Aggregation of 200Go Data. We want the collection to always be available with old data until the full commit is done

Working with Data
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1

Hello everyone,
We use an aggregation of 200Go Data. We want the collection to always be available with old data until the full commit is done.

// For a replica set, include the replica set name and a seedlist of the members in the URI string; e.g.
// string uri = “mongodb://mongodb0.example.com:27017,mongodb1.example.com:27017/?replicaSet=myRepl”;
// For a sharded cluster, connect to the mongos instances; e.g.
// string uri = “mongodb://mongos0.example.com:27017,mongos1.example.com:27017/”;
var client = new MongoClient(connectionString);
// Prereq: Create collections.
var database1 = client.GetDatabase(“mydb1”);
var collection1 = database1.GetCollection(“foo”).WithWriteConcern(WriteConcern.WMajority);
collection1.InsertOne(new BsonDocument(“abc”, 0));
var database2 = client.GetDatabase(“mydb2”);
var collection2 = database2.GetCollection(“bar”).WithWriteConcern(WriteConcern.WMajority);
collection2.InsertOne(new BsonDocument(“xyz”, 0));
// Step 1: Start a client session.
using (var session = client.StartSession())
{
// Step 2: Optional. Define options to use for the transaction.
var transactionOptions = new TransactionOptions(
writeConcern: WriteConcern.WMajority);
// Step 3: Define the sequence of operations to perform inside the transactions
var cancellationToken = CancellationToken.None; // normally a real token would be used
result = session.WithTransaction(
(s, ct) =>
{
db.collection1.aggregate( [
{ $group : { _id : “$author”, books: { $push: “$title” } } },
{ $out : “authors” }
] )
return “Inserted into collections in different databases”;
},
transactionOptions,
cancellationToken);
}

Thanks