db4o Developer Community

Hello!

This is my problem:

1. I create a new empty database
2. then I put 10.000 objects and this takes about 2xx ms
3. commit
4. I read 100 objects from the database and this takes about 42xx ms (4 seconds and 2xx ms)

Is this a normal value? It seems to me too big. Can you tell me if i'm doing something wrong, or how to speed up the reads?

Thanks.

 

I run this program on an high performance laptop (3GB RAM, 2.2Ghz dual core ...)

I use a simple POJO object to be persisted: only 1 private field (int) .

This is the code i use to execute this very simple test:

public static void main(String[] args) {
        new File("database_file").delete();
        ObjectContainer db = Db4o.openFile("database_file");
        long start = System.currentTimeMillis();
        for (int i = 0; i < 10000; i++) {
            db.store(new Number(i));
        }   
        System.out.println("time: " + (System.currentTimeMillis()-start));
        db.commit();
        System.out.println("size: " + db.queryByExample(new Number()).size());
        start = System.currentTimeMillis();
        for (int i = 0; i < 100; i++) {
            db.queryByExample(new Number(i));
        }
        System.out.println("time: " + (System.currentTimeMillis()-start));
        db.close();
    }

 

You should index the integer field of your Number class.  The indexing reference document discusses this and provides examples.

HTH,

Brett

thanks. The difference is really huge. About 2 order of magnitude faster. Now it takes about 70 ms.