CODEWITHSUNDEEP
mongodb
Chabbey François
Chabbey François

Reputation: 95

MongoRestore, skip n first documents

I am restoring a large mongo database (90 GB). I am using mongorestore, and it fails silently around 70..90% of the restoring process. Is there a way to skip the n first documents of the dump when launching mongorestore ?. I know there is a filter options where you can give a filter query, but it does not help.

If i try to restore once again the whole backup, it takes a lot of times, due to duplicate index error. I tried to restore the db once again, but it fails once again (due to a socket exception)

As mongorestore seems to process the bson dump sequentially, i was wondering if there is a way to say : " just skip the 1'234'567 first documents of the dump and restore the rest "

I have just one large collection. I have already break the dump in different parts, but it seems not enough. It would be really easier to tell mongorestore to skip the restored documents and go on.

Thanks

Upvotes: 2

Views: 1803

Answers (1)

Juan Carlos Farah
Juan Carlos Farah

Reputation: 3879

As far as I know, there is no way to tell MongoDB to skip n documents when doing a mongorestore, but you can take advantage of the --filter option in order to do something that emulates this. Assuming you are using ObjectIds or an _id that has some sort of sequence, you can do a query on your collection to find the _id of the nth document. Something like this:

db.collection.find({}, { "_id" : 1 }).skip(n-1).limit(1);

You can then pass this _id as a parameter to the --filter option, telling it to only restore all documents greater than this _id. something like this:

mongorestore --filter '{"_id": { $gt : "<ID>" }}'

If you want to drop the database before you restore, you can add the --drop option to the command above.

This should only restore the documents with an _id greater than the one for the nth document, effectively skipping the first n documents in the collection.

Upvotes: 2

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