java.lang.OutOfMemoryError: Java heap space error when performing millions of queries

Question

In my application, I need to perform millions of queries to MySQL database. The codes look as follows:

for (int i=0; i< num_rows ; i++) {
   String query2="select id from mytable where x='"+ y.get(i) "'";              
   Statement stmt2 = Con0.createStatement(ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);     
   ResultSet rs2 = stmt2.executeQuery(query2);    
   ... // process result in rs2
   rs2.close(); 
}

where num_rows is around 2 million. After 600k loops, java report an error and exit:

java.lang.OutOfMemoryError: Java heap space error.

What's wrong in my codes? How should I avoid such an error?

Thanks in advance!

Answer 1

Close your statements as well.