Java mongodb (morphia) ensure unique document

Question

I've got a task that runs every n seconds scanning the file system for new files and storing them into a collection.

I'm not sure of the best way to ensure I don't end up with the same file twice in the database. At the moment I'm taking the files absolute path and checking that against other absolute paths in the database

public Movie findByAbsolutePath(String absolutePath) {
    return getDatastore().find(Movie.class, "absolutePath", absolutePath).limit(1).get();
}

if this returns null then go ahead and save.

Is checking each file against the database like this the best way to do it? I've tried using the following index annotation but it doesn't seem to work and I end up with duplicates

@Indexes(@Index(fields = {@Field("fileName"), @Field("absolutePath")}, options = @IndexOptions(unique = true, dropDups = true)))

Is that faster (assuming I can get it to work) than the previous way I'm checking against duplicates?

Answer 1

Your index isn't working because the uniqueness constraint is on both fileName and absolutePath. You'll need the unique constraint on a separate index on absolutePath alone.

To do an upsert in Morphia you'd pass an UpdateOptions instance to datastore.update() as documented here. UpdateOptions has an upsert(boolean) that you'd simply pass true to.

Answer 2

You could store file path too in your collection, and have a unique index on file path. When you want to add a new file in your collection, you can do an upsert on file path.