lack of transactions in MongoDB?
  14. MongoDB-CR Authentication failed
  15. Mongodb aggregation lookup with conditions
  16. Updating the path ‘x’ would create a conflict at ‘x’
  17. Why does direction of index matter in MongoDB?
  18. How can I update multiple documents in mongoose?
  19. MongoDB update with condition
  20. mongodb get distinct records
  21. Matching an array field which contains any combination of the provided array in MongoDB
  22. MongoDB lookup when foreign field is an array of objects
  23. Get the latest record from mongodb collection
  24. Collision probability of ObjectId vs UUID in a large distributed system
  25. $skip and $limit in aggregation framework
  26. Read-only file system when attempting mkdir /data/db on Mac [closed]
  27. Mongodb Aggregation Framework | Group over multiple values?
  28. How does MongoDB order their docs in one collection? [duplicate]
  29. MongoDB on Ubuntu won’t start as a service, nothing in the log
  30. Mongodb concat int and string

Leave a Comment