Question 117142 in Mongodb Question posted in
The official documentation can be found here.

how to convert mongoDB Oplog file into actual query

I want to convert the MongoDB local Oplog file into an actual real query so I can execute that query and get the exact copy database.
Is there any package, file, build-in tools, or script for it?

Tags:

3

Answers


  1. 0

    Sorry, but that is impossible.

    The reason is that, that opLog doesn’t have queries. OpLog includes only changes (add, update, delete) to data, and it’s there for replication and redo.

    To get an exact copy of DB, it’s called "replication", and that is of course supported by the system.

    To "replicate" changes to f.ex. one DB or collection, you can use https://www.mongodb.com/docs/manual/changeStreams/.

    Login or Signup to reply.
  2. 0

    It’s not possible to get the exact query from the oplog entry because MongoDB doesn’t save the query.

    The oplog has an entry for each atomic modification performed. Multi-inserts/updates/deletes performed on the mongo instance using a single query are converted to multiple entries and written to the oplog collection. For example, if we insert 10,000 documents using Bulk.insert(), 10,000 new entries will be created in the oplog collection. Now the same can also be done by firing 10,000 Collection.insertOne() queries. The oplog entries would look identical! There is no way to tell which one actually happened.

    Login or Signup to reply.
  3. 0

    You can get the query from the Oplogs. Oplog defines multiple op types, for instance op: "i","u", "d" etc, are for insert, update, delete. For these types, check the "o"/"o2" fields which have corresponding data and filters.
    Now based on the op types call the corresponding driver APIs db.collection.insert()/update()/delete().

    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search