Create test data in MongoDB

Question

I want to generate test data for MongoDB. The size should be 200 Mb. I tried this code:

@Test
    public void testMongoDBTestDataGenerate()
    {
        MongoClient mongoClient = new MongoClient("localhost", 27017);

        DB db = mongoClient.getDB("development");
        DBCollection collection = db.getCollection("ssv");

        for (int i = 0; i < 100; i++)
        {
            BasicDBObject document = new BasicDBObject();
            document.put("database", "test");
            document.put("table", "hosting");

            BasicDBObject documentDetail = new BasicDBObject();
            documentDetail.put("records", 99);
            documentDetail.put("index", "vps_index1");
            documentDetail.put("active", "true");

            document.put("detail", documentDetail);

            collection.insert(document);
        }

        mongoClient.close();

    }

How I can generate data exactly with this size?

Answer 1

I am not getting what are you trying to achieve by setting size 200 Mb.

You can add logical checks.

1. db.testCollection.stats() - You can check size of the collection before every insert.

2. Object.bsonsize(..) - Also you can check document size before inserting to make it exactly 200 MB.

And also you can make capped collection where you can notify number of documents or size of collection.

Hope this helps.

Answer 2

What I would probably do is create a capped collection with size 200MB (209715200 bytes):

db.createCollection( "ssv", { capped: true, size: 209715200 } )

Then insert records as you are doing. Then at intervals inside the for loop, check if the collection if full (or almost full).

So in your code, maybe (totally pseudo code):

if(i % 10 == 0) {
   if(db.ssv.stats().size >= 209715100){ //Or an arbitrary value closer to 200MB
     break;
   }
}