How to keep 2 "columns" in mongodb unique
indexing, mongodb
Solution
Yes, I think a unique compound index will do.
db.collection.ensureIndex({first_column: 1, second_column: 1}, {unique: true});
UPDATE: Deprecated since version 3.0.0: db.collection.ensureIndex() is now an alias for db.collection.createIndex(). Use `db.collection.createIndex()` rather than `db.collection.ensureIndex()` to create new indexes.
Problem
I am merging business databases. So I have data like ``` id1 id2 id1 id2 id1 id4 id1 id5 id1 id2 id4 id5 id4 id5 id4 id5 id4 id5 ``` That sort of thing. I want to sort that into ``` id1 id2 id1 id4 id1 id5 id1 id2 id4 id5 ``` So basically if first column and the second column is the same than it's duplicate Do I need duplicate or just compound indexes with unique attribute will suffice? If so what would be the format of the index.