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mongodbinsertreplicaset

insertMany and replica set

I have a MongoDB db consisting of one PRIMARY and one SECONDARY instance (replica set) on the same server. When i execute a insertMany() command :

let docsArray = []
for(i = 0; i <= 7; i++){
   let docsArray.push(
       {something: i}
   );
}
await collection.insertMany(docsArray)

something odd happens. My primary server saves the data in the correct order(the one I have specified) ,whereas the SECONDARY instance saves the docs in some random way. I have tried inserting the documents one by one throught creating a session and a loop:

for(i = 0; i <= 7; i++){
     let newDoc = something + i;
     await newDoc.save({session});
 }

still give the same result. Why is that? Can the solution be something connected with the Write Concern? Thanks in advance!!!

Solution

  • Documents in MongoDB collections are not ordered.

    If you add some documents to a collection and execute a find without conditions on that collection, you might get the documents back in the order you inserted them or in a different order.

    To get the documents in a particular order, request the order in the query.